import fs from 'fs'
import path from 'path'
import type { Movie } from '@/types'
import { parseMovieNfo } from './nfo'

const HIDDEN_FILES = /^\./

const VIDEO_EXTENSIONS = new Set(['.mkv', '.mp4', '.avi', '.mov', '.m4v', '.wmv', '.ts', '.m2ts'])

function fileApiUrl(libraryId: string, relativePath: string): string {
  return `/api/file?libraryId=${encodeURIComponent(libraryId)}&path=${encodeURIComponent(relativePath)}`
}

function thumbnailApiUrl(libraryId: string, relativePath: string): string {
  return `/api/thumbnail?libraryId=${encodeURIComponent(libraryId)}&path=${encodeURIComponent(relativePath)}`
}

/**
 * Finds the first file in a directory whose basename (without extension)
 * matches the given pattern (case-insensitive).
 */
function findFile(dir: string, pattern: RegExp): string | null {
  let entries: string[]
  try {
    entries = fs.readdirSync(dir)
  } catch {
    return null
  }
  return entries.find(
    (e) => !HIDDEN_FILES.test(e) && pattern.test(path.basename(e, path.extname(e)))
  ) ?? null
}

function findVideoFile(dir: string): string | null {
  let entries: string[]
  try {
    entries = fs.readdirSync(dir)
  } catch {
    return null
  }
  return entries.find(
    (e) => !HIDDEN_FILES.test(e) && VIDEO_EXTENSIONS.has(path.extname(e).toLowerCase())
  ) ?? null
}

function findNfoFile(dir: string, dirName: string): string | null {
  // Try {dirName}.nfo first, then movie.nfo, then any .nfo
  const candidates = [`${dirName}.nfo`, 'movie.nfo']
  let entries: string[]
  try {
    entries = fs.readdirSync(dir)
  } catch {
    return null
  }
  for (const candidate of candidates) {
    if (entries.find((e) => e.toLowerCase() === candidate.toLowerCase())) {
      return entries.find((e) => e.toLowerCase() === candidate.toLowerCase())!
    }
  }
  return entries.find((e) => path.extname(e).toLowerCase() === '.nfo') ?? null
}

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

  const movies: Movie[] = []

  for (const dirName of dirs) {
    const moviePath = path.join(libraryRoot, dirName)

    const videoFile = findVideoFile(moviePath)
    if (!videoFile) continue

    const nfoFile = findNfoFile(moviePath, dirName)
    const nfo = nfoFile ? parseMovieNfo(path.join(moviePath, nfoFile)) : null

    const posterFile = findFile(moviePath, /^(poster|cover|folder)$/i)
    const backdropFile = findFile(moviePath, /^(backdrop|fanart|background)$/i)

    const id = encodeURIComponent(dirName)
    const videoRelPath = path.join(dirName, videoFile)

    movies.push({
      id,
      title: nfo?.title ?? dirName,
      year: nfo?.year ?? null,
      plot: nfo?.plot ?? null,
      rating: nfo?.rating ?? null,
      genres: nfo?.genres ?? [],
      runtime: nfo?.runtime ?? null,
      posterUrl: posterFile
        ? thumbnailApiUrl(libraryId, path.join(dirName, posterFile))
        : null,
      backdropUrl: backdropFile
        ? fileApiUrl(libraryId, path.join(dirName, backdropFile))
        : null,
      videoPath: videoRelPath,
    })
  }

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