import { NextRequest, NextResponse } from 'next/server'
import { prisma } from '@/lib/prisma'
import { requireAuth } from '@/lib/auth'

export async function POST(
  request: NextRequest,
  { params }: { params: Promise<{ id: string }> }
) {
  try {
    const user = await requireAuth()
    const { id } = await params

    const playlist = await prisma.playlist.findUnique({
      where: { id },
      include: {
        songs: {
          orderBy: {
            position: 'desc',
          },
          take: 1,
        },
      },
    })

    if (!playlist) {
      return NextResponse.json({ error: 'Playlist not found' }, { status: 404 })
    }

    if (playlist.userId !== user.id) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 403 })
    }

    const body = await request.json()
    const { songId } = body

    if (!songId) {
      return NextResponse.json({ error: 'songId is required' }, { status: 400 })
    }

    // Check if song exists
    const song = await prisma.song.findUnique({
      where: { id: songId },
    })

    if (!song) {
      return NextResponse.json({ error: 'Song not found' }, { status: 404 })
    }

    // Check if song is already in playlist
    const existingPlaylistSong = await prisma.playlistSong.findUnique({
      where: {
        playlistId_songId: {
          playlistId: id,
          songId,
        },
      },
    })

    if (existingPlaylistSong) {
      return NextResponse.json({ error: 'Song already in playlist' }, { status: 400 })
    }

    // Get the next position
    const nextPosition = playlist.songs.length > 0 ? playlist.songs[0].position + 1 : 0

    const playlistSong = await prisma.playlistSong.create({
      data: {
        playlistId: id,
        songId,
        position: nextPosition,
      },
      include: {
        song: {
          include: {
            artist: {
              select: {
                id: true,
                name: true,
                slug: true,
                avatarUrl: true,
                verified: true,
              },
            },
            album: {
              select: {
                id: true,
                title: true,
                slug: true,
                coverUrl: true,
              },
            },
            genres: {
              include: {
                genre: true,
              },
            },
          },
        },
      },
    })

    return NextResponse.json(playlistSong, { status: 201 })
  } catch (error) {
    if (error instanceof Error && error.message === 'Unauthorized') {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
    }
    console.error('Error adding song to playlist:', error)
    return NextResponse.json({ error: 'Failed to add song to playlist' }, { status: 500 })
  }
}