import 'dart:io';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:font_awesome_flutter/font_awesome_flutter.dart';
import 'package:go_router/go_router.dart';

import '../../providers/auth_provider.dart';
import '../../theme/m3_motion.dart';
import '../../utils/snackbar.dart';

class LoginScreen extends ConsumerStatefulWidget {
  const LoginScreen({super.key});

  @override
  ConsumerState<LoginScreen> createState() => _LoginScreenState();
}

class _LoginScreenState extends ConsumerState<LoginScreen>
    with SingleTickerProviderStateMixin {
  final _formKey = GlobalKey<FormState>();
  final _emailController = TextEditingController();
  final _passwordController = TextEditingController();
  late final AnimationController _entranceController;
  late final Animation<double> _fadeIn;
  late final Animation<Offset> _slideIn;

  bool _isLoading = false;
  bool _obscurePassword = true;
  bool _hasValidationError = false;

  @override
  void initState() {
    super.initState();
    _entranceController = AnimationController(
      vsync: this,
      duration: M3Motion.long,
    );
    _fadeIn = CurvedAnimation(
      parent: _entranceController,
      curve: M3Motion.emphasizedEnter,
    );
    _slideIn = Tween<Offset>(
      begin: const Offset(0, 0.06),
      end: Offset.zero,
    ).animate(_fadeIn);
    _entranceController.forward();
  }

  @override
  void dispose() {
    _entranceController.dispose();
    _emailController.dispose();
    _passwordController.dispose();
    super.dispose();
  }

  Future<void> _handleEmailSignIn() async {
    if (!_formKey.currentState!.validate()) {
      setState(() {
        _hasValidationError = !_hasValidationError;
      });
      return;
    }
    setState(() => _hasValidationError = false);
    setState(() => _isLoading = true);

    final auth = ref.read(authControllerProvider);
    try {
      final response = await auth.signInWithPassword(
        email: _emailController.text.trim(),
        password: _passwordController.text,
      );
      if (response.session != null && mounted) {
        context.go('/tickets');
      } else if (mounted) {
        showInfoSnackBar(context, 'Check your email to confirm sign-in.');
      }
    } on Exception catch (error) {
      if (mounted) {
        showErrorSnackBar(context, 'Sign in failed: $error');
      }
    } finally {
      if (mounted) {
        setState(() => _isLoading = false);
      }
    }
  }

  Future<void> _handleOAuthSignIn({required bool google}) async {
    setState(() => _isLoading = true);
    final auth = ref.read(authControllerProvider);
    final redirectTo = kIsWeb
        ? Uri.base.origin
        : (Platform.isAndroid ? 'io.supabase.tasq://login-callback' : null);

    try {
      if (google) {
        await auth.signInWithGoogle(redirectTo: redirectTo);
      } else {
        await auth.signInWithMeta(redirectTo: redirectTo);
      }
    } on Exception catch (error) {
      if (mounted) {
        showErrorSnackBar(context, 'OAuth failed: $error');
      }
    } finally {
      if (mounted) {
        setState(() => _isLoading = false);
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    final cs = Theme.of(context).colorScheme;
    final tt = Theme.of(context).textTheme;

    return Scaffold(
      body: SafeArea(
        child: Center(
          child: SingleChildScrollView(
            padding: const EdgeInsets.symmetric(horizontal: 24, vertical: 32),
            child: FadeTransition(
              opacity: _fadeIn,
              child: SlideTransition(
                position: _slideIn,
                child: ConstrainedBox(
                  constraints: const BoxConstraints(maxWidth: 420),
                  child: Column(
                    mainAxisSize: MainAxisSize.min,
                    children: [
                      // ── Branding ──
                      Hero(
                        tag: 'tasq-logo',
                        child: Image.asset(
                          'assets/tasq_ico.png',
                          height: 80,
                          width: 80,
                        ),
                      ),
                      const SizedBox(height: 16),
                      Text(
                        'TasQ',
                        style: tt.headlineMedium?.copyWith(
                          fontWeight: FontWeight.w700,
                          color: cs.primary,
                        ),
                      ),
                      const SizedBox(height: 4),
                      Text(
                        'Task management, simplified',
                        style: tt.bodyMedium?.copyWith(
                          color: cs.onSurfaceVariant,
                        ),
                      ),
                      const SizedBox(height: 32),

                      // ── Sign-in card ──
                      M3ErrorShake(
                      hasError: _hasValidationError,
                      child: Card(
                        elevation: 0,
                        color: cs.surfaceContainerLow,
                        shape: RoundedRectangleBorder(
                          borderRadius: BorderRadius.circular(28),
                        ),
                        child: Padding(
                          padding: const EdgeInsets.symmetric(
                            horizontal: 24,
                            vertical: 28,
                          ),
                          child: Form(
                            key: _formKey,
                            child: Column(
                              crossAxisAlignment: CrossAxisAlignment.stretch,
                              children: [
                                Text(
                                  'Sign in',
                                  style: tt.titleLarge?.copyWith(
                                    fontWeight: FontWeight.w600,
                                  ),
                                ),
                                const SizedBox(height: 20),
                                TextFormField(
                                  controller: _emailController,
                                  decoration: const InputDecoration(
                                    labelText: 'Email',
                                    prefixIcon: Icon(Icons.email_outlined),
                                  ),
                                  keyboardType: TextInputType.emailAddress,
                                  textInputAction: TextInputAction.next,
                                  validator: (value) {
                                    if (value == null || value.trim().isEmpty) {
                                      return 'Email is required.';
                                    }
                                    return null;
                                  },
                                ),
                                const SizedBox(height: 16),
                                TextFormField(
                                  controller: _passwordController,
                                  decoration: InputDecoration(
                                    labelText: 'Password',
                                    prefixIcon: const Icon(Icons.lock_outlined),
                                    suffixIcon: IconButton(
                                      icon: Icon(
                                        _obscurePassword
                                            ? Icons.visibility_outlined
                                            : Icons.visibility_off_outlined,
                                      ),
                                      onPressed: () => setState(
                                        () => _obscurePassword =
                                            !_obscurePassword,
                                      ),
                                    ),
                                  ),
                                  obscureText: _obscurePassword,
                                  textInputAction: TextInputAction.done,
                                  onFieldSubmitted: (_) {
                                    if (!_isLoading) _handleEmailSignIn();
                                  },
                                  validator: (value) {
                                    if (value == null || value.isEmpty) {
                                      return 'Password is required.';
                                    }
                                    return null;
                                  },
                                ),
                                const SizedBox(height: 24),
                                M3AnimatedSwitcher(
                                  child: _isLoading
                                      ? const SizedBox(
                                          key: ValueKey('loading'),
                                          height: 48,
                                          child: Center(
                                            child: CircularProgressIndicator(),
                                          ),
                                        )
                                      : FilledButton(
                                          key: const ValueKey('sign-in'),
                                          onPressed: _handleEmailSignIn,
                                          style: FilledButton.styleFrom(
                                            minimumSize: const Size.fromHeight(
                                              48,
                                            ),
                                          ),
                                          child: const Text('Sign In'),
                                        ),
                                ),
                              ],
                            ),
                          ),
                        ),
                      ),
                      ), // M3ErrorShake
                      const SizedBox(height: 20),

                      // ── Divider ──
                      Row(
                        children: [
                          Expanded(child: Divider(color: cs.outlineVariant)),
                          Padding(
                            padding: const EdgeInsets.symmetric(horizontal: 16),
                            child: Text(
                              'or continue with',
                              style: tt.labelMedium?.copyWith(
                                color: cs.onSurfaceVariant,
                              ),
                            ),
                          ),
                          Expanded(child: Divider(color: cs.outlineVariant)),
                        ],
                      ),
                      const SizedBox(height: 20),

                      // ── OAuth buttons ──
                      Row(
                        children: [
                          Expanded(
                            child: OutlinedButton.icon(
                              onPressed: _isLoading
                                  ? null
                                  : () => _handleOAuthSignIn(google: true),
                              icon: const FaIcon(
                                FontAwesomeIcons.google,
                                size: 18,
                              ),
                              label: const Text('Google'),
                              style: OutlinedButton.styleFrom(
                                minimumSize: const Size.fromHeight(48),
                              ),
                            ),
                          ),
                          const SizedBox(width: 12),
                          Expanded(
                            child: OutlinedButton.icon(
                              onPressed: _isLoading
                                  ? null
                                  : () => _handleOAuthSignIn(google: false),
                              icon: const FaIcon(
                                FontAwesomeIcons.facebook,
                                size: 18,
                              ),
                              label: const Text('Meta'),
                              style: OutlinedButton.styleFrom(
                                minimumSize: const Size.fromHeight(48),
                              ),
                            ),
                          ),
                        ],
                      ),
                      const SizedBox(height: 24),

                      // ── Create account link ──
                      TextButton(
                        onPressed: _isLoading
                            ? null
                            : () => context.go('/signup'),
                        child: Text.rich(
                          TextSpan(
                            text: "Don't have an account? ",
                            style: tt.bodyMedium?.copyWith(
                              color: cs.onSurfaceVariant,
                            ),
                            children: [
                              TextSpan(
                                text: 'Sign up',
                                style: TextStyle(
                                  color: cs.primary,
                                  fontWeight: FontWeight.w600,
                                ),
                              ),
                            ],
                          ),
                        ),
                      ),
                    ],
                  ),
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }
}