Implement dismiss expired cases repeating task (#891)

* Implement dismiss expired cases repeating task

I have the time temporarily set to every 1 minute for testing purposes

* Rename cases list variable to be a bit more self documenting

* Switch repeat interval to four hours

* Make no operation log a debug

* Add case expiration unit tests

I called the file ModerationTests in case we want to add more general moderation unit tests in the future

* I blame zaprit

* Fix tests

* Tests nitpicks and use UtcNow instead of Now

* Use Assert.Null and Assert.NotNull for better readability

ProjectLighthouse.Tests/Unit/ModerationTests.cs

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+using System;
+using LBPUnion.ProjectLighthouse.Administration.Maintenance.RepeatingTasks;
+using LBPUnion.ProjectLighthouse.Database;
+using LBPUnion.ProjectLighthouse.Tests.Helpers;
+using LBPUnion.ProjectLighthouse.Types.Entities.Moderation;
+using Microsoft.EntityFrameworkCore;
+using Xunit;
+
+namespace LBPUnion.ProjectLighthouse.Tests.Unit;
+
+[Trait("Category", "Unit")]
+public class ModerationTests
+{
+    [Fact]
+    public async void DismissExpiredCases_ShouldDismissExpiredCase()
+    {
+        await using DatabaseContext database = await MockHelper.GetTestDatabase();
+        
+        ModerationCaseEntity @case = new()
+        {
+            CaseId = 1,
+            ExpiresAt = DateTime.UnixEpoch,
+            CreatorUsername = "unitTestUser",
+        };
+        
+        database.Cases.Add(@case);
+        
+        await database.SaveChangesAsync();
+        
+        DismissExpiredCasesTask task = new();
+        await task.Run(database);
+
+        Assert.Null(await database.Cases.FirstOrDefaultAsync(c => c.CaseId == 1 && c.DismissedAt == null));
+    }
+
+    [Fact]
+    public async void DismissExpiredCases_ShouldNotDismissActiveCase()
+    {
+        await using DatabaseContext database = await MockHelper.GetTestDatabase();
+
+        ModerationCaseEntity @case = new()
+        {
+            CaseId = 2,
+            ExpiresAt = DateTime.UtcNow.AddHours(1),
+            CreatorUsername = "unitTestUser",
+        };
+
+        database.Cases.Add(@case);
+
+        await database.SaveChangesAsync();
+
+        DismissExpiredCasesTask task = new();
+        await task.Run(database);
+
+        Assert.NotNull(await database.Cases.FirstOrDefaultAsync(c => c.CaseId == 2 && c.DismissedAt == null));
+    }
+}

ProjectLighthouse/Administration/Maintenance/RepeatingTasks/DismissExpiredCasesTask.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using LBPUnion.ProjectLighthouse.Database;
+using LBPUnion.ProjectLighthouse.Logging;
+using LBPUnion.ProjectLighthouse.Types.Entities.Moderation;
+using LBPUnion.ProjectLighthouse.Types.Logging;
+using LBPUnion.ProjectLighthouse.Types.Maintenance;
+using Microsoft.EntityFrameworkCore;
+
+namespace LBPUnion.ProjectLighthouse.Administration.Maintenance.RepeatingTasks;
+
+public class DismissExpiredCasesTask : IRepeatingTask
+{
+    public string Name => "Dismiss Expired Cases";
+    public TimeSpan RepeatInterval => TimeSpan.FromHours(4);
+    public DateTime LastRan { get; set; }
+
+    public async Task Run(DatabaseContext database)
+    {
+        List<ModerationCaseEntity> expiredCases =
+            await database.Cases.Where(c => c.ExpiresAt != null && c.ExpiresAt < DateTime.UtcNow).ToListAsync();
+
+        if (expiredCases.Count == 0)
+        {
+            Logger.Debug("There are no expired cases to dismiss", LogArea.Maintenance);
+            return;
+        }
+
+        foreach (ModerationCaseEntity @case in expiredCases)
+        {
+            @case.DismissedAt = DateTime.Now;
+            Logger.Info($"Dismissed expired case {@case.CaseId}", LogArea.Maintenance);
+        }
+
+        await database.SaveChangesAsync();
+    }
+}