import dayjs from 'dayjs';
import PQueue from 'p-queue';
import { v4 as uuid } from 'uuid';
import { sleep } from '#shared/utils/helpers';
import { PUBLIC_PROXY_LIST } from '~/config/public-proxy';
import type { DownloadableArticle } from '~/types/types';
import type { AudioResource, VideoResource } from '~/types/video';

/**
 * 代理实例
 */
export interface ProxyInstance {
  // 唯一标识
  id: string;

  // 代理地址
  address: string;

  // 是否正在被使用
  busy: boolean;

  // 是否处于冷静期
  cooldown: boolean;

  // 使用次数
  usageCount: number;

  // 成功次数
  successCount: number;

  // 失败次数
  failureCount: number;

  // 下载流量
  traffic: number;
}

// 使用代理下载的资源类型
type DownloadResource =
  | string
  | HTMLLinkElement
  | HTMLImageElement
  | DownloadableArticle
  | AudioResource
  | VideoResource;

// 资源下载函数，返回资源大小
type DownloadFn<T extends DownloadResource> = (resource: T, proxy: string) => Promise<number>;

// 资源下载结果
export interface DownloadResult {
  // 总耗时 (s)
  totalTime: number;

  // 是否成功
  success: boolean;

  // 重试次数
  attempts: number;

  // 资源url
  url: string;

  // 资源大小
  size: number;
}

function now() {
  return dayjs(new Date()).format('HH:mm:ss.SSS');
}

class ProxyPool {
  proxies: ProxyInstance[] = [];

  constructor(proxyUrls: string[]) {
    this.proxies = proxyUrls.map(url => ({
      id: uuid(),
      address: url,
      busy: false,
      cooldown: false,
      usageCount: 0,
      successCount: 0,
      failureCount: 0,
      traffic: 0,
    }));
  }

  /**
   * 初始化代理池
   * 可以传入新的代理地址列表（私有代理地址）
   */
  init(proxyUrls: string[] = []) {
    if (proxyUrls.length > 0) {
      this.proxies = proxyUrls.map(url => ({
        id: uuid(),
        address: url,
        busy: false,
        cooldown: false,
        usageCount: 0,
        successCount: 0,
        failureCount: 0,
        traffic: 0,
      }));
    } else {
      this.proxies.forEach(proxy => {
        proxy.busy = false;
        proxy.cooldown = false;
        proxy.usageCount = 0;
        proxy.successCount = 0;
        proxy.failureCount = 0;
      });
    }
  }

  /**
   * 获取可用代理
   */
  async getAvailableProxy() {
    let time = 0;
    while (true) {
      for (const proxy of this.proxies) {
        if (!proxy.busy && !proxy.cooldown) {
          proxy.busy = true;
          proxy.usageCount++;
          return proxy;
        }
      }
      // 如果没有可用代理，稍微等待一下
      await sleep(100);
      time += 100;
      if (time >= 60_000) {
        // 超时1分钟
        throw new Error('无可用代理');
      }
    }
  }

  /**
   * 释放代理
   * @param proxy 代理对象
   * @param success 使用当前代理的本次下载是否成功
   */
  releaseProxy(proxy: ProxyInstance, success: boolean) {
    proxy.busy = false;

    if (success) {
      proxy.successCount++;
    } else {
      proxy.failureCount++;
      proxy.cooldown = true;

      // 2秒冷却时间
      setTimeout(() => {
        proxy.cooldown = false;
      }, 2_000);

      if (proxy.failureCount >= 10 && proxy.successCount === 0) {
        // 代理被识别为不可用，从代理池中移除
        console.warn(`代理 ${proxy.address} 不可用，将被移除`);
        this.removeProxy(proxy);
      }
    }
  }

  /**
   * 移除代理
   */
  removeProxy(proxy: ProxyInstance) {
    this.proxies = this.proxies.filter(p => p.id !== proxy.id);
  }
}

// 代理池
export const pool = new ProxyPool(PUBLIC_PROXY_LIST);

/**
 * 使用代理 proxy 下载资源
 * @param proxy
 * @param resource
 * @param downloadFn
 */
async function downloadResource<T extends DownloadResource>(
  proxy: ProxyInstance,
  resource: T,
  downloadFn: DownloadFn<T>
): Promise<[boolean, number]> {
  try {
    // 执行下载任务
    const size = await downloadFn(resource, proxy.address);
    return [true, size];
  } catch (error) {
    return [false, 0];
  }
}

/**
 * 使用代理池下载资源
 * @param pool
 * @param resource
 * @param downloadFn
 * @param useProxy
 * @param maxRetries
 */
async function downloadWithRetry<T extends DownloadResource>(
  pool: ProxyPool,
  resource: T,
  downloadFn: DownloadFn<T>,
  useProxy = true,
  maxRetries = 10
): Promise<DownloadResult> {
  let attempts = 0;
  let isSuccess = false;
  let size: number = 0;

  let resourceURL: string;
  if (resource instanceof HTMLLinkElement) {
    resourceURL = resource.href;
  } else if (resource instanceof HTMLImageElement) {
    resourceURL = resource.src || resource.dataset.src!;
  } else if (typeof resource === 'string') {
    resourceURL = resource;
  } else {
    resourceURL = resource.url;
  }

  const startTime = Date.now();

  while (attempts < maxRetries) {
    let success: boolean;

    if (useProxy) {
      // 使用代理下载
      const proxy = await pool.getAvailableProxy();
      [success, size] = await downloadResource<T>(proxy, resource, downloadFn);
      pool.releaseProxy(proxy, success);
    } else {
      // 不使用代理下载
      [success, size] = await downloadResource<T>({} as ProxyInstance, resource, downloadFn);
    }

    if (success) {
      isSuccess = true;
      break;
    } else {
      attempts++;
      await sleep(200);
      console.log(`[${now()}] Retrying ${resourceURL} (attempt ${attempts}/${maxRetries})`);
    }
  }

  const endTime = Date.now();
  const totalTime = (endTime - startTime) / 1000;

  if (!isSuccess) {
    console.warn(`[${now()}] Failed to download ${resourceURL} after ${maxRetries} attempts`);
  }

  return {
    totalTime,
    success: isSuccess,
    attempts,
    url: resourceURL,
    size,
  };
}

/**
 * 使用代理池下载单个资源
 * @param resource
 * @param downloadFn
 * @param useProxy
 */
async function download<T extends DownloadResource>(resource: T, downloadFn: DownloadFn<T>, useProxy = true) {
  return await downloadWithRetry<T>(pool, resource, downloadFn, useProxy);
}

/**
 * 使用代理池下载多个资源
 * @param resources
 * @param downloadFn
 * @param useProxy
 */
export async function downloads<T extends DownloadResource>(
  resources: T[],
  downloadFn: DownloadFn<T>,
  useProxy = true
) {
  // 检查是否设置了私有代理地址
  const privateProxy: string[] = [];
  try {
    const proxy = JSON.parse(window.localStorage.getItem('wechat-proxy')!);
    if (Array.isArray(proxy) && proxy.length > 0) {
      privateProxy.push(...proxy);
    }
  } catch (e) {
    console.log(e);
  }

  // 初始化 pool
  pool.init(privateProxy);

  const queue = new PQueue({ concurrency: pool.proxies.length });

  const tasks = resources.map(resource => queue.add(() => download<T>(resource, downloadFn, useProxy)));
  await Promise.all(tasks);
}