// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'dart:math' as math;

import 'package:flutter/material.dart';

class LauncherData {
  const LauncherData({ this.url, this.title });
  final String url;
  final String title;
}

const List<LauncherData> _kLauncherData = const <LauncherData>[
  const LauncherData(
    url: 'mojo:noodles_view',
    title: 'Noodles'
  ),
  const LauncherData(
    url: 'mojo:shapes_view',
    title: 'Shapes'
  ),
];

const Size _kInitialWindowSize = const Size(200.0, 200.0);
const double _kWindowPadding = 10.0;

enum WindowSide {
  topCenter,
  topRight,
  bottomRight,
}

class WindowDecoration extends StatelessComponent {
  WindowDecoration({
    Key key,
    this.side,
    this.color,
    this.onTap,
    this.onPanUpdate
  }) : super(key: key);

  final WindowSide side;
  final Color color;
  final GestureTapCallback onTap;
  final GesturePanUpdateCallback onPanUpdate;

  Widget build(BuildContext context) {
    double top, right, bottom, left, width, height;

    height = _kWindowPadding * 2.0;

    if (side == WindowSide.topCenter || side == WindowSide.topRight)
      top = 0.0;

    if (side == WindowSide.topRight || side == WindowSide.bottomRight) {
      right = 0.0;
      width = _kWindowPadding * 2.0;
    }

    if (side == WindowSide.topCenter) {
      left = _kWindowPadding;
      right = _kWindowPadding;
    }

    if (side == WindowSide.bottomRight)
      bottom = 0.0;

    return new Positioned(
      top: top,
      right: right,
      bottom: bottom,
      left: left,
      width: width,
      height: height,
      child: new GestureDetector(
        onTap: onTap,
        onPanUpdate: onPanUpdate,
        child: new Container(
          decoration: new BoxDecoration(
            backgroundColor: color
          )
        )
      )
    );
  }
}

class Window extends StatefulComponent {
  Window({ Key key, this.child, this.onClose }) : super(key: key);

  final ChildViewConnection child;
  final ValueChanged<ChildViewConnection> onClose;

  _WindowState createState() => new _WindowState();
}

class _WindowState extends State<Window> {
  Offset _offset = Offset.zero;
  Size _size = _kInitialWindowSize;

  void _handleResizerDrag(Offset delta) {
    setState(() {
      _size = new Size(
        math.max(0.0, _size.width + delta.dx),
        math.max(0.0, _size.height + delta.dy)
      );
    });
  }

  void _handleRepositionDrag(Offset delta) {
    setState(() {
      _offset += delta;
    });
  }

  void _handleClose() {
    config.onClose(config.child);
  }

  Widget build(BuildContext context) {
    return new Positioned(
      left: _offset.dx,
      top: _offset.dy,
      width: _size.width + _kWindowPadding * 2.0,
      height: _size.height + _kWindowPadding * 2.0,
      child: new Stack(
        children: <Widget>[
          new WindowDecoration(
            side: WindowSide.topCenter,
            onPanUpdate: _handleRepositionDrag,
            color: Colors.green[200]
          ),
          new WindowDecoration(
            side: WindowSide.topRight,
            onTap: _handleClose,
            color: Colors.red[200]
          ),
          new WindowDecoration(
            side: WindowSide.bottomRight,
            onPanUpdate: _handleResizerDrag,
            color: Colors.blue[200]
          ),
          new Container(
            padding: const EdgeDims.all(_kWindowPadding),
            child: new Material(
              elevation: 8,
              child: new ChildView(child: config.child)
            )
          )
        ]
      )
    );
  }
}

class LauncherItem extends StatelessComponent {
  LauncherItem({
    Key key,
    this.url,
    this.child,
    this.onLaunch
  }) : super(key: key);

  final String url;
  final Widget child;
  final ValueChanged<ChildViewConnection> onLaunch;

  Widget build(BuildContext context) {
    return new RaisedButton(
      onPressed: () { onLaunch(new ChildViewConnection(url: url)); },
      child: child
    );
  }
}

class Launcher extends StatelessComponent {
  Launcher({ Key key, this.items }) : super(key: key);

  final List<Widget> items;

  Widget build(BuildContext context) {
    return new Row(
      justifyContent: FlexJustifyContent.center,
      children: items
    );
  }
}

class WindowManager extends StatefulComponent {
  _WindowManagerState createState() => new _WindowManagerState();
}

class _WindowManagerState extends State<WindowManager> {
  List<ChildViewConnection> _windows = <ChildViewConnection>[];

  void _handleLaunch(ChildViewConnection child) {
    setState(() {
      _windows.add(child);
    });
  }

  void _handleClose(ChildViewConnection child) {
    setState(() {
      _windows.remove(child);
    });
  }

  Widget build(BuildContext context) {
    return new Material(
      child: new Stack(
        children: <Widget>[
          new Positioned(
            left: 0.0,
            right: 0.0,
            bottom: 0.0,
            child: new Launcher(items: _kLauncherData.map((LauncherData data) {
              return new LauncherItem(
                url: data.url,
                onLaunch: _handleLaunch,
                child: new Text(data.title)
              );
            }).toList())
          )
        ]..addAll(_windows.map((ChildViewConnection child) {
          return new Window(
            key: new ObjectKey(child),
            onClose: _handleClose,
            child: child
          );
        }))
      )
    );
  }
}

void main() {
  runApp(new MaterialApp(
    title: 'Mozart',
    routes: <String, RouteBuilder>{ '/': (_) => new WindowManager() }
  ));
}