using AcDream.Core.World;
using Xunit;

namespace AcDream.Core.Tests.World;

/// <summary>
/// #192 (2026-07-09) — login into a non-Holtburg position sometimes showed
/// stabs/scenery floating in the wrong place. Root cause: the streaming/render
/// gate opened as soon as <c>WorldSession</c> reached <c>InWorld</c>
/// (<c>GameWindow.cs</c>'s old <c>!IsLiveModeWaitingForLogin || liveInWorld</c>
/// condition) — but <c>InWorld</c> fires immediately after the login handshake
/// (<c>WorldSession.cs:608</c>), BEFORE the player's own spawn <c>CreateObject</c>
/// (which carries their real position) has even arrived over the network. Any
/// landblock streamed in that window baked its world offset from
/// <c>_liveCenterX/Y</c>'s STARTUP placeholder (Holtburg, 0xA9B4) — a real
/// position, not a "we don't know yet" sentinel — and that stale-baked geometry
/// still got applied once it finished building, landing wherever the guess put
/// it relative to whatever streamed in afterward with the corrected center.
///
/// The fix isn't "pick a different placeholder" (any placeholder racing against
/// the real answer reproduces the same bug) — it's gating on whether the real
/// position is actually known yet, independent of session state.
/// </summary>
public class StreamingReadinessGateTests
{
    [Fact]
    public void ShouldStream_OfflineMode_AlwaysTrue()
    {
        // Not live mode at all — no race is possible, no real position to wait for.
        Assert.True(StreamingReadinessGate.ShouldStream(
            liveModeEnabled: false, chaseModeEverEntered: false, liveInWorld: false, liveCenterKnown: false));
    }

    [Fact]
    public void ShouldStream_ChaseModeEverEntered_AlwaysTrueRegardlessOfCenterKnown()
    {
        // Once chase mode has engaged even once, the gate latches open for the
        // rest of the session (matches the pre-existing IsLiveModeWaitingForLogin
        // latch semantics) — this is well past the login race window.
        Assert.True(StreamingReadinessGate.ShouldStream(
            liveModeEnabled: true, chaseModeEverEntered: true, liveInWorld: true, liveCenterKnown: false));
    }

    [Fact]
    public void ShouldStream_LiveModeNotYetInWorld_False()
    {
        Assert.False(StreamingReadinessGate.ShouldStream(
            liveModeEnabled: true, chaseModeEverEntered: false, liveInWorld: false, liveCenterKnown: false));
    }

    [Fact]
    public void ShouldStream_LiveModeInWorldButCenterUnknown_False()
    {
        // THE REGRESSION TEST. Under the old code, liveInWorld alone opened the
        // gate here — this is exactly the window where InWorld has fired but the
        // player's own spawn CreateObject (and hence the real center) hasn't
        // arrived yet. Must stay closed.
        Assert.False(StreamingReadinessGate.ShouldStream(
            liveModeEnabled: true, chaseModeEverEntered: false, liveInWorld: true, liveCenterKnown: false));
    }

    [Fact]
    public void ShouldStream_LiveModeInWorldAndCenterKnown_True()
    {
        // Once the real position is confirmed, stream even though chase mode
        // hasn't engaged yet — this preserves the #106 gate-3 fix (auto-entry
        // waits for terrain under the spawn; terrain streaming must not wait for
        // auto-entry in turn, or the two deadlock each other).
        Assert.True(StreamingReadinessGate.ShouldStream(
            liveModeEnabled: true, chaseModeEverEntered: false, liveInWorld: true, liveCenterKnown: true));
    }
}