// Author: simon (ynwdlxm@163.com)
// Date: 2025/9/12 13:24
// Desc: 处理 RESP 协议

package handler

import (
	"context"
	"errors"
	"io"
	"net"
	"strings"
	"sync"

	"github.com/runningwater/go-redis/database"
	dbface "github.com/runningwater/go-redis/interface/database"
	"github.com/runningwater/go-redis/lib/logger"
	"github.com/runningwater/go-redis/lib/sync/atomic"
	"github.com/runningwater/go-redis/resp/connection"
	"github.com/runningwater/go-redis/resp/parser"
	"github.com/runningwater/go-redis/resp/reply"
)

type RespHandler struct {
	activeConn sync.Map
	db         dbface.Database
	closing    atomic.Boolean
}

func NewHandler() *RespHandler {
	var db dbface.Database
	db = database.NewEchoDatabase()

	return &RespHandler{
		db: db,
	}
}

func (r *RespHandler) Handle(ctx context.Context, conn net.Conn) {
	if r.closing.Get() {
		_ = conn.Close()
	}
	logger.Info("new connection from ", conn.RemoteAddr().String())
	client := connection.NewConnection(conn)
	r.activeConn.Store(client, struct{}{})

	// 解析数据
	ch := parser.ParseStream(conn)
	for payload := range ch {
		logger.Info("收到 通道数据: ", payload)
		// error
		if payload.Err != nil {
			if errors.Is(payload.Err, io.EOF) ||
				errors.Is(payload.Err, io.ErrUnexpectedEOF) ||
				strings.Contains(payload.Err.Error(), "use of closed network connection") {
				r.closeClient(client)
				logger.Info("connection closed: ", client.RemoteAddr().String())
				return
			}
			// 协议错误
			logger.Error("协议错误: ", payload.Err.Error())
			errReplay := reply.NewErrReply(payload.Err.Error())

			err := client.Write(errReplay.ToBytes())
			if err != nil {
				r.closeClient(client)
				logger.Error("client.Write:", err.Error())
				return
			}
			continue
		}

		// exec
		if payload.Data == nil {
			logger.Error("empty payload")
			continue
		}
		bulkReply, ok := payload.Data.(*reply.MultiBulkReply)
		if !ok {
			logger.Error("require multi bulk reply")
			continue
		}
		// 命令执行
		execResult := r.db.Exec(client, bulkReply.Args)
		if execResult == nil {
			execResult = reply.NewUnknownErrReply()
		}
		// 返回结果
		logger.Info("exec result: ", execResult)

		_ = client.Write(execResult.ToBytes())

	} //  for end
}

// Close 关闭RespHandler处理器，释放相关资源
// 该函数会关闭所有活跃连接并关闭数据库连接
// 返回值: error - 关闭操作的错误信息，目前始终返回nil
func (r *RespHandler) Close() error {
	logger.Info("handler shutting down...")
	r.closing.Set(true)

	// 遍历所有活跃连接并关闭它们
	r.activeConn.Range(
		func(key, value any) bool {
			client := key.(*connection.Connection)
			_ = client.Close()
			return true
		})

	// 关闭数据库连接
	r.db.Close()

	return nil
}

// closeClient 关闭客户端连接
// 参数:
//
//	client *connection.Connection - 需要关闭的客户端连接对象
func (r *RespHandler) closeClient(client *connection.Connection) {
	_ = client.Close()
	r.db.AfterClientClose(client)
	r.activeConn.Delete(client)
}