Fix bugs in license displaying.

Author: JetStream96

LICENSE.txt

@@ -1,4 +1,4 @@
-The navigation data (all files in `/QSimPlanner/[Version]/NavData` folder) 
+The navigation data (all files in /QSimPlanner/[Version]/NavData folder) 
 shipped with this program is Aerosoft's property and is under Aerosoft's 
 NavDataPro license.
 

src/QSP/Program.cs

@@ -65,13 +65,30 @@ internal static void Main(string[] args)
 #if !DEBUG
                 UpdateOnFirstRun();
 #endif
+
+                ShowLicenseIfNeeded();
                 var mainFrm = new QspForm();
                 mainFrm.Init();
 
                 Application.Run(mainFrm);
             }
         }
 
+        private static void ShowLicenseIfNeeded()
+        {
+            if ( ShouldShowLicense())
+            {
+                var frm = new LicenseForm()
+                {
+                    StartPosition = FormStartPosition.CenterScreen
+                };
+
+                frm.Init();
+                frm.ShowDialog();
+                if (!frm.Agreed) Environment.Exit(0);
+            }
+        }
+
         // @Throws
         private static bool UsingLatestVersion()
         {

src/QSP/UI/Forms/LicenseForm.Designer.cs

@@ -1,11 +1,5 @@
 using System;
-using System.Collections.Generic;
-using System.ComponentModel;
-using System.Data;
-using System.Drawing;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
+using System.IO;
 using System.Windows.Forms;
 
 namespace QSP.UI.Forms
@@ -19,9 +13,23 @@ public LicenseForm()
             InitializeComponent();
         }
 
+        public void Init()
+        {
+            try
+            {
+                richTextBox1.Text = File.ReadAllText("LICENSE.txt");
+            }
+            catch
+            {
+                richTextBox1.Text =
+                    "Build the application with InstallerBuilder to have this work properly.";
+            }
+        }
+
         private void agreeBtn_Click(object sender, EventArgs e)
         {
             Agreed = true;
+            this.Close();
         }
     }
 }

src/QSP/UI/Forms/LicenseForm.cs

@@ -1,4 +1,5 @@
-using System;
+using QSP.Common.Options;
+using System;
 using System.IO;
 using System.Xml.Linq;
 
@@ -13,11 +14,13 @@ public static string GetFolder(Version ver)
             return Path.Combine("..", ver.ToString());
         }
 
-        // @Throws
-        // The versions are strings of the format major.minor.build.
-        // Backup version is empty string if the application was never updated.
-        // Do NOT use reflection to get the current version so that it is easier to test the
-        // updater system.
+        /// <summary>
+        /// The versions are strings of the format major.minor.build.
+        /// Backup version is empty string if the application was never updated.
+        /// Do NOT use reflection to get the current version so that it is easier to test the
+        /// updater system.
+        /// </summary>
+        /// <exception cref="Exception"></exception>
         public static VersionInfo GetVersions()
         {
             var root = GetVersionXDoc().Root;
@@ -29,12 +32,33 @@ public static VersionInfo GetVersions()
             };
         }
 
-        // @Throws
+        /// <exception cref="Exception"></exception>
         public static XDocument GetVersionXDoc()
         {
             return XDocument.Load(VersionXmlPath);
         }
 
         public class VersionInfo { public string Backup, Current; }
+
+        // @NoThrow
+        /// <summary>
+        /// Shows the license only if the current version of application is never run,
+        /// and the license text changed from the previous version which the user has.
+        /// </summary>
+        public static bool ShouldShowLicense()
+        {
+            try
+            {
+                if (File.Exists(OptionManager.DefaultPath)) return false;
+
+                var ver = GetVersions();
+                var prevTxt = Path.Combine("..", ver.Backup, "LICENSE.txt");
+                return File.ReadAllText(prevTxt) == File.ReadAllText("LICENSE.txt");
+            }
+            catch
+            {
+                return true;
+            }
+        }
     }
 }