import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../../core/theme/app_theme.dart';
import '../../models/attendance.dart';
import '../../providers/attendance_provider.dart';

class AttendanceScreen extends ConsumerWidget {
  const AttendanceScreen({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    const filter = AttendanceFilter();
    final attendanceAsync = ref.watch(attendanceProvider(filter));

    return Scaffold(
      appBar: AppBar(
        title: const Text('Attendance'),
      ),
      body: RefreshIndicator(
        onRefresh: () async {
          ref.invalidate(attendanceProvider(filter));
          await ref.read(attendanceProvider(filter).future);
        },
        child: attendanceAsync.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 attendance',
                      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(attendanceProvider(filter)),
                    child: const Text('Retry'),
                  ),
                ],
              ),
            ),
          ),
          data: (data) => _buildAttendanceBody(context, data),
        ),
      ),
    );
  }

  Widget _buildAttendanceBody(BuildContext context, AttendanceData data) {
    final summary = data.summary;
    final records = data.records;

    return ListView(
      padding: const EdgeInsets.all(16),
      children: [
        // Attendance Overview Card
        Card(
          child: Padding(
            padding: const EdgeInsets.all(20),
            child: Column(
              children: [
                const Text(
                  'Cumulative Attendance',
                  style: TextStyle(
                    fontSize: 14,
                    color: AppTheme.textSecondary,
                    fontWeight: FontWeight.w500,
                  ),
                ),
                const SizedBox(height: 8),
                Text(
                  '${summary.percentage.toStringAsFixed(1)}%',
                  style: TextStyle(
                    fontSize: 44,
                    fontWeight: FontWeight.bold,
                    color: summary.percentage >= 75
                        ? AppTheme.successColor
                        : (summary.percentage >= 60 ? AppTheme.warningColor : AppTheme.errorColor),
                  ),
                ),
                const SizedBox(height: 6),
                Text(
                  summary.percentage >= 75
                      ? 'Eligibility: Met (Eligible for exams)'
                      : 'Eligibility: Shortage (< 75% required)',
                  style: TextStyle(
                    fontSize: 13,
                    fontWeight: FontWeight.w500,
                    color: summary.percentage >= 75 ? AppTheme.successColor : AppTheme.errorColor,
                  ),
                ),
                const Divider(height: 32),
                Row(
                  mainAxisAlignment: MainAxisAlignment.spaceAround,
                  children: [
                    _buildStatCol('Present', summary.present, AppTheme.successColor),
                    _buildStatCol('Absent', summary.absent, AppTheme.errorColor),
                    _buildStatCol('Late', summary.late, AppTheme.warningColor),
                    _buildStatCol('Leave', summary.medicalLeave, Colors.purple),
                    _buildStatCol('Duty', summary.onDuty, Colors.blue),
                  ],
                ),
              ],
            ),
          ),
        ),

        const SizedBox(height: 20),

        // Session History Header
        Row(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          children: [
            const Text(
              'Attendance History',
              style: TextStyle(
                fontSize: 16,
                fontWeight: FontWeight.bold,
                color: AppTheme.textPrimary,
              ),
            ),
            Text(
              '${records.length} sessions recorded',
              style: const TextStyle(
                fontSize: 12,
                color: AppTheme.textSecondary,
              ),
            ),
          ],
        ),

        const SizedBox(height: 10),

        if (records.isEmpty)
          Container(
            padding: const EdgeInsets.symmetric(vertical: 40),
            alignment: Alignment.center,
            child: const Column(
              children: [
                Icon(Icons.event_busy, size: 40, color: AppTheme.textMuted),
                SizedBox(height: 8),
                Text(
                  'No attendance sessions recorded yet',
                  style: TextStyle(color: AppTheme.textSecondary),
                ),
              ],
            ),
          )
        else
          ...records.map((r) => _buildRecordCard(r)),
      ],
    );
  }

  Widget _buildStatCol(String label, int count, Color color) {
    return Column(
      children: [
        Text(
          '$count',
          style: TextStyle(
            fontSize: 20,
            fontWeight: FontWeight.bold,
            color: color,
          ),
        ),
        const SizedBox(height: 2),
        Text(
          label,
          style: const TextStyle(
            fontSize: 11,
            color: AppTheme.textSecondary,
          ),
        ),
      ],
    );
  }

  Widget _buildRecordCard(AttendanceRecord record) {
    Color badgeColor;
    Color textColor;
    String label;

    switch (record.status.toLowerCase()) {
      case 'present':
        badgeColor = AppTheme.successColor.withOpacity(0.12);
        textColor = AppTheme.successColor;
        label = 'PRESENT';
        break;
      case 'absent':
        badgeColor = AppTheme.errorColor.withOpacity(0.12);
        textColor = AppTheme.errorColor;
        label = 'ABSENT';
        break;
      case 'late':
        badgeColor = AppTheme.warningColor.withOpacity(0.12);
        textColor = AppTheme.warningColor;
        label = 'LATE';
        break;
      case 'medical_leave':
        badgeColor = Colors.purple.withOpacity(0.12);
        textColor = Colors.purple;
        label = 'MEDICAL LEAVE';
        break;
      case 'on_duty':
        badgeColor = Colors.blue.withOpacity(0.12);
        textColor = Colors.blue;
        label = 'ON DUTY';
        break;
      default:
        badgeColor = Colors.grey.withOpacity(0.12);
        textColor = Colors.grey;
        label = record.status.toUpperCase();
    }

    return Card(
      child: Padding(
        padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
        child: Row(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          children: [
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Row(
                    children: [
                      const Icon(Icons.calendar_today_rounded, size: 16, color: AppTheme.textSecondary),
                      const SizedBox(width: 8),
                      Text(
                        record.date,
                        style: const TextStyle(
                          fontSize: 14,
                          fontWeight: FontWeight.w600,
                          color: AppTheme.textPrimary,
                        ),
                      ),
                    ],
                  ),
                  if (record.remarks.isNotEmpty) ...[
                    const SizedBox(height: 4),
                    Text(
                      record.remarks,
                      style: const TextStyle(
                        fontSize: 12,
                        color: AppTheme.textSecondary,
                        fontStyle: FontStyle.italic,
                      ),
                    ),
                  ],
                ],
              ),
            ),
            Container(
              padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 4),
              decoration: BoxDecoration(
                color: badgeColor,
                borderRadius: BorderRadius.circular(6),
              ),
              child: Text(
                label,
                style: TextStyle(
                  fontSize: 11,
                  fontWeight: FontWeight.bold,
                  color: textColor,
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}