using System.Text.Json.Nodes;
using MoShiro.Protocol;
using MoShiro.TestSupport;

namespace MoShiro.Backend.Tests;

/// <summary>重启后端：数据、身份和令牌都必须还在；热层从原始块回填；段文件尾部没有索引的数据被截断。</summary>
public sealed class PersistenceTests : IAsyncLifetime
{
    private readonly BackendFixture _backend = new();
    public ValueTask InitializeAsync() => _backend.InitializeAsync();

    public ValueTask DisposeAsync() => _backend.DisposeAsync();

    [Fact]
    public async Task EverythingSurvivesARestart_AndTheHotLayerIsRebuiltFromRawChunks()
    {
        long minute = 60_000;
        long baseMs = ((TimeProvider.System.GetUtcNow().ToUnixTimeMilliseconds() / minute) - 3) * minute;
        AgentSimulator agent = await _backend.ConnectAgentAsync();
        string id = agent.NodeId.Value;
        for (int k = 0; k < 12; k++)
        {
            Assert.True(await agent.SendChunkAsync(ChunkFactory.Echo(agent.NodeId, "udp_echo", baseMs + (k * 10_000L), 100, 100, i => new EchoPacket(false, i % 4 == 0, 20_000, 20_000))));
        }

        string from = DateTimeOffset.FromUnixTimeMilliseconds(baseMs).UtcDateTime.ToString("yyyy-MM-dd'T'HH:mm:ss.fff'Z'");
        string to = DateTimeOffset.FromUnixTimeMilliseconds(baseMs + (2 * minute)).UtcDateTime.ToString("yyyy-MM-dd'T'HH:mm:ss.fff'Z'");
        string url = $"/api/public/lines/{_backend.Line(id)}/series?from={from}&to={to}&metrics=loss.total,rtt.p95";
        JsonNode before = await _backend.GetJsonAsync(_backend.Admin, url + "&step=1m");
        await BackendFixture.EventuallyAsync(async () => (await _backend.GetJsonAsync(_backend.Admin, url + "&step=1m"))["summary"]!["samples"]!["udp_echo"]?.GetValue<long>() == 1200);
        before = await _backend.GetJsonAsync(_backend.Admin, url + "&step=1m");

        await agent.DisposeAsync();
        await _backend.RestartAsync();
        HttpClient admin = _backend.Admin; // 重启之后用同一个令牌，证明令牌已经落盘

        // 身份与令牌：Agent 记录在，管理员令牌仍然有效
        JsonNode agents = await _backend.GetJsonAsync(admin, "/api/admin/agents");
        JsonNode restored = agents["items"]!.AsArray().Single(a => a!["id"]!.GetValue<string>() == id)!;
        Assert.Equal("active", restored["status"]!.GetValue<string>());
        Assert.False(restored["online"]!.GetValue<bool>());

        // 持久层：重启前算好的分钟窗口原样还在
        JsonNode after = await _backend.GetJsonAsync(admin, url + "&step=1m");
        Assert.Equal(before["summary"]!["metrics"]!["loss.total"]!.GetValue<double>(), after["summary"]!["metrics"]!["loss.total"]!.GetValue<double>(), 9);
        Assert.Equal(25.0, after["summary"]!["metrics"]!["loss.total"]!.GetValue<double>(), 6);

        // 热层：重启后为空，回填之后才会被查询选用；回填完成后 1s 步长能读到同样的数据
        JsonNode hot = null!;
        await BackendFixture.EventuallyAsync(async () =>
        {
            hot = await _backend.GetJsonAsync(admin, url + "&step=1s");
            return hot["source"]!.GetValue<string>() == "hot" && hot["summary"]!["samples"]!["udp_echo"]?.GetValue<long>() == 1200;
        });
        Assert.Equal(25.0, hot["summary"]!["metrics"]!["loss.total"]!.GetValue<double>(), 6);

        // 同一个身份可以重新连接，并拿回当前版本的期望状态
        await using AgentSimulator again = await _backend.ReconnectAsync(agent);
        Assert.NotNull(await again.WaitForTaskSetAsync(s => s.Tasks.Count == Defaults.TaskCount));

        // 已经落盘的块在重启后仍然可以按 ID 下载
        JsonNode chunks = await _backend.GetJsonAsync(admin, $"/api/admin/raw/chunks?agent_id={id}&limit=1");
        string chunkId = chunks["items"]![0]!["chunk_id"]!.GetValue<string>();
        using HttpResponseMessage download = await admin.GetAsync("/api/admin/raw/chunks/" + chunkId);
        Assert.True(RawChunkCodec.Decode(await download.Content.ReadAsByteArrayAsync()).IsSuccess);
    }
}