quid_faciam_hodie/lib/widgets/timeline_page.dart

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:share_location/foreign_types/memory.dart';
import 'package:share_location/models/timeline.dart';
import 'package:share_location/models/timeline_overlay.dart';
import 'package:share_location/widgets/memory_sheet.dart';
import 'package:share_location/widgets/memory_slide.dart';
import 'package:share_location/widgets/timeline_overlay.dart';

class TimelinePage extends StatefulWidget {
  final DateTime date;
  final List<Memory> memories;

  const TimelinePage({
    Key? key,
    required this.date,
    required this.memories,
  }) : super(key: key);

  @override
  State<TimelinePage> createState() => _TimelinePageState();
}

class _TimelinePageState extends State<TimelinePage> {
  final timelineOverlayController = TimelineOverlayModel();
  final pageController = PageController();

  Timer? overlayRemover;

  void _handleOverlayChangeBasedOnMemoryPack() {
    if (!mounted) {
      return;
    }

    final timeline = context.read<TimelineModel>();

    if (timeline.paused) {
      timelineOverlayController.hideOverlay();
    } else {
      timelineOverlayController.restoreOverlay();
    }
  }

  void _jumpToCorrectPageFromMemoryPack() {
    if (!mounted) {
      return;
    }

    final timeline = context.read<TimelineModel>();

    if (timeline.memoryIndex != pageController.page) {
      pageController.animateToPage(
        timeline.memoryIndex,
        duration: const Duration(milliseconds: 300),
        curve: Curves.easeOutQuad,
      );
    }
  }

  @override
  void initState() {
    super.initState();

    final timeline = context.read<TimelineModel>();

    timelineOverlayController.addListener(() {
      if (!mounted) {
        return;
      }

      if (timelineOverlayController.state == TimelineState.completed) {
        timelineOverlayController.reset();
        timeline.nextMemory();
      }
    }, ['state']);

    timelineOverlayController.addListener(() {
      if (!mounted) {
        return;
      }

      // Force update to ensure overlays are up-to-date.
      setState(() {});
    }, ['showOverlay']);

    timelineOverlayController
        .addListener(_handleOverlayChangeBasedOnMemoryPack, ['state']);

    timeline.addListener(_jumpToCorrectPageFromMemoryPack);
  }

  @override
  void dispose() {
    pageController.dispose();

    try {
      final timeline = context.read<TimelineModel>();

      timeline.removeListener(_jumpToCorrectPageFromMemoryPack);
    } catch (error) {
      // Timeline has been removed completely
    }

    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final timeline = context.watch<TimelineModel>();

    return GestureDetector(
      onDoubleTap: () async {
        timeline.pause();

        await showModalBottomSheet(
          context: context,
          backgroundColor: Colors.transparent,
          isScrollControlled: true,
          builder: (sheetContext) => MemorySheet(
            memory: timeline.currentMemory,
            sheetContext: sheetContext,
          ),
        );

        if (!mounted) {
          return;
        }

        timeline.resume();
      },
      onTapDown: (_) {
        timeline.pause();

        overlayRemover = Timer(
          const Duration(milliseconds: 600),
          timelineOverlayController.hideOverlay,
        );
      },
      onTapUp: (_) {
        overlayRemover?.cancel();
        timeline.resume();
        timelineOverlayController.restoreOverlay();
      },
      onTapCancel: () {
        overlayRemover?.cancel();
        timeline.resume();
        timelineOverlayController.restoreOverlay();
      },
      onHorizontalDragEnd: (details) {
        if (details.primaryVelocity! < 0) {
          timeline.nextMemory();
        } else if (details.primaryVelocity! > 0) {
          timeline.previousMemory();
        }
      },
      child: ChangeNotifierProvider.value(
        value: timelineOverlayController,
        child: Stack(
          fit: StackFit.expand,
          children: <Widget>[
            PageView.builder(
              controller: pageController,
              physics: const NeverScrollableScrollPhysics(),
              scrollDirection: Axis.horizontal,
              itemBuilder: (_, index) => MemorySlide(
                key: Key(widget.memories[index].filename),
                memory: widget.memories[index],
              ),
              itemCount: widget.memories.length,
            ),
            TimelineOverlay(
              date: widget.date,
              memoriesAmount: widget.memories.length,
              memoryIndex: timeline.memoryIndex + 1,
            ),
          ],
        ),
      ),
    );
  }
}