using System.Text.Json;
using AcDream.Runtime.Session;

namespace AcDream.Runtime.Tests.Session;

/// <summary>
/// Campaign LA slice LA1: pins the exact JSONL status-stream contract both
/// the App and Headless hosts write into, and the launcher (a process we
/// don't own) reads — see <c>docs/plans/2026-08-14-launcher-campaign.md</c>
/// LA1 and <c>docs/superpowers/specs/2026-08-14-launcher-campaign-design.md</c>
/// §6.
/// </summary>
public sealed class SessionStatusWriterTests
{
    [Fact]
    public void EachEventWritesTheExactPinnedShapeInOrder()
    {
        using TemporaryFile file = TemporaryFile.Create();
        var writer = new SessionStatusWriter(file.Path);

        writer.Started("s1");
        writer.Connected("s1");
        writer.CharacterList(
            "s1",
            new LiveSessionRosterReport(
                "account",
                11,
                [
                    new LiveSessionRosterEntry(0x50000001u, "Ready", 0u),
                    new LiveSessionRosterEntry(0x50000002u, "Grey", 10u),
                ]));
        writer.EnteredWorld("s1", 0x50000001u, "Ready");
        writer.Disconnected("s1", "stopped");
        writer.Exited("s1", 0, "disposed");

        string[] lines = File.ReadAllLines(file.Path);
        Assert.Equal(6, lines.Length);

        JsonElement started = Parse(lines[0]);
        Assert.Equal(1, started.GetProperty("v").GetInt32());
        Assert.Equal("started", started.GetProperty("e").GetString());
        Assert.True(started.TryGetProperty("t", out _));
        Assert.Equal("s1", started.GetProperty("sessionId").GetString());

        JsonElement connected = Parse(lines[1]);
        Assert.Equal("connected", connected.GetProperty("e").GetString());
        Assert.Equal("s1", connected.GetProperty("sessionId").GetString());

        JsonElement characterList = Parse(lines[2]);
        Assert.Equal("characterList", characterList.GetProperty("e").GetString());
        Assert.Equal("account", characterList.GetProperty("accountName").GetString());
        Assert.Equal(11, characterList.GetProperty("slotCount").GetInt32());
        JsonElement characters = characterList.GetProperty("characters");
        Assert.Equal(2, characters.GetArrayLength());
        JsonElement first = characters[0];
        Assert.Equal(0x50000001u, first.GetProperty("id").GetUInt32());
        Assert.Equal("Ready", first.GetProperty("name").GetString());
        Assert.Equal(0u, first.GetProperty("secondsGreyedOut").GetUInt32());

        JsonElement enteredWorld = Parse(lines[3]);
        Assert.Equal("enteredWorld", enteredWorld.GetProperty("e").GetString());
        Assert.Equal(0x50000001u, enteredWorld.GetProperty("characterId").GetUInt32());
        Assert.Equal("Ready", enteredWorld.GetProperty("characterName").GetString());

        JsonElement disconnected = Parse(lines[4]);
        Assert.Equal("disconnected", disconnected.GetProperty("e").GetString());
        Assert.Equal("stopped", disconnected.GetProperty("reason").GetString());

        JsonElement exited = Parse(lines[5]);
        Assert.Equal("exited", exited.GetProperty("e").GetString());
        Assert.Equal(0, exited.GetProperty("code").GetInt32());
        Assert.Equal("disposed", exited.GetProperty("reason").GetString());
    }

    [Fact]
    public void NoOpWriterNeverCreatesAFile()
    {
        using TemporaryFile file = TemporaryFile.Reserve();
        var writer = new SessionStatusWriter(null);

        writer.Started("s1");
        writer.Connected("s1");
        writer.Disconnected("s1", "stopped");
        writer.Exited("s1", 0, "disposed");

        Assert.False(writer.IsEnabled);
        Assert.False(File.Exists(file.Path));
    }

    [Fact]
    public void BlankPathIsTreatedAsAbsent()
    {
        var writer = new SessionStatusWriter("   ");

        Assert.False(writer.IsEnabled);
        // Must not throw even though there is no real path behind it.
        writer.Started("s1");
    }

    [Fact]
    public void PasswordNeverAppearsInTheStatusStream()
    {
        using TemporaryFile file = TemporaryFile.Create();
        var writer = new SessionStatusWriter(file.Path);

        writer.Started("bot");
        writer.Connected("bot");
        writer.CharacterList(
            "bot",
            new LiveSessionRosterReport(
                "account-name",
                11,
                [new LiveSessionRosterEntry(0x50000001u, "Ready", 0u)]));
        writer.EnteredWorld("bot", 0x50000001u, "Ready");
        writer.Disconnected("bot", "stopped");
        writer.Exited("bot", 0, "disposed");

        string contents = File.ReadAllText(file.Path);
        Assert.DoesNotContain("hunter2", contents, StringComparison.Ordinal);
        Assert.DoesNotContain("password", contents, StringComparison.OrdinalIgnoreCase);
    }

    [Fact]
    public void FileIsOpenedShareReadSoAConcurrentTailerCanReadWhileAppending()
    {
        using TemporaryFile file = TemporaryFile.Create();
        var writer = new SessionStatusWriter(file.Path);
        writer.Started("s1");

        // A concurrent reader (the launcher's tailer) must be able to open
        // the file for read while the writer holds it — FileShare.Read on
        // the writer side is what this test is pinning.
        using FileStream tailer = new(
            file.Path,
            FileMode.Open,
            FileAccess.Read,
            FileShare.ReadWrite);
        using var tailerReader = new StreamReader(tailer);
        string? firstLine = tailerReader.ReadLine();
        Assert.NotNull(firstLine);
        Assert.Contains("\"started\"", firstLine);

        // The writer keeps working while the tailer's handle is still open.
        writer.Connected("s1");
        string? secondLine = tailerReader.ReadLine();
        Assert.NotNull(secondLine);
        Assert.Contains("\"connected\"", secondLine);
    }

    private static JsonElement Parse(string line) =>
        JsonDocument.Parse(line).RootElement;

    private sealed class TemporaryFile : IDisposable
    {
        private TemporaryFile(string path) => Path = path;

        internal string Path { get; }

        internal static TemporaryFile Create()
        {
            string path = System.IO.Path.Combine(
                System.IO.Path.GetTempPath(),
                $"acdream-status-{Guid.NewGuid():N}.jsonl");
            return new TemporaryFile(path);
        }

        /// <summary>A path that is never actually created — used by the
        /// no-op test to assert the writer truly never touches disk.</summary>
        internal static TemporaryFile Reserve() => Create();

        public void Dispose()
        {
            if (File.Exists(Path))
                File.Delete(Path);
        }
    }
}