archy/packages/app/src/composables/useImageFallback.ts

type TmdbResult = { posterUrl: string | null; backdropUrl: string | null }
const memoryCache = new Map<string, TmdbResult>()
const SESSION_KEY = 'aiui-poster-cache'
const failedUrls = new Set<string>()

const musicCoverCache = new Map<string, string>()
const SESSION_MUSIC_KEY = 'aiui-music-cover-cache'

function musicCacheKey(artist: string, title: string): string {
  return `${artist.toLowerCase().trim()}|${title.toLowerCase().trim()}`
}

function loadMusicCache(): void {
  try {
    const raw = sessionStorage.getItem(SESSION_MUSIC_KEY)
    if (raw) {
      const parsed = JSON.parse(raw) as Record<string, string>
      Object.entries(parsed).forEach(([k, v]) => musicCoverCache.set(k, v))
    }
  } catch { /* ignore */ }
}

function saveMusicCache(): void {
  try {
    const entries = [...musicCoverCache.entries()].slice(-300)
    sessionStorage.setItem(SESSION_MUSIC_KEY, JSON.stringify(Object.fromEntries(entries)))
  } catch { /* ignore */ }
}

loadMusicCache()

function cacheKey(t: string, y?: number): string {
  return `${t.toLowerCase().trim()}|${y ?? ''}`
}

function loadSessionCache(): void {
  try {
    const raw = sessionStorage.getItem(SESSION_KEY)
    if (raw) {
      const parsed = JSON.parse(raw) as Record<string, TmdbResult>
      Object.entries(parsed).forEach(([k, v]) => memoryCache.set(k, v))
    }
  } catch { /* ignore */ }
}

function saveSessionCache(): void {
  try {
    const entries = [...memoryCache.entries()].slice(-200)
    sessionStorage.setItem(SESSION_KEY, JSON.stringify(Object.fromEntries(entries)))
  } catch { /* ignore */ }
}

loadSessionCache()

export function generateSongCoverFallback(title: string, artist?: string): string {
  const hue = [...(title + (artist ?? ''))].reduce((acc, c) => acc + c.charCodeAt(0), 0) % 360
  const svg = `<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 200 200">
    <rect width="200" height="200" fill="hsl(${hue}, 30%, 14%)"/>
    <rect x="2" y="2" width="196" height="196" rx="8" fill="none" stroke="hsl(${hue}, 40%, 25%)" stroke-width="2"/>
    <path d="M100 50 v100 M70 70 q30-20 60 0 M70 130 q30 20 60 0" fill="none" stroke="hsl(${hue}, 50%, 60%)" stroke-width="4" stroke-linecap="round"/>
    <text x="100" y="115" text-anchor="middle" fill="hsl(${hue}, 50%, 70%)" font-family="system-ui" font-size="14" font-weight="600">${escapeXml(title.length > 12 ? title.slice(0, 10) + '…' : title)}</text>
    ${artist ? `<text x="100" y="135" text-anchor="middle" fill="hsl(${hue}, 30%, 50%)" font-family="system-ui" font-size="10">${escapeXml(artist.length > 14 ? artist.slice(0, 12) + '…' : artist)}</text>` : ''}
  </svg>`
  return `data:image/svg+xml,${encodeURIComponent(svg)}`
}

export function generatePosterFallback(title: string, year?: number): string {
  const hue = [...title].reduce((acc, c) => acc + c.charCodeAt(0), 0) % 360
  const svg = `<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 342 513">
    <rect width="342" height="513" fill="hsl(${hue}, 30%, 15%)"/>
    <rect x="1" y="1" width="340" height="511" rx="8" fill="none" stroke="hsl(${hue}, 40%, 25%)" stroke-width="2"/>
    <text x="171" y="230" text-anchor="middle" fill="hsl(${hue}, 50%, 70%)" font-family="system-ui" font-size="20" font-weight="600">
      ${escapeXml(title.length > 20 ? title.slice(0, 18) + '…' : title)}
    </text>
    ${year ? `<text x="171" y="260" text-anchor="middle" fill="hsl(${hue}, 30%, 50%)" font-family="system-ui" font-size="14">${year}</text>` : ''}
  </svg>`
  return `data:image/svg+xml,${encodeURIComponent(svg)}`
}

function escapeXml(s: string): string {
  return s.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;').replace(/"/g, '&quot;')
}

export async function fetchTmdbPoster(
  title: string,
  year?: number,
): Promise<TmdbResult> {
  const key = cacheKey(title, year)
  const cached = memoryCache.get(key)
  if (cached) return cached

  const empty: TmdbResult = { posterUrl: null, backdropUrl: null }
  try {
    const params = new URLSearchParams({ q: title.trim() })
    if (year && year > 0) params.set('y', String(year))
    const res = await fetch(`/api/tmdb/search?${params}`)
    if (!res.ok) return empty
    const data = (await res.json()) as { posterUrl?: string | null; backdropUrl?: string | null }
    const result: TmdbResult = {
      posterUrl: data.posterUrl ?? null,
      backdropUrl: data.backdropUrl ?? null,
    }
    if (result.posterUrl || result.backdropUrl) {
      memoryCache.set(key, result)
      saveSessionCache()
    }
    return result
  } catch {
    return empty
  }
}

export async function handleImgError(
  e: Event,
  title: string,
  year?: number,
): Promise<void> {
  const img = e.target as HTMLImageElement
  if (img.dataset.fallback === 'done') return

  const originalSrc = img.src
  failedUrls.add(originalSrc)

  const key = cacheKey(title, year)
  const cached = memoryCache.get(key)
  if (cached?.posterUrl && cached.posterUrl !== originalSrc) {
    img.dataset.fallback = 'tmdb'
    img.src = cached.posterUrl
    return
  }

  if (img.dataset.fallback !== 'tmdb') {
    const { posterUrl } = await fetchTmdbPoster(title, year)
    if (posterUrl && posterUrl !== originalSrc) {
      img.dataset.fallback = 'tmdb'
      img.src = posterUrl
      return
    }
  }

  img.dataset.fallback = 'done'
  img.src = generatePosterFallback(title, year)
}

export function isUrlFailed(url: string | undefined): boolean {
  return !!url && failedUrls.has(url)
}

/** Fetch album artwork from iTunes Search API (free, no key). Returns hi-res URL (600x600). */
export async function fetchMusicCover(
  title: string,
  artist: string,
  album?: string,
): Promise<string | null> {
  const key = musicCacheKey(artist, title)
  const cached = musicCoverCache.get(key)
  if (cached) return cached

  try {
    const term = `${artist} ${title}`.trim().replace(/\s+/g, '+')
    const res = await fetch(
      `https://itunes.apple.com/search?term=${encodeURIComponent(term)}&media=music&limit=3`,
    )
    if (!res.ok) return null
    const data = (await res.json()) as { results?: { artworkUrl100?: string }[] }
    const first = data.results?.[0]
    const url = first?.artworkUrl100
    if (!url) return null
    const hiRes = url.replace(/100x100/g, '600x600')
    musicCoverCache.set(key, hiRes)
    saveMusicCache()
    return hiRes
  } catch {
    return null
  }
}