const EXIT_THRESHOLD = 80;
const FAST_SWIPE_VELOCITY = 0.5;

Page({
  isDragging: false,
  isExiting: false,
  startTime: 0,
  startX: 0,
  startY: 0,
  lastX: 0,

  data: {
    nameList: [],
    currentIndex: 0,
    isLoading: true,
    isFlipped: false,
    keyword: '清冷',
    
    // 动画控制
    translateX: 0,
    rotate: 0,
    opacity: 1,
    transition: 'none',
    
    cardKey: 0,
    collectedNames: [],
    showCollection: false
  },

  onLoad(options) {
    const keyword = options.keyword || this.data.keyword;
    this.setData({ keyword });
    this.fetchNames(keyword);
  },

  fetchNames(keyword) {
    this.setData({ isLoading: true });
    wx.showLoading({ title: '见素正在感悟...', mask: true });
    wx.request({
      url: 'http://localhost:8080/api/names/generate',
      data: { keyword },
      success: (res) => {
        if (res.statusCode === 200 && res.data && res.data.length > 0) {
          this.setData({ nameList: res.data, currentIndex: 0, isLoading: false, cardKey: this.data.cardKey + 1 });
        } else {
          wx.showToast({ title: '意境未达，请重试', icon: 'none' });
        }
      },
      fail: () => wx.showToast({ title: '网络疏离，请检查后端', icon: 'none' }),
      complete: () => { this.setData({ isLoading: false }); wx.hideLoading(); }
    });
  },

  onFlip() {
    // 守卫：如果这是一次拖拽，isDragging 会为 true，则不执行翻转
    if (this.isDragging || this.isExiting) return;
    
    getApp().playAudio('flip');
    this.setData({ isFlipped: !this.data.isFlipped });
  },

  onTouchStart(e) {
    if (this.isExiting) return;
    
    this.isDragging = false; // 每次开始触摸时，都假定为点击，而非拖拽
    this.startX = e.touches[0].clientX;
    this.lastX = this.startX;
    this.startY = e.touches[0].clientY;
    this.startTime = Date.now();
    this.setData({ transition: 'none' }); 
  },

  onTouchMove(e) {
    if (this.isExiting) return;

    const deltaX = e.touches[0].clientX - this.startX;
    // 只有移动超过5px，才真正判定为“拖拽”
    if (Math.abs(deltaX) > 5) {
        this.isDragging = true;
    }

    // 如果不是拖拽，则不进行任何移动
    if (!this.isDragging) return;

    this.lastX = e.touches[0].clientX;
    const rotate = deltaX * 0.05;
    const opacity = 1 - Math.abs(deltaX) / 200;
    this.setData({
      translateX: deltaX,
      rotate: rotate,
      opacity: opacity
    });
  },

  onTouchEnd() {
    if (this.isExiting) return;

    // 如果不是拖拽（即这是一次纯点击），则 onTouchEnd 不执行任何操作，交由 onFlip 处理
    if (!this.isDragging) {
      return;
    }
    
    // 以下是拖拽结束后的逻辑
    const deltaX = this.lastX - this.startX;
    const deltaTime = Date.now() - this.startTime;
    const velocity = deltaX / deltaTime;
    const shouldExit = Math.abs(deltaX) > EXIT_THRESHOLD || Math.abs(velocity) > FAST_SWIPE_VELOCITY;

    if (shouldExit) {
      this.isExiting = true;
      const direction = deltaX > 0 ? 1 : -1;
      const targetX = direction * 500;
      this.setData({
        translateX: targetX,
        opacity: 0,
        transition: 'all 0.3s cubic-bezier(0.6, -0.28, 0.735, 0.045)'
      });
    } else {
      this.setData({
        translateX: 0,
        rotate: 0,
        opacity: 1,
        transition: 'all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275)'
      });
    }
    
    // 延迟重置 isDragging 标志位。
    // 这是为了确保在系统触发 tap 事件时，isDragging 标志仍然为 true，
    // 从而让 onFlip 方法可以正确地忽略掉这次由拖拽产生的 tap。
    setTimeout(() => {
      this.isDragging = false;
    }, 100);
  },

  onTransitionEnd() {
    if (!this.isExiting) return;

    const direction = this.data.translateX > 0 ? 'like' : 'dislike';
    if (direction === 'like') {
      this.handleLike();
    } else {
      this.handleCardExit(direction);
    }
  },

  handleLike() {
    wx.vibrateShort({ type: 'medium' });
    getApp().playAudio('success');
    const card = this.data.nameList[this.data.currentIndex];
    if (!this.data.collectedNames.some(item => item.name === card.name)) {
      this.setData({ collectedNames: [...this.data.collectedNames, card] });
    }
    this.handleCardExit('like');
  },

  handleCardExit() {
    const nextIndex = this.data.currentIndex + 1;
    wx.nextTick(() => {
      this.setData({
        transition: 'none',
        translateX: 0,
        rotate: 0,
        opacity: 1,
        isFlipped: false
      }, () => {
        if (nextIndex < this.data.nameList.length) {
          this.setData({ currentIndex: nextIndex, cardKey: this.data.cardKey + 1 });
        } else {
          wx.showModal({
            title: '见素时刻',
            content: '这一波灵感已尽，是否再求几名？',
            confirmText: '再求', cancelText: '返回',
            success: (res) => { if (res.confirm) this.fetchNames(this.data.keyword); }
          });
        }
        this.isExiting = false;
      });
    });
  },

  toggleCollectionView() {
    this.setData({ showCollection: !this.data.showCollection });
  },

  onDeleteCollected(e) {
    const nameToDelete = e.currentTarget.dataset.name;
    this.setData({
      collectedNames: this.data.collectedNames.filter(item => item.name !== nameToDelete)
    });
    wx.vibrateShort({ type: 'light' });
  },
  
  onSavePoster() {
    const card = this.data.nameList[this.data.currentIndex];
    wx.showLoading({ title: '绘笔收录中...', mask: true });
    const query = wx.createSelectorQuery().in(this);
    query.select('#posterCanvas')
      .fields({ node: true, size: true })
      .exec((res) => {
        const canvas = res[0].node;
        const ctx = canvas.getContext('2d');
        const dpr = wx.getSystemInfoSync().pixelRatio;
        canvas.width = 750 * dpr;
        canvas.height = 1334 * dpr;
        ctx.scale(dpr, dpr);
        ctx.fillStyle = '#FFFFFF';
        ctx.fillRect(0, 0, 750, 1334);
        ctx.fillStyle = '#2D2D2D';
        ctx.font = '300 120px serif';
        ctx.textAlign = 'center';
        ctx.textBaseline = 'middle';
        const name = card.name;
        const charArray = name.split('');
        const charHeight = 140;
        const startY = 667 - (charArray.length * charHeight) / 2 + charHeight / 2;
        charArray.forEach((char, index) => ctx.fillText(char, 375, startY + index * charHeight));
        const sealChar = this.data.keyword.substring(0, 1) || '素';
        ctx.fillStyle = '#B22222';
        ctx.fillRect(100, 100, 80, 80);
        ctx.fillStyle = '#FFFFFF';
        ctx.font = '40px serif';
        ctx.fillText(sealChar, 140, 140);
        const randomNum = Math.floor(Math.random() * 9000) + 1000;
        ctx.fillStyle = '#D0D0D0';
        ctx.font = '24px sans-serif';
        ctx.fillText(`见素第 ${randomNum} 号灵感`, 375, 1200);
        setTimeout(() => {
          wx.canvasToTempFilePath({
            canvas: canvas,
            success: (res) => {
              wx.hideLoading();
              wx.showShareImageMenu({ path: res.tempFilePath });
            },
            fail: () => {
              wx.hideLoading();
              wx.showToast({ title: '绘笔受阻', icon: 'none' });
            }
          });
        }, 300);
      });
  }
});