using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Windows.Documents;

namespace System.Windows.Forms
{
    /// <summary>
    /// Specifies how text in a <see cref="RichTextBox"/> is horizontally aligned.
    /// </summary>
    public enum TextAlign
    {
        /// <summary>
        /// The text is aligned to the left.
        /// </summary>
        Left,

        /// <summary>
        /// The text is aligned to the right.
        /// </summary>
        Right,

        /// <summary>
        /// The text is aligned in the center.
        /// </summary>
        Center,

        /// <summary>
        /// The text is justified.
        /// </summary>
        Justify
    }

    public class RichTextBox : Control
    {
        protected new System.Windows.Controls.RichTextBox control { get; }

        public string Rtf
        {
            get
            {
                using (var stream = new MemoryStream())
                {
                    SaveFile(stream, RichTextBoxStreamType.RichText);
                    return Encoding.UTF8.GetString(stream.ToArray());
                }
            }
            set
            {
                var documentBytes = Encoding.UTF8.GetBytes(value);
                using (var stream = new MemoryStream(documentBytes))
                {
                    stream.Position = 0;
                    LoadFile(stream, RichTextBoxStreamType.RichText);
                }
            }
        }

        private RichTextBoxScrollBars scrollBars;
        public RichTextBoxScrollBars ScrollBars
        {
            get => scrollBars;
            set
            {
                scrollBars = value;
                control.HorizontalScrollBarVisibility = value == RichTextBoxScrollBars.Horizontal || value == RichTextBoxScrollBars.Both ?
                    Windows.Controls.ScrollBarVisibility.Visible : Windows.Controls.ScrollBarVisibility.Hidden;
                control.VerticalScrollBarVisibility = value == RichTextBoxScrollBars.Vertical || value == RichTextBoxScrollBars.Both ?
                    Windows.Controls.ScrollBarVisibility.Visible : Windows.Controls.ScrollBarVisibility.Hidden;
            }
        }

        public bool ReadOnly
        {
            get => control.IsReadOnly;
            set => control.IsReadOnly = value;
        }

        public bool AcceptsTab
        {
            get => control.AcceptsTab;
            set => control.AcceptsTab = value;
        }

        public int BulletIndent { get; set; } // TODO?
        
        public bool DetectUrls { get; set; } // TODO?

        public bool HideSelection
        {
            get => !control.IsInactiveSelectionHighlightEnabled; 
            set => control.IsInactiveSelectionHighlightEnabled = !value;
        }

        public Font SelectionFont
        {
            get
            {
                object tmp = control.Selection.GetPropertyValue(Inline.FontFamilyProperty);
                var family = tmp == DependencyProperty.UnsetValue ? this.control.FontFamily : (Media.FontFamily)tmp;
                
                tmp = control.Selection.GetPropertyValue(Inline.FontSizeProperty);
                var size = tmp == DependencyProperty.UnsetValue ? this.control.FontSize : (double)tmp;
                
                tmp = control.Selection.GetPropertyValue(Inline.FontStyleProperty); ;
                var style = tmp == DependencyProperty.UnsetValue ? this.control.FontStyle : (FontStyle)tmp;
                
                tmp = control.Selection.GetPropertyValue(Inline.FontWeightProperty);
                var weight = tmp == DependencyProperty.UnsetValue ? this.control.FontWeight : (FontWeight)tmp;

                tmp = control.Selection.GetPropertyValue(Inline.TextDecorationsProperty);
                bool underline = false;
                bool strikeout = false;
                if (tmp is TextDecorationCollection deco)
                {
                    underline = deco.Where(c => c.Location == TextDecorationLocation.Underline).Any();
                    strikeout = deco.Where(c => c.Location == TextDecorationLocation.Strikethrough).Any();
                }
                
                return Helper.GetFont(DpiScale, family, size, style, weight, underline, strikeout);
            }
            set
            {
                Helper.SetFont(value, DpiScale, out var family, out var size, out var style, out var weight, out var deco);
                control.Selection.ApplyPropertyValue(Inline.FontFamilyProperty, family);
                control.Selection.ApplyPropertyValue(Inline.FontSizeProperty, size);
                control.Selection.ApplyPropertyValue(Inline.FontStyleProperty, style);
                control.Selection.ApplyPropertyValue(Inline.FontWeightProperty, weight);
                control.Selection.ApplyPropertyValue(Inline.TextDecorationsProperty, deco);
            }
        }

        public Color SelectionColor
        {
            get
            {
                object tmp = control.Selection.GetPropertyValue(Inline.ForegroundProperty);
                var color = tmp == DependencyProperty.UnsetValue ? this.control.Foreground : (System.Windows.Media.Brush)tmp;
                return Helper.GetColor(color);
            }
            set
            {
                control.Selection.ApplyPropertyValue(Inline.ForegroundProperty, Helper.GetBrush(value));
            }
        }

        public int SelectionCharOffset
        {
            get
            {
                object tmp = control.Selection.GetPropertyValue(Inline.BaselineAlignmentProperty);
                var baseline = tmp == DependencyProperty.UnsetValue ? BaselineAlignment.Baseline : (BaselineAlignment)tmp;
                if (baseline == BaselineAlignment.Subscript)
                    return -4;
                if (baseline == BaselineAlignment.Superscript)
                    return 4;
                return 0;
            }
            set
            {
                var baseline = BaselineAlignment.Baseline;
                if (value == -4)
                    baseline = BaselineAlignment.Subscript;
                else if (value == 4)
                    baseline = BaselineAlignment.Superscript;
                control.Selection.ApplyPropertyValue(Inline.BaselineAlignmentProperty, baseline);
            }
        }

        public bool SelectionBullet
        {
            get
            {
                var list = control.Document.Blocks
                    .Where(x => x.ContentStart.CompareTo(control.Selection.End) != 1 && x.ContentEnd.CompareTo(control.Selection.Start) != -1)
                    .FirstOrDefault() as List;
                if (list != null)
                    return list.MarkerStyle != TextMarkerStyle.None;
                return false;
            }
            set
            {
                EditingCommands.ToggleBullets.Execute(null, control);
            }
        }

        public TextAlign SelectionAlignment
        {
            get
            {
                object tmp = control.Selection.GetPropertyValue(Paragraph.TextAlignmentProperty);
                var textAlign = tmp == DependencyProperty.UnsetValue ? TextAlignment.Left : (TextAlignment)tmp;
                return (TextAlign)textAlign;
            }
            set
            {
                control.Selection.ApplyPropertyValue(Paragraph.TextAlignmentProperty, (TextAlignment)value);
            }
        }

        public string SelectedText 
        {
            get => control.Selection.Text;
            set => control.Selection.Text = value; 
        }

        public bool Modified { get; set; }

        public event EventHandler SelectionChanged;

        private string GetFormat(RichTextBoxStreamType fileType)
        {
            return fileType switch
            {
                RichTextBoxStreamType.RichText => DataFormats.Rtf,
                RichTextBoxStreamType.RichNoOleObjs => DataFormats.Rtf,
                RichTextBoxStreamType.UnicodePlainText => DataFormats.UnicodeText,
                _ => DataFormats.Text
            };
        }

        protected virtual void OnSelectionChanged(EventArgs e) => SelectionChanged?.Invoke(this, e);

        public void LoadFile(Stream stream, RichTextBoxStreamType fileType)
        {
            control.SelectAll();
            control.Selection.Load(stream, GetFormat(fileType));
            control.Selection.Select(control.Selection.End, control.Selection.End);
        }

        public void LoadFile(string path, RichTextBoxStreamType fileType)
        {
            using (var fs = File.OpenRead(path))
                LoadFile(fs, fileType);
        }

        public void LoadFile(string path) => LoadFile(path, RichTextBoxStreamType.RichText);

        public void SaveFile(Stream stream, RichTextBoxStreamType fileType)
        {
            control.SelectAll();
            control.Selection.Save(stream, GetFormat(fileType));
        }

        public void SaveFile(string path, RichTextBoxStreamType fileType)
        {
            using (var fs = File.OpenWrite(path))
                SaveFile(fs, fileType);
        }

        public void SaveFile(string path) => SaveFile(path, RichTextBoxStreamType.RichText);

        public void Undo() => control.Undo();

        public void Redo() => control.Redo();

        public void SetSelectionFont(string fontName)
        {
            control.Selection.ApplyPropertyValue(Inline.FontFamilyProperty, fontName);
        }

        public void SetSelectionSize(int fontSize)
        {
            control.Selection.ApplyPropertyValue(Inline.FontSizeProperty, fontSize * 96 / 72.0);
        }

        public void SetSelectionBold(bool value)
        {
            control.Selection.ApplyPropertyValue(Inline.FontWeightProperty, value ? FontWeights.Bold : FontWeights.Normal);
        }

        public void SetSelectionItalic(bool value)
        {
            control.Selection.ApplyPropertyValue(Inline.FontStyleProperty, value ? FontStyles.Italic : FontStyles.Normal);
        }

        public void SetSelectionUnderline(bool value)
        {
            control.Selection.ApplyPropertyValue(Inline.TextDecorationsProperty, value ? TextDecorations.Underline : new TextDecorationCollection());
        }

        public void SelectAll() => control.SelectAll();

        public RichTextBox()
        {
            control = new();
            SetControl(control);

            control.SelectionChanged += (s, e) => OnSelectionChanged(e);
            control.TextChanged += (s, e) =>
            {
                OnTextChanged(e);
                Modified = true;
            };
            control.PreviewDragEnter += (s, e) => OnDragEnter(Helper.GetDragEventArgs(control, e));
            control.PreviewDragLeave += (s, e) => OnDragLeave(Helper.GetDragEventArgs(control, e));
            control.PreviewDragOver += (s, e) =>
            {
                var args = Helper.GetDragEventArgs(control, e);
                args.Effect = DragDropEffects.None;
                OnDragOver(args);
                e.Effects = (Windows.DragDropEffects)args.Effect;
                e.Handled = true;
            };
        }
    }
}