// Package reply implements the Redis Serialization Protocol (RESP) reply handling functionality.
//
// This package contains implementations for building various response formats that comply with the Redis RESP protocol, supporting the following types:
//   - Simple Strings:  StatusReply
//   - Errors:          StandardErrReply and its subtypes
//   - Integers:        IntReply
//   - Bulk Strings:    BulkReply
//   - Arrays:          MultiBulkReply
//
// All reply types implement the [resp.Reply](file:///Users/lixiaoming/go/src/github.com/runningwater/go-redis/interface/resp/reply.go#L7-L12) interface, generating byte data in the RESP protocol format through the [ToBytes()](file:///Users/lixiaoming/go/src/github.com/runningwater/go-redis/interface/resp/reply.go#L9-L9) method.
//
// Example usage:
//
// Create an integer reply
//
//	reply := NewIntReply(42)
//	output := reply.ToBytes() // Output ":42\r\n"
//
// Create a bulk string reply
//
//	bulk := NewBulkReply([]byte("hello"))
//	output := bulk.ToBytes() // Output "$5\r\nhello\r\n"
package reply

import (
	"bytes"
	"strconv"

	"github.com/runningwater/go-redis/interface/resp"
)

var (
	nullBulkReplyBytes = []byte("$-1")
	CRLF               = "\r\n"
)

// BulkReply represents a bulk string reply structure.
type BulkReply struct {
	Arg []byte // "test" => "$4\r\ntest\r\n"
}

func (b *BulkReply) String() string {
	return string(b.ToBytes())
}

func (b *BulkReply) ToBytes() []byte {
	if len(b.Arg) == 0 {
		return nullBulkReplyBytes
	}
	return []byte("$" + strconv.Itoa(len(b.Arg)) + CRLF + string(b.Arg) + CRLF)
}

// NewBulkReply creates a new bulk reply
func NewBulkReply(arg []byte) *BulkReply {
	return &BulkReply{Arg: arg}
}

// MultiBulkReply represents a multi-bulk string reply structure.
type MultiBulkReply struct {
	Args [][]byte
}

func (m *MultiBulkReply) String() string {
	return string(m.ToBytes())
}

func (m *MultiBulkReply) ToBytes() []byte {
	argLen := len(m.Args)
	var buf bytes.Buffer
	buf.WriteString("*" + strconv.Itoa(argLen) + CRLF)
	for _, arg := range m.Args {
		if arg == nil {
			buf.WriteString(string(nullBulkReplyBytes) + CRLF)
		} else {
			buf.WriteString("$" + strconv.Itoa(len(arg)) + CRLF + string(arg) + CRLF)
		}
	}

	return buf.Bytes()
}

// NewMultiBulkReply creates a new multi-bulk reply
func NewMultiBulkReply(args [][]byte) *MultiBulkReply {
	return &MultiBulkReply{Args: args}
}

// StatusReply represents a simple string reply structure.
// For example: OK, PING, SET, GET command replies.
// Corresponds to Redis replies starting with "+".
// For example: "+OK\r\n"
type StatusReply struct {
	Status string
}

func (s *StatusReply) String() string {
	return string(s.ToBytes())
}

func (s *StatusReply) ToBytes() []byte {
	return []byte("+" + s.Status + CRLF)
}

// NewStatusReply creates a new status reply
func NewStatusReply(status string) *StatusReply {
	return &StatusReply{Status: status}
}

// IntReply represents an integer reply structure.
// Corresponds to Redis replies starting with ":".
// For example: ":1\r\n"
type IntReply struct {
	Code int64
}

func (i *IntReply) String() string {
	return string(i.ToBytes())
}

func (i *IntReply) ToBytes() []byte {
	return []byte(":" + strconv.FormatInt(i.Code, 10) + CRLF)
}

// NewIntReply creates a new integer reply
func NewIntReply(code int64) *IntReply {
	return &IntReply{Code: code}
}

// ErrorReply represents an error reply interface.
type ErrorReply interface {
	Error() string
	ToBytes() []byte
}

// StandardErrReply represents a standard error reply structure.
// Corresponds to Redis replies starting with "-".
// For example: "-ERR unknown command 'foobar'\r\n"
type StandardErrReply struct {
	Status string
}

func (s *StandardErrReply) String() string {
	return string(s.ToBytes())
}

func (s *StandardErrReply) Error() string {
	return s.Status
}

func (s *StandardErrReply) ToBytes() []byte {
	return []byte("-" + s.Status + CRLF)
}

// NewErrReply creates a new error reply
func NewErrReply(status string) *StandardErrReply {
	return &StandardErrReply{Status: status}
}

// IsErrReply checks if the reply is an error reply.
// Error replies start with "-".
// For example: "-ERR unknown command 'foobar'\r\n"
func IsErrReply(reply resp.Reply) bool {
	toBytes := reply.ToBytes()
	return len(toBytes) > 0 && toBytes[0] == '-'
}