using System.Collections.Generic;
using Unity.UIWidgets.foundation;
using Unity.UIWidgets.gestures;
using Unity.UIWidgets.painting;
using Unity.UIWidgets.rendering;
using Unity.UIWidgets.service;
using Unity.UIWidgets.ui;
using Unity.UIWidgets.widgets;
using StrutStyle = Unity.UIWidgets.painting.StrutStyle;
using TextStyle = Unity.UIWidgets.painting.TextStyle;
using Brightness = Unity.UIWidgets.ui.Brightness;

namespace Unity.UIWidgets.cupertino {
    class CupertinoTextFieldUtils {
        public static readonly BorderSide _kDefaultRoundedBorderSide = new BorderSide(
            color: CupertinoColors.lightBackgroundGray,
            style: BorderStyle.solid,
            width: 0.0f
        );

        public static readonly Border _kDefaultRoundedBorder = new Border(
            top: _kDefaultRoundedBorderSide,
            bottom: _kDefaultRoundedBorderSide,
            left: _kDefaultRoundedBorderSide,
            right: _kDefaultRoundedBorderSide
        );

        public static readonly BoxDecoration _kDefaultRoundedBorderDecoration = new BoxDecoration(
            border: _kDefaultRoundedBorder,
            borderRadius: BorderRadius.all(Radius.circular(4.0f))
        );

        public static readonly Color _kSelectionHighlightColor = new Color(0x667FAACF);

        public static readonly Color _kInactiveTextColor = new Color(0xFFC2C2C2);

        public static readonly Color _kDisabledBackground = new Color(0xFFFAFAFA);

        public const int _iOSHorizontalCursorOffsetPixels = -2;
    }

    public enum OverlayVisibilityMode {
        never,
        editing,
        notEditing,
        always
    }

    public class CupertinoTextField : StatefulWidget {
        public CupertinoTextField(
            Key key = null,
            TextEditingController controller = null,
            FocusNode focusNode = null,
            BoxDecoration decoration = null,
            EdgeInsets padding = null,
            string placeholder = null,
            TextStyle placeholderStyle = null,
            Widget prefix = null,
            OverlayVisibilityMode prefixMode = OverlayVisibilityMode.always,
            Widget suffix = null,
            OverlayVisibilityMode suffixMode = OverlayVisibilityMode.always,
            OverlayVisibilityMode clearButtonMode = OverlayVisibilityMode.never,
            TextInputType keyboardType = null,
            TextInputAction? textInputAction = null,
            TextCapitalization textCapitalization = TextCapitalization.none,
            TextStyle style = null,
            StrutStyle strutStyle = null,
            TextAlign textAlign = TextAlign.left,
            bool autofocus = false,
            bool obscureText = false,
            bool autocorrect = true,
            int? maxLines = 1,
            int? minLines = null,
            bool expands = false,
            int? maxLength = null,
            bool maxLengthEnforced = true,
            ValueChanged<string> onChanged = null,
            VoidCallback onEditingComplete = null,
            ValueChanged<string> onSubmitted = null,
            List<TextInputFormatter> inputFormatters = null,
            bool? enabled = null,
            float cursorWidth = 2.0f,
            Radius cursorRadius = null,
            Color cursorColor = null,
            Brightness? keyboardAppearance = null,
            EdgeInsets scrollPadding = null,
            DragStartBehavior dragStartBehavior = DragStartBehavior.start,
            ScrollPhysics scrollPhysics = null) : base(key: key) {
            D.assert(maxLines == null || maxLines > 0);
            D.assert(minLines == null || minLines > 0);
            D.assert(maxLines == null || minLines == null || maxLines >= minLines,
                () => "minLines can't be greater than maxLines");
            D.assert(!expands || (maxLines == null && minLines == null),
                () => "minLines and maxLines must be null when expands is true.");
            D.assert(maxLength == null || maxLength > 0);

            this.controller = controller;
            this.focusNode = focusNode;
            this.decoration = decoration ?? CupertinoTextFieldUtils._kDefaultRoundedBorderDecoration;
            this.padding = padding ?? EdgeInsets.all(6.0f);
            this.placeholder = placeholder;
            this.placeholderStyle = placeholderStyle ?? new TextStyle(
                                        fontWeight: FontWeight.w300,
                                        color: CupertinoTextFieldUtils._kInactiveTextColor
                                    );
            this.prefix = prefix;
            this.prefixMode = prefixMode;
            this.suffix = suffix;
            this.suffixMode = suffixMode;
            this.clearButtonMode = clearButtonMode;
            this.textInputAction = textInputAction;
            this.textCapitalization = textCapitalization;
            this.style = style;
            this.strutStyle = strutStyle;
            this.textAlign = textAlign;
            this.autofocus = autofocus;
            this.obscureText = obscureText;
            this.autocorrect = autocorrect;
            this.maxLines = maxLines;
            this.minLines = minLines;
            this.expands = expands;
            this.maxLength = maxLength;
            this.maxLengthEnforced = maxLengthEnforced;
            this.onChanged = onChanged;
            this.onEditingComplete = onEditingComplete;
            this.onSubmitted = onSubmitted;
            this.inputFormatters = inputFormatters;
            this.enabled = enabled;
            this.cursorWidth = cursorWidth;
            this.cursorRadius = cursorRadius ?? Radius.circular(2.0f);
            this.cursorColor = cursorColor;
            this.keyboardAppearance = keyboardAppearance;
            this.scrollPadding = scrollPadding ?? EdgeInsets.all(20.0f);
            this.dragStartBehavior = dragStartBehavior;
            this.scrollPhysics = scrollPhysics;
            this.keyboardType = keyboardType ?? (maxLines == 1 ? TextInputType.text : TextInputType.multiline);
        }

        public readonly TextEditingController controller;

        public readonly FocusNode focusNode;

        public readonly BoxDecoration decoration;

        public readonly EdgeInsets padding;

        public readonly string placeholder;

        public readonly TextStyle placeholderStyle;

        public readonly Widget prefix;

        public readonly OverlayVisibilityMode prefixMode;

        public readonly Widget suffix;

        public readonly OverlayVisibilityMode suffixMode;

        public readonly OverlayVisibilityMode clearButtonMode;

        public readonly TextInputType keyboardType;

        public readonly TextInputAction? textInputAction;

        public readonly TextCapitalization textCapitalization;

        public readonly TextStyle style;

        public readonly StrutStyle strutStyle;

        public readonly TextAlign textAlign;

        public readonly bool autofocus;

        public readonly bool obscureText;

        public readonly bool autocorrect;

        public readonly int? maxLines;

        public readonly int? minLines;

        public readonly bool expands;

        public readonly int? maxLength;

        public readonly bool maxLengthEnforced;

        public readonly ValueChanged<string> onChanged;

        public readonly VoidCallback onEditingComplete;

        public readonly ValueChanged<string> onSubmitted;

        public readonly List<TextInputFormatter> inputFormatters;

        public readonly bool? enabled;

        public readonly float cursorWidth;

        public readonly Radius cursorRadius;

        public readonly Color cursorColor;

        public readonly Brightness? keyboardAppearance;

        public readonly EdgeInsets scrollPadding;

        public readonly DragStartBehavior dragStartBehavior;

        public readonly ScrollPhysics scrollPhysics;

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

        public override void debugFillProperties(DiagnosticPropertiesBuilder properties) {
            base.debugFillProperties(properties);

            properties.add(
                new DiagnosticsProperty<TextEditingController>("controller", controller, defaultValue: null));
            properties.add(new DiagnosticsProperty<FocusNode>("focusNode", focusNode, defaultValue: null));
            properties.add(new DiagnosticsProperty<BoxDecoration>("decoration", decoration));
            properties.add(new DiagnosticsProperty<EdgeInsets>("padding", padding));
            properties.add(new StringProperty("placeholder", placeholder));
            properties.add(new DiagnosticsProperty<TextStyle>("placeholderStyle", placeholderStyle));
            properties.add(new DiagnosticsProperty<OverlayVisibilityMode>("prefix",
                prefix == null ? OverlayVisibilityMode.never : prefixMode));
            properties.add(new DiagnosticsProperty<OverlayVisibilityMode>("suffix",
                suffix == null ? OverlayVisibilityMode.never : suffixMode));
            properties.add(new DiagnosticsProperty<OverlayVisibilityMode>("clearButtonMode", clearButtonMode));
            properties.add(new DiagnosticsProperty<TextInputType>("keyboardType", keyboardType,
                defaultValue: TextInputType.text));
            properties.add(new DiagnosticsProperty<TextStyle>("style", style, defaultValue: null));
            properties.add(new DiagnosticsProperty<bool>("autofocus", autofocus, defaultValue: false));
            properties.add(new DiagnosticsProperty<bool>("obscureText", obscureText, defaultValue: false));
            properties.add(new DiagnosticsProperty<bool>("autocorrect", autocorrect, defaultValue: false));
            properties.add(new IntProperty("maxLines", maxLines, defaultValue: 1));
            properties.add(new IntProperty("minLines", minLines, defaultValue: null));
            properties.add(new DiagnosticsProperty<bool>("expands", expands, defaultValue: false));
            properties.add(new IntProperty("maxLength", maxLength, defaultValue: null));
            properties.add(new FlagProperty("maxLengthEnforced", value: maxLengthEnforced,
                ifTrue: "max length enforced"));
            properties.add(new DiagnosticsProperty<Color>("cursorColor", cursorColor, defaultValue: null));
            properties.add(
                new DiagnosticsProperty<ScrollPhysics>("scrollPhysics", scrollPhysics, defaultValue: null));
        }
    }

    class _CupertinoTextFieldState : AutomaticKeepAliveClientMixin<CupertinoTextField> {
        GlobalKey<EditableTextState> _editableTextKey = GlobalKey<EditableTextState>.key();

        TextEditingController _controller;

        TextEditingController _effectiveController {
            get { return widget.controller ?? _controller; }
        }

        FocusNode _focusNode;

        FocusNode _effectiveFocusNode {
            get { return widget.focusNode ?? _focusNode ?? (_focusNode = new FocusNode()); }
        }

        public override void initState() {
            base.initState();
            if (widget.controller == null) {
                _controller = new TextEditingController();
                _controller.addListener(updateKeepAlive);
            }
        }

        public override void didUpdateWidget(StatefulWidget oldWidget) {
            base.didUpdateWidget(oldWidget);
            CupertinoTextField _oldWidget = (CupertinoTextField) oldWidget;

            if (widget.controller == null && _oldWidget.controller != null) {
                _controller = TextEditingController.fromValue(_oldWidget.controller.value);
                _controller.addListener(updateKeepAlive);
            }
            else if (widget.controller != null && _oldWidget.controller == null) {
                _controller = null;
            }

            bool isEnabled = widget.enabled ?? true;
            bool wasEnabled = _oldWidget.enabled ?? true;

            if (wasEnabled && !isEnabled) {
                _effectiveFocusNode.unfocus();
            }
        }

        public override void dispose() {
            _focusNode?.dispose();
            _controller?.removeListener(updateKeepAlive);
            base.dispose();
        }

        void _requestKeyboard() {
            _editableTextKey.currentState?.requestKeyboard();
        }

        RenderEditable _renderEditable {
            get { return _editableTextKey.currentState.renderEditable; }
        }

        void _handleTapDown(TapDownDetails details) {
            _renderEditable.handleTapDown(details);
        }


        void _handleSingleTapUp(TapUpDetails details) {
            _renderEditable.selectWordEdge(cause: SelectionChangedCause.tap);
            _requestKeyboard();
        }

        void _handleSingleLongTapStart(LongPressStartDetails details) {
            _renderEditable.selectPositionAt(
                from: details.globalPosition,
                cause: SelectionChangedCause.longPress
            );
        }

        void _handleSingleLongTapMoveUpdate(LongPressMoveUpdateDetails details) {
            _renderEditable.selectPositionAt(
                from: details.globalPosition,
                cause: SelectionChangedCause.longPress
            );
        }

        void _handleSingleLongTapEnd(LongPressEndDetails details) {
            _editableTextKey.currentState.showToolbar();
        }

        void _handleDoubleTapDown(TapDownDetails details) {
            _renderEditable.selectWord(cause: SelectionChangedCause.tap);
            _editableTextKey.currentState.showToolbar();
        }

        void _handleMouseDragSelectionStart(DragStartDetails details) {
            _renderEditable.selectPositionAt(
                from: details.globalPosition,
                cause: SelectionChangedCause.drag
            );
        }

        void _handleMouseDragSelectionUpdate(
            DragStartDetails startDetails,
            DragUpdateDetails updateDetails
        ) {
            _renderEditable.selectPositionAt(
                from: startDetails.globalPosition,
                to: updateDetails.globalPosition,
                cause: SelectionChangedCause.drag
            );
        }

        void _handleMouseDragSelectionEnd(DragEndDetails details) {
            _requestKeyboard();
        }

        void _handleSelectionChanged(TextSelection selection, SelectionChangedCause cause) {
            if (cause == SelectionChangedCause.longPress) {
                _editableTextKey.currentState?.bringIntoView(selection.basePos);
            }
        }

        protected override bool wantKeepAlive {
            get { return _controller?.text?.isNotEmpty() == true; }
        }

        bool _shouldShowAttachment(
            OverlayVisibilityMode attachment,
            bool hasText
        ) {
            switch (attachment) {
                case OverlayVisibilityMode.never:
                    return false;
                case OverlayVisibilityMode.always:
                    return true;
                case OverlayVisibilityMode.editing:
                    return hasText;
                case OverlayVisibilityMode.notEditing:
                    return !hasText;
            }

            D.assert(false);
            return false;
        }

        bool _showPrefixWidget(TextEditingValue text) {
            return widget.prefix != null && _shouldShowAttachment(
                       attachment: widget.prefixMode,
                       hasText: text.text.isNotEmpty()
                   );
        }

        bool _showSuffixWidget(TextEditingValue text) {
            return widget.suffix != null && _shouldShowAttachment(
                       attachment: widget.suffixMode,
                       hasText: text.text.isNotEmpty()
                   );
        }

        bool _showClearButton(TextEditingValue text) {
            return _shouldShowAttachment(
                attachment: widget.clearButtonMode,
                hasText: text.text.isNotEmpty()
            );
        }

        Widget _addTextDependentAttachments(Widget editableText, TextStyle textStyle, TextStyle placeholderStyle) {
            D.assert(editableText != null);
            D.assert(textStyle != null);
            D.assert(placeholderStyle != null);

            if (widget.placeholder == null &&
                widget.clearButtonMode == OverlayVisibilityMode.never &&
                widget.prefix == null &&
                widget.suffix == null) {
                return editableText;
            }

            return new ValueListenableBuilder<TextEditingValue>(
                valueListenable: _effectiveController,
                child: editableText,
                builder: (BuildContext context, TextEditingValue text, Widget child) => {
                    List<Widget> rowChildren = new List<Widget>();

                    if (_showPrefixWidget(text)) {
                        rowChildren.Add(widget.prefix);
                    }

                    List<Widget> stackChildren = new List<Widget>();
                    if (widget.placeholder != null && text.text.isEmpty()) {
                        stackChildren.Add(
                            new Padding(
                                padding: widget.padding,
                                child: new Text(
                                    widget.placeholder,
                                    maxLines: 1,
                                    overflow: TextOverflow.ellipsis,
                                    style: placeholderStyle
                                )
                            )
                        );
                    }

                    stackChildren.Add(child);
                    rowChildren.Add(
                        new Expanded
                        (child: new Stack
                            (children: stackChildren)));

                    if (_showSuffixWidget(text)) {
                        rowChildren.Add(widget.suffix);
                    }
                    else if (_showClearButton(text)) {
                        rowChildren.Add(
                            new GestureDetector(
                                onTap: widget.enabled ?? true
                                    ? () => {
                                        bool textChanged = _effectiveController.text.isNotEmpty();
                                        _effectiveController.clear();
                                        if (widget.onChanged != null && textChanged) {
                                            widget.onChanged(_effectiveController.text);
                                        }
                                    }
                                    : (GestureTapCallback) null,
                                child: new Padding(
                                    padding: EdgeInsets.symmetric(horizontal: 6.0f),
                                    child: new Icon(
                                        CupertinoIcons.clear_thick_circled,
                                        size: 18.0f,
                                        color: CupertinoTextFieldUtils._kInactiveTextColor
                                    )
                                )
                            )
                        );
                    }

                    return new Row(children: rowChildren);
                }
            );
        }

        public override Widget build(BuildContext context) {
            base.build(context);
            TextEditingController controller = _effectiveController;
            List<TextInputFormatter> formatters = widget.inputFormatters ?? new List<TextInputFormatter>();
            bool enabled = widget.enabled ?? true;
            Offset cursorOffset =
                new Offset(
                    CupertinoTextFieldUtils._iOSHorizontalCursorOffsetPixels / MediaQuery.of(context).devicePixelRatio,
                    0);
            if (widget.maxLength != null && widget.maxLengthEnforced) {
                formatters.Add(new LengthLimitingTextInputFormatter(widget.maxLength));
            }

            CupertinoThemeData themeData = CupertinoTheme.of(context);
            TextStyle textStyle = themeData.textTheme.textStyle.merge(widget.style);
            TextStyle placeholderStyle = textStyle.merge(widget.placeholderStyle);
            Brightness? keyboardAppearance = widget.keyboardAppearance ?? themeData.brightness;
            Color cursorColor = widget.cursorColor ?? themeData.primaryColor;

            Widget paddedEditable = new Padding(
                padding: widget.padding,
                child: new RepaintBoundary(
                    child: new EditableText(
                        key: _editableTextKey,
                        controller: controller,
                        focusNode: _effectiveFocusNode,
                        keyboardType: widget.keyboardType,
                        textInputAction: widget.textInputAction,
                        textCapitalization: widget.textCapitalization,
                        style: textStyle,
                        strutStyle: widget.strutStyle,
                        textAlign: widget.textAlign,
                        autofocus: widget.autofocus,
                        obscureText: widget.obscureText,
                        autocorrect: widget.autocorrect,
                        maxLines: widget.maxLines,
                        minLines: widget.minLines,
                        expands: widget.expands,
                        selectionColor: CupertinoTextFieldUtils._kSelectionHighlightColor,
                        selectionControls: CupertinoTextSelectionUtils.cupertinoTextSelectionControls,
                        onChanged: widget.onChanged,
                        onSelectionChanged: _handleSelectionChanged,
                        onEditingComplete: widget.onEditingComplete,
                        onSubmitted: widget.onSubmitted,
                        inputFormatters: formatters,
                        rendererIgnoresPointer: true,
                        cursorWidth: widget.cursorWidth,
                        cursorRadius: widget.cursorRadius,
                        cursorColor: cursorColor,
                        cursorOpacityAnimates: true,
                        cursorOffset: cursorOffset,
                        paintCursorAboveText: true,
                        backgroundCursorColor: CupertinoColors.inactiveGray,
                        scrollPadding: widget.scrollPadding,
                        keyboardAppearance: keyboardAppearance,
                        dragStartBehavior: widget.dragStartBehavior,
                        scrollPhysics: widget.scrollPhysics
                    )
                )
            );

            return new IgnorePointer(
                ignoring: !enabled,
                child: new Container(
                    decoration: widget.decoration,
                    child: new Container(
                        color: enabled
                            ? null
                            : CupertinoTheme.of(context).brightness == Brightness.light
                                ? CupertinoTextFieldUtils._kDisabledBackground
                                : CupertinoColors.darkBackgroundGray,
                        child: new TextSelectionGestureDetector(
                            onTapDown: _handleTapDown,
                            onSingleTapUp: _handleSingleTapUp,
                            onSingleLongTapStart: _handleSingleLongTapStart,
                            onSingleLongTapMoveUpdate: _handleSingleLongTapMoveUpdate,
                            onSingleLongTapEnd: _handleSingleLongTapEnd,
                            onDoubleTapDown: _handleDoubleTapDown,
                            onDragSelectionStart: _handleMouseDragSelectionStart,
                            onDragSelectionUpdate: _handleMouseDragSelectionUpdate,
                            onDragSelectionEnd: _handleMouseDragSelectionEnd,
                            behavior: HitTestBehavior.translucent,
                            child: _addTextDependentAttachments(paddedEditable, textStyle, placeholderStyle)
                        )
                    )
                )
            );
        }
    }
}