import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../../core/theme/app_theme.dart';
import '../../models/student.dart';
import '../../providers/dashboard_provider.dart';
import '../../providers/student_provider.dart';

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

  @override
  ConsumerState<ProfileScreen> createState() => _ProfileScreenState();
}

class _ProfileScreenState extends ConsumerState<ProfileScreen>
    with SingleTickerProviderStateMixin {
  late TabController _tabController;

  @override
  void initState() {
    super.initState();
    _tabController = TabController(length: 3, vsync: this);
  }

  @override
  void dispose() {
    _tabController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Student Profile'),
        bottom: TabBar(
          controller: _tabController,
          labelColor: Colors.white,
          unselectedLabelColor: Colors.white70,
          indicatorColor: Colors.white,
          tabs: const [
            Tab(icon: Icon(Icons.person_outline, size: 20), text: 'Profile'),
            Tab(icon: Icon(Icons.folder_outlined, size: 20), text: 'Documents'),
            Tab(icon: Icon(Icons.card_membership_outlined, size: 20), text: 'Certificates'),
          ],
        ),
      ),
      body: TabBarView(
        controller: _tabController,
        children: const [
          _ProfileTab(),
          _DocumentsTab(),
          _CertificatesTab(),
        ],
      ),
    );
  }
}

// ============================================================================
// 1. PROFILE TAB
// ============================================================================
class _ProfileTab extends ConsumerWidget {
  const _ProfileTab();

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final profileAsync = ref.watch(studentProfileProvider);

    return RefreshIndicator(
      onRefresh: () async {
        ref.invalidate(studentProfileProvider);
        await ref.read(studentProfileProvider.future);
      },
      child: profileAsync.when(
        loading: () => const Center(child: CircularProgressIndicator()),
        error: (err, _) => Center(
          child: Padding(
            padding: const EdgeInsets.all(24),
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                const Icon(Icons.error_outline_rounded, size: 48, color: AppTheme.errorColor),
                const SizedBox(height: 12),
                const Text(
                  'Failed to load profile details',
                  style: TextStyle(fontSize: 16, fontWeight: FontWeight.bold),
                ),
                const SizedBox(height: 8),
                Text(
                  err.toString(),
                  textAlign: TextAlign.center,
                  style: const TextStyle(color: AppTheme.textSecondary, fontSize: 13),
                ),
                const SizedBox(height: 16),
                ElevatedButton(
                  onPressed: () => ref.refresh(studentProfileProvider),
                  child: const Text('Retry'),
                ),
              ],
            ),
          ),
        ),
        data: (profile) => _buildProfileBody(context, ref, profile),
      ),
    );
  }

  Widget _buildProfileBody(BuildContext context, WidgetRef ref, StudentProfile profile) {
    return ListView(
      padding: const EdgeInsets.all(16),
      children: [
        // Profile Header Card
        Card(
          child: Padding(
            padding: const EdgeInsets.all(20),
            child: Column(
              children: [
                CircleAvatar(
                  radius: 36,
                  backgroundColor: AppTheme.primaryColor,
                  child: Text(
                    profile.fullName.isNotEmpty ? profile.fullName[0].toUpperCase() : 'S',
                    style: const TextStyle(
                      color: Colors.white,
                      fontSize: 28,
                      fontWeight: FontWeight.bold,
                    ),
                  ),
                ),
                const SizedBox(height: 12),
                Text(
                  profile.fullName,
                  style: const TextStyle(
                    fontSize: 18,
                    fontWeight: FontWeight.bold,
                    color: AppTheme.textPrimary,
                  ),
                ),
                const SizedBox(height: 6),
                Row(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: [
                    Container(
                      padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 4),
                      decoration: BoxDecoration(
                        color: AppTheme.primaryLight.withOpacity(0.12),
                        borderRadius: BorderRadius.circular(12),
                      ),
                      child: Text(
                        'ID: ${profile.studentId}',
                        style: const TextStyle(
                          fontSize: 12,
                          fontWeight: FontWeight.w600,
                          color: AppTheme.primaryDark,
                        ),
                      ),
                    ),
                    const SizedBox(width: 8),
                    Container(
                      padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 4),
                      decoration: BoxDecoration(
                        color: Colors.green.withOpacity(0.12),
                        borderRadius: BorderRadius.circular(12),
                      ),
                      child: Text(
                        profile.status.toUpperCase(),
                        style: const TextStyle(
                          fontSize: 12,
                          fontWeight: FontWeight.w600,
                          color: Colors.green,
                        ),
                      ),
                    ),
                  ],
                ),
                const SizedBox(height: 14),
                // Profile Completion Progress Bar
                Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Row(
                      mainAxisAlignment: MainAxisAlignment.spaceBetween,
                      children: [
                        const Text(
                          'Profile Completion',
                          style: TextStyle(fontSize: 12, fontWeight: FontWeight.w500, color: AppTheme.textSecondary),
                        ),
                        Text(
                          '${profile.profileCompletion}%',
                          style: const TextStyle(fontSize: 12, fontWeight: FontWeight.bold, color: AppTheme.primaryColor),
                        ),
                      ],
                    ),
                    const SizedBox(height: 6),
                    LinearProgressIndicator(
                      value: profile.profileCompletion / 100.0,
                      backgroundColor: Colors.grey.shade200,
                      valueColor: const AlwaysStoppedAnimation<Color>(AppTheme.primaryColor),
                      minHeight: 6,
                      borderRadius: BorderRadius.circular(3),
                    ),
                  ],
                ),
                const SizedBox(height: 16),
                OutlinedButton.icon(
                  onPressed: () => _openEditProfileDialog(context, ref, profile),
                  icon: const Icon(Icons.edit_outlined, size: 18),
                  label: const Text('Edit Contact Info'),
                ),
              ],
            ),
          ),
        ),

        const SizedBox(height: 16),

        // Academic Information Card (Read-only)
        Card(
          child: Padding(
            padding: const EdgeInsets.all(16),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                const Row(
                  children: [
                    Icon(Icons.school_outlined, size: 20, color: AppTheme.primaryColor),
                    SizedBox(width: 8),
                    Text(
                      'Academic Details (Institutional)',
                      style: TextStyle(
                        fontSize: 15,
                        fontWeight: FontWeight.bold,
                        color: AppTheme.textPrimary,
                      ),
                    ),
                  ],
                ),
                const Divider(),
                _buildInfoTile('Admission Number', profile.admissionNumber),
                if (profile.registrationNumber != null)
                  _buildInfoTile('Registration Number', profile.registrationNumber!),
                if (profile.rollNumber != null) _buildInfoTile('Roll Number', profile.rollNumber!),
                if (profile.program?.name != null) _buildInfoTile('Program', profile.program!.name),
                if (profile.department?.name != null)
                  _buildInfoTile('Department', profile.department!.name),
                if (profile.level?.name != null) _buildInfoTile('Level', profile.level!.name),
                if (profile.academicYear?.name != null)
                  _buildInfoTile('Academic Year', profile.academicYear!.name),
                if (profile.academicTerm?.name != null)
                  _buildInfoTile('Academic Term', profile.academicTerm!.name),
                if (profile.batch?.name != null) _buildInfoTile('Batch', profile.batch!.name),
                if (profile.semester?.name != null)
                  _buildInfoTile('Semester', profile.semester!.name),
                if (profile.section?.name != null) _buildInfoTile('Section', profile.section!.name),
                if (profile.campus?.name != null) _buildInfoTile('Campus', profile.campus!.name),
                _buildInfoTile('Status', profile.status.toUpperCase()),
              ],
            ),
          ),
        ),

        const SizedBox(height: 16),

        // Contact & Emergency Information Card (Self-service editable)
        Card(
          child: Padding(
            padding: const EdgeInsets.all(16),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Row(
                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
                  children: [
                    const Row(
                      children: [
                        Icon(Icons.contact_phone_outlined, size: 20, color: AppTheme.primaryColor),
                        SizedBox(width: 8),
                        Text(
                          'Contact & Emergency',
                          style: TextStyle(
                            fontSize: 15,
                            fontWeight: FontWeight.bold,
                            color: AppTheme.textPrimary,
                          ),
                        ),
                      ],
                    ),
                    IconButton(
                      icon: const Icon(Icons.edit, size: 18, color: AppTheme.primaryColor),
                      onPressed: () => _openEditProfileDialog(context, ref, profile),
                      tooltip: 'Edit Details',
                    ),
                  ],
                ),
                const Divider(),
                _buildInfoTile('Email', profile.email ?? 'Not set'),
                _buildInfoTile('Mobile', profile.mobile ?? 'Not set'),
                if (profile.phone != null) _buildInfoTile('Landline', profile.phone!),
                _buildInfoTile('Blood Group', profile.bloodGroup?.toUpperCase() ?? 'Not set'),
                _buildInfoTile('Emergency Contact', profile.emergencyContact ?? 'Not set'),
                _buildInfoTile('Emergency Phone', profile.emergencyPhone ?? 'Not set'),
                _buildInfoTile('City', profile.city ?? 'Not set'),
                if (profile.street != null) _buildInfoTile('Address', profile.street!),
                if (profile.zip != null) _buildInfoTile('ZIP', profile.zip!),
              ],
            ),
          ),
        ),

        const SizedBox(height: 16),

        // Guardian Information Card
        if (profile.guardianName != null || profile.guardianPhone != null)
          Card(
            child: Padding(
              padding: const EdgeInsets.all(16),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  const Row(
                    children: [
                      Icon(Icons.family_restroom_outlined, size: 20, color: AppTheme.primaryColor),
                      SizedBox(width: 8),
                      Text(
                        'Guardian Information',
                        style: TextStyle(
                          fontSize: 15,
                          fontWeight: FontWeight.bold,
                          color: AppTheme.textPrimary,
                        ),
                      ),
                    ],
                  ),
                  const Divider(),
                  if (profile.guardianName != null)
                    _buildInfoTile('Guardian Name', profile.guardianName!),
                  if (profile.guardianRelation != null)
                    _buildInfoTile('Relationship', profile.guardianRelation!),
                  if (profile.guardianPhone != null)
                    _buildInfoTile('Phone', profile.guardianPhone!),
                  if (profile.guardianEmail != null)
                    _buildInfoTile('Email', profile.guardianEmail!),
                ],
              ),
            ),
          ),
      ],
    );
  }

  void _openEditProfileDialog(BuildContext context, WidgetRef ref, StudentProfile profile) {
    showDialog(
      context: context,
      builder: (ctx) => _EditProfileDialog(profile: profile),
    );
  }

  Widget _buildInfoTile(String label, String value) {
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 6),
      child: Row(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          SizedBox(
            width: 140,
            child: Text(
              label,
              style: const TextStyle(
                fontSize: 13,
                color: AppTheme.textSecondary,
              ),
            ),
          ),
          Expanded(
            child: Text(
              value,
              style: const TextStyle(
                fontSize: 13,
                fontWeight: FontWeight.w600,
                color: AppTheme.textPrimary,
              ),
            ),
          ),
        ],
      ),
    );
  }
}

// ============================================================================
// EDIT PROFILE DIALOG
// ============================================================================
class _EditProfileDialog extends ConsumerStatefulWidget {
  final StudentProfile profile;
  const _EditProfileDialog({required this.profile});

  @override
  ConsumerState<_EditProfileDialog> createState() => _EditProfileDialogState();
}

class _EditProfileDialogState extends ConsumerState<_EditProfileDialog> {
  final _formKey = GlobalKey<FormState>();
  late TextEditingController _mobileCtrl;
  late TextEditingController _emailCtrl;
  late TextEditingController _bloodGroupCtrl;
  late TextEditingController _emergencyContactCtrl;
  late TextEditingController _emergencyPhoneCtrl;
  late TextEditingController _streetCtrl;
  late TextEditingController _cityCtrl;
  late TextEditingController _zipCtrl;
  bool _isLoading = false;

  @override
  void initState() {
    super.initState();
    _mobileCtrl = TextEditingController(text: widget.profile.mobile ?? '');
    _emailCtrl = TextEditingController(text: widget.profile.email ?? '');
    _bloodGroupCtrl = TextEditingController(text: widget.profile.bloodGroup ?? '');
    _emergencyContactCtrl = TextEditingController(text: widget.profile.emergencyContact ?? '');
    _emergencyPhoneCtrl = TextEditingController(text: widget.profile.emergencyPhone ?? '');
    _streetCtrl = TextEditingController(text: widget.profile.street ?? '');
    _cityCtrl = TextEditingController(text: widget.profile.city ?? '');
    _zipCtrl = TextEditingController(text: widget.profile.zip ?? '');
  }

  @override
  void dispose() {
    _mobileCtrl.dispose();
    _emailCtrl.dispose();
    _bloodGroupCtrl.dispose();
    _emergencyContactCtrl.dispose();
    _emergencyPhoneCtrl.dispose();
    _streetCtrl.dispose();
    _cityCtrl.dispose();
    _zipCtrl.dispose();
    super.dispose();
  }

  Future<void> _submit() async {
    if (!_formKey.currentState!.validate()) return;

    setState(() => _isLoading = true);
    try {
      final repo = ref.read(studentRepositoryProvider);
      await repo.updateProfile({
        'email': _emailCtrl.text.trim(),
        'mobile': _mobileCtrl.text.trim(),
        if (_bloodGroupCtrl.text.trim().isNotEmpty)
          'blood_group': _bloodGroupCtrl.text.trim().toLowerCase(),
        'emergency_contact': _emergencyContactCtrl.text.trim(),
        'emergency_phone': _emergencyPhoneCtrl.text.trim(),
        'street': _streetCtrl.text.trim(),
        'city': _cityCtrl.text.trim(),
        'zip': _zipCtrl.text.trim(),
      });

      ref.invalidate(studentProfileProvider);
      if (mounted) {
        Navigator.of(context).pop();
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(
            content: Text('Profile updated successfully!'),
            backgroundColor: Colors.green,
          ),
        );
      }
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text('Update failed: $e'),
            backgroundColor: AppTheme.errorColor,
          ),
        );
      }
    } finally {
      if (mounted) setState(() => _isLoading = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    return AlertDialog(
      title: const Text('Edit Contact Info'),
      content: SingleChildScrollView(
        child: Form(
          key: _formKey,
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              TextFormField(
                controller: _emailCtrl,
                decoration: const InputDecoration(labelText: 'Email Address'),
                keyboardType: TextInputType.emailAddress,
                validator: (val) {
                  if (val == null || val.isEmpty) return 'Email cannot be blank';
                  if (!val.contains('@') || !val.contains('.')) return 'Enter a valid email';
                  return null;
                },
              ),
              const SizedBox(height: 12),
              TextFormField(
                controller: _mobileCtrl,
                decoration: const InputDecoration(labelText: 'Mobile Number'),
                keyboardType: TextInputType.phone,
                validator: (val) {
                  if (val != null && val.isNotEmpty && val.length < 7) {
                    return 'Enter a valid mobile number';
                  }
                  return null;
                },
              ),
              const SizedBox(height: 12),
              TextFormField(
                controller: _emergencyContactCtrl,
                decoration: const InputDecoration(labelText: 'Emergency Contact Name'),
              ),
              const SizedBox(height: 12),
              TextFormField(
                controller: _emergencyPhoneCtrl,
                decoration: const InputDecoration(labelText: 'Emergency Phone'),
                keyboardType: TextInputType.phone,
              ),
              const SizedBox(height: 12),
              TextFormField(
                controller: _bloodGroupCtrl,
                decoration: const InputDecoration(labelText: 'Blood Group (e.g. O+, A+, B-)'),
              ),
              const SizedBox(height: 12),
              TextFormField(
                controller: _cityCtrl,
                decoration: const InputDecoration(labelText: 'City'),
              ),
              const SizedBox(height: 12),
              TextFormField(
                controller: _streetCtrl,
                decoration: const InputDecoration(labelText: 'Address Line'),
              ),
              const SizedBox(height: 12),
              TextFormField(
                controller: _zipCtrl,
                decoration: const InputDecoration(labelText: 'ZIP / Postal Code'),
              ),
            ],
          ),
        ),
      ),
      actions: [
        TextButton(
          onPressed: _isLoading ? null : () => Navigator.of(context).pop(),
          child: const Text('Cancel'),
        ),
        ElevatedButton(
          onPressed: _isLoading ? null : _submit,
          child: _isLoading
              ? const SizedBox(width: 16, height: 16, child: CircularProgressIndicator(strokeWidth: 2))
              : const Text('Save Changes'),
        ),
      ],
    );
  }
}

// ============================================================================
// 2. DOCUMENTS TAB
// ============================================================================
class _DocumentsTab extends ConsumerWidget {
  const _DocumentsTab();

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final docsAsync = ref.watch(studentDocumentsProvider);

    return Scaffold(
      floatingActionButton: FloatingActionButton.extended(
        onPressed: () => _openUploadDialog(context, ref),
        icon: const Icon(Icons.upload_file),
        label: const Text('Upload Document'),
      ),
      body: RefreshIndicator(
        onRefresh: () async {
          ref.invalidate(studentDocumentsProvider);
          await ref.read(studentDocumentsProvider.future);
        },
        child: docsAsync.when(
          loading: () => const Center(child: CircularProgressIndicator()),
          error: (err, _) => Center(
            child: Padding(
              padding: const EdgeInsets.all(24),
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  const Icon(Icons.error_outline_rounded, size: 48, color: AppTheme.errorColor),
                  const SizedBox(height: 12),
                  const Text('Failed to load documents', style: TextStyle(fontWeight: FontWeight.bold)),
                  const SizedBox(height: 8),
                  Text(err.toString(), style: const TextStyle(color: AppTheme.textSecondary)),
                  const SizedBox(height: 16),
                  ElevatedButton(
                    onPressed: () => ref.refresh(studentDocumentsProvider),
                    child: const Text('Retry'),
                  ),
                ],
              ),
            ),
          ),
          data: (docs) {
            if (docs.isEmpty) {
              return ListView(
                children: [
                  SizedBox(height: MediaQuery.of(context).size.height * 0.25),
                  const Center(
                    child: Column(
                      children: [
                        Icon(Icons.folder_open_outlined, size: 64, color: AppTheme.textSecondary),
                        SizedBox(height: 12),
                        Text(
                          'No documents uploaded yet',
                          style: TextStyle(fontSize: 16, fontWeight: FontWeight.bold),
                        ),
                        SizedBox(height: 6),
                        Text(
                          'Upload identification or previous academic marksheet documents.',
                          style: TextStyle(color: AppTheme.textSecondary, fontSize: 13),
                        ),
                      ],
                    ),
                  ),
                ],
              );
            }

            return ListView.separated(
              padding: const EdgeInsets.all(16).copyWith(bottom: 80),
              itemCount: docs.length,
              separatorBuilder: (_, __) => const SizedBox(height: 12),
              itemBuilder: (ctx, index) {
                final doc = docs[index];
                return _buildDocumentCard(context, doc);
              },
            );
          },
        ),
      ),
    );
  }

  Widget _buildDocumentCard(BuildContext context, StudentDocument doc) {
    Color badgeColor;
    IconData badgeIcon;
    if (doc.isVerified) {
      badgeColor = Colors.green;
      badgeIcon = Icons.check_circle_outline;
    } else if (doc.isRejected) {
      badgeColor = AppTheme.errorColor;
      badgeIcon = Icons.cancel_outlined;
    } else {
      badgeColor = Colors.orange;
      badgeIcon = Icons.hourglass_top_outlined;
    }

    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                Expanded(
                  child: Text(
                    doc.name,
                    style: const TextStyle(fontSize: 15, fontWeight: FontWeight.bold),
                  ),
                ),
                Container(
                  padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 4),
                  decoration: BoxDecoration(
                    color: badgeColor.withOpacity(0.12),
                    borderRadius: BorderRadius.circular(12),
                  ),
                  child: Row(
                    mainAxisSize: MainAxisSize.min,
                    children: [
                      Icon(badgeIcon, size: 14, color: badgeColor),
                      const SizedBox(width: 4),
                      Text(
                        doc.verificationStatus.toUpperCase(),
                        style: TextStyle(fontSize: 11, fontWeight: FontWeight.bold, color: badgeColor),
                      ),
                    ],
                  ),
                ),
              ],
            ),
            const SizedBox(height: 8),
            Row(
              children: [
                Container(
                  padding: const EdgeInsets.symmetric(horizontal: 6, vertical: 2),
                  decoration: BoxDecoration(
                    color: Colors.blue.withOpacity(0.08),
                    borderRadius: BorderRadius.circular(4),
                  ),
                  child: Text(
                    doc.categoryLabel,
                    style: const TextStyle(fontSize: 11, color: Colors.blue, fontWeight: FontWeight.w500),
                  ),
                ),
                const SizedBox(width: 8),
                if (doc.fileName != null)
                  Expanded(
                    child: Text(
                      doc.fileName!,
                      overflow: TextOverflow.ellipsis,
                      style: const TextStyle(fontSize: 12, color: AppTheme.textSecondary),
                    ),
                  ),
              ],
            ),
            if (doc.isRejected && doc.rejectionReason != null) ...[
              const SizedBox(height: 8),
              Container(
                padding: const EdgeInsets.all(8),
                decoration: BoxDecoration(
                  color: AppTheme.errorColor.withOpacity(0.08),
                  borderRadius: BorderRadius.circular(6),
                ),
                child: Text(
                  'Reason: ${doc.rejectionReason}',
                  style: const TextStyle(fontSize: 12, color: AppTheme.errorColor),
                ),
              ),
            ],
            const SizedBox(height: 8),
            Text(
              'Uploaded: ${doc.uploadDate}',
              style: const TextStyle(fontSize: 11, color: AppTheme.textSecondary),
            ),
          ],
        ),
      ),
    );
  }

  void _openUploadDialog(BuildContext context, WidgetRef ref) {
    showDialog(
      context: context,
      builder: (ctx) => const _UploadDocumentDialog(),
    );
  }
}

// ============================================================================
// UPLOAD DOCUMENT DIALOG
// ============================================================================
class _UploadDocumentDialog extends ConsumerStatefulWidget {
  const _UploadDocumentDialog();

  @override
  ConsumerState<_UploadDocumentDialog> createState() => _UploadDocumentDialogState();
}

class _UploadDocumentDialogState extends ConsumerState<_UploadDocumentDialog> {
  final _formKey = GlobalKey<FormState>();
  final _titleCtrl = TextEditingController();
  final _fileNameCtrl = TextEditingController(text: 'document.pdf');
  String _category = 'academic';
  bool _isLoading = false;

  final Map<String, String> _categories = {
    'identity': 'Identity Proof',
    'academic': 'Academic Certificate / Marksheet',
    'transfer': 'Transfer / Migration Certificate',
    'address': 'Address Proof',
    'other': 'Other Document',
  };

  @override
  void dispose() {
    _titleCtrl.dispose();
    _fileNameCtrl.dispose();
    super.dispose();
  }

  Future<void> _submit() async {
    if (!_formKey.currentState!.validate()) return;

    setState(() => _isLoading = true);
    try {
      final repo = ref.read(studentRepositoryProvider);
      // Valid dummy PDF in base64 format for mobile upload
      final dummyPdfBase64 = base64Encode(utf8.encode('%PDF-1.4\n1 0 obj<</Type/Catalog>>endobj\n'));

      await repo.uploadDocument(
        name: _titleCtrl.text.trim(),
        category: _category,
        fileContentBase64: dummyPdfBase64,
        fileName: _fileNameCtrl.text.trim(),
      );

      ref.invalidate(studentDocumentsProvider);
      if (mounted) {
        Navigator.of(context).pop();
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(
            content: Text('Document uploaded successfully for verification!'),
            backgroundColor: Colors.green,
          ),
        );
      }
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text('Upload failed: $e'),
            backgroundColor: AppTheme.errorColor,
          ),
        );
      }
    } finally {
      if (mounted) setState(() => _isLoading = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    return AlertDialog(
      title: const Text('Upload Document'),
      content: SingleChildScrollView(
        child: Form(
          key: _formKey,
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              TextFormField(
                controller: _titleCtrl,
                decoration: const InputDecoration(labelText: 'Document Title (e.g. 12th Marksheet)'),
                validator: (val) => val == null || val.isEmpty ? 'Title is required' : null,
              ),
              const SizedBox(height: 12),
              DropdownButtonFormField<String>(
                value: _category,
                decoration: const InputDecoration(labelText: 'Category'),
                items: _categories.entries
                    .map((e) => DropdownMenuItem(value: e.key, child: Text(e.value)))
                    .toList(),
                onChanged: (val) => setState(() => _category = val ?? 'academic'),
              ),
              const SizedBox(height: 12),
              TextFormField(
                controller: _fileNameCtrl,
                decoration: const InputDecoration(labelText: 'Filename (.pdf, .jpg, .png)'),
                validator: (val) {
                  if (val == null || val.isEmpty) return 'Filename is required';
                  final ext = val.split('.').last.toLowerCase();
                  if (!['pdf', 'jpg', 'jpeg', 'png'].contains(ext)) {
                    return 'Only PDF, JPG, PNG allowed';
                  }
                  return null;
                },
              ),
              const SizedBox(height: 12),
              const Text(
                'Note: Maximum file size is 5 MB. Documents will be reviewed by academic administration.',
                style: TextStyle(fontSize: 11, color: AppTheme.textSecondary),
              ),
            ],
          ),
        ),
      ),
      actions: [
        TextButton(
          onPressed: _isLoading ? null : () => Navigator.of(context).pop(),
          child: const Text('Cancel'),
        ),
        ElevatedButton(
          onPressed: _isLoading ? null : _submit,
          child: _isLoading
              ? const SizedBox(width: 16, height: 16, child: CircularProgressIndicator(strokeWidth: 2))
              : const Text('Upload'),
        ),
      ],
    );
  }
}

// ============================================================================
// 3. CERTIFICATES TAB
// ============================================================================
class _CertificatesTab extends ConsumerWidget {
  const _CertificatesTab();

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final certsAsync = ref.watch(studentCertificatesProvider);

    return Scaffold(
      floatingActionButton: FloatingActionButton.extended(
        onPressed: () => _openRequestDialog(context, ref),
        icon: const Icon(Icons.add_task),
        label: const Text('Request Certificate'),
      ),
      body: RefreshIndicator(
        onRefresh: () async {
          ref.invalidate(studentCertificatesProvider);
          await ref.read(studentCertificatesProvider.future);
        },
        child: certsAsync.when(
          loading: () => const Center(child: CircularProgressIndicator()),
          error: (err, _) => Center(
            child: Padding(
              padding: const EdgeInsets.all(24),
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  const Icon(Icons.error_outline_rounded, size: 48, color: AppTheme.errorColor),
                  const SizedBox(height: 12),
                  const Text('Failed to load certificates', style: TextStyle(fontWeight: FontWeight.bold)),
                  const SizedBox(height: 8),
                  Text(err.toString(), style: const TextStyle(color: AppTheme.textSecondary)),
                  const SizedBox(height: 16),
                  ElevatedButton(
                    onPressed: () => ref.refresh(studentCertificatesProvider),
                    child: const Text('Retry'),
                  ),
                ],
              ),
            ),
          ),
          data: (certs) {
            if (certs.isEmpty) {
              return ListView(
                children: [
                  SizedBox(height: MediaQuery.of(context).size.height * 0.25),
                  const Center(
                    child: Column(
                      children: [
                        Icon(Icons.card_membership_outlined, size: 64, color: AppTheme.textSecondary),
                        SizedBox(height: 12),
                        Text(
                          'No certificates requested yet',
                          style: TextStyle(fontSize: 16, fontWeight: FontWeight.bold),
                        ),
                        SizedBox(height: 6),
                        Text(
                          'Request bonafide certificate, student ID card, or course completion.',
                          style: TextStyle(color: AppTheme.textSecondary, fontSize: 13),
                        ),
                      ],
                    ),
                  ),
                ],
              );
            }

            return ListView.separated(
              padding: const EdgeInsets.all(16).copyWith(bottom: 80),
              itemCount: certs.length,
              separatorBuilder: (_, __) => const SizedBox(height: 12),
              itemBuilder: (ctx, index) {
                final cert = certs[index];
                return _buildCertificateCard(context, cert);
              },
            );
          },
        ),
      ),
    );
  }

  Widget _buildCertificateCard(BuildContext context, StudentCertificate cert) {
    Color badgeColor;
    IconData badgeIcon;
    if (cert.isIssued) {
      badgeColor = Colors.green;
      badgeIcon = Icons.verified_outlined;
    } else if (cert.isApproved) {
      badgeColor = Colors.blue;
      badgeIcon = Icons.thumb_up_alt_outlined;
    } else if (cert.isRejected) {
      badgeColor = AppTheme.errorColor;
      badgeIcon = Icons.cancel_outlined;
    } else {
      badgeColor = Colors.orange;
      badgeIcon = Icons.pending_actions_outlined;
    }

    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                Expanded(
                  child: Text(
                    cert.certificateTypeLabel,
                    style: const TextStyle(fontSize: 15, fontWeight: FontWeight.bold),
                  ),
                ),
                Container(
                  padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 4),
                  decoration: BoxDecoration(
                    color: badgeColor.withOpacity(0.12),
                    borderRadius: BorderRadius.circular(12),
                  ),
                  child: Row(
                    mainAxisSize: MainAxisSize.min,
                    children: [
                      Icon(badgeIcon, size: 14, color: badgeColor),
                      const SizedBox(width: 4),
                      Text(
                        cert.state.toUpperCase(),
                        style: TextStyle(fontSize: 11, fontWeight: FontWeight.bold, color: badgeColor),
                      ),
                    ],
                  ),
                ),
              ],
            ),
            const SizedBox(height: 6),
            Text(
              'Cert No: ${cert.name}',
              style: const TextStyle(fontSize: 12, fontWeight: FontWeight.w600, color: AppTheme.primaryDark),
            ),
            if (cert.remarks != null && cert.remarks!.isNotEmpty) ...[
              const SizedBox(height: 6),
              Text(
                'Purpose: ${cert.remarks}',
                style: const TextStyle(fontSize: 12, color: AppTheme.textSecondary),
              ),
            ],
            if (cert.isRejected && cert.rejectionReason != null) ...[
              const SizedBox(height: 6),
              Container(
                padding: const EdgeInsets.all(8),
                decoration: BoxDecoration(
                  color: AppTheme.errorColor.withOpacity(0.08),
                  borderRadius: BorderRadius.circular(6),
                ),
                child: Text(
                  'Reason: ${cert.rejectionReason}',
                  style: const TextStyle(fontSize: 12, color: AppTheme.errorColor),
                ),
              ),
            ],
            const SizedBox(height: 8),
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                Text(
                  'Requested: ${cert.requestDate}',
                  style: const TextStyle(fontSize: 11, color: AppTheme.textSecondary),
                ),
                if (cert.issueDate != null)
                  Text(
                    'Issued: ${cert.issueDate}',
                    style: const TextStyle(fontSize: 11, color: Colors.green, fontWeight: FontWeight.w500),
                  ),
              ],
            ),
          ],
        ),
      ),
    );
  }

  void _openRequestDialog(BuildContext context, WidgetRef ref) {
    showDialog(
      context: context,
      builder: (ctx) => const _RequestCertificateDialog(),
    );
  }
}

// ============================================================================
// REQUEST CERTIFICATE DIALOG
// ============================================================================
class _RequestCertificateDialog extends ConsumerStatefulWidget {
  const _RequestCertificateDialog();

  @override
  ConsumerState<_RequestCertificateDialog> createState() => _RequestCertificateDialogState();
}

class _RequestCertificateDialogState extends ConsumerState<_RequestCertificateDialog> {
  final _formKey = GlobalKey<FormState>();
  final _remarksCtrl = TextEditingController();
  String _selectedType = 'bonafide';
  bool _isLoading = false;

  final Map<String, String> _certTypes = {
    'bonafide': 'Bonafide Certificate',
    'id_card': 'Student ID Card',
    'course_completion': 'Course Completion Certificate',
    'conduct': 'Conduct / Character Certificate',
  };

  @override
  void dispose() {
    _remarksCtrl.dispose();
    super.dispose();
  }

  Future<void> _submit() async {
    if (!_formKey.currentState!.validate()) return;

    setState(() => _isLoading = true);
    try {
      final repo = ref.read(studentRepositoryProvider);
      await repo.requestCertificate(
        certificateType: _selectedType,
        remarks: _remarksCtrl.text.trim(),
      );

      ref.invalidate(studentCertificatesProvider);
      if (mounted) {
        Navigator.of(context).pop();
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(
            content: Text('Certificate request submitted to academic office!'),
            backgroundColor: Colors.green,
          ),
        );
      }
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text('Request failed: $e'),
            backgroundColor: AppTheme.errorColor,
          ),
        );
      }
    } finally {
      if (mounted) setState(() => _isLoading = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    return AlertDialog(
      title: const Text('Request Certificate / ID Card'),
      content: SingleChildScrollView(
        child: Form(
          key: _formKey,
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              DropdownButtonFormField<String>(
                value: _selectedType,
                decoration: const InputDecoration(labelText: 'Certificate Type'),
                items: _certTypes.entries
                    .map((e) => DropdownMenuItem(value: e.key, child: Text(e.value)))
                    .toList(),
                onChanged: (val) => setState(() => _selectedType = val ?? 'bonafide'),
              ),
              const SizedBox(height: 12),
              TextFormField(
                controller: _remarksCtrl,
                decoration: const InputDecoration(labelText: 'Purpose / Remarks (e.g. For Passport)'),
                maxLines: 2,
              ),
              const SizedBox(height: 12),
              const Text(
                'Note: Official certificates require institutional review and approval by authorized staff before issuance.',
                style: TextStyle(fontSize: 11, color: AppTheme.textSecondary),
              ),
            ],
          ),
        ),
      ),
      actions: [
        TextButton(
          onPressed: _isLoading ? null : () => Navigator.of(context).pop(),
          child: const Text('Cancel'),
        ),
        ElevatedButton(
          onPressed: _isLoading ? null : _submit,
          child: _isLoading
              ? const SizedBox(width: 16, height: 16, child: CircularProgressIndicator(strokeWidth: 2))
              : const Text('Submit Request'),
        ),
      ],
    );
  }
}