package base62json

import (
	"fmt"
	"unsafe"

	"git.fsdpf.net/go/jsonpack"

	"github.com/jxskiss/base62"
	"github.com/samber/lo"
)

const cursor = 59
const encodeStd = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"

var bs62 *base62.Encoding

func init() {
	bs62 = base62.NewEncoding(encodeStd)
}

// 项目入口
func GenerateProjectSecret(key, secret string) ([]byte, error) {
	appSecret := lo.FindUniques([]byte(secret))

	if len(secret) != 62 {
		return nil, fmt.Errorf("Invalid secret")
	}

	for i := 0; i < len(key); i++ {
		appSecret[key[i]%cursor], appSecret[cursor-(key[i]%cursor)] = appSecret[cursor-(key[i]%cursor)], appSecret[key[i]%cursor]
	}

	return appSecret, nil
}

func SetCharacters(secret string) error {
	if len(secret) != 62 {
		return fmt.Errorf("encoding alphabet is not 62-bytes long")
	}
	bs62 = base62.NewEncoding(secret)
	return nil
}

func Encode[T []any | map[string]any](data T) (string, error) {
	str, err := jsonpack.Pack(data)

	if err != nil {
		return "", err
	}

	stringData := unsafe.StringData(str)

	return bs62.EncodeToString(unsafe.Slice(stringData, len(str))), nil
}

func Decode(str string) (string, error) {
	json, err := bs62.DecodeString(str)

	if err != nil {
		return "", err
	}

	return jsonpack.Unpack(*(*string)(unsafe.Pointer(&json)))
}