using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;

// The Basic Page item template is documented at http://go.microsoft.com/fwlink/?LinkId=234237

namespace SimpleTextEditor
{
    using Windows.System;
    using Windows.Storage;
    using Windows.Storage.Pickers;
    using Windows.UI.Popups;

    /// <summary>
    /// A basic page that provides characteristics common to most applications.
    /// </summary>
    public sealed partial class MainPage : SimpleTextEditor.Common.LayoutAwarePage
    {
        public MainPage()
        {
            this.InitializeComponent();
        }

        /// <summary>
        /// Populates the page with content passed during navigation.  Any saved state is also
        /// provided when recreating a page from a prior session.
        /// </summary>
        /// <param name="navigationParameter">The parameter value passed to
        /// <see cref="Frame.Navigate(Type, Object)"/> when this page was initially requested.
        /// </param>
        /// <param name="pageState">A dictionary of state preserved by this page during an earlier
        /// session.  This will be null the first time a page is visited.</param>
        protected override void LoadState(Object navigationParameter, Dictionary<String, Object> pageState)
        {
        }

        /// <summary>
        /// Preserves state associated with this page in case the application is suspended or the
        /// page is discarded from the navigation cache.  Values must conform to the serialization
        /// requirements of <see cref="SuspensionManager.SessionState"/>.
        /// </summary>
        /// <param name="pageState">An empty dictionary to be populated with serializable state.</param>
        protected override void SaveState(Dictionary<String, Object> pageState)
        {
        }



        bool textChanged = false;
        bool loading = false;
        IStorageFile saveFile = null;

        private async void openButton_Click(object sender, RoutedEventArgs e)
        {
            if (textChanged)
            {
                MessageDialog overwriteDialog = new MessageDialog(
                   "You have unsaved changes. Are you sure you want to load a new file?");
                overwriteDialog.Commands.Add(new UICommand("Yes"));
                overwriteDialog.Commands.Add(new UICommand("No"));
                overwriteDialog.DefaultCommandIndex = 1;
                UICommand result = await overwriteDialog.ShowAsync() as UICommand;
                if (result != null && result.Label == "No")
                    return;
            }
            OpenFile();
        }

        private void saveButton_Click(object sender, RoutedEventArgs e)
        {
            SaveFile();
        }

        private void text_TextChanged(object sender, TextChangedEventArgs e)
        {
            if (loading)
            {
                loading = false;
                return;
            }
            if (!textChanged)
            {
                filename.Text += "*";
                saveButton.IsEnabled = true;
                textChanged = true;
            }
        }

        private async void OpenFile()
        {
            FileOpenPicker picker = new FileOpenPicker
            {
                ViewMode = PickerViewMode.List,
                SuggestedStartLocation = PickerLocationId.DocumentsLibrary
            };
            picker.FileTypeFilter.Add(".txt");
            picker.FileTypeFilter.Add(".xml");
            picker.FileTypeFilter.Add(".xaml");
            IStorageFile file = await picker.PickSingleFileAsync();
            if (file != null)
            {
                string fileContents = await FileIO.ReadTextAsync(file);
                loading = true;
                text.Text = fileContents;
                textChanged = false;
                filename.Text = file.Name;
                saveFile = file;
            }
        }
        private async void SaveFile()
        {
            if (saveFile == null)
            {
                FileSavePicker picker = new FileSavePicker
                {
                    DefaultFileExtension = ".txt",
                    SuggestedStartLocation = PickerLocationId.DocumentsLibrary
                };
                picker.FileTypeChoices.Add("Text File", new List<string>() { ".txt" });
                picker.FileTypeChoices.Add("XML File", new List<string>() { ".xml", ".xaml" });
                saveFile = await picker.PickSaveFileAsync();
                if (saveFile == null) return;
            }
            await FileIO.WriteTextAsync(saveFile, text.Text);
            await new MessageDialog("Wrote " + saveFile.Name).ShowAsync();
            textChanged = false;
            filename.Text = saveFile.Name;
        }
    }
}
