using System.IO.Compression;
using Microsoft.Data.Sqlite;
using Microsoft.Extensions.DependencyInjection;
using static WebDrop.Api.Tests.ServerFixture;

namespace WebDrop.Api.Tests;

/// <summary>主后端每天把数据库快照压缩后传到外部存储(S3 协议),按保留期清理旧的。</summary>
public sealed class BackupTests : IAsyncLifetime
{
    private readonly FakeS3 _s3 = new();
    private ServerFixture _server = null!;

    public async Task InitializeAsync()
    {
        await _s3.StartAsync();
        _server = ServerFixture.WithSettings(new()
        {
            ["WebDrop:Backup:S3:Endpoint"] = _s3.Url,
            ["WebDrop:Backup:S3:AccessKey"] = FakeS3.AccessKey,
            ["WebDrop:Backup:S3:SecretKey"] = FakeS3.SecretKey,
            ["WebDrop:Backup:S3:BasePath"] = "webdrop",
            ["WebDrop:Backup:S3:Bucket"] = FakeS3.Bucket,
            ["WebDrop:Backup:RetainDays"] = "30",
        });
        await _server.InitializeAsync();
    }

    public async Task DisposeAsync()
    {
        await _server.DisposeAsync();
        await _s3.DisposeAsync();
    }

    [Fact]
    public async Task TheSnapshotIsAConsistentCompressedDatabaseAndOldOnesAreRetired()
    {
        var ch = await _server.CreateAsync();
        var worker = _server.App.Services.GetServices<Microsoft.Extensions.Hosting.IHostedService>().OfType<WebDrop.Api.BackupWorker>().Single();

        // 40 天前做的一份,和今天的一份
        var old = await worker.RunOnceAsync(DateTime.Now.AddDays(-40), CancellationToken.None);
        Assert.Equal(0, old.Purged);
        Assert.True(_s3.Files.ContainsKey($"webdrop/chat/{old.Name}"));

        var today = await worker.RunOnceAsync(DateTime.Now, CancellationToken.None);
        Assert.Equal(1, today.Purged);                                     // 超过 30 天的那份被清掉
        Assert.False(_s3.Files.ContainsKey($"webdrop/chat/{old.Name}"));
        Assert.True(_s3.Files.ContainsKey($"webdrop/chat/{today.Name}"));

        // 备份能还原成数据库,里面有刚建的频道和账号
        string path = Path.Combine(Path.GetTempPath(), "restore-" + Guid.NewGuid().ToString("N") + ".db");
        try
        {
            using (var input = new MemoryStream(_s3.Files[$"webdrop/chat/{today.Name}"]))
            using (var zip = new GZipStream(input, CompressionMode.Decompress))
            using (var output = File.Create(path))
                zip.CopyTo(output);
            using var conn = new SqliteConnection($"Data Source={path};Mode=ReadOnly");
            conn.Open();
            using var count = conn.CreateCommand();
            count.CommandText = "SELECT (SELECT COUNT(*) FROM channels), (SELECT COUNT(*) FROM accounts)";
            using var reader = count.ExecuteReader();
            Assert.True(reader.Read());
            Assert.True(reader.GetInt64(0) >= 1 && reader.GetInt64(1) >= 2);
        }
        finally { SqliteConnection.ClearAllPools(); try { File.Delete(path); } catch (IOException) { } }

        // 本地不留临时文件
        Assert.Empty(Directory.EnumerateFiles(Path.Combine(_server.DataDir, "v2", "backup-tmp")));
    }
}