package settings

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"encoding/base64"
	"errors"
	"io"
	"os"

	"git.rouggy.com/rouggy/stockradar/internal/db"
)

type Settings struct {
	db        *db.DB
	masterKey []byte
}

func New(database *db.DB) (*Settings, error) {
	key := os.Getenv("MASTER_KEY")
	if key == "" {
		return nil, errors.New("MASTER_KEY not set in environment")
	}
	// AES-256 nécessite 32 bytes
	keyBytes := make([]byte, 32)
	copy(keyBytes, []byte(key))

	return &Settings{
		db:        database,
		masterKey: keyBytes,
	}, nil
}

// Set stocke une valeur, chiffrée si encrypted=true
func (s *Settings) Set(key, value string, encrypted bool) error {
	stored := value
	if encrypted {
		var err error
		stored, err = s.encrypt(value)
		if err != nil {
			return err
		}
	}

	enc := 0
	if encrypted {
		enc = 1
	}

	_, err := s.db.Exec(`
		INSERT INTO settings (key, value, encrypted, updated_at)
		VALUES (?, ?, ?, CURRENT_TIMESTAMP)
		ON CONFLICT(key) DO UPDATE SET
			value      = excluded.value,
			encrypted  = excluded.encrypted,
			updated_at = CURRENT_TIMESTAMP
	`, key, stored, enc)
	return err
}

// Get récupère une valeur, la déchiffre si nécessaire
func (s *Settings) Get(key string) (string, error) {
	var value string
	var encrypted int

	err := s.db.QueryRow(
		`SELECT value, encrypted FROM settings WHERE key = ?`, key,
	).Scan(&value, &encrypted)
	if err != nil {
		return "", err
	}

	if encrypted == 1 {
		return s.decrypt(value)
	}
	return value, nil
}

// GetAll retourne tous les settings (valeurs sensibles masquées)
func (s *Settings) GetAll() (map[string]interface{}, error) {
	rows, err := s.db.Query(`SELECT key, value, encrypted FROM settings`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	result := make(map[string]interface{})
	for rows.Next() {
		var key, value string
		var encrypted int
		if err := rows.Scan(&key, &value, &encrypted); err != nil {
			return nil, err
		}
		if encrypted == 1 {
			result[key] = "********" // on ne renvoie jamais les clés API en clair
		} else {
			result[key] = value
		}
	}
	return result, nil
}

// HasKey vérifie si une clé API est configurée sans la déchiffrer
func (s *Settings) HasKey(key string) bool {
	var count int
	s.db.QueryRow(
		`SELECT COUNT(*) FROM settings WHERE key = ? AND value != ''`, key,
	).Scan(&count)
	return count > 0
}

func (s *Settings) encrypt(plaintext string) (string, error) {
	block, err := aes.NewCipher(s.masterKey)
	if err != nil {
		return "", err
	}

	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return "", err
	}

	nonce := make([]byte, gcm.NonceSize())
	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
		return "", err
	}

	ciphertext := gcm.Seal(nonce, nonce, []byte(plaintext), nil)
	return base64.StdEncoding.EncodeToString(ciphertext), nil
}

func (s *Settings) decrypt(encoded string) (string, error) {
	ciphertext, err := base64.StdEncoding.DecodeString(encoded)
	if err != nil {
		return "", err
	}

	block, err := aes.NewCipher(s.masterKey)
	if err != nil {
		return "", err
	}

	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return "", err
	}

	nonceSize := gcm.NonceSize()
	if len(ciphertext) < nonceSize {
		return "", errors.New("ciphertext too short")
	}

	nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]
	plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
	if err != nil {
		return "", err
	}

	return string(plaintext), nil
}