pptList/src/utils/aiPptResources.ts

import type { AiCoursewareOutline } from "@/api/aiCourseware"
import type { Slide } from "@/types/slides"
import type { AiPptQualityIssue } from "@/utils/aiPptQuality"

// 仅在浏览器检查实际可加载性，不以 URL 格式代替媒体可用性。
export async function inspectAiPptResources(outline: AiCoursewareOutline, slides: Slide[]): Promise<AiPptQualityIssue[]> {
  const pending = new Map<string, Promise<{ width: number; height: number }>>()
  const issues: AiPptQualityIssue[] = []
  const probe = (url: string, kind: "image" | "audio" | "video") => {
    const key = `${kind}:${url}`
    if (!pending.has(key)) pending.set(key, new Promise((resolve, reject) => {
      const media = kind === "image" ? new Image() : document.createElement(kind)
      const finish = (error?: string) => {
        clearTimeout(timer)
        media.onload = media.onerror = null
        if (media instanceof HTMLMediaElement) {
          media.onloadedmetadata = null
          media.removeAttribute("src")
          media.load()
        }
        if (error) reject(new Error(error))
        else resolve(media instanceof HTMLImageElement ? { width: media.naturalWidth, height: media.naturalHeight } : { width: 0, height: 0 })
      }
      const timer = window.setTimeout(() => finish("加载超时"), 15000)
      media.onerror = () => finish("无法加载或格式不受支持")
      if (media instanceof HTMLMediaElement) {
        media.preload = "metadata"
        media.onloadedmetadata = () => finish()
      } else media.onload = () => finish()
      media.src = url
    }))
    return pending.get(key)!
  }
  await Promise.all(slides.map(async (slide, index) => {
    const scoreUrls = new Set((outline.pages[index]?.resourceBindings || []).filter(item => item.resourceType === "MUSIC").map(item => item.scoreImageUrl))
    await Promise.all(slide.elements.map(async element => {
      const kind = element.type === "image" ? "image" : element.type === "elf" && element.subtype === "elf-audio" ? "audio" : element.type === "elf" && element.subtype === "elf-video" ? "video" : undefined
      if (!kind || !("src" in element)) return
      try {
        const size = await probe(element.src, kind)
        // 谱图完整等比放进原槽位，禁止拉伸音符或裁掉小节。
        if (element.type === "image" && scoreUrls.has(element.src) && size.width && size.height) {
          const scale = Math.min(element.width / size.width, element.height / size.height)
          const width = size.width * scale
          const height = size.height * scale
          element.left += (element.width - width) / 2
          element.top += (element.height - height) / 2
          element.width = width
          element.height = height
        }
      } catch (error) {
        issues.push({ code: "resource_unavailable", severity: "error", pageNo: index + 1,
          message: `${kind === "image" ? "图片" : kind === "audio" ? "音频" : "视频"}${error instanceof Error ? error.message : "不可用"}，请更换资源后重试` })
      }
    }))
  }))
  return issues
}