using ICSharpCode.AvalonEdit.CodeCompletion;
using ICSharpCode.AvalonEdit.Folding;
using ICSharpCode.AvalonEdit.Highlighting;
using System;
using System.Collections.Generic;
using System.Windows.Forms;
using System.Windows.Input;
using System.Windows.Media;

namespace FastReport.Design.PageDesigners.Code
{
    internal enum CompletionAction
    {
        None,
        DotEntered,
        EqualEntered,
        CtrlSpacePressed
    }

    internal class CompletionEventArgs : EventArgs
    {
        public IList<ICompletionData> CompletionData { get; }

        public string Text { get; }

        public CompletionAction Action { get; }

        public CompletionEventArgs(IList<ICompletionData> completionData, string text, CompletionAction action)
        {
            CompletionData = completionData;
            Text = text;
            Action = action;
        }
    }

    internal delegate void CompletionEventHandler(object sender, CompletionEventArgs e);


    internal partial class AvalonSyntaxEditor : SyntaxEditorBase
    {
        private ICSharpCode.AvalonEdit.TextEditor editor;
        private FoldingManager foldingManager;
        private CompletionWindow completionWindow;
        private Report report;

        public override string Text 
        { 
            get => editor.Text; 
            set => editor.Text = value; 
        }

        public override string SelectedText
        {
            get => editor.SelectedText;
            set => editor.SelectedText = value;
        }

        public override bool Modified
        {
            get => editor.IsModified;
            set => editor.IsModified = value;
        }

        public override bool ShowLineNumbers
        {
            get => editor.ShowLineNumbers;
            set => editor.ShowLineNumbers = value;
        }

        public override bool EnableVirtualSpace
        {
            get => editor.Options.EnableVirtualSpace;
            set => editor.Options.EnableVirtualSpace = value;
        }

        public override bool ConvertTabsToSpaces
        {
            get => editor.Options.ConvertTabsToSpaces;
            set => editor.Options.ConvertTabsToSpaces = value;
        }

        public override int IndentationSize
        {
            get => editor.Options.IndentationSize; 
            set => editor.Options.IndentationSize = value;
        }

        private SyntaxType syntaxType;
        public override SyntaxType SyntaxType
        {
            get => syntaxType;
            set
            {
                syntaxType = value;
                switch (value)
                {
                    case SyntaxType.None:
                        editor.SyntaxHighlighting = null;
                        break;
                    case SyntaxType.Cs:
                        editor.SyntaxHighlighting = HighlightingManager.Instance.GetDefinition("C#");
                        UpdateCSSyntaxColors();
                        break;
                    case SyntaxType.Vb:
                        editor.SyntaxHighlighting = HighlightingManager.Instance.GetDefinition("VB");
                        break;
                    case SyntaxType.Xml:
                        editor.SyntaxHighlighting = HighlightingManager.Instance.GetDefinition("XML");
                        break;
                }
            }
        }

        public override bool AllowCodeCompletion { get; set; }

        private void UpdateCSSyntaxColors()
        {
            var hl = editor.SyntaxHighlighting;
            hl.GetNamedColor("StringInterpolation").Foreground =
            hl.GetNamedColor("Punctuation").Foreground =
            hl.GetNamedColor("NumberLiteral").Foreground = new SimpleHighlightingBrush(Colors.Black);
            hl.GetNamedColor("Comment").Foreground = new SimpleHighlightingBrush(Colors.Green);
            hl.GetNamedColor("MethodCall").Foreground = new SimpleHighlightingBrush(Color.FromRgb(116, 83, 31));
            hl.GetNamedColor("String").Foreground = new SimpleHighlightingBrush(Colors.Brown);
            hl.GetNamedColor("Char").Foreground = new SimpleHighlightingBrush(Colors.Red);
            hl.GetNamedColor("Preprocessor").Foreground = new SimpleHighlightingBrush(Colors.DarkGray);
            hl.GetNamedColor("GetSetAddRemove").Foreground =
            hl.GetNamedColor("Visibility").Foreground = 
            hl.GetNamedColor("ParameterModifiers").Foreground = 
            hl.GetNamedColor("Modifiers").Foreground = 
            hl.GetNamedColor("TrueFalse").Foreground = 
            hl.GetNamedColor("Keywords").Foreground = 
            hl.GetNamedColor("ValueTypeKeywords").Foreground = 
            hl.GetNamedColor("SemanticKeywords").Foreground = 
            hl.GetNamedColor("NamespaceKeywords").Foreground = 
            hl.GetNamedColor("ReferenceTypeKeywords").Foreground = 
            hl.GetNamedColor("ThisOrBaseReference").Foreground = 
            hl.GetNamedColor("NullOrValueKeywords").Foreground = 
            hl.GetNamedColor("GotoKeywords").Foreground = 
            hl.GetNamedColor("ContextKeywords").Foreground = 
            hl.GetNamedColor("ExceptionKeywords").Foreground = 
            hl.GetNamedColor("CheckedKeyword").Foreground = 
            hl.GetNamedColor("UnsafeKeywords").Foreground = 
            hl.GetNamedColor("OperatorKeywords").Foreground =
            hl.GetNamedColor("TypeKeywords").Foreground =
            hl.GetNamedColor("SemanticKeywords").Foreground = new SimpleHighlightingBrush(Colors.Blue);

            foreach (var color in hl.NamedHighlightingColors)
            {
                color.FontWeight = null;
            }
            editor.SyntaxHighlighting = null;
            editor.SyntaxHighlighting = hl;
        }

        private string GetTextAtCaret(int caretPosition)
        {
            int i = caretPosition - 1;
            string text = editor.Text;
            while (i > 0 && (char.IsLetterOrDigit(text[i]) || text[i] == '.'))
                i--;
            if (i > 0)
                i++;
            return caretPosition - i > 0 ? text.Substring(i, caretPosition - i) : "";
        }

        private char GetCharAtCaret(int caretPosition)
        {
            string text = editor.Text;
            return caretPosition >= 0 && caretPosition < text.Length ? text[caretPosition] : '\0';
        }

        private string GetWordAtCaret(int caretPosition)
        {
            int i = caretPosition - 1;
            string text = editor.Text;
            while (i > 0 && char.IsLetterOrDigit(text[i]))
                i--;
            if (i > 0)
                i++;
            return caretPosition - i > 0 ? text.Substring(i, caretPosition - i) : "";
        }

        private void ShowCompletion(string enteredText, bool ctrlSpace)
        {
            if (!AllowCodeCompletion)
                return;

            string textAtCaret = "";
            CompletionAction action = CompletionAction.None;
            if (enteredText == ".")
            {
                action = CompletionAction.DotEntered;
                textAtCaret = GetTextAtCaret(editor.CaretOffset - 1);
            }
            else if (ctrlSpace)
            {
                action = CompletionAction.CtrlSpacePressed;
                textAtCaret = GetTextAtCaret(editor.CaretOffset);
            }
            else if (enteredText == " " && GetCharAtCaret(editor.CaretOffset - 2) == '=')
            {
                action = CompletionAction.EqualEntered;
                textAtCaret = GetTextAtCaret(editor.CaretOffset - 3);
            }

            if (action != CompletionAction.None)
            {
                completionWindow = new CompletionWindow(editor.TextArea);
                completionWindow.ResizeMode = System.Windows.ResizeMode.NoResize;

                IList<ICompletionData> data = completionWindow.CompletionList.CompletionData;
                DoCodeCompletion(new CompletionEventArgs(data, textAtCaret, action));

                if (action == CompletionAction.CtrlSpacePressed)
                {
                    string lastWord = GetWordAtCaret(editor.CaretOffset);
                    completionWindow.StartOffset -= lastWord.Length;
                }

                if (data.Count > 0)
                {
                    completionWindow.Show();
                    completionWindow.Closed += (s, args) => completionWindow = null;
                }
            }
        }

        private void editor_TextArea_TextEntered(object sender, TextCompositionEventArgs e)
        {
            ShowCompletion(e.Text, false);
        }

        private void OnCtrlSpaceCommand(object sender, ExecutedRoutedEventArgs executedRoutedEventArgs)
        {
            ShowCompletion(null, true);
        }

        private void editor_TextArea_TextEntering(object sender, TextCompositionEventArgs e)
        {
            if (!AllowCodeCompletion)
                return;

            if (e.Text.Length > 0 && completionWindow != null)
            {
                if (!char.IsLetterOrDigit(e.Text[0]))
                {
                    // Whenever a non-letter is typed while the completion window is open,
                    // insert the currently selected element.
                    completionWindow.CompletionList.RequestInsertion(e);
                }
            }
        }

        public override void Cut() => editor.Cut();

        public override void Copy() => editor.Copy();

        public override void Paste() => editor.Paste();

        public override bool CanUndo => editor.CanUndo;

        public override void Undo() => editor.Undo();

        public override bool CanRedo => editor.CanRedo;

        public override void Redo() => editor.Redo();

        public override void Select(int start, int length)
        {
            editor.Select(start, length);
        }

        public override void SelectAll() => editor.SelectAll();

        public override void Focus()
        {
            Application.DoEvents();
            editor.Dispatcher.InvokeAsync(() => editor.Focus());
        }

        public override void Locate(int line, int column)
        {
            editor.CaretOffset = editor.Document.GetOffset(line, column);
        }

        public override void SetCaretFromMousePosition(System.Drawing.Point pos)
        {
            var textPos = editor.GetPositionFromPoint(new System.Windows.Point(pos.X / DpiScale, pos.Y / DpiScale));
            if (textPos != null)
            {
                Locate(textPos.Value.Line, textPos.Value.Column);
            }
        }

        public override void UpdateInternals(Report report)
        {
            this.report = report;
        }

        public AvalonSyntaxEditor() 
        {
            editor = new ICSharpCode.AvalonEdit.TextEditor();
            SetControl(editor);
            
            foldingManager = FoldingManager.Install(editor.TextArea);
            editor.HorizontalScrollBarVisibility = editor.VerticalScrollBarVisibility = System.Windows.Controls.ScrollBarVisibility.Auto;
            editor.Padding = new System.Windows.Thickness(4, 2, 0, 0);

            editor.TextChanged += (s, e) => OnTextChanged();
            editor.TextArea.TextEntering += editor_TextArea_TextEntering;
            editor.TextArea.TextEntered += editor_TextArea_TextEntered;

            var ctrlSpace = new RoutedCommand();
            ctrlSpace.InputGestures.Add(new KeyGesture(Key.Space, System.Windows.Input.ModifierKeys.Control));
            editor.CommandBindings.Add(new CommandBinding(ctrlSpace, OnCtrlSpaceCommand));
        }
    }
}