using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using ChatComponents;
using JetBrains.Annotations;
using Unity.UIWidgets.animation;
using Unity.UIWidgets.async;
using Unity.UIWidgets.foundation;
using Unity.UIWidgets.painting;
using Unity.UIWidgets.rendering;
using Unity.UIWidgets.ui;
using Unity.UIWidgets.widgets;
using Image = Unity.UIWidgets.widgets.Image;
using TextStyle = Unity.UIWidgets.painting.TextStyle;

namespace UIWidgetsSample
{
    public delegate void OnLinkPressed(string str);

    public class LinkPreview : StatefulWidget
    {
        /// Expand animation duration
        public readonly TimeSpan? animationDuration;

        /// Enables expand animation. Default value is false.
        public readonly bool? enableAnimation;

        /// Custom header above provided text
        public readonly string header;

        /// Style of the custom header
        public readonly TextStyle headerStyle;

        /// Style of highlighted links in the text
        public readonly TextStyle linkStyle;

        /// Style of preview's description
        public readonly TextStyle metadataTextStyle;

        /// Style of preview's title
        public readonly TextStyle metadataTitleStyle;

        /// Custom link press handler
        public readonly OnLinkPressed onLinkPressed;


        /// Callback which is called when [PreviewData] was successfully parsed.
        /// Use it to save [PreviewData] to the state and pass it back
        /// to the [LinkPreview.previewData] so the [LinkPreview] would not fetch
        /// preview data again.
        public readonly OnPreviewDataFetched onPreviewDataFetched;

        /// Padding around initial text widget
        public readonly EdgeInsets padding;

        /// Pass saved [PreviewData] here so [LinkPreview] would not fetch preview
        /// data again
        public readonly PreviewData previewData;

        /// Text used for parsing
        public readonly string text;

        /// Style of the provided text
        public readonly TextStyle textStyle;

        /// Width of the [LinkPreview] widget
        public readonly float width;

        /// Creates [LinkPreview]
        public LinkPreview(
            OnPreviewDataFetched onPreviewDataFetched,
            PreviewData previewData,
            string text,
            float width,
            Key key = null,
            TimeSpan? animationDuration = null,
            bool enableAnimation = false,
            [CanBeNull] string header = null,
            TextStyle headerStyle = null,
            TextStyle linkStyle = null,
            TextStyle metadataTextStyle = null,
            TextStyle metadataTitleStyle = null,
            OnLinkPressed onLinkPressed = null,
            [CanBeNull] EdgeInsets padding = null,
             TextStyle textStyle = null
        ) : base(key)
        {
            this.onPreviewDataFetched = onPreviewDataFetched;
            this.previewData = previewData;
            this.text = text;
            this.width = width;
            this.animationDuration = animationDuration;
            this.enableAnimation = enableAnimation;
            this.header = header;
            this.headerStyle = headerStyle;
            this.linkStyle = linkStyle;
            this.metadataTextStyle = metadataTextStyle;
            this.metadataTitleStyle = metadataTitleStyle;
            this.onLinkPressed = onLinkPressed;
            this.padding = padding;
            this.textStyle = textStyle;
        }

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

    public class _LinkPreviewState : SingleTickerProviderStateMixin<LinkPreview>
    {
        public Animation<float> _animation;

        public AnimationController _controller;

        private bool isFetchingPreviewData;
        private bool shouldAnimate;

        public override void initState()
        {
            base.initState();
            didUpdateWidget(widget);
            _controller = new AnimationController(
                duration: widget.animationDuration ?? TimeSpan.FromMilliseconds(300),
                vsync: this);
            _animation = new  CurvedAnimation(
                parent: _controller,
                curve: Curves.easeOutQuad
            );
        }

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

            if (!isFetchingPreviewData && widget.previewData == null) _fetchData(widget.text);

            if (widget.previewData != null && ((LinkPreview) oldWidget).previewData == null)
            {
                setState(() => { shouldAnimate = true; });
                _controller.reset();
                _controller.forward();
            }
            else if (widget.previewData != null)
            {
                setState(() => { shouldAnimate = false; });
            }
        }

        public override void dispose()
        {
            _controller.dispose();
            base.dispose();
        }

        private PreviewData _fetchData(string text)
        {
            setState(() => { isFetchingPreviewData = true; });

            var previewData = getPreviewData(text);
            _handlePreviewDataFetched(previewData);
            return previewData;
        }

        private void _handlePreviewDataFetched(PreviewData previewData)
        {
            Future.delayed(
                widget.animationDuration ?? TimeSpan.FromMilliseconds(300)
            );

            if (mounted)
            {
                widget.onPreviewDataFetched(previewData);
                setState(() => { isFetchingPreviewData = false; });
            }
        }

        private bool _hasData(PreviewData previewData)
        {
            return previewData?.title != null ||
                   previewData?.description != null ||
                   previewData?.image?.url != null;
        }

        private bool _hasOnlyImage()
        {
            return widget.previewData?.title == null &&
                   widget.previewData?.description == null &&
                   widget.previewData?.image?.url != null;
        }

        /*private Future _onOpen(LinkableElement link)
        {
            if (canLaunch(link.url))
                launch(link.url);
            else
                throw $"Could not launch {link}";
        }*/

        private Widget _animated(Widget child)
        {
            return new SizeTransition(
                axis: Axis.vertical,
                axisAlignment: -1,
                sizeFactor: _animation,
                child: child
            );
        }

        private Widget _bodyWidget(PreviewData data, string text, float width)
        {
            var _padding = widget.padding ??
                           EdgeInsets.only(
                               bottom: 16,
                               left: 24,
                               right: 24
                           );

            var results = new List<Widget>();
            if (data.title != null) results.Add(_titleWidget((string)data.title ));
            if (data.description != null)
                results.Add(_descriptionWidget((string)data.description));
            var final_results = new List<Widget>();
            final_results.Add(new Container(
                padding: EdgeInsets.only(
                    bottom: _padding.bottom,
                    left: _padding.left,
                    right: _padding.right
                ),
                child: new Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: results
                )
            ));
            if (data.image?.url != null) final_results.Add(_imageWidget(data.image.url, width));
            return new Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: final_results
            );
        }

        private Widget _containerWidget(
            bool animate,
            bool withPadding = false,
            Widget child = null
        )
        {
            var _padding = widget.padding ??
                           EdgeInsets.symmetric(
                               horizontal: 24,
                               vertical: 16
                           );

            var shouldAnimate = widget.enableAnimation == true && animate;
            var results = new List<Widget>();
            if (widget.header != null)
                results.Add(new Padding(
                    padding: EdgeInsets.only(bottom: 6),
                    child: new Text(
                        (string)widget.header,
                        maxLines: 1,
                        overflow: TextOverflow.ellipsis,
                        style: widget.headerStyle
                    )
                ));
            //results.Add(_linkify());
            if (withPadding && child != null)
                results.Add(shouldAnimate ? _animated(child) : child);
            var final_results = new List<Widget>();
            final_results.Add(new Padding(
                padding: withPadding
                    ? EdgeInsets.all(0)
                    : EdgeInsets.only(
                        _padding.left,
                        right: _padding.right,
                        top: _padding.top,
                        bottom: _hasOnlyImage() ? 0 : 16
                    ),
                child: new Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: results
                )
            ));
            if (!withPadding && child != null)
                final_results.Add(shouldAnimate ? _animated(child) : child);
            return new Container(
                constraints: new BoxConstraints(maxWidth: widget.width),
                padding: withPadding ? _padding : null,
                child: new Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: final_results
                )
            );
        }

        private Widget _descriptionWidget(string description)
        {
            return new Container(
                margin: EdgeInsets.only(top: 8),
                child: new Text(
                    description,
                    maxLines: 3,
                    overflow: TextOverflow.ellipsis,
                    style: widget.metadataTextStyle
                )
            );
        }

        private Widget _imageWidget(string url, float width)
        {
            return new Container(
                constraints: new BoxConstraints(
                    maxHeight: width
                ),
                width: width,
                child: Image.network(
                    url,
                    fit: BoxFit.fitWidth
                )
            );
        }

        /*private Widget _linkify()
        {
            return SelectableLinkify(
                linkifiers:[UrlLinkifier()],
            widget.linkStyle,
            100,
            1,
            widget.onLinkPressed != null
                ? element => widget.onLinkPressed!(element.url)
                : _onOpen,
            LinkifyOptions(
                defaultToHttps: true,
                humanize: false,
                looseUrl: true,
            ),
            widget.text,
            widget.textStyle
                );
        }*/

        private Widget _minimizedBodyWidget(PreviewData data, string text)
        {
            var inner_results = new List<Widget>();
            if (data.title != null)
                inner_results.Add(_titleWidget(data.title));
            if (data.description != null)
                inner_results.Add(_descriptionWidget(data.description));

            if (data.image.url != null)
                _minimizedImageWidget(data.image.url);
            var results = new List<Widget>();
            results.Add(new Expanded(
                child: new Container(
                    margin: EdgeInsets.only(right: 4),
                    child: new Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: inner_results
                    )
                )
            ));
            if (data.image.url != null)
                results.Add(_minimizedImageWidget(data.image.url));
            var outerResults = (Widget) null;
            if (data.title != null || data.description != null)
                outerResults = new Container(
                    margin: EdgeInsets.only(top: 16),
                    child: new Row(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: results
                    )
                );
            return new Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: new List<Widget> {outerResults}
            );
        }

        private Widget _minimizedImageWidget(string url)
        {
            return new ClipRRect(
                borderRadius: BorderRadius.all(
                    Radius.circular(12)
                ),
                child: new SizedBox(
                    height: 48,
                    width: 48,
                    child: Image.network(url)
                )
            );
        }

        private Widget _titleWidget(string title)
        {
            var style = widget.metadataTitleStyle ??
                        new TextStyle(
                            fontWeight: FontWeight.bold
                        );

            return new Text(
                title,
                maxLines: 2,
                overflow: TextOverflow.ellipsis,
                style: style
            );
        }

        public override Widget build(BuildContext context)
        {
            if (widget.previewData != null && _hasData(widget.previewData))
            {
                var aspectRatio = widget.previewData.image == null
                    ? 0f
                    : widget.previewData.image.width /
                      widget.previewData.image.height;

                var _width = aspectRatio == 1 ? widget.width : widget.width - 32;

                return _containerWidget(
                    shouldAnimate,
                    child: aspectRatio == 1
                        ? _minimizedBodyWidget(widget.previewData, widget.text)
                        : _bodyWidget(widget.previewData, widget.text, _width),
                    withPadding: aspectRatio == 1
                );
            }

            return _containerWidget(false);
        }

        private PreviewData getPreviewData(string text)
        {
            var previewData = new PreviewData();

            string previewDataDescription = null;
            PreviewDataImage previewDataImage = null;
            
            string previewDataTitle ="";
            string previewDataUrl ="";
            var REGEX_LINK =
                @"([\w+]+\:\/\/)?([\w\d-]+\.)*[\w-]+[\.\:]\w+([\/\?\=\&\#\.]?[\w-]+)*\/?";
            var REGEX_IMAGE_CONTENT_TYPE = @"image\/*";
           /* try
            {
                var urlRegexp = new Regex(REGEX_LINK);
                var matches = urlRegexp.Match(text.ToLower());
                if (matches.Length == 0) return previewData;

                var url = text.Substring(matches.first.start, matches.first.end);
                if (!url.ToLower().StartsWith("http")) url = "https://" + url;
                previewDataUrl = url;
                var uri = Uri.parse(url);
                var response = http.get(uri);
                var document = parser.parse(response.body);

                var imageRegexp = new Regex(REGEX_IMAGE_CONTENT_TYPE);

                if (imageRegexp.hasMatch(response.headers["content-type"] ?? ""))
                {
                    var imageSize = _getImageSize(previewDataUrl);
                    previewDataImage = new PreviewDataImage(
                        imageSize.height,
                        previewDataUrl,
                        imageSize.width
                    );
                    return new PreviewData(
                        image: previewDataImage,
                        link: previewDataUrl
                    );
                }

                if (!_hasUTF8Charset(document)) return previewData;

                var title = _getTitle(document);
                if (title != null) previewDataTitle = title.trim();

                var description = _getDescription(document);
                if (description != null) previewDataDescription = description.trim();

                var imageUrls = _getImageUrls(document, url);

                Size imageSize;
                string imageUrl;

                if (imageUrls.isNotEmpty)
                {
                    imageUrl = imageUrls.length == 1
                        ? imageUrls[0]
                        : _getBiggestImageUrl(imageUrls);

                    imageSize = _getImageSize(imageUrl);
                    previewDataImage = new PreviewDataImage(
                        imageSize.height,
                        imageUrl,
                        imageSize.width
                    );
                }

                return new PreviewData(
                    previewDataDescription,
                    previewDataImage,
                    previewDataUrl,
                    previewDataTitle
                );
            }
            catch (Exception e)
            {
                return new PreviewData(
                    previewDataDescription,
                    previewDataImage,
                    previewDataUrl,
                    previewDataTitle
                );
            }*/
            return new PreviewData(
                previewDataDescription,
                previewDataImage,
                previewDataUrl,
                previewDataTitle
            );
        }
    }
}