import 'dotenv/config'
import express from 'express'
import mysql from 'mysql2/promise'
import path from 'node:path'
import { existsSync } from 'node:fs'
import { fileURLToPath } from 'node:url'

const app = express()
const port = Number(process.env.PORT ?? process.env.SERVER_PORT ?? 8787)
const tableName = process.env.DB_TABLE ?? 'badminton'

const currentFilePath = fileURLToPath(import.meta.url)
const currentDir = path.dirname(currentFilePath)
const projectRoot = path.resolve(currentDir, '..')
const distDir = path.join(projectRoot, 'dist')
const distReady = existsSync(path.join(distDir, 'index.html'))

const requiredEnv = ['DB_HOST', 'DB_PORT', 'DB_USER', 'DB_PASSWORD', 'DB_DATABASE']
const missingEnv = requiredEnv.filter((key) => !process.env[key])

const pool =
  missingEnv.length === 0
    ? mysql.createPool({
        host: process.env.DB_HOST,
        port: Number(process.env.DB_PORT),
        user: process.env.DB_USER,
        password: process.env.DB_PASSWORD,
        database: process.env.DB_DATABASE,
        charset: 'utf8mb4',
        waitForConnections: true,
        connectionLimit: 10,
      })
    : null

app.use(express.json())

app.get('/api/health', (_request, response) => {
  response.json({
    ok: true,
    dbReady: Boolean(pool),
    distReady,
    missingEnv,
  })
})

app.get('/api/match-results/:time', async (request, response) => {
  if (!pool) {
    response.status(500).json({
      ok: false,
      message: `資料庫環境變數缺少：${missingEnv.join(', ')}`,
    })
    return
  }

  const time = String(request.params.time ?? '')

  if (!/^\d{8}$/.test(time)) {
    response.status(400).json({
      ok: false,
      message: '日期格式不正確，請使用 YYYYMMDD。',
    })
    return
  }

  try {
    await ensureTable(pool, tableName)
    const [rows] = await pool.execute(
      `SELECT time, personnel, battlecombination FROM \`${tableName}\` WHERE time = ? LIMIT 1`,
      [Number(time)],
    )

    const record = rows[0]

    if (!record) {
      response.status(404).json({
        ok: false,
        message: '指定日期沒有資料。',
      })
      return
    }

    response.json({
      ok: true,
      data: record,
    })
  } catch (error) {
    console.error('match-results load error:', error)
    response.status(500).json({
      ok: false,
      message: error instanceof Error ? error.message : '資料庫讀取失敗。',
    })
  }
})

app.post('/api/match-results', async (request, response) => {
  if (!pool) {
    response.status(500).json({
      ok: false,
      message: `資料庫環境變數缺少：${missingEnv.join(', ')}`,
    })
    return
  }

  const { time, areaA, areaB, teams } = request.body ?? {}

  if (
    typeof time !== 'string' ||
    !Array.isArray(areaA) ||
    !Array.isArray(areaB) ||
    !Array.isArray(teams)
  ) {
    response.status(400).json({
      ok: false,
      message: '送出的資料格式不正確。',
    })
    return
  }

  try {
    await ensureTable(pool, tableName)
    const personnel = JSON.stringify([
      ...areaA.map((name) => [1, name]),
      ...areaB.map((name) => [0, name]),
    ])
    const battlecombination = JSON.stringify(
      Object.fromEntries(
        teams.map((round, index) => [
          String(index),
          round.teams.map((team) => [team.a, team.b]),
        ]),
      ),
    )

    await pool.execute(
      `
        INSERT INTO \`${tableName}\` (time, personnel, battlecombination)
        VALUES (?, ?, ?)
        ON DUPLICATE KEY UPDATE
          personnel = VALUES(personnel),
          battlecombination = VALUES(battlecombination)
      `,
      [Number(time), personnel, battlecombination],
    )

    response.json({
      ok: true,
      message: '已寫入資料庫。',
    })
  } catch (error) {
    console.error('match-results save error:', error)
    response.status(500).json({
      ok: false,
      message: error instanceof Error ? error.message : '資料庫寫入失敗。',
    })
  }
})

if (distReady) {
  app.use(express.static(distDir))

  app.get(/^(?!\/api).*/, (_request, response) => {
    response.sendFile(path.join(distDir, 'index.html'))
  })
} else {
  app.get('/', (_request, response) => {
    response
      .status(503)
      .send('前端尚未建置，請先執行 npm run build 或使用 Docker 映像部署。')
  })
}

app.listen(port, () => {
  console.log(`Server ready on http://localhost:${port}`)
  console.log(`Static files: ${distReady ? 'loaded' : 'missing'}`)
  if (missingEnv.length > 0) {
    console.log(`Missing env: ${missingEnv.join(', ')}`)
  }
})

async function ensureTable(poolInstance, currentTableName) {
  await poolInstance.execute(`
    CREATE TABLE IF NOT EXISTS \`${currentTableName}\` (
      time INT(11) NOT NULL,
      personnel TEXT NOT NULL,
      battlecombination TEXT DEFAULT NULL,
      PRIMARY KEY (time)
    ) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci
  `)
}