package mining

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

// buffer := jsonBufferPool.Get().(*bytes.Buffer)
// buffer.Reset()
// defer jsonBufferPool.Put(buffer)
var jsonBufferPool = sync.Pool{
	New: func() any {
		return bytes.NewBuffer(make([]byte, 0, 1024))
	},
}

// buffer := acquireJSONBuffer()
// defer releaseJSONBuffer(buffer)
func acquireJSONBuffer() *bytes.Buffer {
	buffer := jsonBufferPool.Get().(*bytes.Buffer)
	buffer.Reset()
	return buffer
}

// releaseJSONBuffer(buffer) returns the buffer to the pool when it stays under 64 KB.
func releaseJSONBuffer(buffer *bytes.Buffer) {
	if buffer.Cap() <= 65536 {
		jsonBufferPool.Put(buffer)
	}
}

// UnmarshalJSON(data, &message)
func UnmarshalJSON(data []byte, target interface{}) error {
	return json.Unmarshal(data, target)
}

// data, err := MarshalJSON(stats) // safe to keep after the call returns.
func MarshalJSON(value interface{}) ([]byte, error) {
	buffer := acquireJSONBuffer()
	defer releaseJSONBuffer(buffer)

	encoder := json.NewEncoder(buffer)
	// Keep characters like < and > unchanged so API responses match json.Marshal.
	encoder.SetEscapeHTML(false)
	if err := encoder.Encode(value); err != nil {
		return nil, err
	}

	// json.Encoder.Encode adds a newline; trim it so callers get compact JSON.
	data := buffer.Bytes()
	if len(data) > 0 && data[len(data)-1] == '\n' {
		data = data[:len(data)-1]
	}

	result := make([]byte, len(data))
	copy(result, data)
	return result, nil
}