[Proposal] Add an API to Track App Versions

Caboodle/VersionTracking/VersionTracking.shared.cs

@@ -0,0 +1,118 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace Microsoft.Caboodle
+{
+    public static class VersionTracking
+    {
+        const string versionTrailKey = "VersionTracking.Trail";
+        const string versionsKey = "VersionTracking.Versions";
+        const string buildsKey = "VersionTracking.Builds";
+
+        static readonly Preferences preferences = new Preferences($"{AppInfo.PackageName}.caboodle");
+
+        static Dictionary<string, List<string>> versionTrail;
+
+        public static void Track()
+        {
+            IsFirstLaunchEver = !preferences.ContainsKey(versionsKey) || !preferences.ContainsKey(buildsKey);
+            if (IsFirstLaunchEver)
+            {
+                versionTrail = new Dictionary<string, List<string>>
+                {
+                    { versionsKey, new List<string>() },
+                    { buildsKey, new List<string>() }
+                };
+            }
+            else
+            {
+                versionTrail = new Dictionary<string, List<string>>
+                {
+                    { versionsKey, ReadHistory(versionsKey).ToList() },
+                    { buildsKey, ReadHistory(buildsKey).ToList() }
+                };
+            }
+
+            IsFirstLaunchForCurrentVersion = !versionTrail[versionsKey].Contains(CurrentVersion);
+            if (IsFirstLaunchForCurrentVersion)
+            {
+                versionTrail[versionsKey].Add(CurrentVersion);
+            }
+
+            IsFirstLaunchForCurrentBuild = !versionTrail[buildsKey].Contains(CurrentBuild);
+            if (IsFirstLaunchForCurrentBuild)
+            {
+                versionTrail[buildsKey].Add(CurrentBuild);
+            }
+
+            if (IsFirstLaunchForCurrentVersion || IsFirstLaunchForCurrentBuild)
+            {
+                WriteHistory(versionsKey, versionTrail[versionsKey]);
+                WriteHistory(buildsKey, versionTrail[buildsKey]);
+            }
+        }
+
+        public static bool IsFirstLaunchEver { get; private set; }
+
+        public static bool IsFirstLaunchForCurrentVersion { get; private set; }
+
+        public static bool IsFirstLaunchForCurrentBuild { get; private set; }
+
+        public static string CurrentVersion => AppInfo.VersionString;
+
+        public static string CurrentBuild => AppInfo.BuildString;
+
+        public static string PreviousVersion => GetPrevious(versionsKey);
+
+        public static string PreviousBuild => GetPrevious(buildsKey);
+
+        public static string FirstInstalledVersion => versionTrail[versionsKey].FirstOrDefault();
+
+        public static string FirstInstalledBuild => versionTrail[buildsKey].FirstOrDefault();
+
+        public static IEnumerable<string> VersionHistory => versionTrail[versionsKey].ToArray();
+
+        public static IEnumerable<string> BuildHistory => versionTrail[buildsKey].ToArray();
+
+        public static bool IsFirstLaunchForVersion(string version)
+            => CurrentVersion == version && IsFirstLaunchForCurrentVersion;
+
+        public static bool IsFirstLaunchForBuild(string build)
+            => CurrentBuild == build && IsFirstLaunchForCurrentBuild;
+
+        internal static string GetStatus()
+        {
+            var sb = new StringBuilder();
+            sb.AppendLine();
+            sb.AppendLine("VersionTracking");
+            sb.AppendLine($"  IsFirstLaunchEver:              {IsFirstLaunchEver}");
+            sb.AppendLine($"  IsFirstLaunchForCurrentVersion: {IsFirstLaunchForCurrentVersion}");
+            sb.AppendLine($"  IsFirstLaunchForCurrentBuild:   {IsFirstLaunchForCurrentBuild}");
+            sb.AppendLine();
+            sb.AppendLine($"  CurrentVersion:                 {CurrentVersion}");
+            sb.AppendLine($"  PreviousVersion:                {PreviousVersion}");
+            sb.AppendLine($"  FirstInstalledVersion:          {FirstInstalledVersion}");
+            sb.AppendLine($"  VersionHistory:                 [{string.Join(", ", VersionHistory)}]");
+            sb.AppendLine();
+            sb.AppendLine($"  CurrentBuild:                   {CurrentBuild}");
+            sb.AppendLine($"  PreviousBuild:                  {PreviousBuild}");
+            sb.AppendLine($"  FirstInstalledBuild:            {FirstInstalledBuild}");
+            sb.AppendLine($"  BuildHistory:                   [{string.Join(", ", BuildHistory)}]");
+            return sb.ToString();
+        }
+
+        static string[] ReadHistory(string key)
+            => preferences.Get(key, null)?.Split(new[] { '|' }, StringSplitOptions.RemoveEmptyEntries) ?? new string[0];
+
+        static void WriteHistory(string key, IEnumerable<string> history)
+            => string.Join("|", history);
+
+        static string GetPrevious(string key)
+        {
+            var trail = versionTrail[key];
+            return (trail.Count >= 2) ? trail[trail.Count - 2] : null;
+        }
+    }
+}