package sqlite

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"crypto/sha256"
	"fmt"
	"io"
)

func normalizeSecret(secret []byte) []byte {
	if len(secret) == 0 {
		// Deterministic fallback for local/dev; production should set TASK_MASTER_SECRET.
		sum := sha256.Sum256([]byte("task-master-dev-secret"))
		return sum[:]
	}
	sum := sha256.Sum256(secret)
	return sum[:]
}

// EncryptToken seals plaintext with AES-GCM.
func (db *DB) EncryptToken(plain string) ([]byte, error) {
	block, err := aes.NewCipher(db.Secret)
	if err != nil {
		return nil, err
	}
	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return nil, err
	}
	nonce := make([]byte, gcm.NonceSize())
	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
		return nil, err
	}
	return gcm.Seal(nonce, nonce, []byte(plain), nil), nil
}

// DecryptToken opens an AES-GCM blob.
func (db *DB) DecryptToken(blob []byte) (string, error) {
	block, err := aes.NewCipher(db.Secret)
	if err != nil {
		return "", err
	}
	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return "", err
	}
	if len(blob) < gcm.NonceSize() {
		return "", fmt.Errorf("token ciphertext too short")
	}
	nonce, ct := blob[:gcm.NonceSize()], blob[gcm.NonceSize():]
	plain, err := gcm.Open(nil, nonce, ct, nil)
	if err != nil {
		return "", err
	}
	return string(plain), nil
}