using System;
using System.IO;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Windows.Forms;

namespace QuizApp {
   public partial class frmQuizApp : Form {
      private FileInfo _DataFile = new FileInfo(@"..\..\Data.xml");
      public frmQuizApp() {
         InitializeComponent();
         btLoad.Click += btLoad_Click;
         btSave.Click += btSave_Click;
         LoadData();
      }

      void btLoad_Click(object sender, EventArgs e) { LoadData(); }

      void btSave_Click(object sender, EventArgs e) {
         if (!this.Validate()) return;
         quizDts.WriteXml(_DataFile.FullName);
         quizDts.AcceptChanges();  // Doku lesen! AcceptChanges() bei hinterlegter Datenbank **nicht** verwenden! Unbedingt vorher Doku lesen und **verstehen**
         System.Media.SystemSounds.Asterisk.Play();
      }

      void LoadData() {
         quizDts.QuizFrage.ColumnChanged -= QuizFrage_ColumnChanged; // Event vor Massen-Operationen deaktivieren
         var bss = components.Components.OfType<BindingSource>().ToArray();
         foreach (var bs in bss) bs.RaiseListChangedEvents = false;
         quizDts.Clear();
         quizDts.ReadXml(_DataFile.FullName);
         quizDts.AcceptChanges();  // Doku lesen! AcceptChanges() bei hinterlegter Datenbank **nicht** verwenden! Unbedingt vorher Doku lesen und **verstehen**
         foreach (var bs in bss) {
            bs.RaiseListChangedEvents = true;
            bs.ResetBindings(false);
         }
         quizDts.QuizFrage.ColumnChanged += QuizFrage_ColumnChanged;
      }

      void QuizFrage_ColumnChanged(object sender, DataColumnChangeEventArgs e) {
         if (e.ProposedValue == null) return;
         quizDts.QuizFrage.ColumnChanged -= QuizFrage_ColumnChanged; // Event deaktivieren, sonst Selbst-Auslösung
         var tb = quizDts.QuizFrage;
         foreach (var col in new DataColumn[] { tb.SpellFrageIDColumn, tb.MCFrageIDColumn, tb.BildFrageIDColumn }) {
            if (col != e.Column && !e.Row.IsNull(col)) e.Row[col] = Convert.DBNull;
         }
         quizDts.QuizFrage.ColumnChanged += QuizFrage_ColumnChanged;
      }

      protected override void OnClosing(CancelEventArgs e) {
         if (quizDts.HasChanges()) {
            switch (MessageBox.Show(this, "Save Changes?", "Save Changes?", MessageBoxButtons.YesNoCancel)) {
            case DialogResult.Yes: btSave.PerformClick();
               break;
            case DialogResult.No:
               break;
            case DialogResult.Cancel: e.Cancel = true;
               break;
            }
         }
         base.OnClosing(e);
      }
      protected override void OnClosed(EventArgs e) {
         tabControl1.Dispose();
         base.OnClosed(e);
      }

      private void mCAntwortDataGridView_CellContentClick(object sender, DataGridViewCellEventArgs e) {
         var grd = (DataGridView)sender;
         if (grd.Columns[e.ColumnIndex].DataPropertyName != "IsTrue") return;
         var rwAntw = (QuizDts.MCAntwortRow)((DataRowView)bsMcFrageMcAntwort.Current).Row;
         var rwFrage = rwAntw.MCFrageRow;
         rwFrage.MCAntwortRow = rwFrage.MCAntwortRow == rwAntw ? null : rwAntw;
      }
   }
}