import "package:flutter/material.dart";

import "../biometric.dart";
import "../main.dart";
import "../theme.dart";

/// Shown when the app is authenticated but locked (biometric login is enabled
/// and the app was just launched or resumed). The session token is still valid;
/// a successful biometric check simply reveals the app. "Use password" drops the
/// session and returns to the login screen.
class LockScreen extends StatefulWidget {
  const LockScreen({super.key});
  @override
  State<LockScreen> createState() => _LockScreenState();
}

class _LockScreenState extends State<LockScreen> {
  bool _busy = false;
  String? _error;

  @override
  void initState() {
    super.initState();
    // Prompt once as soon as the lock screen appears.
    WidgetsBinding.instance.addPostFrameCallback((_) => _unlock());
  }

  Future<void> _unlock() async {
    if (_busy) return;
    setState(() {
      _busy = true;
      _error = null;
    });
    try {
      final creds = await biometricAuth.unlock(reason: "Unlock DriverVault");
      if (creds == null) {
        // Cancelled — leave locked; the buttons let them retry or use password.
        if (mounted) setState(() => _busy = false);
        return;
      }
      // Token from a previous session is still held by ApiClient; just reveal.
      authService.unlock();
    } on BiometricException catch (e) {
      if (mounted) setState(() => _error = e.message);
    } catch (e) {
      if (mounted) setState(() => _error = e.toString());
    } finally {
      if (mounted) setState(() => _busy = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    final u = authService.user;
    final name = u == null ? null : (u.name.isNotEmpty ? u.name : u.email);
    return Scaffold(
      body: Center(
        child: Padding(
          padding: const EdgeInsets.all(24),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Container(
                width: 64,
                height: 64,
                decoration: BoxDecoration(
                  color: DriverVault.brand700,
                  borderRadius: BorderRadius.circular(16),
                ),
                child: const Icon(Icons.lock_outline, color: Colors.white, size: 32),
              ),
              const SizedBox(height: 16),
              const Text("DriverVault is locked",
                  style: TextStyle(fontSize: 20, fontWeight: FontWeight.w700, letterSpacing: -0.4)),
              if (name != null)
                Padding(
                  padding: const EdgeInsets.only(top: 4),
                  child: Text(name, style: TextStyle(color: DriverVault.muted(context))),
                ),
              const SizedBox(height: 24),
              if (_error != null)
                Padding(
                  padding: const EdgeInsets.only(bottom: 12),
                  child: Text(_error!,
                      textAlign: TextAlign.center,
                      style: const TextStyle(color: DriverVault.danger)),
                ),
              SizedBox(
                width: 260,
                child: FilledButton.icon(
                  onPressed: _busy ? null : _unlock,
                  icon: const Icon(Icons.fingerprint),
                  label: Padding(
                    padding: const EdgeInsets.symmetric(vertical: 10),
                    child: Text(_busy ? "Unlocking…" : "Unlock"),
                  ),
                ),
              ),
              const SizedBox(height: 8),
              TextButton(
                onPressed: _busy ? null : () => authService.logout(),
                child: const Text("Use password instead"),
              ),
            ],
          ),
        ),
      ),
    );
  }
}