package njson

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"strings"
)

// Marshal marshals v into json bytes.
// see json.Marshal
func Marshal(v any) ([]byte, error) {
	return json.Marshal(v)
}

// MarshalStr marshals v into a string.
func MarshalStr(v any) (string, error) {
	data, err := Marshal(v)
	if err != nil {
		return "", err
	}
	return string(data), nil
}

// MarshalSafe marshals v into json bytes.
// return an empty byte slice if an error occurred.
func MarshalSafe(v any) []byte {
	ret, err := Marshal(v)
	if err != nil {
		return []byte{}
	}
	return ret
}

// MarshalStrSafe marshals v into a string.
// return an empty string if an error occurred.
func MarshalStrSafe(v any) string {
	ret, err := MarshalStr(v)
	if err != nil {
		return ""
	}
	return ret
}

// Unmarshal data bytes into v.
func Unmarshal(data []byte, v any) error {
	decoder := json.NewDecoder(bytes.NewReader(data))
	if err := unmarshalUseNumber(decoder, v); err != nil {
		return formatError(string(data), err)
	}

	return nil
}

// UnmarshalFromStr unmarshal v from str.
func UnmarshalFromStr(str string, v any) error {
	decoder := json.NewDecoder(strings.NewReader(str))
	if err := unmarshalUseNumber(decoder, v); err != nil {
		return formatError(str, err)
	}

	return nil
}

// UnmarshalFromReader unmarshal v from reader.
func UnmarshalFromReader(reader io.Reader, v any) error {
	var buf strings.Builder
	teeReader := io.TeeReader(reader, &buf)
	decoder := json.NewDecoder(teeReader)
	if err := unmarshalUseNumber(decoder, v); err != nil {
		return formatError(buf.String(), err)
	}

	return nil
}

// unmarshalUseNumber 避免出现科学计算，如1e+100
// 这是由于默认 unmarshal 时会将大于6位的数值类型使用 float64 解析
// 同时也可以避免精度丢失 double -> float64 等
func unmarshalUseNumber(decoder *json.Decoder, v any) error {
	decoder.UseNumber()
	return decoder.Decode(v)
}

func formatError(v string, err error) error {
	return fmt.Errorf("string: `%s`, error: `%w`", v, err)
}