/**
 * 贴纸合成引擎（Canvas 2D）
 *
 * 将贴纸/装饰素材按指定位置、旋转、缩放、透明度、混合模式
 * 叠加到目标人物图片上，输出高清合成图。
 *
 * 数据库对齐：asset_material_relations 表的字段
 *   material_type, pos_x, pos_y, opacity, rotation,
 *   scale_x, scale_y, layer_order
 */

const DEFAULT_EXPORT_W = 450
const DEFAULT_EXPORT_H = 600
const CORNER_RADIUS = 32

// ---- 图片工具 ----

function getImageInfo(src) {
  return new Promise((resolve, reject) => {
    uni.getImageInfo({
      src,
      success: resolve,
      fail: (e) => reject(e || new Error('读取图片失败')),
    })
  })
}

function computeCover(iw, ih, cw, ch) {
  const w = Number(iw) || 1
  const h = Number(ih) || 1
  const scale = Math.max(cw / w, ch / h)
  const dw = w * scale
  const dh = h * scale
  return { dx: (cw - dw) / 2, dy: (ch - dh) / 2, dw, dh }
}

function clamp(v, lo, hi) {
  return Math.max(lo, Math.min(hi, v))
}

// ---- Canvas 兼容工具 ----

function canvasDraw(ctx) {
  return new Promise((resolve) => {
    ctx.draw(false, () => setTimeout(resolve, 80))
  })
}

function setBlend(ctx, mode) {
  if (typeof ctx.setGlobalCompositeOperation === 'function') {
    ctx.setGlobalCompositeOperation(mode)
  }
}

function clipRoundRect(ctx, cw, ch, r) {
  const rr = r || Math.min(32, cw * 0.065, ch * 0.048)
  ctx.beginPath()
  ctx.moveTo(rr, 0)
  ctx.lineTo(cw - rr, 0)
  ctx.arc(cw - rr, rr, rr, -Math.PI / 2, 0, false)
  ctx.lineTo(cw, ch - rr)
  ctx.arc(cw - rr, ch - rr, rr, 0, Math.PI / 2, false)
  ctx.lineTo(rr, ch)
  ctx.arc(rr, ch - rr, rr, Math.PI / 2, Math.PI, false)
  ctx.lineTo(0, rr)
  ctx.arc(rr, rr, rr, Math.PI, Math.PI * 1.5, false)
  ctx.closePath()
  ctx.clip()
}

function canvasToTemp(canvasId, w, h) {
  return new Promise((resolve, reject) => {
    uni.canvasToTempFilePath({
      canvasId,
      width: w,
      height: h,
      destWidth: w * 2,
      destHeight: h * 2,
      fileType: 'jpg',
      quality: 0.96,
      success: (res) => resolve(res.tempFilePath),
      fail: (e) => reject(e || new Error('导出失败')),
    })
  })
}

// ---- 阴影绘制（让贴纸看起来真实贴合） ----

function drawStickerShadow(ctx, stickerData, cw, ch) {
  const { pos_x = 0.5, pos_y = 0.5, scale_x = 1, scale_y = 1, rotation = 0, stickerLayout } = stickerData
  if (!stickerLayout) return

  const cx = pos_x * cw
  const cy = pos_y * ch
  const sw = stickerLayout.dw * scale_x
  const sh = stickerLayout.dh * scale_y
  const approxR = Math.max(sw, sh) * 0.55

  ctx.save()
  ctx.translate(cx + 2, cy + 2)
  ctx.rotate((rotation * Math.PI) / 180)

  const shadowGrad = ctx.createRadialGradient
    ? ctx.createRadialGradient(0, 0, approxR * 0.2, 0, 0, approxR)
    : ctx.createCircularGradient
      ? ctx.createCircularGradient(0, 0, approxR)
      : ctx.createLinearGradient(-approxR, -approxR, approxR, approxR)

  if (shadowGrad.addColorStop) {
    shadowGrad.addColorStop(0, 'rgba(0,0,0,0.25)')
    shadowGrad.addColorStop(0.5, 'rgba(0,0,0,0.08)')
    shadowGrad.addColorStop(1, 'rgba(0,0,0,0)')
  }

  ctx.setGlobalAlpha(0.6)
  ctx.setFillStyle(shadowGrad || 'rgba(0,0,0,0.12)')
  ctx.fillRect(-approxR, -approxR, approxR * 2, approxR * 2)

  ctx.restore()
  ctx.setGlobalAlpha(1)
}

// ---- 贴纸绘制 ----

function drawSticker(ctx, stickerData, cw, ch) {
  const {
    pos_x = 0.5,
    pos_y = 0.5,
    scale_x = 1,
    scale_y = 1,
    rotation = 0,
    opacity = 1,
    blendMode = 'source-over',
    stickerLayout,
  } = stickerData

  if (!stickerLayout || !stickerLayout.path) return

  const cx = pos_x * cw
  const cy = pos_y * ch
  const sw = stickerLayout.dw * scale_x
  const sh = stickerLayout.dh * scale_y

  ctx.save()
  ctx.translate(cx, cy)
  ctx.rotate((rotation * Math.PI) / 180)
  ctx.setGlobalAlpha(clamp(opacity, 0, 1))
  setBlend(ctx, blendMode)

  ctx.drawImage(stickerLayout.path, -sw / 2, -sh / 2, sw, sh)

  ctx.restore()
  ctx.setGlobalAlpha(1)
  setBlend(ctx, 'source-over')
}

// ---- 边缘微光（让贴纸融入场景） ----

function drawStickerEdgeGlow(ctx, stickerData, cw, ch) {
  const {
    pos_x = 0.5,
    pos_y = 0.5,
    scale_x = 1,
    scale_y = 1,
    rotation = 0,
    opacity = 1,
    stickerLayout,
  } = stickerData

  if (opacity < 0.3 || !stickerLayout) return

  const cx = pos_x * cw
  const cy = pos_y * ch
  const sw = stickerLayout.dw * scale_x
  const sh = stickerLayout.dh * scale_y
  const approxR = Math.max(sw, sh) * 0.55

  ctx.save()
  ctx.translate(cx, cy)
  ctx.rotate((rotation * Math.PI) / 180)

  const glowGrad = ctx.createRadialGradient
    ? ctx.createRadialGradient(0, 0, approxR * 0.35, 0, 0, approxR)
    : ctx.createLinearGradient(-approxR, -approxR, approxR, approxR)

  if (glowGrad.addColorStop) {
    glowGrad.addColorStop(0, 'rgba(255,255,255,0)')
    glowGrad.addColorStop(0.7, 'rgba(255,255,255,0.06)')
    glowGrad.addColorStop(1, 'rgba(255,255,255,0)')
  }

  setBlend(ctx, 'soft-light')
  ctx.setGlobalAlpha(clamp(opacity * 0.35, 0, 0.35))
  ctx.setFillStyle(glowGrad || 'rgba(255,255,255,0.04)')
  ctx.fillRect(-approxR, -approxR, approxR * 2, approxR * 2)

  ctx.restore()
  ctx.setGlobalAlpha(1)
  setBlend(ctx, 'source-over')
}

// ============ 公开 API ============

/**
 * 预计算贴纸的 cover 布局
 * @param {string} stickerSrc 贴纸图片路径
 * @param {number} cw  画布宽度
 * @param {number} ch  画布高度
 * @param {number} [targetFraction=0.22] 贴纸占画布的比例
 */
export async function computeStickerLayout(stickerSrc, cw, ch, targetFraction = 0.22) {
  const info = await getImageInfo(stickerSrc)
  const targetW = cw * targetFraction
  const targetH = ch * targetFraction
  const cover = computeCover(info.width, info.height, targetW, targetH)
  return { ...cover, path: info.path }
}

/**
 * 在画布上绘制完整贴纸合成层
 *
 * @param {CanvasContext} ctx       uni-app Canvas 上下文
 * @param {number} cw              画布宽度
 * @param {number} ch              画布高度
 * @param {Array} stickers         贴纸数组，每项包含：
 *   { pos_x, pos_y, scale_x, scale_y, rotation, opacity, blendMode, stickerLayout }
 * @param {boolean} [drawShadow=true]  是否绘制投影
 * @param {boolean} [drawGlow=true]    是否绘制边缘柔光
 */
export function drawStickers(ctx, cw, ch, stickers, { drawShadow = true, drawGlow = true } = {}) {
  if (!stickers || !stickers.length) return

  const sorted = [...stickers].sort((a, b) => (a.layer_order || 0) - (b.layer_order || 0))

  for (const sticker of sorted) {
    if (!sticker.stickerLayout || !sticker.stickerLayout.path) continue
    if (drawShadow) drawStickerShadow(ctx, sticker, cw, ch)
    drawSticker(ctx, sticker, cw, ch)
    if (drawGlow) drawStickerEdgeGlow(ctx, sticker, cw, ch)
  }
}

/**
 * 完整贴纸合成：人物底图 → 贴纸叠加 → 导出
 *
 * @param {object} opts
 * @param {string} opts.baseImageSrc    人物底图路径
 * @param {Array}  opts.stickers        贴纸配置数组
 * @param {number} [opts.exportW=450]   导出宽度
 * @param {number} [opts.exportH=600]   导出高度
 * @param {string} [opts.canvasId]      uni-app canvas-id
 * @param {number} [opts.cornerRadius]  圆角半径
 * @returns {Promise<string>} 导出后的临时文件路径
 */
export async function composeStickers(opts) {
  const {
    baseImageSrc,
    stickers = [],
    exportW = DEFAULT_EXPORT_W,
    exportH = DEFAULT_EXPORT_H,
    canvasId = 'stickerCompositCanvas',
    cornerRadius = CORNER_RADIUS,
  } = opts

  const ctx = uni.createCanvasContext(canvasId)

  // 1. 预加载贴纸布局
  const stickerLayouts = await Promise.all(
    stickers.map(async (s) => {
      if (!s.src) return { ...s, stickerLayout: null }
      try {
        const layout = await computeStickerLayout(s.src, exportW, exportH, s.sizeFraction || 0.22)
        return { ...s, stickerLayout: layout }
      } catch (e) {
        console.warn('[sticker-compositor] load sticker failed:', s.src, e)
        return { ...s, stickerLayout: null }
      }
    })
  )

  // 2. 绘制底色
  ctx.setFillStyle('#0a0a0a')
  ctx.fillRect(0, 0, exportW, exportH)

  // 3. 圆角裁剪
  ctx.save()
  clipRoundRect(ctx, exportW, exportH, cornerRadius)

  // 4. 绘制人物底图（cover 填满）
  if (baseImageSrc) {
    const baseInfo = await getImageInfo(baseImageSrc)
    const cover = computeCover(baseInfo.width, baseInfo.height, exportW, exportH)
    ctx.drawImage(baseInfo.path, cover.dx, cover.dy, cover.dw, cover.dh)
  }

  await canvasDraw(ctx)

  // 5. 逐层叠加贴纸
  drawStickers(ctx, exportW, exportH, stickerLayouts, { drawShadow: true, drawGlow: true })

  ctx.restore()
  await canvasDraw(ctx)

  // 6. 导出高清图
  const tempPath = await canvasToTemp(canvasId, exportW, exportH)
  return tempPath
}

/**
 * 从 asset_material_relations 记录转换为贴纸配置
 *
 * @param {Array} relations  asset_material_relations 行数组
 * @returns {Array} 贴纸配置数组
 */
export function relationsToStickers(relations) {
  if (!relations || !relations.length) return []
  return relations
    .filter((r) => r.material_type === 'sticker' || r.material_type === 'patch')
    .map((r) => ({
      src: r.oss_key || r.material_url || '',
      pos_x: r.pos_x != null ? Number(r.pos_x) : 0.5,
      pos_y: r.pos_y != null ? Number(r.pos_y) : 0.5,
      opacity: r.opacity != null ? Number(r.opacity) : 1,
      rotation: r.rotation != null ? Number(r.rotation) : 0,
      scale_x: r.scale_x != null ? Number(r.scale_x) : 1,
      scale_y: r.scale_y != null ? Number(r.scale_y) : 1,
      layer_order: r.layer_order != null ? Number(r.layer_order) : 0,
      blendMode: r.blend_mode || 'source-over',
    }))
}