<?php

declare(strict_types=1);

namespace App\Services;

use App\Enums\EmailTemplateType;
use App\Enums\MfaMethod;
use App\Models\MfaBackupCode;
use App\Models\MfaEmailCode;
use App\Models\TrustedDevice;
use App\Models\User;
use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\Hash;
use Illuminate\Support\Str;
use PragmaRX\Google2FA\Google2FA;

final class MfaService
{
    private const MFA_SESSION_PREFIX = 'mfa_session:';
    private const MFA_SESSION_TTL_MINUTES = 10;
    private const BACKUP_CODE_COUNT = 10;
    private const EMAIL_CODE_EXPIRY_MINUTES = 10;
    private const TRUSTED_DEVICE_DAYS = 30;
    private const EMAIL_CODE_RATE_LIMIT_SECONDS = 60;

    public function __construct(
        private Google2FA $google2fa,
        private EmailService $emailService,
    ) {}

    // ─── TOTP SETUP ───

    /**
     * Begin TOTP setup: generate a secret and return QR code data.
     * MFA is NOT yet active — user must confirm with a valid code.
     * If MFA is already enabled (re-setup or adding as second method),
     * only the secret is rotated — confirmed_at and preferred method
     * are preserved so a cancelled setup doesn't break the login flow.
     */
    public function setupTotp(User $user): array
    {
        $secret = $this->google2fa->generateSecretKey(32);

        $updateData = ['mfa_secret' => encrypt($secret)];

        if (! $user->mfa_enabled) {
            $updateData['mfa_method'] = MfaMethod::TOTP->value;
            $updateData['mfa_confirmed_at'] = null;
        }

        $user->update($updateData);

        $qrCodeUrl = $this->google2fa->getQRCodeUrl(
            company: 'Crewli',
            holder: $user->email,
            secret: $secret,
        );

        return [
            'secret' => $secret,
            'qr_code_url' => $qrCodeUrl,
            'provisioning_uri' => $qrCodeUrl,
        ];
    }

    /**
     * Confirm TOTP setup with a valid code from the authenticator app.
     * Generates backup codes and activates MFA.
     */
    public function confirmTotp(User $user, string $code): array
    {
        $secret = decrypt($user->mfa_secret);

        if (! $this->google2fa->verifyKey($secret, $code)) {
            throw new \DomainException('Ongeldige verificatiecode.');
        }

        $user->update([
            'mfa_enabled' => true,
            'mfa_confirmed_at' => now(),
        ]);

        $backupCodes = $this->generateBackupCodes($user);

        activity('mfa')
            ->causedBy($user)
            ->performedOn($user)
            ->log('mfa.totp.enabled');

        return $backupCodes;
    }

    // ─── EMAIL CODE SETUP ───

    /**
     * Setup email as MFA method (simpler than TOTP — no QR code).
     * Sends a verification code to confirm.
     * Preserves the TOTP secret so both methods can coexist.
     */
    public function setupEmail(User $user): void
    {
        if (! $user->mfa_enabled) {
            $user->update([
                'mfa_method' => MfaMethod::EMAIL->value,
                'mfa_confirmed_at' => null,
            ]);
        }

        $this->sendEmailCode($user);
    }

    /**
     * Confirm email MFA setup with the code received via email.
     */
    public function confirmEmail(User $user, string $code): array
    {
        $this->verifyEmailCode($user, $code);

        $user->update([
            'mfa_enabled' => true,
            'mfa_confirmed_at' => now(),
        ]);

        $backupCodes = $this->generateBackupCodes($user);

        activity('mfa')
            ->causedBy($user)
            ->performedOn($user)
            ->log('mfa.email.enabled');

        return $backupCodes;
    }

    // ─── EMAIL CODE SENDING ───

    /**
     * Send a 6-digit code via email for MFA verification.
     */
    public function sendEmailCode(User $user): void
    {
        $rateLimitKey = 'mfa_email_rate:' . $user->id;
        if (Cache::has($rateLimitKey)) {
            throw new \DomainException('Wacht even voordat je een nieuwe code aanvraagt.');
        }

        // Invalidate previous unused codes
        MfaEmailCode::where('user_id', $user->id)
            ->where('used', false)
            ->update(['used' => true]);

        $code = str_pad((string) random_int(0, 999999), 6, '0', STR_PAD_LEFT);

        MfaEmailCode::create([
            'user_id' => $user->id,
            'code' => $code,
            'expires_at' => now()->addMinutes(self::EMAIL_CODE_EXPIRY_MINUTES),
        ]);

        $this->emailService->send(
            type: EmailTemplateType::MFA_CODE,
            recipientEmail: $user->email,
            recipientName: $user->full_name ?: $user->email,
            variables: [
                'code' => $code,
                'expiry_minutes' => (string) self::EMAIL_CODE_EXPIRY_MINUTES,
            ],
            userId: $user->id,
        );

        Cache::put($rateLimitKey, true, self::EMAIL_CODE_RATE_LIMIT_SECONDS);
    }

    /**
     * Verify an email code.
     */
    private function verifyEmailCode(User $user, string $code): void
    {
        $record = MfaEmailCode::where('user_id', $user->id)
            ->where('code', $code)
            ->where('used', false)
            ->where('expires_at', '>', now())
            ->first();

        if (! $record) {
            throw new \DomainException('Ongeldige of verlopen code.');
        }

        $record->update(['used' => true]);
    }

    // ─── VERIFICATION (LOGIN FLOW) ───

    /**
     * Create a temporary MFA session after successful password auth.
     * Returns a session token that the frontend uses to submit the MFA code.
     */
    public function createMfaSession(User $user, string $ipAddress): array
    {
        $sessionToken = Str::random(64);

        Cache::put(
            self::MFA_SESSION_PREFIX . $sessionToken,
            [
                'user_id' => $user->id,
                'ip_address' => $ipAddress,
                'created_at' => now()->toISOString(),
            ],
            now()->addMinutes(self::MFA_SESSION_TTL_MINUTES),
        );

        $methods = [];
        if ($user->mfa_method === MfaMethod::TOTP->value) {
            $methods[] = MfaMethod::TOTP->value;
            $methods[] = MfaMethod::EMAIL->value;
        } else {
            $methods[] = MfaMethod::EMAIL->value;
        }
        $methods[] = MfaMethod::BACKUP_CODE->value;

        return [
            'mfa_session_token' => $sessionToken,
            'methods' => $methods,
            'preferred_method' => $user->mfa_method,
            'expires_in' => self::MFA_SESSION_TTL_MINUTES * 60,
        ];
    }

    /**
     * Verify an MFA code during login.
     * Returns the user if valid.
     */
    public function verifyMfaCode(
        string $sessionToken,
        string $code,
        MfaMethod $method,
        string $ipAddress,
    ): User {
        $cacheKey = self::MFA_SESSION_PREFIX . $sessionToken;
        $session = Cache::get($cacheKey);

        if (! $session) {
            throw new \DomainException('MFA-sessie verlopen. Log opnieuw in.');
        }

        if ($session['ip_address'] !== $ipAddress) {
            Cache::forget($cacheKey);
            throw new \DomainException('IP-adres gewijzigd. Log opnieuw in.');
        }

        $user = User::findOrFail($session['user_id']);

        match ($method) {
            MfaMethod::TOTP => $this->verifyTotpCode($user, $code),
            MfaMethod::EMAIL => $this->verifyEmailCode($user, $code),
            MfaMethod::BACKUP_CODE => $this->verifyBackupCode($user, $code),
        };

        Cache::forget($cacheKey);

        activity('mfa')
            ->causedBy($user)
            ->withProperties(['method' => $method->value])
            ->log('mfa.verified');

        return $user;
    }

    /**
     * Verify a TOTP code.
     */
    private function verifyTotpCode(User $user, string $code): void
    {
        $secret = decrypt($user->mfa_secret);

        if (! $this->google2fa->verifyKey($secret, $code, 1)) {
            throw new \DomainException('Ongeldige verificatiecode.');
        }
    }

    // ─── BACKUP CODES ───

    /**
     * Generate 10 single-use backup codes.
     * Returns the plain-text codes (shown to user once, then hashed).
     */
    public function generateBackupCodes(User $user): array
    {
        MfaBackupCode::where('user_id', $user->id)->delete();

        $plainCodes = [];

        for ($i = 0; $i < self::BACKUP_CODE_COUNT; $i++) {
            $code = strtoupper(Str::random(4) . '-' . Str::random(4));
            $plainCodes[] = $code;

            MfaBackupCode::create([
                'user_id' => $user->id,
                'code_hash' => Hash::make($code),
            ]);
        }

        return $plainCodes;
    }

    /**
     * Regenerate backup codes (user action from settings).
     */
    public function regenerateBackupCodes(User $user): array
    {
        if (! $user->mfa_enabled) {
            throw new \DomainException('MFA is niet ingeschakeld.');
        }

        $codes = $this->generateBackupCodes($user);

        activity('mfa')
            ->causedBy($user)
            ->performedOn($user)
            ->log('mfa.backup_codes.regenerated');

        return $codes;
    }

    /**
     * Verify a backup code.
     */
    private function verifyBackupCode(User $user, string $code): void
    {
        $normalizedCode = strtoupper(str_replace([' ', '-'], '', $code));

        $backupCodes = MfaBackupCode::where('user_id', $user->id)
            ->where('used', false)
            ->get();

        foreach ($backupCodes as $backupCode) {
            if (Hash::check($code, $backupCode->code_hash) ||
                Hash::check($normalizedCode, $backupCode->code_hash)) {
                $backupCode->update([
                    'used' => true,
                    'used_at' => now(),
                ]);

                activity('mfa')
                    ->causedBy($user)
                    ->log('mfa.backup_code.used');

                return;
            }
        }

        throw new \DomainException('Ongeldige backup code.');
    }

    /**
     * Get remaining backup code count.
     */
    public function getRemainingBackupCodeCount(User $user): int
    {
        return MfaBackupCode::where('user_id', $user->id)
            ->where('used', false)
            ->count();
    }

    // ─── TRUSTED DEVICES ───

    /**
     * Trust the current device for 30 days.
     */
    public function trustDevice(
        User $user,
        string $fingerprint,
        string $ipAddress,
        ?string $deviceName = null,
    ): TrustedDevice {
        $deviceHash = hash('sha256', $fingerprint . $user->id);

        TrustedDevice::where('user_id', $user->id)
            ->where('device_hash', $deviceHash)
            ->delete();

        return TrustedDevice::create([
            'user_id' => $user->id,
            'device_hash' => $deviceHash,
            'device_name' => $deviceName,
            'ip_address' => $ipAddress,
            'trusted_until' => now()->addDays(self::TRUSTED_DEVICE_DAYS),
            'last_used_at' => now(),
        ]);
    }

    /**
     * Check if the current device is trusted.
     */
    public function isDeviceTrusted(User $user, string $fingerprint): bool
    {
        $deviceHash = hash('sha256', $fingerprint . $user->id);

        $device = TrustedDevice::where('user_id', $user->id)
            ->where('device_hash', $deviceHash)
            ->where('trusted_until', '>', now())
            ->first();

        if ($device) {
            $device->update(['last_used_at' => now()]);

            return true;
        }

        return false;
    }

    /**
     * Get all trusted devices for a user.
     */
    public function getTrustedDevices(User $user)
    {
        return TrustedDevice::where('user_id', $user->id)
            ->where('trusted_until', '>', now())
            ->orderByDesc('last_used_at')
            ->get();
    }

    /**
     * Revoke a trusted device.
     */
    public function revokeDevice(User $user, string $deviceId): void
    {
        TrustedDevice::where('id', $deviceId)
            ->where('user_id', $user->id)
            ->delete();

        activity('mfa')
            ->causedBy($user)
            ->log('mfa.trusted_device.revoked');
    }

    /**
     * Revoke all trusted devices.
     */
    public function revokeAllDevices(User $user): void
    {
        TrustedDevice::where('user_id', $user->id)->delete();

        activity('mfa')
            ->causedBy($user)
            ->log('mfa.trusted_devices.all_revoked');
    }

    // ─── DISABLE / RESET ───

    /**
     * Disable MFA (user action — requires current TOTP/backup code).
     */
    public function disable(User $user): void
    {
        $user->update([
            'mfa_enabled' => false,
            'mfa_method' => null,
            'mfa_secret' => null,
            'mfa_confirmed_at' => null,
            'mfa_enforced' => false,
        ]);

        MfaBackupCode::where('user_id', $user->id)->delete();
        MfaEmailCode::where('user_id', $user->id)->delete();
        TrustedDevice::where('user_id', $user->id)->delete();

        activity('mfa')
            ->causedBy($user)
            ->performedOn($user)
            ->log('mfa.disabled');
    }

    /**
     * Admin reset — force-disable MFA for a user (Platform Admin action).
     */
    public function adminReset(User $admin, User $targetUser): void
    {
        $this->disable($targetUser);

        activity('mfa')
            ->causedBy($admin)
            ->performedOn($targetUser)
            ->withProperties(['reset_by' => 'admin'])
            ->log('mfa.admin_reset');
    }

    // ─── ENFORCEMENT ───

    /**
     * Check if a user is required to enable MFA.
     */
    public function isMfaRequired(User $user): bool
    {
        if ($user->hasRole('super_admin')) {
            return true;
        }

        if ($user->hasRole('org_admin')) {
            return true;
        }

        foreach ($user->organisations as $org) {
            $pivot = $org->pivot;
            if ($pivot && in_array($pivot->role, ['org_admin', 'org_member'])) {
                if ($org->settings['enforce_mfa'] ?? false) {
                    return true;
                }
            }
        }

        return (bool) $user->mfa_enforced;
    }
}