1.js

var jsonUrl = "https://raw.githubusercontent.com/Sinongamess/pic/main/tree.json";
//json文件的地址
var urlIndex = "https://raw.githubusercontent.com/Cheshire-Nya/easy-random-image-api/main/html-template/index.html";
//主页模板地址
var url404 = "https://raw.githubusercontent.com/Cheshire-Nya/easy-random-image-api/main/html-template/404.html";
//404模板地址
var imgHost = "https://raw.githubusercontent.com/Sinongamess/pic/main/";
//图片地址前部不会发生改变的部分
//用github作为图库应按照此格式"https://raw.githubusercontent.com/<github用户名>/<仓库名>/<分支名>/"
var redirectProxy = 2;
//type=302时返回的链接是否是经过代理的，0 不代理(返回github原链接)，1 worker代理，2 ghproxy代理

var ghproxyUrl = "https://ghproxy.com/";


addEventListener('fetch', event => {
  event.respondWith(handleRequest(event.request));
});


function handleRequest(request) {
  let nowUrl = new URL(request.url);
  let wholePath = nowUrl.pathname;
  let urlSearch = nowUrl.search;
  if (nowUrl.pathname === '/api' || nowUrl.pathname === '/api/') {
    if (nowUrl.search) {
      return extractSearch(urlSearch, request);
    }
	  else {
     return error();
    };
  }
  else if (nowUrl.pathname === '/') {
	return index();
  }
  else {
    return error();
  }
}

//开始吟唱
async function extractSearch(urlSearch, request) {
  let searchParams = new URLSearchParams(urlSearch);
  let id = searchParams.get('id');
  let cats = searchParams.getAll('cat');
  let type = searchParams.get('type');
  if (cats) {
    const response = await fetch(jsonUrl);
    const jsonData = await response.json();

    const existingCats = cats.filter(cat => jsonData.hasOwnProperty(cat));
    if (existingCats.length !== cats.length) {
      return error();
    }

    const category = existingCats[Math.floor(Math.random() * existingCats.length)];
    if (!searchParams.has('id')) {
      const values = jsonData[category];
      const trueId = Math.floor(Math.random() * values.length);
      const img = values[trueId];
      if (type === '302') {
        return redirect(trueId + 1, img, category, request);
      }
      else if (type === 'json') {
        return typejson(trueId + 1, img, category, request);
      }
      else if (!searchParams.has('type')) {
        return image(img);
      }
      else return error();
    }
    else if (id) {
      const values = jsonData[category];
      const trueId = id - 1;
      const img = values[trueId];
      if (type === 'json') {
        return typejson(id, img, category, request);
      }
      else if (!searchParams.has('type')) {
        return image(img);
      }
      else return error();
    }
    else return error()
  }
  else return error();//cat为必须，没有则抛出错误
}


function image(img) {
  let encodedImg = encodeURIComponent(img);
  let imgUrl = imgHost + encodedImg;
  let getimg = new Request(imgUrl);
  return fetch(getimg, {
    headers: {
      'cache-control': 'max-age=36000',
      'content-type': 'application/octet-stream',
    },
  });  
}


function redirect(id, img, category, request) {
  let encodedImh = encodeURIComponent(img);
  if (redirectProxy === 0) {
    const redirectUrl = imgHost + img;
    return type302(redirectUrl);
  }
  else if (redirectProxy === 1) {
    const nowUrl = new URL(request.url);
    const myHost = nowUrl.hostname;
    const redirectUrl = "https://" + myHost + "/api" + "?cat=" + category + "&id=" + id;
    return type302(redirectUrl);
  }
  else if (redirectProxy === 2) {
    const redirectUrl = ghproxyUrl + imgHost + img;
    return type302(redirectUrl);
  }
  else return error();
  
}


function type302(redirectUrl) {
  return new Response("", {
    status: 302,
    headers: {
      Location: redirectUrl
    }
  });
}


function typejson(id, img, category, request) {
  let nowUrl = new URL(request.url);
  let myHost = nowUrl.hostname;
	let githubUrl = imgHost + img;
	let workerUrl = "https://" + myHost + "/api" + "?cat=" + category + "&id=" + id;
	let proxyUrl = ghproxyUrl + imgHost + img;   
	return new Response(
    JSON.stringify({
      "category": category,
      "id": id,
      "githubUrl": githubUrl,
      "workerUrl": workerUrl,
      "proxyUrl": proxyUrl
    }, null, 2), {
    headers: {
      'Content-Type': 'application/json'
    }
  });

}


async function error() {
  let response = await fetch(url404);
  response = new Response(response.body, {
      status: 404,
      statusText: 'Not Found',
      headers: { 'Content-Type': 'text/html' }
  });
  return response
}


async function index() {
  let response = await fetch(urlIndex);
  response = new Response(response.body, {
      status: 200,
      statusText: 'OK',
      headers: { 'Content-Type': 'text/html' }
  });
  return response
}