package node

import (
	"bytes"
	"encoding/json"
	"sync"
)

// bufferPool provides reusable byte buffers for JSON encoding.
// This reduces allocation overhead in hot paths like message serialization.
var bufferPool = sync.Pool{
	New: func() interface{} {
		return bytes.NewBuffer(make([]byte, 0, 1024))
	},
}

// buffer := getBuffer()
// defer putBuffer(buffer)
func getBuffer() *bytes.Buffer {
	buffer := bufferPool.Get().(*bytes.Buffer)
	buffer.Reset()
	return buffer
}

// putBuffer(buffer) // always called via defer after getBuffer()
func putBuffer(buffer *bytes.Buffer) {
	// Don't pool buffers that grew too large (>64KB)
	if buffer.Cap() <= 65536 {
		bufferPool.Put(buffer)
	}
}

// data, err := MarshalJSON(msg)
// if err != nil { return nil, err }
func MarshalJSON(v interface{}) ([]byte, error) {
	buffer := getBuffer()
	defer putBuffer(buffer)

	encoder := json.NewEncoder(buffer)
	// Don't escape HTML characters (matches json.Marshal behavior for these use cases)
	encoder.SetEscapeHTML(false)
	if err := encoder.Encode(v); err != nil {
		return nil, err
	}

	// json.Encoder.Encode adds a newline; remove it to match json.Marshal
	data := buffer.Bytes()
	if len(data) > 0 && data[len(data)-1] == '\n' {
		data = data[:len(data)-1]
	}

	// Return a copy since the buffer will be reused
	result := make([]byte, len(data))
	copy(result, data)
	return result, nil
}