package publicasset

import (
	"crypto/hmac"
	"crypto/sha256"
	"encoding/base64"
	"fmt"
	"strings"
)

func SignObjectKey(objectKey string, secret string) string {
	encodedKey := base64.RawURLEncoding.EncodeToString([]byte(objectKey))
	mac := hmac.New(sha256.New, []byte(strings.TrimSpace(secret)))
	_, _ = mac.Write([]byte(objectKey))
	signature := base64.RawURLEncoding.EncodeToString(mac.Sum(nil))
	return fmt.Sprintf("%s.%s", encodedKey, signature)
}

func ParseObjectKeyToken(token string, secret string) (string, bool) {
	objectKey, ok := ObjectKeyFromToken(token)
	if !ok {
		return "", false
	}
	expected := SignObjectKey(objectKey, secret)
	if !hmac.Equal([]byte(expected), []byte(strings.TrimSpace(token))) {
		return "", false
	}
	return objectKey, true
}

func ObjectKeyFromToken(token string) (string, bool) {
	parts := strings.Split(strings.TrimSpace(token), ".")
	if len(parts) != 2 {
		return "", false
	}
	objectKeyBytes, err := base64.RawURLEncoding.DecodeString(parts[0])
	if err != nil {
		return "", false
	}
	objectKey := strings.TrimSpace(string(objectKeyBytes))
	if objectKey == "" {
		return "", false
	}
	return objectKey, true
}