import 'package:appflowy_popover/layout.dart';
import 'package:flutter/gestures.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

/// If multiple popovers are exclusive,
/// pass the same mutex to them.
class PopoverMutex {
  final ValueNotifier<PopoverState?> _stateNotifier = ValueNotifier(null);
  PopoverMutex();

  void removePopoverStateListener(VoidCallback listener) {
    _stateNotifier.removeListener(listener);
  }

  VoidCallback listenOnPopoverStateChanged(VoidCallback callback) {
    listenerCallback() {
      callback();
    }

    _stateNotifier.addListener(listenerCallback);
    return listenerCallback;
  }

  void close() {
    _stateNotifier.value?.close();
  }

  PopoverState? get state => _stateNotifier.value;

  set state(PopoverState? newState) {
    if (_stateNotifier.value != null && _stateNotifier.value != newState) {
      _stateNotifier.value?.close();
    }
    _stateNotifier.value = newState;
  }

  void _removeState() {
    _stateNotifier.value = null;
  }

  void dispose() {
    _stateNotifier.dispose();
  }
}

class PopoverController {
  PopoverState? state;

  close() {
    state?.close();
  }

  show() {
    state?.showOverlay();
  }
}

class PopoverTriggerActionFlags {
  static int click = 0x01;
  static int hover = 0x02;
}

enum PopoverDirection {
  // Corner aligned with a corner of the SourceWidget
  topLeft,
  topRight,
  bottomLeft,
  bottomRight,
  center,

  // Edge aligned with a edge of the SourceWidget
  topWithLeftAligned,
  topWithCenterAligned,
  topWithRightAligned,
  rightWithTopAligned,
  rightWithCenterAligned,
  rightWithBottomAligned,
  bottomWithLeftAligned,
  bottomWithCenterAligned,
  bottomWithRightAligned,
  leftWithTopAligned,
  leftWithCenterAligned,
  leftWithBottomAligned,

  custom,
}

class Popover extends StatefulWidget {
  final PopoverController? controller;

  final Offset? offset;

  final Decoration? maskDecoration;

  /// The function used to build the popover.
  final Widget? Function(BuildContext context) popupBuilder;

  final int triggerActions;

  /// If multiple popovers are exclusive,
  /// pass the same mutex to them.
  final PopoverMutex? mutex;

  /// The direction of the popover
  final PopoverDirection direction;

  final void Function()? onClose;

  /// The content area of the popover.
  final Widget child;

  const Popover({
    Key? key,
    required this.child,
    required this.popupBuilder,
    this.controller,
    this.offset,
    this.maskDecoration,
    this.triggerActions = 0,
    this.direction = PopoverDirection.rightWithTopAligned,
    this.mutex,
    this.onClose,
  }) : super(key: key);

  @override
  State<Popover> createState() => PopoverState();
}

class PopoverState extends State<Popover> {
  final PopoverLink popoverLink = PopoverLink();
  OverlayEntry? _overlayEntry;
  bool hasMask = true;

  static PopoverState? _popoverWithMask;

  @override
  void initState() {
    widget.controller?.state = this;
    super.initState();
  }

  showOverlay() {
    close();

    if (widget.mutex != null) {
      widget.mutex?.state = this;
    }

    if (_popoverWithMask == null) {
      _popoverWithMask = this;
    } else {
      hasMask = false;
    }

    final newEntry = OverlayEntry(builder: (context) {
      final children = <Widget>[];

      if (hasMask) {
        children.add(_PopoverMask(
          decoration: widget.maskDecoration,
          onTap: () => close(),
          onExit: () => close(),
        ));
      }

      children.add(PopoverContainer(
        direction: widget.direction,
        popoverLink: popoverLink,
        offset: widget.offset ?? Offset.zero,
        popupBuilder: widget.popupBuilder,
        onClose: () => close(),
        onCloseAll: () => closeAll(),
      ));

      return Stack(children: children);
    });

    _overlayEntry = newEntry;

    Overlay.of(context)?.insert(newEntry);
  }

  close() {
    if (_overlayEntry != null) {
      _overlayEntry!.remove();
      _overlayEntry = null;
      if (_popoverWithMask == this) {
        _popoverWithMask = null;
      }
      if (widget.onClose != null) {
        widget.onClose!();
      }
    }

    if (widget.mutex?.state == this) {
      widget.mutex?._removeState();
    }
  }

  closeAll() {
    _popoverWithMask?.close();
  }

  @override
  void deactivate() {
    close();
    super.deactivate();
  }

  _handleTargetPointerDown(PointerDownEvent event) {
    if (widget.triggerActions & PopoverTriggerActionFlags.click != 0) {
      showOverlay();
    }
  }

  _handleTargetPointerEnter(PointerEnterEvent event) {
    if (widget.triggerActions & PopoverTriggerActionFlags.hover != 0) {
      showOverlay();
    }
  }

  _buildContent(BuildContext context) {
    if (widget.triggerActions == 0) {
      return widget.child;
    }

    return MouseRegion(
      onEnter: _handleTargetPointerEnter,
      child: Listener(
        onPointerDown: _handleTargetPointerDown,
        child: widget.child,
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return PopoverTarget(
      link: popoverLink,
      child: _buildContent(context),
    );
  }
}

class _PopoverMask extends StatefulWidget {
  final void Function() onTap;
  final void Function()? onExit;
  final Decoration? decoration;

  const _PopoverMask(
      {Key? key, required this.onTap, this.onExit, this.decoration})
      : super(key: key);

  @override
  State<StatefulWidget> createState() => _PopoverMaskState();
}

class _PopoverMaskState extends State<_PopoverMask> {
  @override
  void initState() {
    HardwareKeyboard.instance.addHandler(_handleGlobalKeyEvent);
    super.initState();
  }

  bool _handleGlobalKeyEvent(KeyEvent event) {
    if (event.logicalKey == LogicalKeyboardKey.escape) {
      if (widget.onExit != null) {
        widget.onExit!();
      }

      return true;
    }
    return false;
  }

  @override
  void deactivate() {
    HardwareKeyboard.instance.removeHandler(_handleGlobalKeyEvent);
    super.deactivate();
  }

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onTap: widget.onTap,
      child: Container(
        // decoration: widget.decoration,
        decoration: widget.decoration ??
            const BoxDecoration(
              color: Color.fromARGB(0, 244, 67, 54),
            ),
      ),
    );
  }
}

class PopoverContainer extends StatefulWidget {
  final Widget? Function(BuildContext context) popupBuilder;
  final PopoverDirection direction;
  final PopoverLink popoverLink;
  final Offset offset;
  final void Function() onClose;
  final void Function() onCloseAll;

  const PopoverContainer({
    Key? key,
    required this.popupBuilder,
    required this.direction,
    required this.popoverLink,
    required this.offset,
    required this.onClose,
    required this.onCloseAll,
  }) : super(key: key);

  @override
  State<StatefulWidget> createState() => PopoverContainerState();

  static PopoverContainerState of(BuildContext context) {
    if (context is StatefulElement && context.state is PopoverContainerState) {
      return context.state as PopoverContainerState;
    }
    final PopoverContainerState? result =
        context.findAncestorStateOfType<PopoverContainerState>();
    return result!;
  }
}

class PopoverContainerState extends State<PopoverContainer> {
  @override
  Widget build(BuildContext context) {
    return CustomSingleChildLayout(
      delegate: PopoverLayoutDelegate(
        direction: widget.direction,
        link: widget.popoverLink,
        offset: widget.offset,
      ),
      child: widget.popupBuilder(context),
    );
  }

  close() => widget.onClose();

  closeAll() => widget.onCloseAll();
}