using System;
using System.Collections.Generic;
using uiwidgets;
using Unity.UIWidgets.animation;
using Unity.UIWidgets.foundation;
using Unity.UIWidgets.material;
using Unity.UIWidgets.rendering;
using Unity.UIWidgets.scheduler;
using Unity.UIWidgets.ui;
using Unity.UIWidgets.widgets;
using UnityEngine;
using Canvas = Unity.UIWidgets.ui.Canvas;
using Color = Unity.UIWidgets.ui.Color;
using Rect = Unity.UIWidgets.ui.Rect;

namespace UIWidgetsSample.RaycastableScene {
    class CheckboxUtils {
        public const float _kEdgeSize = Checkbox.width;
        public static readonly Radius _kEdgeRadius = Radius.circular(1.0f);
        public const float _kStrokeWidth = 2.0f;
        public static Color checkColor = Colors.blue;
        public static float kRadialReactionRadius = 12f;
    }

    public class Checkbox : StatefulWidget {
        public Checkbox(
            Key key = null,
            bool? value = false,
            bool tristate = false,
            ValueChanged<bool?> onChanged = null,
            Color activeColor = null,
            Color checkColor = null,
            Color focusColor = null,
            Color hoverColor = null,
            MaterialTapTargetSize? materialTapTargetSize = null,
            VisualDensity visualDensity = null,
            FocusNode focusNode = null,
            bool autofocus = false
        ) : base(key: key) {
            D.assert(tristate || value != null);
            this.value = value;
            this.onChanged = onChanged;
            this.activeColor = activeColor;
            this.checkColor = checkColor;
            this.focusColor = focusColor;
            this.hoverColor = hoverColor;
            this.tristate = tristate;
            this.materialTapTargetSize = materialTapTargetSize;
            this.visualDensity = visualDensity;
            this.focusNode = focusNode;
            this.autofocus = autofocus;
        }

        public readonly bool? value;

        public readonly ValueChanged<bool?> onChanged;

        public readonly Color activeColor;

        public readonly Color checkColor;

        public readonly bool tristate;

        public readonly MaterialTapTargetSize? materialTapTargetSize;

        public readonly VisualDensity visualDensity;

        public readonly Color focusColor;

        public readonly Color hoverColor;

        public readonly FocusNode focusNode;

        public readonly bool autofocus;

        public const float width = 10.0f;

        public override State createState() {
            return new _CheckboxState();
        }
    }

    class _CheckboxState : TickerProviderStateMixin<Checkbox> {
        bool enabled {
            get { return widget.onChanged != null; }
        }

        Dictionary<LocalKey, ActionFactory> _actionMap;

        public override void initState() {
            base.initState();
            _actionMap = new Dictionary<LocalKey, ActionFactory> {
                {ActivateAction.key, _createAction}
            };
        }

        void _actionHandler(FocusNode node, Intent intent) {
            if (widget.onChanged != null) {
                switch (widget.value) {
                    case false:
                        widget.onChanged(true);
                        break;
                    case true:
                        widget.onChanged(widget.tristate);
                        break;
                    default: // case null:
                        widget.onChanged(false);
                        break;
                }
            }

            RenderObject renderObject = node.context.findRenderObject();
            // renderObject.sendSemanticsEvent(const TapSemanticEvent());
        }

        UiWidgetAction _createAction() {
            return new CallbackAction(
                ActivateAction.key,
                onInvoke: _actionHandler
            );
        }

        bool _focused = false;

        void _handleFocusHighlightChanged(bool focused) {
            
        }

        bool _hovering = false;

        void _handleHoverChanged(bool hovering) {
            
        }

        public override Widget build(BuildContext context) {
            Size size;
            switch (widget.materialTapTargetSize ?? MaterialTapTargetSize.padded) {
                case MaterialTapTargetSize.padded:
                    size = new Size(2 * CheckboxUtils.kRadialReactionRadius,
                        2 * CheckboxUtils.kRadialReactionRadius);
                    break;
                case MaterialTapTargetSize.shrinkWrap:
                    size = new Size(2 * CheckboxUtils.kRadialReactionRadius, 2 * CheckboxUtils.kRadialReactionRadius);
                    break;
                default:
                    throw new Exception("Unknown target size: " + widget.materialTapTargetSize);
            }

            size += (widget.visualDensity ?? VisualDensity.standard).baseSizeAdjustment;
            BoxConstraints additionalConstraints = BoxConstraints.tight(size);
            return new FocusableActionDetector(
                actions: _actionMap,
                focusNode: widget.focusNode,
                autofocus: widget.autofocus,
                enabled: enabled,
                onShowFocusHighlight: _handleFocusHighlightChanged,
                onShowHoverHighlight: _handleHoverChanged,
                child: new Builder(
                    builder: (BuildContext _context) => {
                        return new _CheckboxRenderObjectWidget(
                            value: widget.value,
                            tristate: widget.tristate,
                            activeColor: widget.activeColor ?? CheckboxUtils.checkColor,
                            checkColor: widget.checkColor ?? new Color(0xFFFFFFFF),
                            inactiveColor: enabled ? CheckboxUtils.checkColor : Colors.grey,
                            focusColor: widget.focusColor ?? CheckboxUtils.checkColor,
                            hoverColor: widget.hoverColor ?? CheckboxUtils.checkColor,
                            onChanged: widget.onChanged,
                            additionalConstraints: additionalConstraints,
                            vsync: this,
                            hasFocus: _focused,
                            hovering: _hovering
                        );
                    }
                )
            );
        }
    }

    class _CheckboxRenderObjectWidget : LeafRenderObjectWidget {
        public _CheckboxRenderObjectWidget(
            Key key = null,
            bool? value = null,
            bool tristate = false,
            Color activeColor = null,
            Color checkColor = null,
            Color inactiveColor = null,
            Color focusColor = null,
            Color hoverColor = null,
            ValueChanged<bool?> onChanged = null,
            TickerProvider vsync = null,
            BoxConstraints additionalConstraints = null,
            bool? hasFocus = null,
            bool? hovering = null
        ) : base(key: key) {
            D.assert(tristate || value != null);
            D.assert(activeColor != null);
            D.assert(inactiveColor != null);
            D.assert(vsync != null);
            this.value = value;
            this.tristate = tristate;
            this.activeColor = activeColor;
            this.checkColor = checkColor;
            this.inactiveColor = inactiveColor;
            this.focusColor = focusColor;
            this.hoverColor = hoverColor;
            this.onChanged = onChanged;
            this.vsync = vsync;
            this.additionalConstraints = additionalConstraints;
            this.hasFocus = hasFocus;
            this.hovering = hovering;
        }

        public readonly bool? value;
        public readonly bool tristate;
        public readonly bool? hasFocus;
        public readonly bool? hovering;
        public readonly Color activeColor;
        public readonly Color checkColor;
        public readonly Color inactiveColor;
        public readonly Color focusColor;
        public readonly Color hoverColor;
        public readonly ValueChanged<bool?> onChanged;
        public readonly TickerProvider vsync;
        public readonly BoxConstraints additionalConstraints;

        public override RenderObject createRenderObject(BuildContext context) {
            return new _RenderCheckbox(
                value: value,
                tristate: tristate,
                activeColor: activeColor,
                checkColor: checkColor,
                inactiveColor: inactiveColor,
                focusColor: focusColor,
                hoverColor: hoverColor,
                onChanged: onChanged,
                vsync: vsync,
                additionalConstraints: additionalConstraints,
                hasFocus: hasFocus,
                hovering: hovering
            );
        }

        public override void updateRenderObject(BuildContext context, RenderObject _renderObject) {
            _RenderCheckbox renderObject = _renderObject as _RenderCheckbox;
            renderObject.value = value;
            renderObject.tristate = tristate;
            renderObject.activeColor = activeColor;
            renderObject.checkColor = checkColor;
            renderObject.focusColor = focusColor;
            renderObject.hoverColor = hoverColor;
            renderObject.inactiveColor = inactiveColor;
            renderObject.onChanged = onChanged;
            renderObject.additionalConstraints = additionalConstraints;
            renderObject.vsync = vsync;
            renderObject.hasFocus = hasFocus ?? false;
            renderObject.hovering = hovering ?? false;
        }
    }


    class _RenderCheckbox : RenderToggleable {
        public _RenderCheckbox(
            bool? value = null,
            bool tristate = false,
            Color activeColor = null,
            Color checkColor = null,
            Color inactiveColor = null,
            Color focusColor = null,
            Color hoverColor = null,
            BoxConstraints additionalConstraints = null,
            ValueChanged<bool?> onChanged = null,
            TickerProvider vsync = null,
            bool? hasFocus = null,
            bool? hovering = null
        ) : base(
            value: value,
            tristate: tristate,
            activeColor: activeColor,
            inactiveColor: inactiveColor,
            focusColor: focusColor,
            hoverColor: hoverColor,
            onChanged: onChanged,
            additionalConstraints: additionalConstraints,
            vsync: vsync,
            hasFocus: hasFocus ?? false,
            hovering: hovering ?? false
        ) {
            _oldValue = value;
            this.checkColor = checkColor;
        }

        bool? _oldValue;
        public Color checkColor;

        public override bool? value {
            set {
                if (value == this.value) {
                    return;
                }

                _oldValue = this.value;
                base.value = value;
            }
        }

        RRect _outerRectAt(Offset origin, float t) {
            float inset = 1.0f - (t - 0.5f).abs() * 2.0f;
            float size = CheckboxUtils._kEdgeSize - inset * CheckboxUtils._kStrokeWidth;
            Rect rect = Rect.fromLTWH(origin.dx + inset, origin.dy + inset, size, size);
            return RRect.fromRectAndRadius(rect, CheckboxUtils._kEdgeRadius);
        }

        Color _colorAt(float t) {
            return onChanged == null
                ? inactiveColor
                : (t >= 0.25f ? activeColor : Color.lerp(inactiveColor, activeColor, t * 4.0f));
        }

        Paint _createStrokePaint() {
            var paint = new Paint();
            paint.color = checkColor;
            paint.style = PaintingStyle.stroke;
            paint.strokeWidth = CheckboxUtils._kStrokeWidth;
            return paint;
        }

        void _drawBorder(Canvas canvas, RRect outer, float t, Paint paint) {
            D.assert(t >= 0.0f && t <= 0.5f);
            float size = outer.width;
            RRect inner = outer.deflate(Mathf.Min(size / 2.0f, CheckboxUtils._kStrokeWidth + size * t));
            canvas.drawDRRect(outer, inner, paint);
        }

        void _drawCheck(Canvas canvas, Offset origin, float t, Paint paint) {
            D.assert(t >= 0.0f && t <= 1.0f);
            Path path = new Path();
            Offset start = new Offset(CheckboxUtils._kEdgeSize * 0.15f, CheckboxUtils._kEdgeSize * 0.45f);
            Offset mid = new Offset(CheckboxUtils._kEdgeSize * 0.4f, CheckboxUtils._kEdgeSize * 0.7f);
            Offset end = new Offset(CheckboxUtils._kEdgeSize * 0.85f, CheckboxUtils._kEdgeSize * 0.25f);
            if (t < 0.5f) {
                float strokeT = t * 2.0f;
                Offset drawMid = Offset.lerp(start, mid, strokeT);
                path.moveTo(origin.dx + start.dx, origin.dy + start.dy);
                path.lineTo(origin.dx + drawMid.dx, origin.dy + drawMid.dy);
            }
            else {
                float strokeT = (t - 0.5f) * 2.0f;
                Offset drawEnd = Offset.lerp(mid, end, strokeT);
                path.moveTo(origin.dx + start.dx, origin.dy + start.dy);
                path.lineTo(origin.dx + mid.dx, origin.dy + mid.dy);
                path.lineTo(origin.dx + drawEnd.dx, origin.dy + drawEnd.dy);
            }

            canvas.drawPath(path, paint);
        }

        void _drawDash(Canvas canvas, Offset origin, float t, Paint paint) {
            D.assert(t >= 0.0f && t <= 1.0f);
            Offset start = new Offset(CheckboxUtils._kEdgeSize * 0.2f, CheckboxUtils._kEdgeSize * 0.5f);
            Offset mid = new Offset(CheckboxUtils._kEdgeSize * 0.5f, CheckboxUtils._kEdgeSize * 0.5f);
            Offset end = new Offset(CheckboxUtils._kEdgeSize * 0.8f, CheckboxUtils._kEdgeSize * 0.5f);
            Offset drawStart = Offset.lerp(start, mid, 1.0f - t);
            Offset drawEnd = Offset.lerp(mid, end, t);
            canvas.drawLine(origin + drawStart, origin + drawEnd, paint);
        }

        public override void paint(PaintingContext context, Offset offset) {
            Canvas canvas = context.canvas;
            paintRadialReaction(canvas, offset, size.center(Offset.zero));

            Paint strokePaint = _createStrokePaint();
            Offset origin = offset + (size / 2.0f - Size.square(CheckboxUtils._kEdgeSize) / 2.0f);
            AnimationStatus status = position.status;
            float tNormalized = status == AnimationStatus.forward || status == AnimationStatus.completed
                ? position.value
                : 1.0f - position.value;

            if (_oldValue == false || value == false) {
                float t = value == false ? 1.0f - tNormalized : tNormalized;
                RRect outer = _outerRectAt(origin, t);
                Paint paint = new Paint();
                paint.color = _colorAt(t);

                if (t <= 0.5f) {
                    _drawBorder(canvas, outer, t, paint);
                }
                else {
                    canvas.drawRRect(outer, paint);

                    float tShrink = (t - 0.5f) * 2.0f;
                    if (_oldValue == null || value == null) {
                        _drawDash(canvas, origin, tShrink, strokePaint);
                    }
                    else {
                        _drawCheck(canvas, origin, tShrink, strokePaint);
                    }
                }
            }
            else {
                // Two cases: null to true, true to null
                RRect outer = _outerRectAt(origin, 1.0f);
                Paint paint = new Paint();
                paint.color = _colorAt(1.0f);
                canvas.drawRRect(outer, paint);

                if (tNormalized <= 0.5f) {
                    float tShrink = 1.0f - tNormalized * 2.0f;
                    if (_oldValue == true) {
                        _drawCheck(canvas, origin, tShrink, strokePaint);
                    }
                    else {
                        _drawDash(canvas, origin, tShrink, strokePaint);
                    }
                }
                else {
                    float tExpand = (tNormalized - 0.5f) * 2.0f;
                    if (value == true) {
                        _drawCheck(canvas, origin, tExpand, strokePaint);
                    }
                    else {
                        _drawDash(canvas, origin, tExpand, strokePaint);
                    }
                }
            }
        }
    }
}