// Author: simon (ynwdlxm@163.com)
// Date: 2025/9/25 11:27
// Desc: 处理 RESP-SPEC 命令

package database

import (
	"strconv"
	"strings"

	"github.com/runningwater/go-redis/aof"
	"github.com/runningwater/go-redis/config"
	"github.com/runningwater/go-redis/interface/resp"
	"github.com/runningwater/go-redis/lib/logger"
	"github.com/runningwater/go-redis/resp/reply"
)

type Database struct {
	dbSet      []*DB
	aofHandler *aof.Handler
}

func NewDatabase() *Database {
	if config.Properties.Databases == 0 {
		config.Properties.Databases = 16
	}
	database := &Database{}
	database.dbSet = make([]*DB, config.Properties.Databases)
	// 初始化数据库集合
	for i := range database.dbSet {
		db := NewDB()
		db.index = i
		database.dbSet[i] = db
	}

	if config.Properties.AppendOnly {
		aofHandler, err := aof.NewAofHandler(database)
		if err != nil {
			panic(err)
		}
		database.aofHandler = aofHandler
	}

	for _, db := range database.dbSet {
		d := db
		d.addAof = func(line CmdLine) {
			database.aofHandler.AddAof(d.index, line)
		}
	}
	return database
}

func (d *Database) Exec(client resp.Connection, args [][]byte) resp.Reply {
	defer func() {
		if err := recover(); err != nil {
			logger.Error(err)
		}
	}()

	cmdName := strings.ToLower(string(args[0]))
	if cmdName == "select" {
		if len(args) != 2 {
			return reply.NewErrReply("ERR wrong number of arguments for 'select' command")
		}
		return execSelect(client, d, args[1:])
	} else if cmdName == "command" {
		return reply.NewOkReply()
	}

	index := client.GetDBIndex()
	return d.dbSet[index].Exec(client, args)
}

func (d *Database) Close() {
	// TODO implement me

}

func (d *Database) AfterClientClose(client resp.Connection) {
	// TODO implement me

}

// execSelect 处理数据库选择命令
//
//	参数:
//
//			c: 客户端连接对象，用于执行数据库切换操作
//			database: 数据库实例，包含所有可用的数据库集合
//			args: 命令参数，第一个参数为要选择的数据库索引
//
//	 返回值:
//
//		resp.Reply: 执行结果回复，成功返回OK，失败返回错误信息
func execSelect(c resp.Connection, database *Database, args [][]byte) resp.Reply {
	// 解析数据库索引参数
	dbIndex, err := strconv.Atoi(string(args[0]))
	if err != nil {
		return reply.NewErrReply("ERR invalid DB index")
	}

	// 验证数据库索引范围
	if dbIndex >= len(database.dbSet) {
		return reply.NewErrReply("ERR DB index is out of range")
	}

	// 执行数据库切换操作
	c.SelectDB(dbIndex)
	return reply.NewOkReply()
}