var session = require('./session');
var util = require('./util');

var originApiMap = {};
var transferToTaskMethod = function (apiMap, apiName) {
  originApiMap[apiName] = apiMap[apiName];
  apiMap[apiName] = function (params, callback) {
    if (params.SkipTask) {
      originApiMap[apiName].call(this, params, callback);
    } else {
      this._addTask(apiName, params, callback);
    }
  };
};

var initTask = function (cos) {
  var queue = [];
  var tasks = {};
  var uploadingFileCount = 0;
  var nextUploadIndex = 0;

  // 接口返回简略的任务信息
  var formatTask = function (task) {
    var t = {
      id: task.id,
      Bucket: task.Bucket,
      Region: task.Region,
      Key: task.Key,
      FilePath: task.FilePath,
      state: task.state,
      loaded: task.loaded,
      size: task.size,
      speed: task.speed,
      percent: task.percent,
      hashPercent: task.hashPercent,
      error: task.error,
    };
    if (task.FilePath) t.FilePath = task.FilePath;
    return t;
  };

  var emitListUpdate = (function () {
    var timer;
    var emit = function () {
      timer = 0;
      cos.emit('task-list-update', { list: util.map(queue, formatTask) });
      cos.emit('list-update', { list: util.map(queue, formatTask) });
    };
    return function () {
      if (!timer) timer = setTimeout(emit);
    };
  })();

  var clearQueue = function () {
    if (queue.length <= cos.options.UploadQueueSize) return;
    for (
      var i = 0;
      i < nextUploadIndex && // 小于当前操作的 index 才清理
      i < queue.length && // 大于队列才清理
      queue.length > cos.options.UploadQueueSize; // 如果还太多，才继续清理

    ) {
      var isActive = queue[i].state === 'waiting' || queue[i].state === 'checking' || queue[i].state === 'uploading';
      if (!queue[i] || !isActive) {
        tasks[queue[i].id] && delete tasks[queue[i].id];
        queue.splice(i, 1);
        nextUploadIndex--;
      } else {
        i++;
      }
    }
    emitListUpdate();
  };

  var startNextTask = function () {
    // 检查是否允许增加执行进程
    if (uploadingFileCount >= cos.options.FileParallelLimit) return;
    // 跳过不可执行的任务
    while (queue[nextUploadIndex] && queue[nextUploadIndex].state !== 'waiting') nextUploadIndex++;
    // 检查是否已遍历结束
    if (nextUploadIndex >= queue.length) return;
    // 上传该遍历到的任务
    var task = queue[nextUploadIndex];
    nextUploadIndex++;
    uploadingFileCount++;
    task.state = 'checking';
    task.params.onTaskStart && task.params.onTaskStart(formatTask(task));
    !task.params.UploadData && (task.params.UploadData = {});
    var apiParams = util.formatParams(task.api, task.params);
    originApiMap[task.api].call(cos, apiParams, function (err, data) {
      if (!cos._isRunningTask(task.id)) return;
      if (task.state === 'checking' || task.state === 'uploading') {
        task.state = err ? 'error' : 'success';
        err && (task.error = err);
        uploadingFileCount--;
        emitListUpdate();
        startNextTask();
        task.callback && task.callback(err, data);
        if (task.state === 'success') {
          if (task.params) {
            delete task.params.UploadData;
            delete task.params.Body;
            delete task.params;
          }
          delete task.callback;
        }
      }
      clearQueue();
    });
    emitListUpdate();
    // 异步执行下一个任务
    setTimeout(startNextTask);
  };

  var killTask = function (id, switchToState) {
    var task = tasks[id];
    if (!task) return;
    var waiting = task && task.state === 'waiting';
    var running = task && (task.state === 'checking' || task.state === 'uploading');
    if (
      (switchToState === 'canceled' && task.state !== 'canceled') ||
      (switchToState === 'paused' && waiting) ||
      (switchToState === 'paused' && running)
    ) {
      if (switchToState === 'paused' && task.params.Body && typeof task.params.Body.pipe === 'function') {
        console.error('stream not support pause');
        return;
      }
      task.state = switchToState;
      cos.emit('inner-kill-task', { TaskId: id, toState: switchToState });
      try {
        var UploadId = task && task.params && task.params.UploadData.UploadId;
      } catch (e) {}
      if (switchToState === 'canceled' && UploadId) session.removeUsing(UploadId);
      emitListUpdate();
      if (running) {
        uploadingFileCount--;
        startNextTask();
      }
      if (switchToState === 'canceled') {
        if (task.params) {
          delete task.params.UploadData;
          delete task.params.Body;
          delete task.params;
        }
        delete task.callback;
      }
    }
    clearQueue();
  };

  cos._addTasks = function (taskList) {
    util.each(taskList, function (task) {
      cos._addTask(task.api, task.params, task.callback, true);
    });
    emitListUpdate();
  };

  var isTaskReadyWarning = true;
  cos._addTask = function (api, params, callback, ignoreAddEvent) {
    // 复制参数对象
    params = util.formatParams(api, params);

    // 生成 id
    var id = util.uuid();
    params.TaskId = id;
    params.onTaskReady && params.onTaskReady(id);
    if (params.TaskReady) {
      params.TaskReady(id);
      isTaskReadyWarning &&
        console.warn('warning: Param "TaskReady" has been deprecated. Please use "onTaskReady" instead.');
      isTaskReadyWarning = false;
    }

    var task = {
      // env
      params: params,
      callback: callback,
      api: api,
      index: queue.length,
      // task
      id: id,
      Bucket: params.Bucket,
      Region: params.Region,
      Key: params.Key,
      FilePath: params.FilePath || '',
      state: 'waiting',
      loaded: 0,
      size: 0,
      speed: 0,
      percent: 0,
      hashPercent: 0,
      error: null,
    };
    var onHashProgress = params.onHashProgress;
    params.onHashProgress = function (info) {
      if (!cos._isRunningTask(task.id)) return;
      task.hashPercent = info.percent;
      onHashProgress && onHashProgress(info);
      emitListUpdate();
    };
    var onProgress = params.onProgress;
    params.onProgress = function (info) {
      if (!cos._isRunningTask(task.id)) return;
      task.state === 'checking' && (task.state = 'uploading');
      task.loaded = info.loaded;
      task.speed = info.speed;
      task.percent = info.percent;
      onProgress && onProgress(info);
      emitListUpdate();
    };

    // 异步获取 filesize
    util.getFileSize(api, params, function (err, size) {
      // 开始处理上传
      if (err) return callback(util.error(err)); // 如果获取大小出错，不加入队列
      // 获取完文件大小再把任务加入队列
      tasks[id] = task;
      queue.push(task);
      task.size = size;
      !ignoreAddEvent && emitListUpdate();
      startNextTask();
      clearQueue();
    });
    return id;
  };
  cos._isRunningTask = function (id) {
    var task = tasks[id];
    return !!(task && (task.state === 'checking' || task.state === 'uploading'));
  };
  cos.getTaskList = function () {
    return util.map(queue, formatTask);
  };
  cos.cancelTask = function (id) {
    killTask(id, 'canceled');
  };
  cos.pauseTask = function (id) {
    killTask(id, 'paused');
  };
  cos.restartTask = function (id) {
    var task = tasks[id];
    if (task && (task.state === 'paused' || task.state === 'error')) {
      task.state = 'waiting';
      emitListUpdate();
      nextUploadIndex = Math.min(nextUploadIndex, task.index);
      startNextTask();
    }
  };
  cos.isUploadRunning = function () {
    return uploadingFileCount || nextUploadIndex < queue.length;
  };
};

module.exports.transferToTaskMethod = transferToTaskMethod;
module.exports.init = initTask;