import { db } from '~/drizzle/db'
import { expectedPlayDates, songs } from '~/drizzle/schema'
import { eq, and } from 'drizzle-orm'

export default defineEventHandler(async (event) => {
  const songId = Number(event.context.params?.id)
  const body = await readBody(event)

  if (!songId || isNaN(songId)) {
    throw createError({
      statusCode: 400,
      message: '无效的歌曲ID'
    })
  }

  // user check
  const user = event.context.user
  if (!user) {
    throw createError({
      statusCode: 401,
      message: '需要登录'
    })
  }

  const { expectedPlayDate, expectedPlaySequence } = body

  // 如果传空值，说明用户取消选择或清空
  if (!expectedPlayDate || expectedPlaySequence === undefined) {
    await db.update(songs).set({
      expectedPlayDate: null,
      expectedPlaySequence: null
    }).where(eq(songs.id, songId))
    
    return { success: true }
  }

  try {
    // 开启事务检查冲突
    const updatedSong = await db.transaction(async (tx) => {
      // 1. 检查日期和序号是否有效
      const dateSetting = await tx.select().from(expectedPlayDates).where(eq(expectedPlayDates.date, expectedPlayDate))
      
      if (dateSetting.length === 0 || !dateSetting[0].enabled) {
        throw createError({
          statusCode: 400,
          message: '该日期未开放选座'
        })
      }

      const availableSeqs = dateSetting[0].availableSequences.split(',').map(s => parseInt(s.trim(), 10))
      if (!availableSeqs.includes(expectedPlaySequence)) {
        throw createError({
          statusCode: 400,
          message: '无效的序号'
        })
      }

      // 2. 检查是否已被占用
      const takenSongs = await tx.select({ id: songs.id })
        .from(songs)
        .where(
          and(
            eq(songs.expectedPlayDate, expectedPlayDate),
            eq(songs.expectedPlaySequence, expectedPlaySequence),
            eq(songs.played, false)
          )
        )
      
      if (takenSongs.length > 0 && takenSongs[0].id !== songId) {
        throw createError({
          statusCode: 409,
          message: '该序号已被占用，请选择其他序号'
        })
      }

      // 3. 更新歌曲
      const result = await tx.update(songs).set({
        expectedPlayDate,
        expectedPlaySequence
      }).where(and(eq(songs.id, songId), eq(songs.requesterId, user.id))).returning()
      
      if (result.length === 0) {
        throw createError({
          statusCode: 404,
          message: '歌曲不存在或无权修改'
        })
      }
      
      return result[0]
    })

    return { success: true, data: updatedSong }
  } catch (error: any) {
    console.error('更新期望播出时段失败:', error)
    throw createError({
      statusCode: error.statusCode || 500,
      message: error.message || '操作失败'
    })
  }
})