/**
 * 下拉刷新的控制
 */
var startmark = 0; // 开始触摸屏幕的位置
var newmark = 0; // 当前移动到的位置
var maxDistance = 75; // 下拉最大距离（单位px）
var triggered = false; // 当前下拉刷新状态，true表示下拉刷新已经被触发，false表示下拉刷新未被触发

/**
 * 手指触摸动作开始
 */
var touchStart = function(e, instance) {
  var scrollTop = e.instance.getDataset().scrolltop;
  // 当前处于顶部并且没有处于刷新状态
  if (scrollTop && !triggered) {
    startmark = e.touches[0].pageY;
  } else {
    return;
  }
}

/**
 * 手指触摸后移动
 */
var touchMove = function(e, instance) {
  var scrollTop = e.instance.getDataset().scrolltop;
  var circleProgressBarHeight = e.instance.getDataset().progressbarheight;
  // 当前处于顶部并且没有处于刷新状态
  if (scrollTop && !triggered) {
    newmark = e.touches[0].pageY;
    if (newmark < startmark) {
      // 向上滑动
      instance.selectComponent('.circle-progress-bar').setStyle({ 'transform': 'none' })
      instance.selectComponent('.icon-shuaxin').setStyle({ 'transform': 'none', 'opacity': 0 })
    } else if (newmark - startmark > maxDistance + circleProgressBarHeight) {
      // 达到最大滑动距离
      instance.selectComponent('.circle-progress-bar').setStyle({
        'transform': 'translateY(' + (maxDistance + circleProgressBarHeight) + 'px)'
      });
      instance.selectComponent('.icon-shuaxin').setStyle({
        'transform': 'rotate(270deg)',
        'opacity': 1
      });
    } else {
      // 向下滑动，未到达最大滑动距离
      instance.selectComponent('.circle-progress-bar').setStyle({
        'transform': 'translateY(' + (newmark - startmark) + 'px)'
      });
      // 计算加载进度条的透明度，当滑动距离为最大滑动距离的一半时opacity为1
      var opacity = 0;
      if (newmark - startmark <= (maxDistance + circleProgressBarHeight) / 2) {
        opacity = 1 * (newmark - startmark) / (maxDistance + circleProgressBarHeight);
      } else {
        opacity = 1;
      }
      instance.selectComponent('.icon-shuaxin').setStyle({
        'transform': 'rotate(' + 270 * (newmark - startmark) / (maxDistance + circleProgressBarHeight) + 'deg)',
        'opacity': opacity
      });
    }
  } else {
    return
  }
}

/**
 * 手指触摸动作结束
 */
var touchEnd = function(e, instance) {
  var scrollTop = e.instance.getDataset().scrolltop;
  var threshold = e.instance.getDataset().threshold;
  // 当前处于顶部并且没有处于刷新状态
  if (scrollTop && !triggered) {
    if (newmark - startmark < (threshold + 40)) {
      // 滑动距离未达到阈值（这里的40为加载圈高度），回到原位
      startmark = 0;
      newmark = 0;
      instance.selectComponent('.circle-progress-bar').setStyle({
        'transform': 'none',
        'opacity': 0,
        'transition-duration': '0.6s'
      });
    } else {
      // 滑动距离达到阈值，触发刷新
      startmark = 0;
      newmark = 0;
      instance.selectComponent('.circle-progress-bar').setStyle({
        'transform': 'none',
        'opacity': 0
      });
      instance.callMethod('setRefresh', true);
    }
  } else {
    return;
  }
}

/**
 * 手指触摸动作被打断，如来电提醒，弹窗
 */
var touchCancel = function(e, instance) {
  // 回到原位
  startmark = 0;
  newmark = 0;
  instance.selectComponent('.circle-progress-bar').setStyle({
    'transform': 'none',
    'opacity': 0
  });
}

/**
 * 刷新状态变化监听
 */
var refreshStateChange = function(newValue, oldValue, ownerInstance, ins) {
  triggered = newValue;
}

module.exports = {
  touchStart: touchStart,
  touchMove: touchMove,
  touchEnd: touchEnd,
  touchCancel: touchCancel,
  refreshStateChange: refreshStateChange
}