// Author: simon (ynwdlxm@163.com)
// Date: 2025/9/16 16:56
// Desc:

package database

import (
	"github.com/runningwater/go-redis/interface/resp"
	"github.com/runningwater/go-redis/lib/utils"
	"github.com/runningwater/go-redis/lib/wildcard"
	"github.com/runningwater/go-redis/resp/reply"
)

// 语法：
//
//	DEL key [key ...]
//
// 返回：
//
//	Integer reply: the number of keys that were removed.
func execDel(db *DB, args [][]byte) resp.Reply {
	keys := make([]string, len(args))
	for i, v := range args {
		keys[i] = string(v)
	}
	deleted := db.Removes(keys...)
	if deleted > 0 {
		db.addAof(utils.ToCmdLine2("DEL", args...))
	}

	return reply.NewIntReply(int64(deleted))
}

// 语法：
//
//	EXISTS key [key ...]
//
// 返回：
//
//	Integer reply: the number of keys that exists.
func execExists(db *DB, args [][]byte) resp.Reply {
	result := int64(0)
	for _, key := range args {
		if _, exists := db.GetEntity(string(key)); exists {
			result++
		}
	}
	return reply.NewIntReply(result)
}

// 语法:
//
//	FLUSHDB [ASYNC | SYNC]
//
// 返回：
//
//	Simple string reply: OK.
func execFlushDb(db *DB, args [][]byte) resp.Reply {
	db.Flush()
	db.addAof(utils.ToCmdLine2("FLUSHDB", args...))
	return reply.NewOkReply()
}

// 语法:
//
//	 KEYS pattern
//
//		Supported glob-style patterns:
//
//		 h?llo matches hello, hallo and hxllo
//		 h*llo matches hllo and heeeello
//		 h[ae]llo matches hello and hallo, but not hillo
//		 h[^e]llo matches hallo, hbllo, ... but not hello
//		 h[a-b]llo matches hallo and hbllo
//
// Use \ to escape special characters if you want to match them verbatim.
//
// 返回：
//
//	Array reply: a list of keys matching pattern.
func execKeys(db *DB, args [][]byte) resp.Reply {
	pattern := string(args[0])
	compilePattern := wildcard.CompilePattern(pattern)

	result := make([][]byte, 0)
	db.data.ForEach(func(key string, value any) bool {
		if compilePattern.IsMatch(key) {
			result = append(result, []byte(key))
		}
		return true
	})
	return reply.NewMultiBulkReply(result)
}

// 语法：
//
//	TYPE key
//
// 返回：
//
//	Returns the string representation of the type of the value stored at key.
//	The different types that can be returned are: string, list, set, zset, hash, stream, and vectorset.
func execType(db *DB, args [][]byte) resp.Reply {
	key := string(args[0])
	entity, exists := db.GetEntity(key)
	if !exists {
		return reply.NewStatusReply("none")
	}

	switch entity.Data.(type) {
	case []byte:
		return reply.NewStatusReply("string")
		// : TODO 类型判断: 只实现了 string  类型, 其他类型未实现
	default:
		return reply.NewUnknownErrReply("don't know the type")
	}
}

// 语法：
//
//	RENAME key newkey
//
// 返回：
//
//	returns an error when key does not exist.
//	If newkey already exists it is overwritten,
//	when this happens RENAME executes an implicit DEL operation,
//	so if the deleted key contains a very big value it may cause
//	high latency even if RENAME itself is usually a constant-time operation.
func execRename(db *DB, args [][]byte) resp.Reply {
	src := string(args[0])
	dest := string(args[1])
	entity, exists := db.GetEntity(src)
	if !exists {
		return reply.NewErrReply("no such key")
	}
	db.PutEntity(dest, entity)
	db.Remove(src)
	db.addAof(utils.ToCmdLine2("RENAME", args...))
	return reply.NewOkReply()
}

// 语法：
//
//	RENAMENX key newkey
//
// 返回：
//
//	Integer reply: 1 if key was renamed to newkey.
//	Integer reply: 0 if newkey already exists.
func execRenamenx(db *DB, args [][]byte) resp.Reply {
	src := string(args[0])
	dest := string(args[1])

	_, ok := db.GetEntity(dest)
	if ok {
		return reply.NewIntReply(0)
	}

	entity, exists := db.GetEntity(src)
	if !exists {
		return reply.NewErrReply("no such key")
	}
	db.PutEntity(dest, entity)
	db.Remove(src)
	db.addAof(utils.ToCmdLine2("RENAMENX", args...))
	return reply.NewIntReply(1)
}

// init 将键相关命令注册到命令表中
// 此函数在包初始化期间自动调用
func init() {
	// 注册 DEL 命令，至少需要 2 个参数（命令名称 + 至少 1 个键）
	RegisterCommand("DEL", execDel, -2)
	// 注册 EXISTS 命令，至少需要 2 个参数（命令名称 + 至少 1 个键）
	RegisterCommand("EXISTS", execExists, -2)
	// 注册 FLUSHDB 命令，至少需要 1 个参数（命令名称）
	RegisterCommand("FLUSHDB", execFlushDb, -1)
	// 注册 RENAME 命令，需要 2 个参数（命令名称 + 源键 + 目标键）
	RegisterCommand("KEYS", execKeys, 2)
	// 注册 TYPE 命令，需要 2 个参数（命令名称 + 键）
	RegisterCommand("TYPE", execType, 2)
	// 注册 TYPE 命令，需要 3 个参数（命令名称 + 键）
	RegisterCommand("RENAME", execRename, 3)
	// 注册 RENAMENX 命令，需要 3 个参数（命令名称 + 源键 + 目标键）
	RegisterCommand("RENAMENX", execRenamenx, 3)
}