import "dart:math" as math;

import "package:flutter/material.dart";

class SidebarSwiper extends StatefulWidget {
  const SidebarSwiper({
    required this.sidebar,
    required this.child,
    this.maxSidebarWidth = 360,
    this.sidebarWidthFactor = 0.92,
    this.edgeDragWidth = 44,
    this.animationDuration = const Duration(milliseconds: 220),
    super.key,
  });

  final Widget sidebar;
  final Widget child;
  final double maxSidebarWidth;
  final double sidebarWidthFactor;
  final double edgeDragWidth;
  final Duration animationDuration;

  @override
  State<SidebarSwiper> createState() => _SidebarSwiperState();
}

class _SidebarSwiperState extends State<SidebarSwiper> {
  static const double _closedExtraOffset = 12;

  double _progress = 0; // 0 = closed, 1 = fully open
  bool _isDragging = false;
  bool _canDrag = false;
  double _dragStartGlobalX = 0;
  double _dragStartProgress = 0;

  void _setOpen(bool value) {
    setState(() {
      _isDragging = false;
      _progress = value ? 1 : 0;
    });
  }

  void _handleDragStart(DragStartDetails details, double sidebarWidth) {
    final isOpen = _progress > 0.001;
    final fromEdge = details.globalPosition.dx <= widget.edgeDragWidth;
    final fromSidebarZone = details.globalPosition.dx <= sidebarWidth;
    _canDrag = fromEdge || (isOpen && fromSidebarZone);
    if (!_canDrag) return;
    setState(() {
      _isDragging = true;
      _dragStartGlobalX = details.globalPosition.dx;
      _dragStartProgress = _progress;
    });
  }

  void _handleDragUpdate(DragUpdateDetails details, double sidebarWidth) {
    if (!_canDrag || !_isDragging) return;
    if (sidebarWidth <= 0) return;
    final movedX = details.globalPosition.dx - _dragStartGlobalX;
    setState(() {
      _progress = (_dragStartProgress + (movedX / sidebarWidth)).clamp(0, 1);
    });
  }

  void _handleDragEnd(DragEndDetails details) {
    if (!_canDrag) return;
    _canDrag = false;
    final velocity = details.primaryVelocity ?? 0;
    final shouldOpen = velocity > 250
        ? true
        : (velocity < -250 ? false : _progress >= 0.35);
    _setOpen(shouldOpen);
  }

  @override
  Widget build(BuildContext context) {
    final screenWidth = MediaQuery.of(context).size.width;
    final sidebarWidth = math.min(
      widget.maxSidebarWidth,
      screenWidth * widget.sidebarWidthFactor,
    );
    final leftOffset =
        -(sidebarWidth + _closedExtraOffset) +
        ((sidebarWidth + _closedExtraOffset) * _progress);
    final showScrim = _progress > 0;

    return Stack(
      children: [
        widget.child,
        Positioned.fill(
          child: GestureDetector(
            behavior: HitTestBehavior.translucent,
            onHorizontalDragStart: (details) =>
                _handleDragStart(details, sidebarWidth),
            onHorizontalDragUpdate: (details) =>
                _handleDragUpdate(details, sidebarWidth),
            onHorizontalDragEnd: _handleDragEnd,
            child: const SizedBox.expand(),
          ),
        ),
        if (showScrim)
          Positioned.fill(
            child: GestureDetector(
              behavior: HitTestBehavior.opaque,
              onTap: () => _setOpen(false),
              child: Container(
                color: Colors.black.withValues(alpha: 0.45 * _progress),
              ),
            ),
          ),
        AnimatedPositioned(
          duration: _isDragging ? Duration.zero : widget.animationDuration,
          curve: Curves.easeOutCubic,
          left: leftOffset,
          top: 0,
          bottom: 0,
          width: sidebarWidth,
          child: Material(
            color: Theme.of(context).scaffoldBackgroundColor,
            child: widget.sidebar,
          ),
        ),
      ],
    );
  }
}