using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text.RegularExpressions;
using System.Windows.Data;
using System.Windows.Documents;

namespace Juick.Classes
{
    public class RichTextConverter : IValueConverter
    {
        static readonly Regex UrlRegex = new Regex(@"http(s)?://([\w+?\.\w+])+([a-zA-Z0-9\~\!\@\#\$\%\^\&\*\(\)_\-\=\+\\\/\?\.\:\;\'\,]*)?", RegexOptions.Compiled);
        // TODO: Add more entities
        static readonly Regex JuickEntityRegex = new Regex(@"#(\d+)(/\d+)?", RegexOptions.Compiled);

        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            var stringValue = (string)value;
            if (string.IsNullOrEmpty(stringValue))
            {
                return Enumerable.Empty<Inline>();
            }

            var result = new List<Inline>();
            var index = 0;
            foreach (var match in UrlRegex.Matches(stringValue).OfType<Match>().Union(JuickEntityRegex.Matches(stringValue).OfType<Match>()))
            {
                Uri uri = null;
                if (!Uri.TryCreate(match.Value, UriKind.Absolute, out uri))
                {
                    // Juick entity
                    uri = new Uri(string.Format("/ThreadView.xaml?mid={0}", JuickEntityRegex.Replace(match.Value, "$1")), UriKind.Relative);
                }
                if (match.Index > 0)
                {
                    var length = match.Index - index;
                    if (length > 0)
                    {
                        result.Add(new Run { Text = stringValue.Substring(index, length) });
                    }
                }

                var hyperLink = new Hyperlink
                {
                    NavigateUri = uri                    
                };
                if (uri.IsAbsoluteUri)
                {
                    hyperLink.TargetName = "_blank";
                    hyperLink.Inlines.Add(uri.Host);
                }
                else
                {
                    hyperLink.Inlines.Add(match.Value);
                }                
                result.Add(hyperLink);

                index = match.Index + match.Length;
            }

            if (index == 0 || index < stringValue.Length - 1)
            {
                var lastRunText = stringValue.Substring(index);
                if (lastRunText.Length > 0)
                {
                    result.Add(new Run { Text = lastRunText });
                }
            }
            return result;
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return value;
        }
    }
}