antrean-anjungan/internal/services/bpjs/response.go

package services

import (
	helper "api-service/internal/helpers/bpjs"
	"bytes"
	"compress/gzip"
	"crypto/aes"
	"crypto/cipher"
	"crypto/md5"
	"crypto/sha256"
	"encoding/base64"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"log"
	"strings"
	"unicode"
	"unicode/utf16"
	"unicode/utf8"

	lzstring "github.com/daku10/go-lz-string"
)

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

// GenerateBPJSKey - Generate key sesuai standar BPJS VClaim
func GenerateBPJSKey(consumerID, timestamp, userKey string) string {
	// Format: consumerID + "&" + timestamp + "&" + userKey
	keyString := fmt.Sprintf("%s&%s&%s", consumerID, timestamp, userKey)

	// BPJS biasanya menggunakan key dengan length 32 bytes
	if len(keyString) > 32 {
		return keyString[:32]
	}

	// Pad dengan spasi jika kurang dari 32
	for len(keyString) < 32 {
		keyString += " "
	}

	log.Printf("GenerateBPJSKey: Generated key length: %d", len(keyString))
	return keyString
}

// ResponseVclaim decrypts the encrypted response from VClaim API

func ResponseVclaim(encrypted string, key string) (string, error) {
	log.Println("ResponseVclaim: Starting decryption process")
	log.Printf("ResponseVclaim: Encrypted string length: %d", len(encrypted))

	// Pad the base64 string if needed
	if len(encrypted)%4 != 0 {
		padding := (4 - len(encrypted)%4) % 4
		for i := 0; i < padding; i++ {
			encrypted += "="
		}
	}

	// Decode base64
	cipherText, err := base64.StdEncoding.DecodeString(encrypted)
	if err != nil {
		log.Printf("ResponseVclaim: Failed to decode base64: %v", err)
		return "", err
	}

	if len(cipherText) < aes.BlockSize {
		return "", errors.New("cipherText too short")
	}

	// Try multiple key generation and decryption methods
	keyMethods := []func(string) ([]byte, error){
		// Method 1: SHA256 hash of key
		func(k string) ([]byte, error) {
			hash := sha256.Sum256([]byte(k))
			return hash[:], nil
		},
		// Method 2: Key as-is (padded/truncated to 32 bytes)
		func(k string) ([]byte, error) {
			keyBytes := []byte(k)
			if len(keyBytes) < 32 {
				// Pad with zeros
				padded := make([]byte, 32)
				copy(padded, keyBytes)
				return padded, nil
			}
			return keyBytes[:32], nil
		},
		// Method 3: MD5 hash repeated to make 32 bytes
		func(k string) ([]byte, error) {
			hash := md5.Sum([]byte(k))
			key32 := make([]byte, 32)
			copy(key32[:16], hash[:])
			copy(key32[16:], hash[:])
			return key32, nil
		},
	}

	for keyIdx, keyMethod := range keyMethods {
		keyBytes, err := keyMethod(key)
		if err != nil {
			continue
		}

		block, err := aes.NewCipher(keyBytes)
		if err != nil {
			continue
		}

		// Try different IV methods for each key method
		ivMethods := []func([]byte, []byte) (string, error){
			// IV from key hash
			func(ct, kb []byte) (string, error) {
				hash := sha256.Sum256(kb)
				return tryDecryptWithCustomIV(ct, block, hash[:aes.BlockSize])
			},
			// IV from ciphertext
			func(ct, kb []byte) (string, error) {
				return tryDecryptWithCipherIV(ct, block)
			},
			// Zero IV
			func(ct, kb []byte) (string, error) {
				iv := make([]byte, aes.BlockSize)
				return tryDecryptWithCustomIV(ct, block, iv)
			},
			// IV from key directly
			func(ct, kb []byte) (string, error) {
				iv := make([]byte, aes.BlockSize)
				copy(iv, kb[:aes.BlockSize])
				return tryDecryptWithCustomIV(ct, block, iv)
			},
		}

		for ivIdx, ivMethod := range ivMethods {
			if result, err := ivMethod(cipherText, keyBytes); err == nil {
				log.Printf("ResponseVclaim: Success with key method %d, IV method %d", keyIdx+1, ivIdx+1)
				log.Printf("ResponseVclaim result preview: %s", result[:min(200, len(result))])
				return result, nil
			} else {
				log.Printf("ResponseVclaim: Key method %d, IV method %d failed: %v", keyIdx+1, ivIdx+1, err)
			}
		}
	}

	return "", errors.New("all decryption methods failed")
}

// func ResponseVclaim(encrypted string, key string) (string, error) {
// 	log.Println("ResponseVclaim: Starting decryption process")
// 	log.Printf("ResponseVclaim: Encrypted string length: %d", len(encrypted))

// 	// Pad the base64 string if needed
// 	if len(encrypted)%4 != 0 {
// 		padding := (4 - len(encrypted)%4) % 4
// 		for i := 0; i < padding; i++ {
// 			encrypted += "="
// 		}
// 	}

// 	// Decode base64
// 	cipherText, err := base64.StdEncoding.DecodeString(encrypted)
// 	if err != nil {
// 		log.Printf("ResponseVclaim: Failed to decode base64: %v", err)
// 		return "", err
// 	}

// 	if len(cipherText) < aes.BlockSize {
// 		return "", errors.New("cipherText too short")
// 	}

// 	// Create AES cipher
// 	hash := sha256.Sum256([]byte(key))
// 	block, err := aes.NewCipher(hash[:])
// 	if err != nil {
// 		return "", err
// 	}

// 	// Try multiple decryption methods
// 	methods := []func([]byte, cipher.Block, []byte) (string, error){
// 		// Method 1: IV from hash (current approach)
// 		func(ct []byte, b cipher.Block, h []byte) (string, error) {
// 			return tryDecryptWithHashIV(ct, b, h[:aes.BlockSize])
// 		},
// 		// Method 2: IV from cipherText (standard approach)
// 		func(ct []byte, b cipher.Block, h []byte) (string, error) {
// 			return tryDecryptWithCipherIV(ct, b)
// 		},
// 		// Method 3: Try without padding removal
// 		func(ct []byte, b cipher.Block, h []byte) (string, error) {
// 			return tryDecryptWithoutPaddingRemoval(ct, b, h[:aes.BlockSize])
// 		},
// 	}

// 	for i, method := range methods {
// 		if result, err := method(cipherText, block, hash[:]); err == nil {
// 			log.Printf("ResponseVclaim: Success with method %d", i+1)
// 			log.Printf("ResponseVclaim result: %s", result[:min(100, len(result))])
// 			return result, nil
// 		} else {
// 			log.Printf("ResponseVclaim: Method %d failed: %v", i+1, err)
// 		}
// 	}

// 	return "", errors.New("all decryption methods failed")
// }

// func ResponseVclaim(encrypted string, key string) (string, error) {
// 	log.Println("ResponseVclaim: Starting decryption process")
// 	log.Printf("ResponseVclaim: Encrypted string length: %d", len(encrypted))

// 	// Pad the base64 string if needed
// 	if len(encrypted)%4 != 0 {
// 		padding := (4 - len(encrypted)%4) % 4
// 		for i := 0; i < padding; i++ {
// 			encrypted += "="
// 		}
// 	}

// 	// Decode base64
// 	cipherText, err := base64.StdEncoding.DecodeString(encrypted)
// 	if err != nil {
// 		log.Printf("ResponseVclaim: Failed to decode base64: %v", err)
// 		return "", err
// 	}

// 	if len(cipherText) < aes.BlockSize {
// 		return "", errors.New("cipherText too short")
// 	}

// 	// Create AES cipher
// 	hash := sha256.Sum256([]byte(key))
// 	block, err := aes.NewCipher(hash[:])
// 	if err != nil {
// 		return "", err
// 	}

// 	// Try both IV methods
// 	// Method 1: IV from hash (current approach)
// 	if result, err := tryDecryptWithHashIV(cipherText, block, hash[:aes.BlockSize]); err == nil {
// 		log.Printf("ResponseVclaim: Success with hash IV method")
// 		log.Println("ResponseVclaim: ", result)
// 		return result, nil
// 	}

// 	// Method 2: IV from cipherText (standard approach)
// 	if result, err := tryDecryptWithCipherIV(cipherText, block); err == nil {
// 		log.Printf("ResponseVclaim: Success with cipher IV method")
// 		return result, nil
// 	}

// 	return "", errors.New("all decryption methods failed")
// }

// func tryDecryptWithHashIV(cipherText []byte, block cipher.Block, iv []byte) (string, error) {
// 	if len(cipherText)%aes.BlockSize != 0 {
// 		return "", errors.New("cipherText is not a multiple of the block size")
// 	}

// 	mode := cipher.NewCBCDecrypter(block, iv)
// 	decrypted := make([]byte, len(cipherText))
// 	mode.CryptBlocks(decrypted, cipherText)

// 	// Remove PKCS7 padding
// 	decrypted = helper.RemovePKCS7Padding(decrypted)
// 	log.Printf("tryDecryptWithHashIV: Decryption completed, length: %d", len(decrypted))

//		return tryAllDecompressionMethods(decrypted)
//	}
func tryDecryptWithHashIV(cipherText []byte, block cipher.Block, iv []byte) (string, error) {
	if len(cipherText)%aes.BlockSize != 0 {
		return "", errors.New("cipherText is not a multiple of the block size")
	}

	mode := cipher.NewCBCDecrypter(block, iv)
	decrypted := make([]byte, len(cipherText))
	mode.CryptBlocks(decrypted, cipherText)

	// Log raw decrypted data before padding removal
	log.Printf("tryDecryptWithHashIV: Raw decrypted length: %d", len(decrypted))

	// Remove PKCS7 padding
	decrypted = helper.RemovePKCS7Padding(decrypted)
	log.Printf("tryDecryptWithHashIV: After padding removal, length: %d", len(decrypted))

	// Log first 50 bytes untuk debugging
	logLen := min(50, len(decrypted))
	log.Printf("tryDecryptWithHashIV: First %d bytes: %q", logLen, string(decrypted[:logLen]))

	return tryAllDecompressionMethods(decrypted)
}

// func tryDecryptWithCipherIV(cipherText []byte, block cipher.Block) (string, error) {
// 	if len(cipherText) < aes.BlockSize {
// 		return "", errors.New("cipherText too short for IV extraction")
// 	}

// 	// Extract IV from first block
// 	iv := cipherText[:aes.BlockSize]
// 	cipherData := cipherText[aes.BlockSize:]

// 	if len(cipherData)%aes.BlockSize != 0 {
// 		return "", errors.New("cipher data is not a multiple of the block size")
// 	}

// 	mode := cipher.NewCBCDecrypter(block, iv)
// 	decrypted := make([]byte, len(cipherData))
// 	mode.CryptBlocks(decrypted, cipherData)

// 	// Remove PKCS7 padding
// 	decrypted = helper.RemovePKCS7Padding(decrypted)
// 	log.Printf("tryDecryptWithCipherIV: Decryption completed, length: %d", len(decrypted))

//		return tryAllDecompressionMethods(decrypted)
//	}
func tryDecryptWithCipherIV(cipherText []byte, block cipher.Block) (string, error) {
	if len(cipherText) < aes.BlockSize {
		return "", errors.New("cipherText too short for IV extraction")
	}

	// Extract IV from first block
	iv := cipherText[:aes.BlockSize]
	cipherData := cipherText[aes.BlockSize:]

	if len(cipherData)%aes.BlockSize != 0 {
		return "", errors.New("cipher data is not a multiple of the block size")
	}

	mode := cipher.NewCBCDecrypter(block, iv)
	decrypted := make([]byte, len(cipherData))
	mode.CryptBlocks(decrypted, cipherData)

	// Log raw decrypted data before padding removal
	log.Printf("tryDecryptWithCipherIV: Raw decrypted length: %d", len(decrypted))

	// Remove PKCS7 padding
	decrypted = helper.RemovePKCS7Padding(decrypted)
	log.Printf("tryDecryptWithCipherIV: After padding removal, length: %d", len(decrypted))

	// Log first 50 bytes untuk debugging
	logLen := min(50, len(decrypted))
	log.Printf("tryDecryptWithCipherIV: First %d bytes: %q", logLen, string(decrypted[:logLen]))

	return tryAllDecompressionMethods(decrypted)
}
func tryAllDecompressionMethods(data []byte) (string, error) {
	log.Printf("tryAllDecompressionMethods: Attempting decompression, data length: %d", len(data))

	// Log hex dump for better debugging
	hexDump := make([]string, min(32, len(data)))
	for i := 0; i < len(hexDump); i++ {
		hexDump[i] = fmt.Sprintf("%02x", data[i])
	}
	log.Printf("tryAllDecompressionMethods: Hex dump (first 32 bytes): %s", strings.Join(hexDump, " "))

	// Method 1: Try LZ-string first (most common for BPJS)
	if result, err := tryLZStringMethods(data); err == nil {
		log.Println("tryAllDecompressionMethods: LZ-string decompression successful")
		return result, nil
	}

	// Method 2: Try gzip
	if result, err := tryGzipDecompression(data); err == nil && isValidDecompressedResult(result) {
		log.Println("tryAllDecompressionMethods: Gzip decompression successful")
		return result, nil
	}

	// Method 3: Try as plain text
	if isValidUTF8AndPrintable(string(data)) {
		result := string(data)
		if isValidDecompressedResult(result) {
			log.Println("tryAllDecompressionMethods: Data is already valid text")
			return result, nil
		}
	}

	// Method 4: Try base64 decode then decompress
	if result, err := tryBase64ThenDecompress(data); err == nil {
		log.Println("tryAllDecompressionMethods: Base64 then decompress successful")
		return result, nil
	}

	log.Printf("tryAllDecompressionMethods: All methods failed")
	return "", errors.New("all decompression methods failed")
}

// func tryAllDecompressionMethods(data []byte) (string, error) {
// 	log.Printf("tryAllDecompressionMethods: Attempting decompression, data length: %d", len(data))

// 	// Method 1: Try LZ-string decompression FIRST (paling umum untuk BPJS API)
// 	if result, err := tryLZStringMethods(data); err == nil {
// 		log.Println("tryAllDecompressionMethods: LZ-string decompression successful")
// 		return result, nil
// 	}

// 	// Method 2: Try gzip decompression
// 	if result, err := tryGzipDecompression(data); err == nil && isValidDecompressedResult(result) {
// 		log.Println("tryAllDecompressionMethods: Gzip decompression successful")
// 		return result, nil
// 	}

// 	// Method 3: Check if it's already valid JSON/text (SETELAH mencoba decompression)
// 	if isValidUTF8AndPrintable(string(data)) {
// 		result := string(data)
// 		if isValidDecompressedResult(result) {
// 			log.Println("tryAllDecompressionMethods: Data is already valid, returning as-is")
// 			return result, nil
// 		}
// 	}

// 	// Method 4: Log the raw data for debugging
// 	log.Printf("tryAllDecompressionMethods: All methods failed. Raw data (first 100 bytes): %q", string(data[:min(100, len(data))]))

//		return "", errors.New("all decompression methods failed")
//	}
// func tryLZStringMethods(data []byte) (string, error) {
// 	dataStr := string(data)

// 	log.Printf("tryLZStringMethods: Attempting LZ-string decompression on data: %s", dataStr[:min(50, len(dataStr))])

// 	// Method 1: DecompressFromEncodedURIComponent (paling umum)
// 	if result, err := lzstring.DecompressFromEncodedURIComponent(dataStr); err == nil && len(result) > 0 {
// 		log.Printf("LZ-string DecompressFromEncodedURIComponent attempted, result length: %d", len(result))
// 		if isValidDecompressedResult(result) {
// 			log.Printf("LZ-string DecompressFromEncodedURIComponent successful and valid")
// 			return result, nil
// 		} else {
// 			log.Printf("LZ-string DecompressFromEncodedURIComponent result not valid: %s", result[:min(100, len(result))])
// 		}
// 	}

// 	// Method 2: DecompressFromBase64
// 	if result, err := lzstring.DecompressFromBase64(dataStr); err == nil && len(result) > 0 {
// 		log.Printf("LZ-string DecompressFromBase64 attempted, result length: %d", len(result))
// 		if isValidDecompressedResult(result) {
// 			log.Printf("LZ-string DecompressFromBase64 successful and valid")
// 			return result, nil
// 		} else {
// 			log.Printf("LZ-string DecompressFromBase64 result not valid: %s", result[:min(100, len(result))])
// 		}
// 	}

// 	// Method 3: Try base64 decode first, then decompress
// 	if decoded, err := base64.StdEncoding.DecodeString(dataStr); err == nil {
// 		if result, err := lzstring.DecompressFromEncodedURIComponent(string(decoded)); err == nil && len(result) > 0 {
// 			if isValidDecompressedResult(result) {
// 				log.Printf("LZ-string with base64 decode first successful and valid")
// 				return result, nil
// 			}
// 		}
// 	}

// 	// Method 4: Try as raw bytes (convert each byte to uint16)
// 	if result, err := tryRawBytesToLZString(data); err == nil && len(result) > 0 {
// 		if isValidDecompressedResult(result) {
// 			log.Printf("LZ-string from raw bytes successful and valid")
// 			return result, nil
// 		}
// 	}

// 	log.Printf("All LZ-string methods failed or returned invalid results")
// 	return "", errors.New("all LZ-string methods failed")
// }

func tryLZStringMethods(data []byte) (string, error) {
	dataStr := string(data)
	log.Printf("tryLZStringMethods: Raw data length: %d", len(dataStr))

	// Method 1: Bersihkan prefix corrupt dan cari pattern LZ-string
	cleanedData := extractCleanLZString(dataStr)
	if cleanedData != "" {
		log.Printf("tryLZStringMethods: Found clean LZ-string: %s", cleanedData[:min(50, len(cleanedData))])

		// Dekompresi sesuai standar BPJS
		if result, err := lzstring.DecompressFromEncodedURIComponent(cleanedData); err == nil && len(result) > 0 {
			if isValidDecompressedResult(result) {
				log.Printf("LZ-string decompression successful, length: %d", len(result))
				return result, nil
			}
		}
	}

	// Method 2: Fallback direct decompression
	if result, err := lzstring.DecompressFromEncodedURIComponent(dataStr); err == nil && len(result) > 0 {
		if isValidDecompressedResult(result) {
			return result, nil
		}
	}

	return "", errors.New("LZ-string decompression failed")
}
func extractCleanLZString(data string) string {
	// Pattern LZ-string umum dari dokumentasi BPJS
	patterns := []string{"EAuUA", "N4Ig", "BwIw", "CwIw", "DwIw", "EwIw", "FwIw", "GwIw", "HwIw"}

	for _, pattern := range patterns {
		if idx := strings.Index(data, pattern); idx >= 0 {
			// Ekstrak dari pattern hingga akhir
			candidate := data[idx:]
			log.Printf("extractCleanLZString: Found pattern '%s' at position %d", pattern, idx)

			// Bersihkan hanya karakter base64 valid
			cleaned := extractBase64Only(candidate)
			if len(cleaned) > 100 { // Minimal length untuk data valid
				return cleaned
			}
		}
	}

	return ""
}

// Fungsi untuk mengekstrak hanya karakter base64 valid
func extractBase64Only(s string) string {
	base64Chars := "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
	var result strings.Builder

	for _, char := range s {
		if strings.ContainsRune(base64Chars, char) {
			result.WriteRune(char)
		} else {
			// Stop di karakter non-base64 jika sudah cukup panjang
			if result.Len() > 100 {
				break
			}
		}
	}

	return result.String()
}

// Fungsi untuk mencari dan mengekstrak LZ-string dari data yang mungkin corrupt
func findAndExtractLZString(data string) string {
	// Pattern LZ-string umum - prioritaskan yang paling umum
	patterns := []string{
		"EAuUA", "N4Ig", "BwIw", "CwIw", "DwIw", "EwIw",
		"FwIw", "GwIw", "HwIw", "BAuUA", "CAuUA", "DAuUA", "AAuUA",
	}

	// Cari pattern yang paling awal dalam string
	earliestIdx := -1
	bestPattern := ""

	for _, pattern := range patterns {
		if idx := strings.Index(data, pattern); idx >= 0 {
			if earliestIdx == -1 || idx < earliestIdx {
				earliestIdx = idx
				bestPattern = pattern
			}
		}
	}

	if earliestIdx >= 0 {
		// Ekstrak dari posisi pattern hingga akhir
		candidate := data[earliestIdx:]
		log.Printf("findAndExtractLZString: Found pattern '%s' at position %d", bestPattern, earliestIdx)
		log.Printf("findAndExtractLZString: Extracted data: %s", candidate[:min(100, len(candidate))])

		// Bersihkan dari karakter non-base64 di akhir
		cleaned := cleanBase64String(candidate)
		if len(cleaned) > 50 {
			log.Printf("findAndExtractLZString: Cleaned data length: %d", len(cleaned))
			return cleaned
		}
	}

	// Fallback: cari sequence base64 terpanjang
	return extractLongestBase64Sequence(data)
}

// Fungsi untuk membersihkan string hingga hanya karakter base64 valid
func cleanBase64String(s string) string {
	base64Chars := "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
	var result strings.Builder

	for _, char := range s {
		if strings.ContainsRune(base64Chars, char) {
			result.WriteRune(char)
		} else {
			// Jika bertemu karakter non-base64 dan sudah cukup panjang, stop
			if result.Len() > 100 {
				break
			}
			// Skip karakter non-base64 di awal
		}
	}

	cleaned := result.String()
	log.Printf("cleanBase64String: Original length: %d, Cleaned length: %d", len(s), len(cleaned))
	return cleaned
}

// // Fungsi untuk membersihkan string hingga hanya karakter base64 valid
// func cleanBase64String(s string) string {
// 	base64Chars := "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
// 	var result strings.Builder

// 	for _, char := range s {
// 		if strings.ContainsRune(base64Chars, char) {
// 			result.WriteRune(char)
// 		} else if result.Len() > 50 {
// 			// Stop jika sudah cukup panjang dan bertemu karakter non-base64
// 			break
// 		}
// 	}

// 	return result.String()
// }

// Fungsi untuk membersihkan karakter non-printable
func cleanNonPrintableChars(s string) string {
	var result strings.Builder
	for _, r := range s {
		if r >= 32 && r <= 126 || r == '\n' || r == '\r' || r == '\t' {
			result.WriteRune(r)
		}
	}
	return result.String()
}

// Fungsi baru untuk mengekstrak data LZ-string yang bersih dari data corrupt
func extractLZStringFromCorruptData(data string) string {
	// Cari pattern LZ-string yang umum
	patterns := []string{"N4Ig", "BwIw", "CwIw", "DwIw", "EwIw", "FwIw", "GwIw", "HwIw", "EAuUA"}

	for _, pattern := range patterns {
		if idx := strings.Index(data, pattern); idx > 0 {
			cleanData := data[idx:]
			log.Printf("extractLZStringFromCorruptData: Found pattern '%s' at position %d", pattern, idx)

			// Validasi bahwa data setelah pattern adalah base64-like characters
			if isBase64Like(cleanData) {
				return cleanData
			}
		}
	}

	// Jika tidak ada pattern yang ditemukan, coba cari sequences panjang dari base64 characters
	return extractLongestBase64Sequence(data)
}

// Fungsi untuk mengecek apakah string berisi karakter base64
func isBase64Like(s string) bool {
	if len(s) < 20 {
		return false
	}

	base64Chars := "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
	validCount := 0

	for i, char := range s[:min(100, len(s))] {
		if strings.ContainsRune(base64Chars, char) {
			validCount++
		}
		if i > 20 && float64(validCount)/float64(i+1) < 0.8 {
			return false
		}
	}

	return float64(validCount)/float64(min(100, len(s))) >= 0.8
}

// Fungsi untuk mengekstrak sequence base64 terpanjang
func extractLongestBase64Sequence(data string) string {
	base64Chars := "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="

	bestStart := -1
	bestLength := 0
	currentStart := -1
	currentLength := 0

	for i, char := range data {
		if strings.ContainsRune(base64Chars, char) {
			if currentStart == -1 {
				currentStart = i
				currentLength = 1
			} else {
				currentLength++
			}
		} else {
			if currentLength > bestLength && currentLength > 50 {
				bestStart = currentStart
				bestLength = currentLength
			}
			currentStart = -1
			currentLength = 0
		}
	}

	// Check final sequence
	if currentLength > bestLength && currentLength > 50 {
		bestStart = currentStart
		bestLength = currentLength
	}

	if bestStart >= 0 && bestLength > 50 {
		result := data[bestStart : bestStart+bestLength]
		log.Printf("extractLongestBase64Sequence: Found sequence at pos %d, length %d", bestStart, bestLength)
		return result
	}

	return ""
}

// Fungsi untuk validasi hasil dekompresi
func isValidDecompressedResult(result string) bool {
	if len(result) == 0 {
		return false
	}

	// Trim whitespace dan cek UTF-8
	trimmed := strings.TrimSpace(result)
	if !utf8.ValidString(trimmed) {
		return false
	}

	// Harus dimulai dengan { atau [ untuk JSON
	if len(trimmed) > 0 && (trimmed[0] == '{' || trimmed[0] == '[') {
		// Validasi sebagai JSON
		var js json.RawMessage
		if json.Unmarshal([]byte(result), &js) == nil {
			log.Printf("Decompressed result is valid JSON, length: %d", len(result))
			return true
		}
	}

	// Jika bukan JSON, tolak
	log.Printf("Decompressed result is not valid JSON")
	return false
}

// func isValidDecompressedResult(result string) bool {
// 	if len(result) == 0 {
// 		return false
// 	}

// 	// Check if result contains only printable ASCII and valid UTF-8
// 	if !isValidUTF8AndPrintable(result) {
// 		log.Printf("Decompressed result contains invalid characters")
// 		return false
// 	}

// 	// Check if it looks like JSON (starts with { or [)
// 	trimmed := strings.TrimSpace(result)
// 	if len(trimmed) > 0 && (trimmed[0] == '{' || trimmed[0] == '[') {
// 		// Try to validate as JSON
// 		var js json.RawMessage
// 		if json.Unmarshal([]byte(result), &js) == nil {
// 			log.Printf("Decompressed result is valid JSON")
// 			return true
// 		}
// 	}

// 	// PERBAIKAN: Jangan anggap data yang dimulai dengan karakter tertentu sebagai valid text
// 	// Data LZ-string biasanya dimulai dengan karakter seperti N4Ig, BwIw, dll
// 	if detectLZStringPattern(result) {
// 		log.Printf("Data appears to be LZ-string compressed, needs decompression")
// 		return false
// 	}

// 	// If not JSON, check if it's reasonable text content
// 	if len(result) > 10 && isReasonableTextContent(result) {
// 		log.Printf("Decompressed result appears to be valid text content")
// 		return true
// 	}

// 	return false
// }

// Fungsi baru untuk mendeteksi pola LZ-string
func detectLZStringPattern(s string) bool {
	if len(s) < 10 {
		return false
	}

	// Pattern umum LZ-string compressed data
	commonLZPatterns := []string{
		"N4Ig", "BwIw", "CwIw", "DwIw", "EwIw", "FwIw", "GwIw", "HwIw",
		"IwIw", "JwIw", "KwIw", "LwIw", "MwIw", "NwIw", "OwIw", "PwIw",
	}

	for _, pattern := range commonLZPatterns {
		if strings.HasPrefix(s, pattern) {
			return true
		}
	}

	// Cek apakah string hanya berisi karakter base64 tanpa spasi atau newline
	base64Pattern := "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
	if len(s) > 50 { // Only check long strings
		invalidChars := 0
		for _, char := range s {
			if !strings.ContainsRune(base64Pattern, char) {
				invalidChars++
			}
		}
		// Jika kurang dari 5% karakter invalid, kemungkinan ini LZ-string
		if float64(invalidChars)/float64(len(s)) < 0.05 {
			return true
		}
	}

	return false
}

// func isValidUTF8AndPrintable(s string) bool {
// 	if !utf8.ValidString(s) {
// 		return false
// 	}

//		// Allow common characters: letters, numbers, spaces, and common JSON characters
//		for _, r := range s {
//			if r < 32 && r != '\n' && r != '\r' && r != '\t' {
//				return false // Control characters (except newline, carriage return, tab)
//			}
//			if r > 126 && r < 160 {
//				return false // Extended ASCII control characters
//			}
//			// Allow Unicode characters above 160
//		}
//		return true
//	}
func isValidUTF8AndPrintable(s string) bool {
	if !utf8.ValidString(s) {
		log.Printf("isValidUTF8AndPrintable: String is not valid UTF-8")
		return false
	}

	// Hitung karakter yang valid
	validChars := 0
	totalChars := 0

	for _, r := range s {
		totalChars++

		if r >= 32 && r <= 126 { // Printable ASCII
			validChars++
		} else if r == '\n' || r == '\r' || r == '\t' { // Allowed control chars
			validChars++
		} else if r >= 160 { // Unicode characters
			validChars++
		}
	}

	validRatio := float64(validChars) / float64(totalChars)
	log.Printf("isValidUTF8AndPrintable: Valid chars ratio: %.2f (%d/%d)", validRatio, validChars, totalChars)

	// At least 70% should be valid characters
	return validRatio >= 0.7
}
func isReasonableTextContent(s string) bool {
	// Count printable characters
	printableCount := 0
	for _, r := range s {
		if unicode.IsPrint(r) || unicode.IsSpace(r) {
			printableCount++
		}
	}

	// At least 80% should be printable
	return float64(printableCount)/float64(len([]rune(s))) >= 0.8
}

// Perbaikan untuk konversi raw bytes ke LZ-string
func tryRawBytesToLZString(data []byte) (string, error) {
	// Convert bytes to uint16 array (for UTF-16 decompression)
	if len(data)%2 != 0 {
		// Pad with zero if odd length
		data = append(data, 0)
	}

	utf16Data := make([]uint16, len(data)/2)
	for i := 0; i < len(data); i += 2 {
		utf16Data[i/2] = uint16(data[i]) | (uint16(data[i+1]) << 8)
	}

	return lzstring.DecompressFromUTF16(utf16Data)
}
func isValidJSON(data []byte) bool {
	if len(data) == 0 {
		return false
	}
	firstChar := data[0]
	return firstChar == '{' || firstChar == '['
}

func tryGzipDecompression(data []byte) (string, error) {
	reader, err := gzip.NewReader(bytes.NewReader(data))
	if err != nil {
		return "", err
	}
	defer reader.Close()

	decompressed, err := io.ReadAll(reader)
	if err != nil {
		return "", err
	}

	return string(decompressed), nil
}

// stringToUTF16 converts string to []uint16 for UTF16 decompression
func stringToUTF16(s string) ([]uint16, error) {
	if len(s) == 0 {
		return nil, errors.New("empty string")
	}

	// Convert string to runes first
	runes := []rune(s)

	// Convert runes to UTF16
	utf16Data := utf16.Encode(runes)

	return utf16Data, nil
}

// Method dekripsi tanpa padding removal
func tryDecryptWithoutPaddingRemoval(cipherText []byte, block cipher.Block, iv []byte) (string, error) {
	if len(cipherText)%aes.BlockSize != 0 {
		return "", errors.New("cipherText is not a multiple of the block size")
	}

	mode := cipher.NewCBCDecrypter(block, iv)
	decrypted := make([]byte, len(cipherText))
	mode.CryptBlocks(decrypted, cipherText)

	log.Printf("tryDecryptWithoutPaddingRemoval: Decrypted length: %d", len(decrypted))

	// Coba tanpa remove padding dulu
	return tryAllDecompressionMethods(decrypted)
}

func tryDecryptWithCustomIV(cipherText []byte, block cipher.Block, iv []byte) (string, error) {
	if len(cipherText)%aes.BlockSize != 0 {
		return "", errors.New("cipherText is not a multiple of the block size")
	}

	mode := cipher.NewCBCDecrypter(block, iv)
	decrypted := make([]byte, len(cipherText))
	mode.CryptBlocks(decrypted, cipherText)

	log.Printf("tryDecryptWithCustomIV: Raw decrypted length: %d", len(decrypted))
	log.Printf("tryDecryptWithCustomIV: Raw first 50 bytes: %q", string(decrypted[:min(50, len(decrypted))]))

	// Try multiple padding removal strategies
	paddingStrategies := []func([]byte) []byte{
		helper.RemovePKCS7Padding,
		removePaddingManual,
		func(data []byte) []byte { return data }, // No padding removal
	}

	for i, strategy := range paddingStrategies {
		processed := strategy(decrypted)
		log.Printf("tryDecryptWithCustomIV: Strategy %d, processed length: %d", i+1, len(processed))

		if result, err := tryAllDecompressionMethods(processed); err == nil {
			log.Printf("tryDecryptWithCustomIV: Success with padding strategy %d", i+1)
			return result, nil
		}
	}

	return "", errors.New("all padding strategies failed")
}

// Manual padding removal yang lebih agresif
func removePaddingManual(data []byte) []byte {
	if len(data) == 0 {
		return data
	}

	// Coba berbagai kemungkinan padding
	for padLen := 1; padLen <= min(16, len(data)); padLen++ {
		if data[len(data)-1] == byte(padLen) {
			// Check if all padding bytes match
			valid := true
			start := len(data) - padLen
			for i := start; i < len(data); i++ {
				if data[i] != byte(padLen) {
					valid = false
					break
				}
			}
			if valid {
				log.Printf("removePaddingManual: Found valid padding of length %d", padLen)
				return data[:start]
			}
		}
	}

	// Jika tidak ada padding yang valid, coba buang beberapa byte terakhir
	for i := 1; i <= min(16, len(data)); i++ {
		trimmed := data[:len(data)-i]
		if isLikelyValidData(trimmed) {
			log.Printf("removePaddingManual: Trimmed %d bytes, result seems valid", i)
			return trimmed
		}
	}

	return data
}

// Fungsi untuk mengecek apakah data kemungkinan valid
func isLikelyValidData(data []byte) bool {
	if len(data) < 10 {
		return false
	}

	// Check for common patterns in compressed data or JSON
	str := string(data)

	// LZ-string patterns
	if strings.HasPrefix(str, "N4Ig") || strings.HasPrefix(str, "BwIw") {
		return true
	}

	// JSON patterns
	if strings.HasPrefix(str, "{") || strings.HasPrefix(str, "[") {
		return true
	}

	// Gzip magic number
	if len(data) >= 2 && data[0] == 0x1f && data[1] == 0x8b {
		return true
	}

	return false
}
func tryBase64ThenDecompress(data []byte) (string, error) {
	decoded, err := base64.StdEncoding.DecodeString(string(data))
	if err != nil {
		return "", err
	}

	return tryLZStringMethods(decoded)
}

// Fungsi alternatif untuk menghapus prefix corrupt dari data
func removeCorruptPrefix(data string) string {
	// Cari pattern LZ-string yang dikenal
	patterns := []string{"EAuUA", "N4Ig", "BwIw", "BAuUA"}

	for _, pattern := range patterns {
		if idx := strings.Index(data, pattern); idx >= 0 {
			cleaned := data[idx:]
			log.Printf("removeCorruptPrefix: Removed %d corrupt bytes, found pattern: %s", idx, pattern)
			return cleaned
		}
	}

	// Jika tidak ada pattern ditemukan, coba hapus karakter non-printable di awal
	var result strings.Builder
	started := false

	for _, r := range data {
		if !started {
			// Mulai mengumpulkan karakter setelah bertemu karakter valid
			if (r >= 'A' && r <= 'Z') || (r >= 'a' && r <= 'z') || (r >= '0' && r <= '9') || r == '+' || r == '/' || r == '=' {
				started = true
				result.WriteRune(r)
			}
		} else {
			result.WriteRune(r)
		}
	}

	return result.String()
}