Elwig: Add BackupService

Elwig/Services/BackupService.cs

@@ -0,0 +1,110 @@
+using Elwig.Helpers;
+using Elwig.Helpers.Export;
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.IO;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace Elwig.Services {
+    public static class BackupService {
+
+        public static bool IsAnyBackupUpToDate {
+            get {
+                var lastDbWrite = File.GetLastWriteTime(App.Config.DatabaseFile);
+                lastDbWrite += new TimeSpan(0, 0, -1);
+                return Directory.GetFiles(App.Config.BackupPath, "????-??-??_??-??-??.*.zip")
+                    .Any(n => DateTime.ParseExact(Path.GetFileName(n)[..19], "yyyy-MM-dd_HH-mm-ss", CultureInfo.InvariantCulture, DateTimeStyles.None) >= lastDbWrite);
+            }
+        }
+
+        public static async Task TryDatabaseBackup() {
+            if (IsAnyBackupUpToDate) return;
+            await BackupDatabase();
+            PruneBackups();
+        }
+
+        public static async Task BackupDatabase() {
+            await Database.ExportSql(Path.Combine(App.Config.BackupPath, $"{File.GetLastWriteTime(App.Config.DatabaseFile):yyyy-MM-dd_HH-mm-ss}.sql.zip"), true);
+        }
+
+        public static void PruneBackups() {
+            var retain = new HashSet<string>();
+            var backups = Directory.GetFiles(App.Config.BackupPath, "????-??-??_??-??-??.*.zip")
+                .Select(n => (FileName: n, Timestamp: DateTime.ParseExact(Path.GetFileName(n)[..19], "yyyy-MM-dd_HH-mm-ss", CultureInfo.InvariantCulture, DateTimeStyles.None)))
+                .OrderByDescending(t => t.Timestamp).ToArray();
+
+            DateTime now;
+
+            // retain hourly backups
+            now = DateTime.Now;
+            for (int i = 0; i < App.Config.BackupRetainHours; i++, now = now.AddHours(-1)) {
+                foreach (var b in backups) {
+                    if (b.Timestamp.Date == now.Date && b.Timestamp.Hour == now.Hour) {
+                        retain.Add(b.FileName);
+                        break;
+                    }
+                }
+            }
+
+            // retain daily backups
+            now = DateTime.Now;
+            for (int i = 0; i < App.Config.BackupRetainDays; i++, now = now.AddDays(-1)) {
+                foreach (var b in backups) {
+                    if (b.Timestamp.Date == now.Date) {
+                        retain.Add(b.FileName);
+                        break;
+                    }
+                }
+            }
+
+            // retain weekly backups
+            now = DateTime.Now;
+            for (int i = 0; i < App.Config.BackupRetainWeeks; i++, now = now.AddDays(-7)) {
+                foreach (var b in backups) {
+                    if (b.Timestamp.GetYearAndWeek() == now.GetYearAndWeek()) {
+                        retain.Add(b.FileName);
+                        break;
+                    }
+                }
+            }
+
+            // retain monthly backups
+            now = DateTime.Now;
+            for (int i = 0; i < App.Config.BackupRetainMonths; i++, now = now.AddMonths(-1)) {
+                foreach (var b in backups) {
+                    if (b.Timestamp.Year == now.Year && b.Timestamp.Month == now.Month) {
+                        retain.Add(b.FileName);
+                        break;
+                    }
+                }
+            }
+
+            // retain tertial backups
+            now = new DateTime(DateTime.Now.Year + 1, 3, 1);
+            for (int i = 0; i < 600; i++, now = now.AddMonths(-4)) {
+                foreach (var b in backups) {
+                    if (b.Timestamp.GetYearAndTertial() == now.GetYearAndTertial()) {
+                        retain.Add(b.FileName);
+                        break;
+                    }
+                }
+            }
+
+            // delete non-retained files
+            foreach (var b in backups) {
+                if (retain.Contains(b.FileName)) continue;
+                try {
+                    File.Delete(b.FileName);
+                } catch { }
+            }
+            // delete temp files
+            foreach (var f in Directory.GetFiles(App.Config.BackupPath, "*.tmp")) {
+                try {
+                    File.Delete(f);
+                } catch { }
+            }
+        }
+    }
+}