'use strict';

module.exports = TaskQueue;

function TaskQueue() {
  this.isReady = false;
  this.failed = false;
  this.queue = [];
}

TaskQueue.prototype.execute = function () {
  var d, func;
  if (this.failed) {
    while ((d = this.queue.shift())) {
      if (typeof d === 'function') {
        d(this.failed);
        continue;
      }
      func = d.parameters[d.parameters.length - 1];
      if (typeof func === 'function') {
        func(this.failed);
      } else if (d.name === 'changes' && typeof func.complete === 'function') {
        func.complete(this.failed);
      }
    }
  } else if (this.isReady) {
    while ((d = this.queue.shift())) {

      if (typeof d === 'function') {
        d();
      } else {
        d.task = this.db[d.name].apply(this.db, d.parameters);
      }
    }
  }
};

TaskQueue.prototype.fail = function (err) {
  this.failed = err;
  this.execute();
};

TaskQueue.prototype.ready = function (db) {
  if (this.failed) {
    return false;
  } else if (arguments.length === 0) {
    return this.isReady;
  }
  this.isReady = db ? true: false;
  this.db = db;
  this.execute();
};

TaskQueue.prototype.addTask = function (name, parameters) {
  if (typeof name === 'function') {
    this.queue.push(name);
    if (this.failed) {
      this.execute();
    }
  } else {
    var task = { name: name, parameters: parameters };
    this.queue.push(task);
    if (this.failed) {
      this.execute();
    }
    return task;
  }
};