import fs from 'fs'
import path from 'path'
import type { Game, GameSeries } from '@/types'
import { getDb } from './db'
import { HIDDEN_FILES, fileApiUrl, thumbnailApiUrl, findFile } from './media-utils'

/**
 * Attempts to build a Game from a directory.
 * @param absPath   Absolute path to the game directory.
 * @param dirName   The directory's own name (used as title).
 * @param relPath   Path relative to the library root (used for IDs and file URLs).
 * @param libraryId Library identifier.
 * @returns Game, or null if the directory contains no .zip file.
 */
function buildGame(
  absPath: string,
  dirName: string,
  relPath: string,
  libraryId: string
): Game | null {
  let allFiles: string[]
  try {
    allFiles = fs.readdirSync(absPath)
  } catch {
    return null
  }

  const zipFiles = allFiles
    .filter((f) => f.toLowerCase().endsWith('.zip'))
    .sort((a, b) => a.localeCompare(b))
  if (zipFiles.length === 0) return null

  const coverFile = findFile(absPath, /^cover$/i)
  const wideCoverFile = findFile(absPath, /^widecover$/i)

  return {
    id: encodeURIComponent(relPath),
    title: dirName,
    coverUrl: coverFile
      ? thumbnailApiUrl(libraryId, path.join(relPath, coverFile))
      : null,
    wideCoverUrl: wideCoverFile
      ? fileApiUrl(libraryId, path.join(relPath, wideCoverFile))
      : null,
    zipFiles: zipFiles.map((f) => path.join(relPath, f)),
  }
}

export function scanGamesLibrary(libraryRoot: string, libraryId: string): (Game | GameSeries)[] {
  let topDirs: string[]
  try {
    topDirs = fs
      .readdirSync(libraryRoot, { withFileTypes: true })
      .filter((d) => d.isDirectory() && !HIDDEN_FILES.test(d.name))
      .map((d) => d.name)
  } catch {
    return []
  }

  const results: (Game | GameSeries)[] = []

  for (const dirName of topDirs) {
    const absPath = path.join(libraryRoot, dirName)

    let allFiles: string[]
    try {
      allFiles = fs.readdirSync(absPath)
    } catch {
      continue
    }

    // Standalone game: directory directly contains a .zip
    const hasZip = allFiles.some((f) => f.toLowerCase().endsWith('.zip'))
    if (hasZip) {
      const game = buildGame(absPath, dirName, dirName, libraryId)
      if (game) results.push(game)
      continue
    }

    // No .zip here — check subdirectories (series detection)
    let subDirs: string[]
    try {
      subDirs = fs
        .readdirSync(absPath, { withFileTypes: true })
        .filter((d) => d.isDirectory() && !HIDDEN_FILES.test(d.name))
        .map((d) => d.name)
    } catch {
      continue
    }

    const seriesGames: Game[] = []
    for (const subDir of subDirs) {
      const game = buildGame(
        path.join(absPath, subDir),
        subDir,
        path.join(dirName, subDir),
        libraryId
      )
      if (game) seriesGames.push(game)
    }

    if (seriesGames.length === 0) continue

    // It's a series — check for an optional series-level cover
    const seriesCoverFile = findFile(absPath, /^cover$/i)
    const seriesWideCoverFile = findFile(absPath, /^widecover$/i)

    results.push({
      id: encodeURIComponent(dirName),
      title: dirName,
      coverUrl: seriesCoverFile
        ? thumbnailApiUrl(libraryId, path.join(dirName, seriesCoverFile))
        : seriesGames[0].coverUrl,
      wideCoverUrl: seriesWideCoverFile
        ? fileApiUrl(libraryId, path.join(dirName, seriesWideCoverFile))
        : null,
      games: seriesGames.sort((a, b) => a.title.localeCompare(b.title)),
    })
  }

  return results.sort((a, b) => a.title.localeCompare(b.title))
}

export function gamesFromDb(libraryId: string): (Game | GameSeries)[] {
  const db = getDb()

  type DbRow = {
    item_key: string
    item_type: string
    parent_key: string | null
    title: string | null
    metadata: string | null
  }

  const allRows = db
    .prepare(`SELECT item_key, item_type, parent_key, title, metadata
              FROM media_items
              WHERE library_id = ? AND item_type IN ('game', 'game_series')
              ORDER BY title`)
    .all(libraryId) as DbRow[]

  const seriesMap = new Map<string, GameSeries>()
  const standaloneGames: Game[] = []

  // First pass: build series
  for (const row of allRows) {
    if (row.item_type !== 'game_series') continue
    const meta = row.metadata ? JSON.parse(row.metadata) : {}
    const idPart = row.item_key.split(':game_series:')[1] ?? row.item_key
    seriesMap.set(row.item_key, {
      id: idPart,
      item_key: row.item_key,
      title: row.title ?? decodeURIComponent(idPart),
      coverUrl: meta.coverUrl ?? null,
      wideCoverUrl: meta.wideCoverUrl ?? null,
      games: [],
    })
  }

  // Second pass: attach games
  for (const row of allRows) {
    if (row.item_type !== 'game') continue
    const meta = row.metadata ? JSON.parse(row.metadata) : {}
    const idPart = row.item_key.split(':game:')[1] ?? row.item_key
    const game: Game = {
      id: idPart,
      item_key: row.item_key,
      title: row.title ?? decodeURIComponent(idPart),
      coverUrl: meta.coverUrl ?? null,
      wideCoverUrl: meta.wideCoverUrl ?? null,
      zipFiles: meta.zipFiles ?? [],
    }
    if (row.parent_key && seriesMap.has(row.parent_key)) {
      seriesMap.get(row.parent_key)!.games.push(game)
    } else {
      standaloneGames.push(game)
    }
  }

  const results: (Game | GameSeries)[] = [
    ...Array.from(seriesMap.values()),
    ...standaloneGames,
  ]
  return results.sort((a, b) => a.title.localeCompare(b.title))
}