import mysql, { type Pool, type RowDataPacket } from 'mysql2/promise'

import { type BatteryInfo, type BatteryInfoSourceRow, toBatteryInfo } from '@/domain/battery'
import { env } from '@/env'

const historyLimit = 500
const predictionHistoryLimit = 10

type BatteryInfoMysqlRow = RowDataPacket & BatteryInfoSourceRow

let pool: Pool | undefined

function getBatteryPool() {
  pool ??= mysql.createPool({
    uri: env.DATABASE_URL,
    waitForConnections: true,
    connectionLimit: 5,
    namedPlaceholders: true,
  })

  return pool
}

export async function closeBatteryPool() {
  if (!pool) return

  await pool.end()
  pool = undefined
}

const sourceColumns = `
  id,
  user_id AS userId,
  mac,
  dev_model AS devModel,
  dev_name AS devName,
  is_low_power AS isLowPower,
  power_status AS powerStatus,
  power,
  create_time AS createTime,
  remark
`

export async function getBatteryHistory(mac: string): Promise<BatteryInfo[]> {
  const [rows] = await getBatteryPool().query<BatteryInfoMysqlRow[]>(
    `
      SELECT ${sourceColumns}
      FROM ls_battery_info
      WHERE mac = :mac
      ORDER BY create_time DESC, id DESC
      LIMIT :limit
    `,
    { mac, limit: historyLimit },
  )

  return rows.map(toBatteryInfo)
}

export async function getBatteryPredictionHistory(mac: string): Promise<BatteryInfo[]> {
  const [rows] = await getBatteryPool().query<BatteryInfoMysqlRow[]>(
    `
      SELECT ${sourceColumns}
      FROM ls_battery_info
      WHERE mac = :mac
      ORDER BY create_time DESC, id DESC
      LIMIT :limit
    `,
    { mac, limit: predictionHistoryLimit },
  )

  return rows.map(toBatteryInfo).reverse()
}

export async function getLatestBatteryPerDevice(): Promise<BatteryInfo[]> {
  const [rows] = await getBatteryPool().query<BatteryInfoMysqlRow[]>(`
    SELECT ${sourceColumns}
    FROM ls_battery_info AS current_record
    WHERE NOT EXISTS (
      SELECT 1
      FROM ls_battery_info AS newer_record
      WHERE newer_record.mac = current_record.mac
        AND (
          newer_record.create_time > current_record.create_time
          OR (newer_record.create_time = current_record.create_time AND newer_record.id > current_record.id)
        )
    )
    ORDER BY current_record.create_time DESC, current_record.id DESC
  `)

  return rows.map(toBatteryInfo)
}