mvvmnotepad

using System;
using System.Diagnostics;
using System.Windows.Input;
using SharpPad.Commands;
using SharpPad.WPF.Notepad.Backend;

namespace SharpPad.WPF.Notepad {
    public class DocumentViewModel : BaseViewModel {
        private string filePath;
        private int caretIndex;
        private int lineIndex;

        public string FilePath {
            get => this.filePath;
            set => this.RaisePropertyChanged(ref this.filePath, value);
        }

        public int CaretIndex {
            get => this.caretIndex;
            private set => this.RaisePropertyChanged(ref this.caretIndex, value);
        }

        public int LineIndex {
            get => this.lineIndex;
            private set => this.RaisePropertyChanged(ref this.lineIndex, value);
        }

        /// <summary>
        /// Gets or sets the document model used as a backend for this document. May be
        /// null, in which case, most document functionality won't work
        /// </summary>
        public ITextDocument DocumentModel { get; set; }

        /// <summary>
        /// Gets the editor model which is used to assist in usage of the document
        /// </summary>
        public ITextEditor Editor { get; private set; }

        public ICommand CloseCommand { get; }

        public DocumentViewModel() {
            this.CloseCommand = new RelayCommand(() => {
                // maybe reference the NotepadviewModel in the document, and remove `this` from the document list?
                // this.Editor?.CloseEditor(this.DocumentModel);
            });
        }

        public void OnDisconnectEditor() {
            if (this.Editor == null) {
                return;
            }

            this.Editor.CaretChanged -= this.OnEditorCaretChanged;
            this.Editor.TextBufferModified -= this.OnTextBufferChanged;
            this.Editor = null;
        }

        public void OnConnectEditor(ITextEditor editor) {
            if (this.Editor == editor)
                return;
            if (this.Editor != null)
                throw new InvalidOperationException("Another editor already connected");

            this.Editor = editor;
            editor.CaretChanged += this.OnEditorCaretChanged;
            editor.TextBufferModified += this.OnTextBufferChanged;
            if (this.DocumentModel == null) {
                this.DocumentModel = editor.NewDocument();
            }
        }

        private void OnEditorCaretChanged(ITextEditor editor) {
            this.RaisePropertyChanged(nameof(this.CaretIndex));
            this.RaisePropertyChanged(nameof(this.LineIndex));
        }

        private void OnTextBufferChanged(ITextEditor editor) {
            this.RaisePropertyChanged(nameof(this.CaretIndex));
            this.RaisePropertyChanged(nameof(this.LineIndex));
        }
    }
}