using System;
using System.IO;
using System.Linq;
using Xunit;
using ytLive.Helpers;

namespace ytLive.Tests;

/// <summary>TASK 55, slice 1 — the creator (2026-10-09): *"we need some sort of log-rotation
/// so that we don't inadvertently fill up a user's drive."*
///
/// <para>One test: the app's log is size-capped. Past the cap the file rolls to
/// <c>startup.1.log</c>, the live file starts fresh with the newest entry, and the SET of
/// files stays bounded — a long stream cannot grow the log without limit. (The old
/// behaviour appended forever; the file was 23 MB and growing every few seconds.)</para></summary>
[Collection("RealApp")]
public class AppLogRotationTests
{
    [Fact]
    public void The_startup_log_rolls_at_its_cap_and_the_file_set_stays_bounded()
    {
        var directory = Path.Combine(Path.GetTempPath(),
            "ytlive-log-rotation-" + Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(directory);
        var live = Path.Combine(directory, "startup.log");
        var rolled = Path.Combine(directory, "startup.1.log");
        const long cap = 4096;
        var first = "first-" + new string('x', 3000);
        var second = "second-" + new string('y', 3000);
        var third = "third-" + new string('z', 3000);

        try
        {
            AppLog.PathOverride = live;
            AppLog.MaxBytes = cap;

            AppLog.Write(first);
            AppLog.Write(second);
            Assert.False(File.Exists(rolled)); // under the cap — nothing rolls yet

            AppLog.Write(third); // this write trips the cap
            Assert.True(File.Exists(rolled));
            Assert.Contains(first, File.ReadAllText(rolled));
            Assert.Contains(second, File.ReadAllText(rolled));
            Assert.DoesNotContain(first, File.ReadAllText(live)); // the live file is fresh
            Assert.Contains(third, File.ReadAllText(live));
            Assert.True(new FileInfo(live).Length < cap);

            // A second roll must not grow the file set: the live file plus one rolled copy.
            AppLog.Write(first);
            AppLog.Write(second);
            AppLog.Write(third);

            var files = Directory.GetFiles(directory)
                .Select(Path.GetFileName)
                .OrderBy(name => name, StringComparer.Ordinal)
                .ToArray();
            Assert.Equal(new[] { "startup.1.log", "startup.log" }, files);
        }
        finally
        {
            AppLog.PathOverride = null;
            AppLog.MaxBytes = 5 * 1024 * 1024;
            try { Directory.Delete(directory, true); } catch { }
        }
    }
}