using System;
using System.Collections.Generic;
using System.Globalization;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Media;

namespace Controls
{
    /// <summary>
    ///     Magically converts a text to 
    /// </summary>
    [ValueConversion(typeof(string), typeof(FrameworkElement))]
    public class MagicSymbolConverter : IValueConverter
    {
        private const string NoParseKeyword = "noParse:";
        private const string PathKeyword = "path:";
        private const string DynResKeyword = "dynRes:";

        /// <inheritdoc />
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return ConvertToFrameworkElement(value);
        }

        /// <summary>
        /// Convert string to Framework element.
        /// </summary>
        /// <param name="value"></param>
        /// <returns></returns>
        public static object ConvertToFrameworkElement(object value)
        {
            var data = value as string;
            if (string.IsNullOrWhiteSpace(data)) return value; //maybe not a string. eventually something else.

            if (data.StartsWith(NoParseKeyword, StringComparison.Ordinal)) return data[NoParseKeyword.Length..];

            if (data.StartsWith(PathKeyword, StringComparison.Ordinal))
            {
                var path = data[PathKeyword.Length..];
                var icon = ObjectImageConverter.GetIcon(Geometry.Parse(path), Brushes.Black);
                return new Image
                {
                    Source = icon,
                    HorizontalAlignment = HorizontalAlignment.Right,
                    VerticalAlignment = VerticalAlignment.Center,
                    Height = 16
                };
            }

            if (data.StartsWith(DynResKeyword, StringComparison.Ordinal))
            {
                var resourceKey = data[DynResKeyword.Length..];
                //get icon from resource dictionary
                return new Image
                {
                    Source = Application.Current.FindResource(resourceKey) as ImageSource,
                    HorizontalAlignment = HorizontalAlignment.Right,
                    VerticalAlignment = VerticalAlignment.Center,
                    Height = 16
                };
            }

            var textComponents = ParseText(data);
            return CreateTextBlock(textComponents);
        }

        private static TextBlock CreateTextBlock(IEnumerable<TextComponent> textComponents)
        {
            //create text block
            var block = new TextBlock();
            foreach (var tc in textComponents)
            {
                var run = new Run(tc.Text) {FontFamily = new FontFamily("Palatino Linotype"), FontSize = 16};
                switch (tc.Style)
                {
                    case BaselineAlignment.Subscript:
                        run.BaselineAlignment = BaselineAlignment.Subscript;
                        run.FontSize = 12;
                        break;
                    case BaselineAlignment.Superscript:
                        run.BaselineAlignment = BaselineAlignment.Superscript;
                        run.FontSize = 12;
                        break;
                }

                block.Inlines.Add(run);
            }

            block.HorizontalAlignment = HorizontalAlignment.Right;
            block.VerticalAlignment = VerticalAlignment.Center;
            return block;
        }

        private static IEnumerable<TextComponent> ParseText(string data)
        {
            //parse text
            var textComponents = new List<TextComponent>();
            var alignment = BaselineAlignment.Baseline;
            var snippet = new StringBuilder();
            foreach (var c in data)
            {
                switch (c)
                {
                    case '~':
                        if (snippet.Length > 0)
                        {
                            var comp = new TextComponent(snippet.ToString(), alignment);
                            textComponents.Add(comp);
                            snippet.Clear();
                        }

                        alignment = alignment == BaselineAlignment.Subscript
                            ? BaselineAlignment.Baseline
                            : BaselineAlignment.Subscript;
                        break;
                    case '^':
                        if (snippet.Length > 0)
                        {
                            var comp = new TextComponent(snippet.ToString(), alignment);
                            textComponents.Add(comp);
                            snippet.Clear();
                        }

                        alignment = alignment == BaselineAlignment.Superscript
                            ? BaselineAlignment.Baseline
                            : BaselineAlignment.Superscript;
                        break;
                    default:
                        snippet.Append(c);
                        break;
                }
            }

            if (snippet.Length > 0)
            {
                var comp = new TextComponent(snippet.ToString(), alignment);
                textComponents.Add(comp);
                snippet.Clear();
            }

            return textComponents;
        }

        /// <inheritdoc />
        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
            => Binding.DoNothing;
    }
}