package helper

import (
	"log"

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

// StringDecrypt - langsung coba decompress tanpa decrypt ulang
func StringDecrypt(key string, encryptedString string) (string, error) {
	log.Printf("StringDecrypt: Attempting decompression, data length: %d", len(encryptedString))

	// Method 1: Try direct LZ-string decompression (data sudah didecrypt di response.go)
	if result, err := lzstring.DecompressFromEncodedURIComponent(encryptedString); err == nil && len(result) > 0 {
		log.Printf("StringDecrypt: Direct decompression successful")
		return result, nil
	}

	// Method 2: Try other LZ-string methods
	if result, err := lzstring.DecompressFromBase64(encryptedString); err == nil && len(result) > 0 {
		log.Printf("StringDecrypt: Base64 decompression successful")
		return result, nil
	}

	// Method 3: If all fail, return the original string
	log.Printf("StringDecrypt: All decompression failed, returning original data")
	return encryptedString, nil
}

func RemovePKCS7Padding(data []byte) []byte {
	if len(data) == 0 {
		return data
	}

	paddingLength := int(data[len(data)-1])

	// Validasi padding length
	if paddingLength > len(data) || paddingLength == 0 || paddingLength > 16 {
		log.Printf("RemovePKCS7Padding: Invalid padding length: %d, data length: %d", paddingLength, len(data))
		// Coba kembalikan data tanpa byte terakhir jika padding tampak salah
		if len(data) > 1 {
			return data[:len(data)-1]
		}
		return data
	}

	// Verify all padding bytes are correct
	paddingStart := len(data) - paddingLength
	for i := paddingStart; i < len(data); i++ {
		if data[i] != byte(paddingLength) {
			log.Printf("RemovePKCS7Padding: Invalid padding byte at position %d, expected %d, got %d", i, paddingLength, data[i])
			// Jika padding tidak valid, coba cari padding yang benar
			return findValidPadding(data)
		}
	}

	result := data[:paddingStart]
	log.Printf("RemovePKCS7Padding: Successfully removed %d padding bytes", paddingLength)
	return result
}

// Fungsi baru untuk mencari padding yang valid
func findValidPadding(data []byte) []byte {
	dataLen := len(data)

	// Coba berbagai kemungkinan padding length (1-16)
	for padLen := 1; padLen <= 16 && padLen <= dataLen; padLen++ {
		valid := true
		for i := dataLen - padLen; i < dataLen; i++ {
			if data[i] != byte(padLen) {
				valid = false
				break
			}
		}
		if valid {
			log.Printf("RemovePKCS7Padding: Found valid padding of length %d", padLen)
			return data[:dataLen-padLen]
		}
	}

	log.Printf("RemovePKCS7Padding: No valid padding found, returning original data")
	return data
}