import 'dart:math' as math;

import 'package:flutter/material.dart';

import '../../domain/schedule_engine.dart';
import '../../domain/app_settings.dart';
import '../../app/app_theme.dart';
import 'course_details.dart';

class WeekGrid extends StatelessWidget {
  const WeekGrid({
    super.key,
    required this.events,
    required this.monday,
    required this.today,
    required this.settings,
  });
  final List<CourseOccurrence> events;
  final DateTime monday, today;
  final AppSettings settings;
  @override
  Widget build(BuildContext context) {
    final scale = MediaQuery.textScalerOf(context).scale(12) / 12;
    final rowHeight = 78.0 * scale.clamp(1, 2.5),
        gap = 20.0,
        header = 56.0 * scale.clamp(1, 2);
    double top(int period) =>
        (period - 1) * rowHeight +
        (period > 4 ? gap : 0) +
        (period > 8 ? gap : 0);
    final height = 11 * rowHeight + 2 * gap;
    return LayoutBuilder(
      builder: (context, constraints) {
        final columnWidth = math.max(
          90.0 * scale.clamp(1, 1.4),
          (constraints.maxWidth - 52) / 7,
        );
        final gridWidth = columnWidth * 7;
        return Row(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            SizedBox(
              width: 52,
              height: header + height,
              child: Stack(
                children: [
                  for (final slot in lessonSlots)
                    Positioned(
                      top: header + top(slot.period),
                      left: 0,
                      right: 0,
                      height: rowHeight,
                      child: Column(
                        mainAxisAlignment: MainAxisAlignment.center,
                        children: [
                          Text(
                            '${slot.period}',
                            style: const TextStyle(
                              fontSize: 13,
                              fontWeight: FontWeight.w700,
                            ),
                          ),
                          const SizedBox(height: 5),
                          Text(
                            minuteLabel(slot.startMinute),
                            style: TextStyle(
                              fontSize: 9,
                              color: ink.withValues(alpha: 0.5),
                            ),
                          ),
                          Text(
                            minuteLabel(slot.endMinute),
                            style: TextStyle(
                              fontSize: 9,
                              color: ink.withValues(alpha: 0.35),
                            ),
                          ),
                        ],
                      ),
                    ),
                ],
              ),
            ),
            Expanded(
              child: SingleChildScrollView(
                key: const Key('week-horizontal'),
                scrollDirection: Axis.horizontal,
                child: SizedBox(
                  width: gridWidth,
                  child: Column(
                    children: [
                      SizedBox(
                        height: header,
                        child: Row(
                          children: List.generate(7, (i) {
                            final date = monday.add(Duration(days: i));
                            final active =
                                date.year == today.year &&
                                date.month == today.month &&
                                date.day == today.day;
                            return SizedBox(
                              width: columnWidth,
                              child: Column(
                                mainAxisAlignment: MainAxisAlignment.center,
                                children: [
                                  Text(
                                    const [
                                      '周一',
                                      '周二',
                                      '周三',
                                      '周四',
                                      '周五',
                                      '周六',
                                      '周日',
                                    ][i],
                                    style: TextStyle(
                                      fontSize: 12,
                                      color: active
                                          ? river
                                          : ink.withValues(alpha: 0.55),
                                    ),
                                  ),
                                  const SizedBox(height: 4),
                                  Container(
                                    padding: const EdgeInsets.symmetric(
                                      horizontal: 9,
                                      vertical: 3,
                                    ),
                                    decoration: BoxDecoration(
                                      color: active
                                          ? river
                                          : Colors.transparent,
                                      borderRadius: BorderRadius.circular(10),
                                    ),
                                    child: Text(
                                      '${date.day}',
                                      style: TextStyle(
                                        fontSize: 13,
                                        fontWeight: FontWeight.w700,
                                        color: active ? Colors.white : ink,
                                      ),
                                    ),
                                  ),
                                ],
                              ),
                            );
                          }),
                        ),
                      ),
                      SizedBox(
                        height: height,
                        child: Stack(
                          children: [
                            for (var i = 0; i < 7; i++)
                              Positioned(
                                left: i * columnWidth,
                                top: 0,
                                width: columnWidth,
                                height: height,
                                child: DecoratedBox(
                                  decoration: BoxDecoration(
                                    color: i < 5
                                        ? Colors.white.withValues(alpha: 0.45)
                                        : river.withValues(alpha: 0.025),
                                    border: Border(
                                      left: BorderSide(
                                        color: ink.withValues(alpha: 0.035),
                                      ),
                                    ),
                                  ),
                                ),
                              ),
                            for (var p = 1; p <= 11; p++)
                              Positioned(
                                left: 0,
                                right: 0,
                                top: top(p),
                                child: Divider(
                                  height: 1,
                                  color: ink.withValues(alpha: 0.05),
                                ),
                              ),
                            for (var day = 1; day <= 7; day++)
                              ..._cards(
                                context,
                                day,
                                columnWidth,
                                rowHeight,
                                top,
                              ),
                          ],
                        ),
                      ),
                    ],
                  ),
                ),
              ),
            ),
          ],
        );
      },
    );
  }

  List<Widget> _cards(
    BuildContext context,
    int day,
    double width,
    double rowHeight,
    double Function(int) top,
  ) {
    final values = events.where((e) => e.course.weekday == day).toList();
    return [
      for (final e in values)
        _position(context, e, values, width, rowHeight, top),
    ];
  }

  Widget _position(
    BuildContext context,
    CourseOccurrence e,
    List<CourseOccurrence> values,
    double width,
    double rowHeight,
    double Function(int) top,
  ) {
    final connected = <CourseOccurrence>{e};
    var grew = true;
    while (grew) {
      grew = false;
      for (final other in values) {
        if (!connected.contains(other) &&
            connected.any((known) => ScheduleEngine.overlaps(known, other))) {
          connected.add(other);
          grew = true;
        }
      }
    }
    final group = values.where(connected.contains).toList();
    final lane = group.indexOf(e), laneWidth = width / group.length;
    return Positioned(
      left: (e.course.weekday - 1) * width + lane * laneWidth + 3,
      top: top(e.course.startPeriod) + 4,
      width: math.max(12, laneWidth - 6),
      height:
          top(e.course.endPeriod) + rowHeight - top(e.course.startPeriod) - 8,
      child: Semantics(
        label: '${e.course.name}，${e.course.teacher}，${e.course.room}',
        button: true,
        child: GestureDetector(
          onTap: () => showCourseDetails(context, e),
          child: Container(
            padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 10),
            clipBehavior: Clip.antiAlias,
            decoration: BoxDecoration(
              color: courseColor(e.course.id, settings),
              borderRadius: BorderRadius.circular(14),
              border: Border.all(color: Colors.white.withValues(alpha: 0.8)),
            ),
            child: SingleChildScrollView(
              physics: const NeverScrollableScrollPhysics(),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  if (group.length > 1)
                    const Text(
                      '时间冲突',
                      style: TextStyle(fontSize: 9, color: Color(0xFFB45D54)),
                    ),
                  Text(
                    e.course.name,
                    maxLines: 2,
                    overflow: TextOverflow.ellipsis,
                    style: const TextStyle(
                      fontSize: 12,
                      fontWeight: FontWeight.w700,
                      height: 1.25,
                    ),
                  ),
                  const SizedBox(height: 7),
                  Text(
                    e.course.teacher,
                    maxLines: 1,
                    overflow: TextOverflow.ellipsis,
                    style: TextStyle(
                      fontSize: 10,
                      color: ink.withValues(alpha: 0.7),
                    ),
                  ),
                  const SizedBox(height: 3),
                  Text(
                    e.course.room,
                    maxLines: 2,
                    overflow: TextOverflow.ellipsis,
                    style: TextStyle(
                      fontSize: 10,
                      color: ink.withValues(alpha: 0.6),
                      height: 1.2,
                    ),
                  ),
                ],
              ),
            ),
          ),
        ),
      ),
    );
  }
}