New settings to cutomize how bytes data are displayed

Fixes #25

README.md

@@ -11,6 +11,8 @@ export PYTHONPATH=${PYTHONPATH}:$(pwd)/tahu/python/core/
 ```
 When launched, the `enki.py` script gives access to a shell with commands to manage topics subscriptions, list EoN and devices, craft metrics into payload. Type `help` to see the list of commands available.
 
+Additional usage information can be found [here](usage.md).
+
 # Demo
 [![asciicast](https://asciinema.org/a/lKGTwxDlLOYwGtsF1kecBLfa0.svg)](https://asciinema.org/a/lKGTwxDlLOYwGtsF1kecBLfa0)
 

shell.py

@@ -1,6 +1,7 @@
 """Enki shell interface."""
 import time
 from datetime import datetime, timezone
+from string import printable
 
 import cmd2
 
@@ -14,6 +15,14 @@
 from sp_network import SPNet
 
 
+# Setting values for displaying of byte data
+BYTE_DATA_DISPLAY_LIST = "list"
+BYTE_DATA_DISPLAY_HEXDUMP = "hexdump"
+BYTE_DATA_DISPLAY_MODE = BYTE_DATA_DISPLAY_LIST
+BYTE_DATA_SHORT_LEN = 10
+BYTE_DATA_MAX_LEN = BYTE_DATA_SHORT_LEN
+
+
 def str_to_int(string):
     """Convert string to int.
 
@@ -38,19 +47,59 @@ def str_to_bool(string):
     return False
 
 
+def bytes_to_list_str(byte_data) -> str:
+    """Converts an iterable containing bytes to a string representation, using a list format"""
+    size = len(byte_data)
+    if BYTE_DATA_MAX_LEN:
+        byte_data = byte_data[0:BYTE_DATA_MAX_LEN]
+    res = "[" + " ,".join([f"0x{val:02X}" for val in byte_data])
+    if BYTE_DATA_MAX_LEN and size > BYTE_DATA_MAX_LEN:
+        res += " ..."
+    res += "]"
+    return res
+
+def bytes_to_hexdump_str(byte_data) -> str:
+    """
+    Converts an iterable containing bytes to a string representation
+    using a hexadecimal dump format
+    """
+    offset = 0
+    size = len(byte_data)
+    if BYTE_DATA_MAX_LEN != 0 and BYTE_DATA_MAX_LEN < size:
+        size = BYTE_DATA_MAX_LEN
+    processed = 0
+    res = ""
+    while processed < size:
+        block_size = 16 if size - processed >= 16 else size - processed
+        block = byte_data[offset:offset+block_size]
+        block_str = [f"{b:02X}" for b in block]
+        pairs = zip(block_str[0::2], block_str[1::2])
+        block_str = " ".join(p[0] + p[1] for p in pairs)
+        if block_size % 2 == 1:
+            if block_size > 1:
+                block_str += " "
+            block_str += f"{block[-1]:02X}"
+        block_ascii = "".join(chr(c) if chr(c) in printable else "." for c in block)
+        if res:
+            res += "\n"
+        res += f"{offset:08X}: {block_str:39}  {block_ascii}"
+        offset += block_size
+        processed += block_size
+    return res
+
+
 def get_bytearray_str(bytes_array):
     """String representation of a bytearray value."""
     size = len(bytes_array)
     res = f"Bytes array of length {size}"
     if size:
-        excerpt = bytes_array[0:10]
-        excerpt = "[" + " ".join([f"0x{val:02X}" for val in excerpt])
-        if size > 10:
-            excerpt += " ..."
-        excerpt += "]"
-        res = res + " " + excerpt
+        if BYTE_DATA_DISPLAY_MODE == BYTE_DATA_DISPLAY_LIST:
+            res += ":\n" + bytes_to_list_str(bytes_array) + "\n"
+        else:
+            res += ":\n" + bytes_to_hexdump_str(bytes_array) + "\n"
     return res
 
+
 def get_dataset_row_str(dataset, row):
     """String representation of a dataset row."""
     return tuple(get_typed_value_str(col_type, row.elements[idx])
@@ -110,6 +159,7 @@ def get_common_info_str(metric):
         res = res + "\n\tproperties: None"
     return res
 
+
 def get_metric_str(metric) -> str:
     """Return a string describing metric if it is known to Device"""
     value_str: str = get_typed_value_str(metric.datatype, metric)
@@ -119,13 +169,37 @@ def get_metric_str(metric) -> str:
 
 @cmd2.with_default_category('Enki')
 class SPShell(cmd2.Cmd):
-    # pylint: disable=too-many-instance-attributes, too-many-public-methods
+    # pylint: disable=too-many-instance-attributes, too-many-public-methods, global-statement
     """Enki Shell Interface"""
 
     def __init__(self, mqtt_if: MQTTInterface):
         cmd2.Cmd.__init__(self, allow_cli_args=False)
         self.mqtt_if = mqtt_if
         self.prompt = "enki> "
+        self.byte_data_display_mode = BYTE_DATA_DISPLAY_MODE
+        self.add_settable(
+            cmd2.Settable("byte_data_display_mode", str, "Display mode for byte data", self,
+                          choices=[BYTE_DATA_DISPLAY_LIST, BYTE_DATA_DISPLAY_HEXDUMP],
+                          onchange_cb=self._on_change_byte_data_display_mode)
+        )
+        self.byte_data_max_len = BYTE_DATA_MAX_LEN
+        self.add_settable(
+            cmd2.Settable("byte_data_max_len", int,
+                          "Maximum number of bytes to display for byte data",
+                          self, onchange_cb=self._on_change_byte_data_max_len)
+        )
+
+    def _on_change_byte_data_display_mode(self, _param_name, _old_value, new_value):
+        global BYTE_DATA_DISPLAY_MODE
+        BYTE_DATA_DISPLAY_MODE = new_value
+
+    def _on_change_byte_data_max_len(self, param_name, old_value, new_value):
+        global BYTE_DATA_MAX_LEN
+        if new_value < 0:
+            print(f"{param_name} should be greater or equal to 0")
+            setattr(self, param_name, old_value)
+        else:
+            BYTE_DATA_MAX_LEN = new_value
 
     def do_exit(self, *_args):
         """Exits the app."""
@@ -148,7 +222,7 @@ def do_list(self, args):
                     print(f"   * {dev.get_id().dev_id}")
 
     def build_target_list(self, include_eon, include_dev):
-        """Returns a list of potentatial handles for autocompletion purposes."""
+        """Returns a list of potential handles for autocompletion purposes."""
         res = []
         sp_net = SPNet()
         for eon in sp_net.eon_nodes:

usage.md

@@ -0,0 +1,28 @@
+# Usage
+
+On startup Enki will connect to the specified broker and subscribe to spBv1.0/#.
+
+Enki will then monitor the EoNs and devices that get born or die on the broker.
+
+## Command line options
+
+Command line options are self documented.
+Their help can be seen by running enki with the option```-h``` or ```--help```.
+
+## Basic commands
+The list of available commands can be accessed with the command ```help```.
+
+Additional help on each command can be seen with ```help <command>```.
+
+## Advanced usage
+### Sending null metrics
+When prompted for a metric value, you can specify you want to send the metric with the null flag set to true,
+by pressing ```Ctrl-d```.
+
+### Application Settings
+The following settings can be set with the command ```set <setting_name> <value>```.
+
+- **byte_data_display_mode** _list_ or _hexdump_:
+  - _list_: The bytes will be displayed as a python list (e.g. [0x01, 0x02, 0x03])
+  - _hexdump_: The bytes will be displayed using a hexadecimal dump format, similar to the output of the xxd command
+- **byte_data_max_len**: The maximum number of bytes to display for either display mode. Set this to 0 to remove the limit and display all bytes.