fetchpost.rs

#![allow(unused_assignments)]
static USAGE: &str = r#"
Fetchpost sends/fetches data to/from web services for every row using HTTP Post.
As opposed to fetch, which uses HTTP Get.

CSV data is posted using two methods:
1. As an HTML Form using using the <column-list> argument
   The columns are used to construct the HTML form data and posted to the server
   as a URL-encoded form. (content-type: application/x-www-form-urlencoded)
2. As a payload using a MiniJinja template with the --payload-tpl <file> option
   The template file is used to construct the payload and posted to the server
   as JSON by default (content-type: application/json), with automatic checking if the
   rendered template is valid JSON.
   The --content-type option can override the expected content type. However, it is
   the user's responsibility to ensure the content-type format is valid.

Fetchpost is integrated with `jaq` (a jq clone) to directly parse out values from an API JSON response.
(See https://github.com/01mf02/jaq for more info on how to use the jaq JSON Query Language)

CACHE OPTIONS:
Fetchpost caches responses to minimize traffic and maximize performance. It has four
mutually-exclusive caching options:

1. In memory cache (the default)
2. Disk cache
3. Redis cache
4. No cache

In memory Cache:
In memory cache is the default and is used if no caching option is set.
It uses a non-persistent, in-memory, 2 million entry Least Recently Used (LRU)
cache for each fetch session. To change the maximum number of entries in the cache,
set the --mem-cache-size option.

Disk Cache:
For persistent, inter-session caching, a DiskCache can be enabled with the --disk-cache flag.
By default, it will store the cache in the directory ~/.qsv/cache/fetchpost, with a cache expiry
Time-to-Live (TTL) of 2,419,200 seconds (28 days), and cache hits NOT refreshing the TTL
of cached values.

Set the --disk-cache-dir option and the environment variables QSV_DISKCACHE_TTL_SECS and
QSV_DISKCACHE_TTL_REFRESH to change default DiskCache settings.

Redis Cache:
Another persistent, inter-session cache option is a Redis cache enabled with the --redis flag. 
By default, it will connect to a local Redis instance at redis://127.0.0.1:6379/2,
with a cache expiry Time-to-Live (TTL) of 2,419,200 seconds (28 days),
and cache hits NOT refreshing the TTL of cached values.

Set the environment variables QSV_FP_REDIS_CONNSTR, QSV_REDIS_TTL_SECONDS and 
QSV_REDIS_TTL_REFRESH to change default Redis settings.

Note that the default values are the same as the fetch command, except fetchpost creates the
cache at database 2, as opposed to database 1 with fetch.

If you don't want responses to be cached at all, use the --no-cache flag.

NETWORK OPTIONS:
Fetchpost recognizes RateLimit and Retry-After headers and dynamically throttles requests
to be as fast as allowed. The --rate-limit option sets the maximum number of queries per second
(QPS) to be made. The default is 0, which means to go as fast as possible, automatically
throttling as required, based on rate-limit and retry-after response headers.

To use a proxy, please set env vars HTTP_PROXY, HTTPS_PROXY or ALL_PROXY
(e.g. export HTTPS_PROXY=socks5://127.0.0.1:1086).

qsv fetchpost supports brotli, gzip and deflate automatic decompression for improved throughput
and performance, preferring brotli over gzip over deflate.

Gzip compression of requests bodies is supported with the --compress flag. Note that
public APIs typically do not support gzip compression of request bodies because of the
"zip bomb" vulnerability. This option should only be used with private APIs where this
is not a concern.

It automatically upgrades its connection to the much faster and more efficient HTTP/2 protocol
with adaptive flow control if the server supports it.
See https://www.cloudflare.com/learning/performance/http2-vs-http1.1/ and
https://medium.com/coderscorner/http-2-flow-control-77e54f7fd518 for more info.

URL OPTIONS:
<url-column> needs to be a fully qualified URL path. It can be specified as a column name
from which the URL value will be retrieved for each record, or as the URL literal itself.

EXAMPLES:

data.csv
  URL, zipcode, country
  https://httpbin.org/post, 90210, USA
  https://httpbin.org/post, 94105, USA
  https://httpbin.org/post, 92802, USA

Given the data.csv above, fetch the JSON response.

  $ qsv fetchpost URL zipcode,country data.csv 

Note the output will be a JSONL file - with a minified JSON response per line, not a CSV file.

Now, if we want to generate a CSV file with a parsed response - getting only the "form" property,
we use the new-column and jaq options.

$ qsv fetchpost URL zipcode,country --new-column form --jaq '."form"' data.csv > data_with_response.csv

data_with_response.csv
  URL,zipcode,country,form
  https://httpbin.org/post,90210,USA,"{""country"": String(""USA""), ""zipcode"": String(""90210"")}"
  https://httpbin.org/post,94105,USA,"{""country"": String(""USA""), ""zipcode"": String(""94105"")}"
  https://httpbin.org/post,92802,USA,"{""country"": String(""USA""), ""zipcode"": String(""92802"")}"

Alternatively, since we're using the same URL for all the rows, we can just pass the url directly on the command-line.

  $ qsv fetchpost https://httpbin.org/post 2,3 --new-column form --jaqfile form.jaq data.csv > data_with_formdata.csv

Also note that for the column-list argument, we used the column index (2,3 for second & third column)
instead of using the column names, and we loaded the jaq selector from the form.jaq file.

The form.jaq file simply contains the string literal ".form", including the enclosing double quotes:

form.jaq
  ".form"

USING THE HTTP-HEADER OPTION:

The --http-header option allows you to append arbitrary key value pairs (a valid pair is a key and value
separated by a colon) to the HTTP header (to authenticate against an API, pass custom header fields, etc.).
Note that you can pass as many key-value pairs by using --http-header option repeatedly. For example:

$ qsv fetchpost https://httpbin.org/post col1-col3 data.csv -H "X-Api-Key:TEST_KEY" -H "X-Api-Secret:ABC123XYZ"

For more extensive examples, see https://github.com/dathere/qsv/blob/master/tests/test_fetch.rs.

Usage:
    qsv fetchpost (<url-column>) (<column-list> | --payload-tpl <file>) [--jaq <selector> | --jaqfile <file>] [--http-header <k:v>...] [options] [<input>]
    qsv fetchpost --help

Fetchpost arguments:
    <url-column>               Name of the column with the URL.
                               Otherwise, if the argument starts with `http`, the URL to use.
    <column-list>              Comma-delimited list of columns to insert into the HTTP Post body.
                               Uses `qsv select` syntax - i.e. Columns can be referenced by index or 
                               by name if there is a header row (duplicate column names can be disambiguated
                               with more indexing). Column ranges can also be specified. Finally, columns
                               can be selected using regular expressions.
                               See 'qsv select --help' for examples.

Fetchpost options:
    -t, --payload-tpl <file>   Instead of <column-list>, use a MiniJinja template file to render a JSON
                               payload in the HTTP Post body. You can also use --payload-tpl to render
                               a non-JSON payload, but --content-type will have to be set manually.
                               If a rendered JSON is invalid, `fetchpost` will abort and return an error.
    --content-type <arg>       Overrides automatic content types for `<column-list>` 
                               (`application/x-www-form-urlencoded`) and `--payload-tpl` (`application/json`).
                               Typical alternative values are `multipart/form-data` and `text/plain`.
                               It is the responsibility of the user to format the payload accordingly
                               when using --payload-tpl.
   -j, --globals-json <file>   A JSON file containing global variables.
                               When posting as an HTML Form, this file is added to the Form data.
                               When constructing a payload using a MiniJinja template, the JSON
                               properties can be accessed in templates using the "qsv_g" namespace
                               (e.g. {{qsv_g.api_key}}, {{qsv_g.base_url}}).
    -c, --new-column <name>    Put the fetched values in a new column. Specifying this option
                               results in a CSV. Otherwise, the output is in JSONL format.
    --jaq <selector>           Apply jaq selector to API returned JSON response.
                               Mutually exclusive with --jaqfile.
    --jaqfile <file>           Load jaq selector from file instead.
                               Mutually exclusive with --jaq.
    --pretty                   Prettify JSON responses. Otherwise, they're minified.
                               If the response is not in JSON format, it's passed through unchanged.
                               Note that --pretty requires the --new-column option.
    --rate-limit <qps>         Rate Limit in Queries Per Second (max: 1000). Note that fetch
                               dynamically throttles as well based on rate-limit and
                               retry-after response headers.
                               Set to 0 to go as fast as possible, automatically throttling as required.
                               CAUTION: Only use zero for APIs that use RateLimit and/or Retry-After headers,
                               otherwise your fetchpost job may look like a Denial Of Service attack.
                               Even though zero is the default, this is mitigated by --max-errors having a
                               default of 10.
                               [default: 0 ]
    --timeout <seconds>        Timeout for each URL request.
                               [default: 30 ]
    -H, --http-header <k:v>    Append custom header(s) to the HTTP header. Pass multiple key-value pairs
                               by adding this option multiple times, once for each pair. The key and value 
                               should be separated by a colon.
    --compress                 Compress the HTTP request body using gzip. Note that most servers do not support
                               compressed request bodies unless they are specifically configured to do so. This
                               should only be enabled for trusted scenarios where "zip bombs" are not a concern.
                               see https://github.com/postmanlabs/httpbin/issues/577#issuecomment-875814469
                               for more info.
    --max-retries <count>      Maximum number of retries per record before an error is raised.
                               [default: 5]
    --max-errors <count>       Maximum number of errors before aborting.
                               Set to zero (0) to continue despite errors.
                               [default: 10 ]
    --store-error              On error, store error code/message instead of blank value.
    --cookies                  Allow cookies.
    --user-agent <agent>       Specify custom user agent. It supports the following variables -
                               $QSV_VERSION, $QSV_TARGET, $QSV_BIN_NAME, $QSV_KIND and $QSV_COMMAND.
                               Try to follow the syntax here -
                               https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/User-Agent
    --report <d|s>             Creates a report of the fetchpost job. The report has the same name as the
                               input file with the ".fetchpost-report" suffix. 
                               There are two kinds of report - d for "detailed" & s for "short". The detailed
                               report has the same columns as the input CSV with seven additional columns - 
                               qsv_fetchp_url, qsv_fetchp_form, qsv_fetchp_status, qsv_fetchp_cache_hit,
                               qsv_fetchp_retries, qsv_fetchp_elapsed_ms & qsv_fetchp_response.
                               The short report only has the seven columns without the "qsv_fetchp_" prefix.
                               [default: none]

                               CACHING OPTIONS:
    --no-cache                 Do not cache responses.

    --mem-cache-size <count>   Maximum number of entries in the in-memory LRU cache.
                               [default: 2000000]

    --disk-cache               Use a persistent disk cache for responses. The cache is stored in the directory
                               specified by --disk-cache-dir. If the directory does not exist, it will be
                               created. If the directory exists, it will be used as is.
                               It has a default Time To Live (TTL)/lifespan of 28 days and cache hits do not
                               refresh the TTL of cached values.
                               Adjust the QSV_DISKCACHE_TTL_SECS & QSV_DISKCACHE_TTL_REFRESH env vars
                               to change DiskCache settings.
    --disk-cache-dir <dir>     The directory <dir> to store the disk cache. Note that if the directory
                               does not exist, it will be created. If the directory exists, it will be used as is,
                               and will not be flushed. This option allows you to maintain several disk caches
                               for different fetchpost jobs (e.g. one for geocoding, another for weather, etc.)
                               [default: ~/.qsv/cache/fetchpost]

    --redis-cache              Use Redis to cache responses. It connects to "redis://127.0.0.1:6379/2"
                               with a connection pool size of 20, with a TTL of 28 days, and a cache hit 
                               NOT renewing an entry's TTL.
                               Adjust the QSV_FP_REDIS_CONNSTR, QSV_REDIS_MAX_POOL_SIZE, QSV_REDIS_TTL_SECONDS & 
                               QSV_REDIS_TTL_REFRESH respectively to change Redis settings.

    --cache-error              Cache error responses even if a request fails. If an identical URL is requested,
                               the cached error is returned. Otherwise, the fetch is attempted again
                               for --max-retries.
    --flush-cache              Flush all the keys in the current cache on startup. This only applies to
                               Disk and Redis caches.

Common options:
    -h, --help                 Display this message
    -o, --output <file>        Write output to <file> instead of stdout.
    -n, --no-headers           When set, the first row will not be interpreted
                               as headers. Namely, it will be sorted with the rest
                               of the rows. Otherwise, the first row will always
                               appear as the header row in the output.
    -d, --delimiter <arg>      The field delimiter for reading CSV data.
                               Must be a single character. (default: ,)
    -p, --progressbar          Show progress bars. Will also show the cache hit rate upon completion.
                               Not valid for stdin.
"#;

use std::{fs, io::Write, num::NonZeroU32, path::PathBuf, sync::OnceLock, thread, time};

use cached::{
    proc_macro::{cached, io_cached},
    stores::DiskCacheBuilder,
    Cached, IOCached, RedisCache, Return, SizedCache,
};
use flate2::{write::GzEncoder, Compression};
use governor::{
    clock::DefaultClock,
    middleware::NoOpMiddleware,
    state::{direct::NotKeyed, InMemoryState},
    Quota, RateLimiter,
};
use indicatif::{HumanCount, MultiProgress, ProgressBar, ProgressDrawTarget};
use log::{
    debug, error, info, log_enabled, warn,
    Level::{Debug, Trace, Warn},
};
use minijinja::Environment;
use minijinja_contrib::pycompat::unknown_method_callback;
use rand::Rng;
use regex::Regex;
use reqwest::{
    blocking::Client,
    header::{HeaderMap, HeaderName, HeaderValue},
};
use serde::Deserialize;
use serde_json::{json, Value};
use url::Url;
use util::expand_tilde;

use crate::{
    cmd::fetch::{
        compile_jaq_filter, get_ratelimit_header_value, parse_ratelimit_header_value, process_jaq,
        CacheType, DiskCacheConfig, FetchResponse, RedisConfig, ReportKind,
        DEFAULT_ACCEPT_ENCODING, JAQ_FILTER,
    },
    config::{Config, Delimiter},
    select::SelectColumns,
    util, CliError, CliResult,
};

#[derive(PartialEq, Eq, Copy, Clone)]
enum ContentType {
    Form,
    Json,
    Manual,
}

impl std::fmt::Display for ContentType {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            ContentType::Form => write!(f, "Form"),
            ContentType::Json => write!(f, "JSON"),
            ContentType::Manual => write!(f, "Manual"),
        }
    }
}

#[derive(Deserialize)]
struct Args {
    flag_payload_tpl:    Option<String>,
    flag_content_type:   Option<String>,
    flag_globals_json:   Option<PathBuf>,
    flag_new_column:     Option<String>,
    flag_jaq:            Option<String>,
    flag_jaqfile:        Option<PathBuf>,
    flag_pretty:         bool,
    flag_rate_limit:     u32,
    flag_timeout:        u16,
    flag_http_header:    Vec<String>,
    flag_compress:       bool,
    flag_max_retries:    u8,
    flag_max_errors:     u64,
    flag_store_error:    bool,
    flag_cookies:        bool,
    flag_user_agent:     Option<String>,
    flag_report:         String,
    flag_no_cache:       bool,
    flag_mem_cache_size: usize,
    flag_disk_cache:     bool,
    flag_disk_cache_dir: Option<String>,
    flag_redis_cache:    bool,
    flag_cache_error:    bool,
    flag_flush_cache:    bool,
    flag_output:         Option<String>,
    flag_no_headers:     bool,
    flag_delimiter:      Option<Delimiter>,
    flag_progressbar:    bool,
    arg_url_column:      SelectColumns,
    arg_column_list:     SelectColumns,
    arg_input:           Option<String>,
}

// set memcache size - the default is 2 million entries
// and is set through the docopt usage text
static MEM_CACHE_SIZE: OnceLock<usize> = OnceLock::new();

static DEFAULT_REDIS_CONN_STRING: OnceLock<String> = OnceLock::new();

static TIMEOUT_FP_SECS: OnceLock<u64> = OnceLock::new();

const FETCHPOST_REPORT_PREFIX: &str = "qsv_fetchp_";
const FETCHPOST_REPORT_SUFFIX: &str = ".fetchpost-report.tsv";

// for governor/ratelimiter
const MINIMUM_WAIT_MS: u64 = 10;
const MIN_WAIT: time::Duration = time::Duration::from_millis(MINIMUM_WAIT_MS);

static DISKCACHE_DIR: OnceLock<String> = OnceLock::new();
static REDISCONFIG: OnceLock<RedisConfig> = OnceLock::new();
static DISKCACHECONFIG: OnceLock<DiskCacheConfig> = OnceLock::new();

pub fn run(argv: &[&str]) -> CliResult<()> {
    let args: Args = util::get_args(USAGE, argv)?;

    // connect to Redis at localhost, using database 2 by default when --redis-cache is enabled
    // fetchpost uses database 2 by default, as opposed to database 1 with fetch
    let fp_redis_conn_str = std::env::var("QSV_FP_REDIS_CONNSTR")
        .unwrap_or_else(|_| "redis://127.0.0.1:6379/2".to_string());

    DEFAULT_REDIS_CONN_STRING.set(fp_redis_conn_str).unwrap();

    // set memcache size
    MEM_CACHE_SIZE.set(args.flag_mem_cache_size).unwrap();

    TIMEOUT_FP_SECS
        .set(util::timeout_secs(args.flag_timeout)?)
        .unwrap();

    // setup diskcache dir response caching
    let diskcache_dir = if let Some(dir) = &args.flag_disk_cache_dir {
        if dir.starts_with('~') {
            // expand the tilde
            let expanded_dir = expand_tilde(dir).unwrap();
            expanded_dir.to_string_lossy().to_string()
        } else {
            dir.to_string()
        }
    } else {
        String::new()
    };

    let cache_type = if args.flag_no_cache {
        CacheType::None
    } else if args.flag_disk_cache {
        // if --flush-cache is set, flush the cache directory first if it exists
        if args.flag_flush_cache
            && !diskcache_dir.is_empty()
            && fs::metadata(&diskcache_dir).is_ok()
        {
            if let Err(e) = fs::remove_dir_all(&diskcache_dir) {
                return fail_clierror!(r#"Cannot remove cache directory "{diskcache_dir}": {e:?}"#);
            }
            info!("flushed DiskCache directory: {diskcache_dir}");
        }
        // check if the cache directory exists, if it doesn't, create it
        if !diskcache_dir.is_empty() {
            if let Err(e) = fs::create_dir_all(&diskcache_dir) {
                return fail_clierror!(r#"Cannot create cache directory "{diskcache_dir}": {e:?}"#);
            }
        }
        DISKCACHE_DIR.set(diskcache_dir).unwrap();
        // initialize DiskCache Config
        DISKCACHECONFIG.set(DiskCacheConfig::new()).unwrap();
        CacheType::Disk
    } else if args.flag_redis_cache {
        // initialize Redis Config
        REDISCONFIG.set(RedisConfig::new()).unwrap();

        // check if redis connection is valid
        let conn_str = &REDISCONFIG.get().unwrap().conn_str;
        let redis_client = match redis::Client::open(conn_str.to_string()) {
            Ok(rc) => rc,
            Err(e) => {
                return fail_incorrectusage_clierror!(
                    r#"Invalid Redis connection string "{conn_str}": {e:?}"#
                )
            },
        };

        let mut redis_conn;
        match redis_client.get_connection() {
            Err(e) => {
                return fail_clierror!(r#"Cannot connect to Redis using "{conn_str}": {e:?}"#)
            },
            Ok(x) => redis_conn = x,
        }

        if args.flag_flush_cache {
            redis::cmd("FLUSHDB")
                .exec(&mut redis_conn)
                .map_err(|_| "Cannot flush Redis cache")?;
            info!("flushed Redis database.");
        }
        CacheType::Redis
    } else {
        CacheType::InMemory
    };
    log::info!("Cache Type: {cache_type:?}");

    // setup globals JSON context if specified
    let mut globals_flag = false;
    let globals_ctx = if let Some(globals_json) = args.flag_globals_json {
        globals_flag = true;
        match std::fs::read(globals_json) {
            Ok(mut bytes) => match simd_json::from_slice(&mut bytes) {
                Ok(json) => json,
                Err(e) => return fail_clierror!("Failed to parse globals JSON file: {e}"),
            },
            Err(e) => return fail_clierror!("Failed to read globals JSON file: {e}"),
        }
    } else {
        json!("")
    };

    let mut rconfig = Config::new(args.arg_input.as_ref())
        .delimiter(args.flag_delimiter)
        .trim(csv::Trim::All)
        .no_headers(args.flag_no_headers);

    let mut rdr = rconfig.reader()?;
    let mut wtr = if args.flag_new_column.is_some() {
        // when adding a new column for the response, the output
        // is a regular CSV file
        Config::new(args.flag_output.as_ref()).writer()?
    } else {
        // otherwise, the output is a JSONL file. So we need to configure
        // the csv writer so it doesn't double double quote the JSON response
        // and its flexible (i.e. "column counts are different row to row")
        Config::new(args.flag_output.as_ref())
            .quote_style(csv::QuoteStyle::Never)
            .flexible(true)
            .writer()?
    };

    let mut headers = rdr.byte_headers()?.clone();

    let include_existing_columns = if let Some(name) = args.flag_new_column {
        // write header with new column
        headers.push_field(name.as_bytes());
        wtr.write_byte_record(&headers)?;
        true
    } else {
        if args.flag_pretty {
            return fail_incorrectusage_clierror!(
                "The --pretty option requires the --new-column option."
            );
        }
        false
    };

    // validate column-list is a list of valid column names
    let cl_config = if args.flag_payload_tpl.is_none() {
        Config::new(args.arg_input.as_ref())
            .delimiter(args.flag_delimiter)
            .trim(csv::Trim::All)
            .no_headers(args.flag_no_headers)
            .select(args.arg_column_list.clone())
    } else {
        Config::new(args.arg_input.as_ref())
            .delimiter(args.flag_delimiter)
            .trim(csv::Trim::All)
            .no_headers(args.flag_no_headers)
            // we're constructing a payload, ensure all the columns are selected
            .select(SelectColumns::parse("1-")?)
    };
    let col_list = cl_config.selection(&headers)?;

    // check if the url_column arg was passed as a URL literal
    // or as a column selector
    let url_column_str = format!("{:?}", args.arg_url_column);
    let re = Regex::new(r"^IndexedName\((.*)\[0\]\)$").unwrap();
    let literal_url = if let Some(caps) = re.captures(&url_column_str) {
        caps[1].to_lowercase()
    } else {
        String::new()
    };
    let literal_url_used = literal_url.starts_with("http");

    let mut column_index = 0;
    if !literal_url_used {
        rconfig = rconfig.select(args.arg_url_column);
        let sel = rconfig.selection(&headers)?;
        column_index = *sel.iter().next().unwrap();
        if sel.len() != 1 {
            return fail!("Only a single URL column may be selected.");
        }
    }

    let rate_limit = match args.flag_rate_limit {
        0 => NonZeroU32::new(u32::MAX).unwrap(),
        1..=1000 => NonZeroU32::new(args.flag_rate_limit).unwrap(),
        _ => {
            return fail_incorrectusage_clierror!(
                "Rate Limit should be between 0 to 1000 queries per second."
            )
        },
    };
    info!("RATE LIMIT: {rate_limit}");

    // build the payload if --payload-tpl is used
    let mut template_content = String::new();
    let mut payload_content_type: ContentType;
    let mut rendered_json: Value;
    let payload_env = if let Some(template_file) = args.flag_payload_tpl {
        template_content = fs::read_to_string(template_file)?;
        let mut env = Environment::new();
        env.set_unknown_method_callback(unknown_method_callback);
        env.add_template("template", &template_content)?;
        payload_content_type = ContentType::Json;
        env
    } else {
        payload_content_type = ContentType::Form;
        Environment::empty()
    };

    let http_headers: HeaderMap = {
        let mut map = HeaderMap::with_capacity(args.flag_http_header.len() + 1);
        for header in args.flag_http_header {
            let vals: Vec<&str> = header.split(':').collect();

            if vals.len() != 2 {
                return fail_incorrectusage_clierror!(
                    "{vals:?} is not a valid key-value pair. Expecting a key and a value \
                     separated by a colon."
                );
            }

            // allocate new String for header key to put into map
            let k: String = String::from(vals[0].trim());
            let header_name: HeaderName =
                match HeaderName::from_lowercase(k.to_lowercase().as_bytes()) {
                    Ok(h) => h,
                    Err(e) => return fail_incorrectusage_clierror!("Invalid header name: {e}"),
                };

            // allocate new String for header value to put into map
            let v: String = String::from(vals[1].trim());
            let header_val: HeaderValue = match HeaderValue::from_str(v.as_str()) {
                Ok(v) => v,
                Err(e) => return fail_incorrectusage_clierror!("Invalid header value: {e}"),
            };

            map.append(header_name, header_val);
        }

        map.append(
            reqwest::header::ACCEPT_ENCODING,
            HeaderValue::from_str(DEFAULT_ACCEPT_ENCODING).unwrap(),
        );

        if let Some(content_type) = args.flag_content_type {
            // if the user set --content-type and uses one of these known content-types,
            // change payload_content_type accordingly so it can take advantage of auto
            // validation of JSON and url encoding of URL Forms.
            payload_content_type = match content_type.to_lowercase().as_str() {
                "application/json" => ContentType::Json,
                "application/x-www-form-urlencoded" => ContentType::Form,
                _ => ContentType::Manual,
            };
            map.append(
                reqwest::header::CONTENT_TYPE,
                HeaderValue::from_str(&content_type).unwrap(),
            );
        } else if payload_content_type == ContentType::Json {
            map.append(
                reqwest::header::CONTENT_TYPE,
                HeaderValue::from_str("application/json").unwrap(),
            );
        } else {
            map.append(
                reqwest::header::CONTENT_TYPE,
                HeaderValue::from_str("application/x-www-form-urlencoded").unwrap(),
            );
        }
        if args.flag_compress {
            map.append(
                reqwest::header::CONTENT_ENCODING,
                HeaderValue::from_str("gzip").unwrap(),
            );
        }
        map
    };
    debug!("HTTP Header: {http_headers:?}");

    let client_timeout = time::Duration::from_secs(*TIMEOUT_FP_SECS.get().unwrap_or(&30));
    let client = Client::builder()
        .user_agent(util::set_user_agent(args.flag_user_agent)?)
        .default_headers(http_headers)
        .cookie_store(args.flag_cookies)
        .brotli(true)
        .gzip(true)
        .deflate(true)
        .zstd(true)
        .use_rustls_tls()
        .http2_adaptive_window(true)
        .connection_verbose(log_enabled!(Debug) || log_enabled!(Trace))
        .timeout(client_timeout)
        .build()?;

    // set rate limiter with allow_burst set to 1 - see https://github.com/antifuchs/governor/issues/39
    let limiter =
        RateLimiter::direct(Quota::per_second(rate_limit).allow_burst(NonZeroU32::new(1).unwrap()));

    // prep progress bars
    let show_progress =
        (args.flag_progressbar || util::get_envvar_flag("QSV_PROGRESSBAR")) && !rconfig.is_stdin();

    // create multi_progress to stderr with a maximum refresh of 5 per second
    let multi_progress = MultiProgress::with_draw_target(ProgressDrawTarget::stderr_with_hz(5));
    let progress = multi_progress.add(ProgressBar::new(0));
    let mut record_count = 0;

    let error_progress = multi_progress.add(ProgressBar::new(args.flag_max_errors));
    if args.flag_max_errors > 0 && show_progress {
        console::set_colors_enabled(true); // as error progress bar is red
        error_progress.set_style(
            indicatif::ProgressStyle::default_bar()
                .template("{bar:37.red/white} {percent}%{msg} ({per_sec:7})")
                .unwrap(),
        );
        error_progress.set_message(format!(
            " of {} max errors",
            HumanCount(args.flag_max_errors)
        ));
    } else {
        error_progress.set_draw_target(ProgressDrawTarget::hidden());
    }

    if show_progress {
        record_count = util::count_rows(&rconfig)?;
        util::prep_progress(&progress, record_count);
    } else {
        multi_progress.set_draw_target(ProgressDrawTarget::hidden());
    }

    let jaq_selector: Option<String> = match args.flag_jaqfile {
        Some(ref jaq_file) => Some(fs::read_to_string(jaq_file)?),
        None => args.flag_jaq.as_ref().map(std::string::ToString::to_string),
    };

    // this is primarily to check if the jaq query is valid
    // and if is, to cache the compiled jaq filter
    if let Some(ref query) = jaq_selector {
        let Ok(()) = JAQ_FILTER.set(compile_jaq_filter(query)?) else {
            return Err(CliError::Other(
                "Failed to cache precompiled JAQ filter".to_string(),
            ));
        };
    }

    // prepare report
    let report = if args.flag_report.to_lowercase().starts_with('d') {
        // if it starts with d, its a detailed report
        ReportKind::Detailed
    } else if args.flag_report.to_lowercase().starts_with('s') {
        // if it starts with s, its a short report
        ReportKind::Short
    } else {
        ReportKind::None
    };

    let mut report_wtr;
    let report_path;
    if report == ReportKind::None {
        // no report, point report_wtr to /dev/null (AKA sink)
        report_wtr = Config::new(Some("sink".to_string()).as_ref()).writer()?;
        report_path = String::new();
    } else {
        report_path = args
            .arg_input
            .clone()
            .unwrap_or_else(|| "stdin.csv".to_string());

        report_wtr = Config::new(Some(report_path.clone() + FETCHPOST_REPORT_SUFFIX).as_ref())
            .flexible(true)
            .writer()?;
        let mut report_headers = if report == ReportKind::Detailed {
            headers.clone()
        } else {
            csv::ByteRecord::new()
        };
        let rptcol_prefix = if report == ReportKind::Detailed {
            FETCHPOST_REPORT_PREFIX
        } else {
            ""
        };
        // the fetchpost report has the following columns:
        // url - URL used, form - form data sent, status - HTTP status code,
        // cache_hit - cache hit flag, retries - retry attempts,
        // elapsed - elapsed time (milliseconds) & response.
        let report_header_fields = vec![
            format!("{rptcol_prefix}url"),
            format!("{rptcol_prefix}status"),
            format!("{rptcol_prefix}cache_hit"),
            format!("{rptcol_prefix}retries"),
            format!("{rptcol_prefix}elapsed_ms"),
            format!("{rptcol_prefix}response"),
        ];
        report_headers = csv::ByteRecord::from(report_header_fields);

        report_wtr.write_byte_record(&report_headers)?;
    }

    // amortize memory allocations
    // why optimize for mem & speed, when we're just doing single-threaded, throttled URL fetches?
    // we still optimize since fetch is backed by a memoized cache (in memory or Redis, when --redis
    // is used), so we want to return responses as fast as possible as we bypass the network
    // request with a cache hit
    let mut record = csv::ByteRecord::new();
    let mut jsonl_record = csv::ByteRecord::new();
    let mut report_record = csv::ByteRecord::new();
    let mut url = String::with_capacity(100);
    let mut redis_cache_hits: u64 = 0;
    let mut disk_cache_hits: u64 = 0;
    let mut intermediate_redis_value: Return<String> = Return {
        was_cached: false,
        value:      String::new(),
    };
    let mut intermediate_value: Return<FetchResponse> = Return {
        was_cached: false,
        value:      FetchResponse {
            response:    String::new(),
            status_code: 0_u16,
            retries:     0_u8,
        },
    };
    let mut final_value = String::with_capacity(150);
    let mut final_response = FetchResponse {
        response:    String::new(),
        status_code: 0_u16,
        retries:     0_u8,
    };
    let empty_response = FetchResponse {
        response:    String::new(),
        status_code: 0_u16,
        retries:     0_u8,
    };
    let mut running_error_count = 0_u64;
    let mut running_success_count = 0_u64;
    let mut was_cached;
    let mut now = time::Instant::now();
    let mut form_body_jsonmap = serde_json::map::Map::with_capacity(col_list.len() + 1);

    let globals_jsonmap = if globals_flag {
        let mut map = serde_json::map::Map::new();
        if payload_content_type == ContentType::Form {
            if let Some(globals_obj) = globals_ctx.as_object() {
                for (key, value) in globals_obj {
                    map.insert(key.clone(), value.clone());
                }
            }
        } else {
            map.insert("qsv_g".to_string(), globals_ctx);
        }
        map
    } else {
        serde_json::map::Map::new()
    };

    let header_key_vec: Vec<String> = headers
        .iter()
        .map(|x| String::from_utf8_lossy(x).to_string())
        .collect();

    let debug_flag = log_enabled!(Debug);

    while rdr.read_byte_record(&mut record)? {
        if show_progress {
            progress.inc(1);
        }

        if report != ReportKind::None {
            now = time::Instant::now();
        }

        // construct body per the column-list
        if globals_flag {
            form_body_jsonmap.clone_from(&globals_jsonmap);
        } else {
            form_body_jsonmap.clear();
        }
        for col_idx in &*col_list {
            form_body_jsonmap.insert(
                (header_key_vec[*col_idx]).to_string(),
                serde_json::Value::String(
                    simdutf8::basic::from_utf8(record.get(*col_idx).unwrap_or_default())
                        .unwrap_or_default()
                        .to_owned(),
                ),
            );
        }

        if payload_content_type != ContentType::Form {
            let rendered_template = payload_env
                .get_template("template")?
                .render(&form_body_jsonmap)?;
            rendered_json = if payload_content_type == ContentType::Json {
                serde_json::from_str::<serde_json::Value>(&rendered_template).map_err(|e| {
                    CliError::Other(format!("Invalid JSON payload: {e}\n{rendered_template}"))
                })?
            } else {
                // ContentType:Manual
                // Wrap raw payload in a JSON object with qsv_plaintext key
                json!({
                    "qsv_plaintext": rendered_template
                })
            };
            // safety: rendered_json is now guaranteed to be a valid JSON object
            form_body_jsonmap.clone_from(rendered_json.as_object().unwrap());
        }

        if debug_flag {
            // deserializing the form_body_jsonmap to a string is expensive
            // so we only do it when debug is enabled
            debug!("{form_body_jsonmap:?}");
        }

        if literal_url_used {
            url.clone_from(&literal_url);
        } else if let Ok(s) = simdutf8::basic::from_utf8(&record[column_index]) {
            s.clone_into(&mut url);
        } else {
            url = String::new();
        }
        if url.is_empty() {
            final_response.clone_from(&empty_response);
            was_cached = false;
        } else {
            match cache_type {
                CacheType::InMemory => {
                    intermediate_value = get_cached_response(
                        &url,
                        &form_body_jsonmap,
                        payload_content_type,
                        &client,
                        &limiter,
                        jaq_selector.as_ref(),
                        args.flag_store_error,
                        args.flag_pretty,
                        args.flag_compress,
                        include_existing_columns,
                        args.flag_max_retries,
                    );
                    final_response = intermediate_value.value;
                    was_cached = intermediate_value.was_cached;
                    if !args.flag_cache_error && final_response.status_code != 200 {
                        let mut cache = GET_CACHED_RESPONSE.lock().unwrap();
                        cache.cache_remove(&url);
                    }
                },
                CacheType::Disk => {
                    intermediate_value = get_diskcache_response(
                        &url,
                        &form_body_jsonmap,
                        payload_content_type,
                        &client,
                        &limiter,
                        jaq_selector.as_ref(),
                        args.flag_store_error,
                        args.flag_pretty,
                        args.flag_compress,
                        include_existing_columns,
                        args.flag_max_retries,
                    )?;
                    final_response = intermediate_value.value;
                    was_cached = intermediate_value.was_cached;
                    if was_cached {
                        disk_cache_hits += 1;
                        // log::debug!("Disk cache hit for {url} hit: {disk_cache_hits}");
                    }
                    if !args.flag_cache_error && final_response.status_code != 200 {
                        let _ = GET_DISKCACHE_RESPONSE.cache_remove(&url);
                        // log::debug!("Removed Disk cache for {url}");
                    }
                },
                CacheType::Redis => {
                    intermediate_redis_value = get_redis_response(
                        &url,
                        &form_body_jsonmap,
                        payload_content_type,
                        &client,
                        &limiter,
                        jaq_selector.as_ref(),
                        args.flag_store_error,
                        args.flag_pretty,
                        args.flag_compress,
                        include_existing_columns,
                        args.flag_max_retries,
                    )?;
                    was_cached = intermediate_redis_value.was_cached;
                    if was_cached {
                        redis_cache_hits += 1;
                    }
                    final_response = match serde_json::from_str(&intermediate_redis_value) {
                        Ok(r) => r,
                        Err(e) => {
                            return fail_clierror!(
                                "Cannot deserialize Redis cache value. Try flushing the Redis \
                                 cache with --flushdb: {e}"
                            )
                        },
                    };
                    if !args.flag_cache_error && final_response.status_code != 200 {
                        let key = format!(
                            "{}{:?}{}{}{}",
                            url,
                            jaq_selector,
                            args.flag_store_error,
                            args.flag_pretty,
                            include_existing_columns
                        );

                        if GET_REDIS_RESPONSE.cache_remove(&key).is_err() && log_enabled!(Warn) {
                            // failure to remove cache keys is non-fatal. Continue, but log it.
                            wwarn!(r#"Cannot remove Redis key "{key}""#);
                        }
                    }
                },
                CacheType::None => {
                    final_response = get_response(
                        &url,
                        &form_body_jsonmap,
                        payload_content_type,
                        &client,
                        &limiter,
                        jaq_selector.as_ref(),
                        args.flag_store_error,
                        args.flag_pretty,
                        args.flag_compress,
                        include_existing_columns,
                        args.flag_max_retries,
                    );
                    was_cached = false;
                },
            }
        }

        if final_response.status_code == 200 {
            running_success_count += 1;
        } else {
            running_error_count += 1;
            error_progress.inc(1);
        }

        final_value.clone_from(&final_response.response);

        if include_existing_columns {
            record.push_field(final_value.as_bytes());
            wtr.write_byte_record(&record)?;
        } else {
            jsonl_record.clear();
            if final_value.is_empty() {
                jsonl_record.push_field(b"{}");
            } else {
                jsonl_record.push_field(final_value.as_bytes());
            }
            wtr.write_byte_record(&jsonl_record)?;
        }

        if report != ReportKind::None {
            if report == ReportKind::Detailed {
                report_record.clone_from(&record);
            } else {
                report_record.clear();
            }
            report_record.push_field(url.as_bytes());
            report_record.push_field(format!("{form_body_jsonmap:?}").as_bytes());
            report_record.push_field(final_response.status_code.to_string().as_bytes());
            report_record.push_field(if was_cached { b"1" } else { b"0" });
            report_record.push_field(final_response.retries.to_string().as_bytes());
            report_record.push_field(now.elapsed().as_millis().to_string().as_bytes());
            if include_existing_columns {
                report_record.push_field(final_value.as_bytes());
            } else {
                report_record.push_field(jsonl_record.as_slice());
            }
            report_wtr.write_byte_record(&report_record)?;
        }

        if args.flag_max_errors > 0 && running_error_count >= args.flag_max_errors {
            break;
        }
    } // main read loop

    report_wtr.flush()?;

    if show_progress {
        match cache_type {
            CacheType::InMemory => {
                util::update_cache_info!(progress, GET_CACHED_RESPONSE);
            },
            CacheType::Disk => {
                util::update_cache_info!(progress, disk_cache_hits, record_count);
            },
            CacheType::Redis => {
                util::update_cache_info!(progress, redis_cache_hits, record_count);
            },
            CacheType::None => (),
        }
        util::finish_progress(&progress);

        if running_error_count == 0 {
            error_progress.finish_and_clear();
        } else if running_error_count >= args.flag_max_errors {
            error_progress.finish();
            // sleep so we can dependably write eprintln without messing up progress bars
            thread::sleep(time::Duration::from_nanos(10));
            let abort_msg = format!(
                "{} max errors. Fetchpost aborted.",
                HumanCount(args.flag_max_errors)
            );
            winfo!("{abort_msg}");
        } else {
            error_progress.abandon();
        }
    }

    let mut end_msg = format!(
        "{} records successfully fetchposted as {}. {} errors.",
        HumanCount(running_success_count),
        if include_existing_columns {
            "CSV"
        } else {
            "JSONL"
        },
        HumanCount(running_error_count)
    );
    if report != ReportKind::None {
        use std::fmt::Write;

        write!(
            &mut end_msg,
            " {} report created: \"{}{FETCHPOST_REPORT_SUFFIX}\"",
            if report == ReportKind::Detailed {
                "Detailed"
            } else {
                "Short"
            },
            report_path
        )
        .unwrap();
    }
    winfo!("{end_msg}");

    // if using a Diskcache, explicitly flush it
    // to ensure all entries are written to disk
    if cache_type == CacheType::Disk {
        GET_DISKCACHE_RESPONSE
            .connection()
            .flush()
            .map_err(|e| CliError::Other(format!("Error flushing DiskCache: {e}")))?;
    }

    Ok(wtr.flush()?)
}

// we only need url in the cache key
// as this is an in-memory cache that is only used for one qsv session
#[cached(
    ty = "SizedCache<String, Return<FetchResponse>>",
    create = r##"{
        let cache_size = MEM_CACHE_SIZE.get().unwrap();
        let memcache = SizedCache::with_size(*cache_size);
        log::info!("In Memory cache created - size: {cache_size} entries");
        memcache
    }"##,
    key = "String",
    convert = r#"{ format!("{:?}", form_body_jsonmap) }"#,
    with_cached_flag = true
)]
fn get_cached_response(
    url: &str,
    form_body_jsonmap: &serde_json::Map<String, Value>,
    payload_content_type: ContentType,
    client: &reqwest::blocking::Client,
    limiter: &governor::RateLimiter<NotKeyed, InMemoryState, DefaultClock, NoOpMiddleware>,
    flag_jaq: Option<&String>,
    flag_store_error: bool,
    flag_pretty: bool,
    flag_compress: bool,
    include_existing_columns: bool,
    flag_max_retries: u8,
) -> cached::Return<FetchResponse> {
    Return::new(get_response(
        url,
        form_body_jsonmap,
        payload_content_type,
        client,
        limiter,
        flag_jaq,
        flag_store_error,
        flag_pretty,
        flag_compress,
        include_existing_columns,
        flag_max_retries,
    ))
}

// this is a disk cache that can be used across qsv sessions
// so we need to include the values of flag_jaq, flag_store_error, flag_pretty and
// include_existing_columns in the cache key
#[io_cached(
    disk = true,
    ty = "cached::DiskCache<String, FetchResponse>",
    cache_prefix_block = r##"{ "dc_" }"##,
    key = "String",
    convert = r#"{ format!("{}{:?}{}{:?}{}{}{}{}", url, form_body_jsonmap, payload_content_type, flag_jaq, flag_store_error, flag_pretty, flag_compress, include_existing_columns) }"#,
    create = r##"{
        let cache_dir = DISKCACHE_DIR.get().unwrap();
        let diskcache_config = DISKCACHECONFIG.get().unwrap();
        let diskcache = DiskCacheBuilder::new("fetchpost")
            .set_disk_directory(cache_dir)
            .set_lifespan(diskcache_config.ttl_secs)
            .set_refresh(diskcache_config.ttl_refresh)
            .build()
            .expect("error building diskcache");
        log::info!("Disk cache created - dir: {cache_dir} - ttl: {ttl_secs}",
            ttl_secs = diskcache_config.ttl_secs);
        diskcache.remove_expired_entries().expect("error removing expired diskcache entries");
        diskcache
    }"##,
    map_error = r##"|e| CliError::Other(format!("Diskcache Error: {:?}", e))"##,
    with_cached_flag = true
)]
fn get_diskcache_response(
    url: &str,
    form_body_jsonmap: &serde_json::Map<String, Value>,
    payload_content_type: ContentType,
    client: &reqwest::blocking::Client,
    limiter: &governor::RateLimiter<NotKeyed, InMemoryState, DefaultClock, NoOpMiddleware>,
    flag_jaq: Option<&String>,
    flag_store_error: bool,
    flag_pretty: bool,
    flag_compress: bool,
    include_existing_columns: bool,
    flag_max_retries: u8,
) -> Result<cached::Return<FetchResponse>, CliError> {
    Ok(Return::new({
        get_response(
            url,
            form_body_jsonmap,
            payload_content_type,
            client,
            limiter,
            flag_jaq,
            flag_store_error,
            flag_pretty,
            flag_compress,
            include_existing_columns,
            flag_max_retries,
        )
    }))
}

// get_redis_response needs a longer key as its a persistent cache and the
// values of flag_jaq, flag_store_error, flag_pretty and include_existing_columns
// may change between sessions
#[io_cached(
    ty = "cached::RedisCache<String, String>",
    key = "String",
    convert = r#"{ format!("{}{:?}{}{:?}{}{}{}{}", url, form_body_jsonmap, payload_content_type, flag_jaq, flag_store_error, flag_pretty, flag_compress, include_existing_columns) }"#,
    create = r##" {
        let redis_config = REDISCONFIG.get().unwrap();
        let rediscache = RedisCache::new("fp", redis_config.ttl_secs)
            .set_namespace("q")
            .set_refresh(redis_config.ttl_refresh)
            .set_connection_string(&redis_config.conn_str)
            .set_connection_pool_max_size(redis_config.max_pool_size)
            .build()
            .expect("error building redis cache");
        log::info!("Redis cache created - conn_str: {conn_str} - refresh: {ttl_refresh} - ttl: {ttl_secs} - pool_size: {pool_size}",
            conn_str = redis_config.conn_str,
            ttl_refresh = redis_config.ttl_refresh,
            ttl_secs = redis_config.ttl_secs,
            pool_size = redis_config.max_pool_size);
        rediscache
    } "##,
    map_error = r##"|e| CliError::Other(format!("Redis Error: {:?}", e))"##,
    with_cached_flag = true
)]
fn get_redis_response(
    url: &str,
    form_body_jsonmap: &serde_json::Map<String, Value>,
    payload_content_type: ContentType,
    client: &reqwest::blocking::Client,
    limiter: &governor::RateLimiter<NotKeyed, InMemoryState, DefaultClock, NoOpMiddleware>,
    flag_jaq: Option<&String>,
    flag_store_error: bool,
    flag_pretty: bool,
    flag_compress: bool,
    include_existing_columns: bool,
    flag_max_retries: u8,
) -> Result<cached::Return<String>, CliError> {
    Ok(Return::new({
        serde_json::to_string(&get_response(
            url,
            form_body_jsonmap,
            payload_content_type,
            client,
            limiter,
            flag_jaq,
            flag_store_error,
            flag_pretty,
            flag_compress,
            include_existing_columns,
            flag_max_retries,
        ))
        .unwrap()
    }))
}

#[allow(clippy::fn_params_excessive_bools)]
#[inline]
fn get_response(
    url: &str,
    form_body_jsonmap: &serde_json::Map<String, Value>,
    payload_content_type: ContentType,
    client: &reqwest::blocking::Client,
    limiter: &governor::RateLimiter<NotKeyed, InMemoryState, DefaultClock, NoOpMiddleware>,
    flag_jaq: Option<&String>,
    flag_store_error: bool,
    flag_pretty: bool,
    flag_compress: bool,
    include_existing_columns: bool,
    flag_max_retries: u8,
) -> FetchResponse {
    // validate the URL
    let valid_url = match Url::parse(url) {
        Ok(valid) => valid.to_string(),
        Err(e) => {
            let url_invalid_err = if flag_store_error {
                if include_existing_columns {
                    // the output is a CSV
                    format!("Invalid URL: {e}")
                } else {
                    // the output is a JSONL file, so return the error
                    // in a JSON API compliant format
                    let json_error = json!({
                        "errors": [{
                            "title": "Invalid URL",
                            "detail": e.to_string()
                        }]
                    });
                    format!("{json_error}")
                }
            } else {
                String::new()
            };
            error!("Invalid URL: Store_error: {flag_store_error} - {url_invalid_err}");
            return FetchResponse {
                response:    url_invalid_err,
                status_code: reqwest::StatusCode::NOT_FOUND.as_u16(),
                retries:     0_u8,
            };
        },
    };
    debug!("Using URL: {valid_url}");

    // wait until RateLimiter gives Okay or we timeout
    let mut limiter_total_wait: u64;
    let timeout_secs = *TIMEOUT_FP_SECS.get().unwrap_or(&30_u64);
    let governor_timeout_ms = timeout_secs * 1_000;

    let mut retries = 0_u8;
    let mut error_flag;
    let mut final_value = String::new();
    let mut api_status;
    let mut api_respheader = HeaderMap::new();
    let mut api_value = String::new();
    let mut api_value_json_result: Result<serde_json::Value, serde_json::Error>;

    let debug_flag = log_enabled!(Debug);

    // request with --max-retries
    'retry: loop {
        // check the rate-limiter
        limiter_total_wait = 0;
        while limiter.check().is_err() {
            limiter_total_wait += MINIMUM_WAIT_MS;
            thread::sleep(MIN_WAIT);
            if limiter_total_wait > governor_timeout_ms {
                debug!("rate limit timed out after {limiter_total_wait} ms");
                break;
            } else if debug_flag && limiter_total_wait == MINIMUM_WAIT_MS {
                debug!("throttling...");
            }
        }
        if debug_flag && limiter_total_wait > 0 && limiter_total_wait <= governor_timeout_ms {
            debug!("throttled for {limiter_total_wait} ms");
        }

        // send the actual request
        let form_body_raw = match payload_content_type {
            ContentType::Json => serde_json::to_string(&form_body_jsonmap)
                .unwrap() // safety: we know form_body_jsonmap is a valid JSON at this point
                .as_bytes()
                .to_owned(),
            ContentType::Form => match serde_urlencoded::to_string(form_body_jsonmap) {
                Ok(form_str) => form_str.as_bytes().to_owned(),
                Err(e) => {
                    let err_msg = format!("Failed to encode form data: {e}");
                    error!("{err_msg}");
                    if flag_store_error {
                        err_msg.as_bytes().to_owned()
                    } else {
                        String::new().as_bytes().to_owned()
                    }
                },
            },
            ContentType::Manual => form_body_jsonmap
                .values()
                .next()
                .map(std::string::ToString::to_string)
                .unwrap_or_default()
                .as_bytes()
                .to_owned(),
        };
        let resp_result = if flag_compress {
            // gzip the request body
            let mut gz_enc = GzEncoder::new(Vec::new(), Compression::default());
            gz_enc.write_all(&form_body_raw).unwrap();
            let gzipped_request_body = gz_enc.finish().unwrap();
            client.post(&valid_url).body(gzipped_request_body).send()
        } else {
            client.post(&valid_url).body(form_body_raw).send()
        };

        if let Ok(resp) = resp_result {
            // debug!("{resp:?}");
            api_respheader.clone_from(resp.headers());
            api_status = resp.status();
            api_value = resp.text().unwrap_or_default();

            if api_status.is_client_error() || api_status.is_server_error() {
                error_flag = true;
                error!(
                    "HTTP error. url: {valid_url:?}, error: {:?}",
                    api_status.canonical_reason().unwrap_or("unknown error")
                );

                if flag_store_error {
                    final_value = format!(
                        "HTTP ERROR {} - {}",
                        api_status.as_str(),
                        api_status.canonical_reason().unwrap_or("unknown error")
                    );
                } else {
                    final_value = String::new();
                }
            } else {
                error_flag = false;
                // apply jaq selector if provided
                if let Some(selectors) = flag_jaq {
                    match process_jaq(&api_value, selectors) {
                        Ok(s) => {
                            final_value = s;
                        },
                        Err(e) => {
                            error!(
                                "jaq error. json: {api_value:?}, selectors: {selectors:?}, error: \
                                 {e:?}"
                            );

                            if flag_store_error {
                                final_value = e.to_string();
                            } else {
                                final_value = String::new();
                            }
                            error_flag = true;
                        },
                    }
                } else {
                    // validate the JSON response
                    api_value_json_result = serde_json::from_str::<serde_json::Value>(&api_value);
                    match api_value_json_result {
                        Ok(api_value_json) => {
                            if flag_pretty {
                                final_value = format!("{api_value_json:#}");
                            } else {
                                // use serde_json CompactFormatter to minify the JSON
                                final_value = format!("{api_value_json}");
                            }
                        },
                        Err(e) => {
                            error!("json error. json: {api_value:?}, error: {e:?}");

                            if flag_store_error {
                                final_value = e.to_string();
                            } else {
                                final_value = String::new();
                            }
                            error_flag = true;
                        },
                    }
                }
            }
        } else {
            error_flag = true;
            api_respheader.clear();
            api_status = reqwest::StatusCode::BAD_REQUEST;
        }

        // debug!("final value: {final_value}");

        // check if there's an API error (likely 503-service not available or 493-too many requests)
        // or if the API has ratelimits and we need to do dynamic throttling to respect limits
        if error_flag
            || (!api_respheader.is_empty()
                && (api_respheader.contains_key("ratelimit-limit")
                    || api_respheader.contains_key("x-ratelimit-limit")
                    || api_respheader.contains_key("retry-after")))
        {
            let ratelimit_remaining = get_ratelimit_header_value(
                &api_respheader,
                "ratelimit-remaining",
                "x-ratelimit-remaining",
            );

            let ratelimit_reset =
                get_ratelimit_header_value(&api_respheader, "ratelimit-reset", "x-ratelimit-reset");

            // some APIs add the "-second" suffix to ratelimit fields
            let ratelimit_remaining_sec = get_ratelimit_header_value(
                &api_respheader,
                "ratelimit-remaining-second",
                "x-ratelimit-remaining-second",
            );

            let ratelimit_reset_sec = get_ratelimit_header_value(
                &api_respheader,
                "ratelimit-reset-second",
                "x-ratelimit-reset-second",
            );

            let retry_after = api_respheader.get("retry-after");

            if debug_flag {
                let rapidapi_proxy_response = api_respheader.get("X-RapidAPI-Proxy-Response");

                debug!(
                    "api_status:{api_status:?} rate_limit_remaining:{ratelimit_remaining:?} \
                     {ratelimit_remaining_sec:?} ratelimit_reset:{ratelimit_reset:?} \
                     {ratelimit_reset_sec:?} retry_after:{retry_after:?} \
                     rapid_api_proxy_response:{rapidapi_proxy_response:?}"
                );
            }

            // if there's a ratelimit_remaining field in the response header, get it
            // otherwise, set remaining to sentinel value 9999
            let remaining =
                parse_ratelimit_header_value(ratelimit_remaining.or(ratelimit_remaining_sec), 9999);

            // if there's a ratelimit_reset field in the response header, get it
            // otherwise, set reset to sentinel value 0
            let mut reset_secs =
                parse_ratelimit_header_value(ratelimit_reset.or(ratelimit_reset_sec), 0);

            // if there's a retry_after field in the response header, get it
            // and set reset to it
            if let Some(retry_after) = retry_after {
                let retry_str = retry_after.to_str().unwrap();
                // if we cannot parse its value as u64, the retry after value
                // is most likely an rfc2822 date and not number of seconds to
                // wait before retrying, which is a valid value
                // however, we don't want to do date-parsing here, so we just
                // wait timeout_secs seconds before retrying
                reset_secs = retry_str.parse::<u64>().unwrap_or(timeout_secs);
            }

            // if reset_secs > timeout, then just time out and skip the retries
            if reset_secs > timeout_secs {
                warn!("Reset_secs {reset_secs} > timeout_secs {timeout_secs}.");
                break 'retry;
            }

            // if there is only one more remaining call per our ratelimit quota or reset >= 1,
            // dynamically throttle and sleep for ~reset seconds
            if remaining <= 1 || reset_secs >= 1 {
                // we add a small random delta to how long fetch sleeps
                // as we need to add a little jitter as per the spec to avoid thundering herd issues
                // https://tools.ietf.org/id/draft-polli-ratelimit-headers-00.html#rfc.section.7.5
                // we multiply by retries as a simple backoff multiplier
                // we multiply reset_secs by 1001 instead of 1000 to give the server a teeny bit
                // more breathing room before we hit it again
                let pause_time =
                    (reset_secs * 1001) + (retries as u64 * rand::rng().random_range(10..30));
                debug!(
                    "sleeping for {pause_time} ms until ratelimit is reset/retry_after has elapsed"
                );

                thread::sleep(time::Duration::from_millis(pause_time));
            }

            if retries >= flag_max_retries {
                wwarn!("{flag_max_retries} max-retries reached.");
                break 'retry;
            }
            retries += 1;
            debug!("retrying {retries}...");
        } else {
            // there's no request error or ratelimits nor retry-after
            break 'retry;
        }
    } // end retry loop

    if error_flag {
        if flag_store_error && !include_existing_columns {
            let json_error = json!({
                "errors": [{
                    "title": "HTTP ERROR",
                    "detail": final_value
                }]
            });
            FetchResponse {
                response: format!("{json_error}"),
                status_code: api_status.as_u16(),
                retries,
            }
        } else {
            FetchResponse {
                response: String::new(),
                status_code: api_status.as_u16(),
                retries,
            }
        }
    } else {
        FetchResponse {
            response: final_value,
            status_code: api_status.as_u16(),
            retries,
        }
    }
}