using System.Numerics;
using AcDream.App.Rendering;
using AcDream.App.Rendering.Gpu;
using AcDream.App.Rendering.Walk;
using AcDream.App.Tests.Rendering;
using AcDream.Core.Rendering;

namespace AcDream.App.Tests.Rendering.Walk;

/// <summary>
/// Campaign OVERHAUL S3 chunk 1 (§11.2): tests T1/T2 for the print-only walk
/// transcript emitter (<see cref="WalkTranscriptDump"/>, gated by
/// <see cref="RenderingDiagnostics.DumpWalkTranscriptEnabled"/>), plus the
/// §11.2 B4 offline signature-diff self-check. Reuses
/// <see cref="WalkFrameDriverTests"/>'s own private fixture types via the
/// shared <c>partial class</c> — the SAME minimal interior two-cell flood
/// (one exit view) that file's own
/// <c>RunFrame_InteriorFloodWithExitView_FreshDriverSkipsTheGatedClearThenDrawsSealsAndFloodCells</c>
/// test already exercises and proves correct; here only
/// <see cref="WalkFrameDriver.Collect"/> runs (no <c>Replay</c>/GPU
/// submission), since every transcript print fires synchronously during the
/// walk itself.
///
/// <para>
/// <see cref="RenderingDiagnostics.DumpWalkTranscriptEnabled"/> and
/// <see cref="Console.Out"/> are both process-wide mutable statics — joins
/// <see cref="CameraDiagnosticsCollection"/> for the SAME reason
/// <c>CornerFloodReplayTests</c>/<c>Issue181WallPressEquilibriumTests</c> do
/// (that collection's own doc comment, issue #251): interleaved
/// <c>Console.SetOut</c> redirection across parallel test classes can
/// restore a disposed <see cref="StringWriter"/> process-wide.
/// </para>
/// </summary>
[Collection(CameraDiagnosticsCollection.Name)]
public sealed partial class WalkFrameDriverTests
{
    private static (WalkCell Cell1, WalkCell Cell2) BuildTranscriptFixtureCells(TestContext ctx)
    {
        var cell1 = new WalkCell
        {
            CellId = 0x100,
            StabList = [0x101u],
            Portals =
            [
                new WalkCellPortal
                {
                    OtherCellId = 0x101, PolygonIndex = 0, PortalSide = 0, OtherPortalId = 0,
                },
                // The exit portal — raises ov to 1, so the flood draws the
                // (empty, zero-block) landscape too, exercising LS.
                new WalkCellPortal
                {
                    OtherCellId = 0xFFFFFFFF, PolygonIndex = 1, PortalSide = 0, OtherPortalId = -1,
                },
            ],
            PortalPolygons = [Quad(-2f), Quad(-3f)],
        };
        var cell2 = new WalkCell
        {
            CellId = 0x101,
            Portals = [new WalkCellPortal
            {
                OtherCellId = 0x100, PolygonIndex = 0, PortalSide = 1, OtherPortalId = 0,
            }],
            PortalPolygons = [Quad(-2f)],
        };
        ctx.Cells[cell1.CellId] = cell1;
        ctx.Cells[cell2.CellId] = cell2;
        return (cell1, cell2);
    }

    /// <summary>T1 (§11.3): the flag off — zero output, and the emitter's
    /// own methods (the only code this chunk adds to the walk path)
    /// allocate nothing. The walk itself is NOT independently zero-alloc
    /// (e.g. <c>RetailFrameWalk.EmitDrawCells</c> allocates its cell-id
    /// array on every call — pre-existing, unrelated to this chunk), so the
    /// allocation bound below is scoped to <see cref="WalkTranscriptDump"/>
    /// itself, matching B1's actual contract ("allocates nothing EXTRA").</summary>
    [Fact]
    public void TranscriptEmitter_FlagOff_EveryPrintMethodIsAZeroCostNoOp()
    {
        bool previous = RenderingDiagnostics.DumpWalkTranscriptEnabled;
        RenderingDiagnostics.DumpWalkTranscriptEnabled = false;
        TextWriter originalOut = Console.Out;
        var capture = new StringWriter();
        try
        {
            Console.SetOut(capture);

            var cells = new List<uint> { 0x100u, 0x101u };
            void Step()
            {
                WalkTranscriptDump.PrintFrameRoot(1, 0x100u, Vector3.Zero, Vector3.UnitY);
                WalkTranscriptDump.PrintLandscape();
                WalkTranscriptDump.PrintBuilding(0x100u);
                WalkTranscriptDump.PrintDrawInside(0x100u);
                WalkTranscriptDump.PrintDrawCells(outdoorPview: false, 1, cells);
                WalkTranscriptDump.PrintLandCell(0xF4180001u);
                WalkTranscriptDump.PrintSortCell(0xF4180001u);
                WalkTranscriptDump.PrintEnvCellShell(0x101u);
                WalkTranscriptDump.PrintObjectCellTurn(0x101u);
            }

            ZeroAllocationProbe.AssertAllocatesNothing(
                "WalkTranscriptDump.Print* (flag off)", Step);

            AssertNoTranscriptLines(capture);
        }
        finally
        {
            Console.SetOut(originalOut);
            RenderingDiagnostics.DumpWalkTranscriptEnabled = previous;
        }
    }

    /// <summary>T1's integration half: a full synthetic interior frame,
    /// driven through the SAME <see cref="WalkFrameDriver.Collect"/> path
    /// production uses, produces literally NO transcript output when the
    /// flag is off.</summary>
    [Fact]
    public void Collect_TranscriptFlagOff_ProducesNoConsoleOutput()
    {
        bool previous = RenderingDiagnostics.DumpWalkTranscriptEnabled;
        RenderingDiagnostics.DumpWalkTranscriptEnabled = false;
        TextWriter originalOut = Console.Out;
        var capture = new StringWriter();
        try
        {
            Console.SetOut(capture);

            using var fx = new DispatcherFixture();
            var ctx = new TestContext();
            (WalkCell cell1, _) = BuildTranscriptFixtureCells(ctx);
            var landscape = new WalkLandscape { MidWidth = 1, Blocks = new WalkLandBlock?[1] };
            var worldData = new FakeWorldData();
            var leaf = new RecordingLeafRenderer(new List<string>());
            using ClipFrame clipFrame = ClipFrame.NoClip();
            var driver = new WalkFrameDriver(fx.Dispatcher, leaf, worldData, clipFrame: clipFrame);
            var walk = new RetailFrameWalk();

            driver.Collect(
                walk, cell1.CellId, cell1, landscape, ctx, Matrix4x4.Identity, Vector3.Zero);

            AssertNoTranscriptLines(capture);
        }
        finally
        {
            Console.SetOut(originalOut);
            RenderingDiagnostics.DumpWalkTranscriptEnabled = previous;
        }
    }

    /// <summary>
    /// Asserts NONE of <see cref="WalkTranscriptDump"/>'s own line kinds
    /// appear in <paramref name="capture"/> — robust to unrelated
    /// <see cref="Console"/> noise from another test class running in
    /// parallel (a real, observed hazard: xUnit runs distinct classes
    /// concurrently by default, and <see cref="Console.Out"/> is a
    /// process-wide static — see <c>CameraDiagnosticsCollection</c>'s own
    /// doc comment, issue #251). A plain <c>Assert.Empty(capture.ToString())</c>
    /// is NOT this robust: an unrelated class's unconditional
    /// <c>Console.WriteLine</c> can land inside this test's redirect window
    /// and fail it for a reason that has nothing to do with the transcript
    /// flag. <see cref="WalkOracleTrace.Parse"/> only ever appends a frame
    /// once it sees a well-formed <c>F &lt;n&gt;</c> marker line — arbitrary
    /// unrelated text can never satisfy that regex, so a truly EMPTY parsed
    /// frame list is exactly as strong a proof that THIS code printed
    /// nothing, without being sensitive to what else shares the process
    /// console.
    /// </summary>
    private static void AssertNoTranscriptLines(StringWriter capture)
    {
        string[] lines = capture.ToString()
            .Split('\n', StringSplitOptions.RemoveEmptyEntries)
            .Select(l => l.TrimEnd('\r'))
            .ToArray();
        Assert.Empty(WalkOracleTrace.Parse(lines));
    }

    /// <summary>T2 (§11.3): flag on, one synthetic interior frame — the
    /// printed lines parse with the extended <see cref="WalkOracleTrace"/>
    /// into the same events the driver recorded (emitter/parser round
    /// trip). Asserted structurally (kinds, cell ids, counts) rather than
    /// against a hand-predicted exact ordering, so the test does not
    /// silently pin an assumption about traversal order it never
    /// independently verified.</summary>
    [Fact]
    public void Collect_TranscriptFlagOn_PrintedLinesRoundTripThroughTheParser()
    {
        bool previous = RenderingDiagnostics.DumpWalkTranscriptEnabled;
        RenderingDiagnostics.DumpWalkTranscriptEnabled = true;
        TextWriter originalOut = Console.Out;
        var capture = new StringWriter();
        try
        {
            Console.SetOut(capture);

            using var fx = new DispatcherFixture();
            var ctx = new TestContext();
            (WalkCell cell1, WalkCell cell2) = BuildTranscriptFixtureCells(ctx);
            var landscape = new WalkLandscape { MidWidth = 1, Blocks = new WalkLandBlock?[1] };
            var worldData = new FakeWorldData();
            var leaf = new RecordingLeafRenderer(new List<string>());
            using ClipFrame clipFrame = ClipFrame.NoClip();
            var driver = new WalkFrameDriver(fx.Dispatcher, leaf, worldData, clipFrame: clipFrame);
            var walk = new RetailFrameWalk();

            // Two Collect calls: WalkOracleTrace.Parse (like every real
            // capture) only flushes a frame once the NEXT "F n" marker
            // appears — it deliberately drops the final in-progress frame
            // (the detach-frame rule). One frame alone would parse to zero
            // complete frames.
            driver.Collect(
                walk, cell1.CellId, cell1, landscape, ctx, Matrix4x4.Identity, Vector3.Zero);
            driver.Collect(
                walk, cell1.CellId, cell1, landscape, ctx, Matrix4x4.Identity, Vector3.Zero);

            Console.Out.Flush();
            string[] lines = capture.ToString()
                .Split('\n', StringSplitOptions.RemoveEmptyEntries)
                .Select(l => l.TrimEnd('\r'))
                .ToArray();
            Assert.NotEmpty(lines);

            IReadOnlyList<WalkOracleFrame> frames = WalkOracleTrace.Parse(lines);
            WalkOracleFrame frame = Assert.Single(frames);
            Assert.Equal(1, frame.Number);

            Assert.NotNull(frame.Pose);
            Assert.Equal(cell1.CellId, frame.Pose!.CellId);

            Assert.Equal(cell1.CellId, frame.InteriorRootCell);
            Assert.True(frame.HasLandscape);

            WalkOracleEvent dc = Assert.Single(
                frame.Events, e => e.Kind == WalkOracleEventKind.DrawCells);
            Assert.Equal(1, dc.OutsideViewCount);
            Assert.Equal(
                new HashSet<uint> { cell1.CellId, cell2.CellId },
                dc.Cells.ToHashSet());

            // The interior root's own flood visits both cells for a shell
            // AND an object-list turn — EC/OC pair, one line per cell, no
            // dedupe (WalkTranscriptDump.PrintEnvCellShell's own doc
            // comment: EC/OC counts are always exactly equal per pose).
            List<uint> ec = frame.Events
                .Where(e => e.Kind == WalkOracleEventKind.EnvCellShell)
                .Select(e => e.CellId!.Value).ToList();
            List<uint> oc = frame.Events
                .Where(e => e.Kind == WalkOracleEventKind.ObjectCellTurn)
                .Select(e => e.CellId!.Value).ToList();
            Assert.Equal(new HashSet<uint> { cell1.CellId, cell2.CellId }, ec.ToHashSet());
            Assert.Equal(new HashSet<uint> { cell1.CellId, cell2.CellId }, oc.ToHashSet());
            Assert.Equal(2, ec.Count);
            Assert.Equal(2, oc.Count);

            // No landblocks were published (the stub 1x1 landscape), so no
            // LC/SC/BLD turns exist this frame — the transcript format for
            // those three kinds is proven separately, against real retail
            // data, by WalkOracleTraceTests.AllFixtures and
            // WalkLandCellOrderTests.
            Assert.DoesNotContain(frame.Events, e => e.Kind
                is WalkOracleEventKind.LandCell or WalkOracleEventKind.SortCell
                or WalkOracleEventKind.Building);
        }
        finally
        {
            Console.SetOut(originalOut);
            RenderingDiagnostics.DumpWalkTranscriptEnabled = previous;
        }
    }

    /// <summary>§11.2 B4: the offline signature diff, self-checked over a
    /// synthetic pair — the SAME captured T2 transcript versus itself with
    /// its own LAST event removed. Reuses <c>Collect_TranscriptFlagOn_…</c>'s
    /// own capture rather than duplicating the walk drive.</summary>
    [Fact]
    public void SignatureDiff_ReportsTheExactRemovedEvent()
    {
        bool previous = RenderingDiagnostics.DumpWalkTranscriptEnabled;
        RenderingDiagnostics.DumpWalkTranscriptEnabled = true;
        TextWriter originalOut = Console.Out;
        var capture = new StringWriter();
        try
        {
            Console.SetOut(capture);

            using var fx = new DispatcherFixture();
            var ctx = new TestContext();
            (WalkCell cell1, _) = BuildTranscriptFixtureCells(ctx);
            var landscape = new WalkLandscape { MidWidth = 1, Blocks = new WalkLandBlock?[1] };
            var worldData = new FakeWorldData();
            var leaf = new RecordingLeafRenderer(new List<string>());
            using ClipFrame clipFrame = ClipFrame.NoClip();
            var driver = new WalkFrameDriver(fx.Dispatcher, leaf, worldData, clipFrame: clipFrame);
            var walk = new RetailFrameWalk();

            // Two Collect calls — see the round-trip test's own comment on
            // why one alone parses to zero complete frames.
            driver.Collect(
                walk, cell1.CellId, cell1, landscape, ctx, Matrix4x4.Identity, Vector3.Zero);
            driver.Collect(
                walk, cell1.CellId, cell1, landscape, ctx, Matrix4x4.Identity, Vector3.Zero);

            Console.Out.Flush();
            string[] lines = capture.ToString()
                .Split('\n', StringSplitOptions.RemoveEmptyEntries)
                .Select(l => l.TrimEnd('\r'))
                .ToArray();

            IReadOnlyList<WalkOracleFrame> expected = WalkOracleTrace.Parse(lines);
            WalkOracleFrame expectedFrame = Assert.Single(expected);
            Assert.NotEmpty(expectedFrame.Events);

            // Self-vs-self (unmutated copy): no divergence at all.
            IReadOnlyList<WalkOracleFrame> unchanged =
                [expectedFrame with { Events = expectedFrame.Events.ToList() }];
            Assert.Null(WalkTranscriptSignatureDiff.FirstDivergence(expected, unchanged));

            // Self-vs-self-minus-one (the LAST event removed): the reported
            // divergence is exact — same frame number, position exactly at
            // the new (shorter) end, expected = the removed event's own
            // signature string, actual = "<end of frame>".
            int lastIndex = expectedFrame.Events.Count - 1;
            List<WalkOracleEvent> truncated = expectedFrame.Events.Take(lastIndex).ToList();
            IReadOnlyList<WalkOracleFrame> actual =
                [expectedFrame with { Events = truncated }];

            WalkTranscriptSignatureDiff.Divergence? divergence =
                WalkTranscriptSignatureDiff.FirstDivergence(expected, actual);

            Assert.NotNull(divergence);
            Assert.Equal(expectedFrame.Number, divergence!.Value.FrameNumber);
            Assert.Equal(lastIndex, divergence.Value.Position);
            Assert.Equal("<end of frame>", divergence.Value.Actual);
            Assert.NotEqual("<end of frame>", divergence.Value.Expected);
        }
        finally
        {
            Console.SetOut(originalOut);
            RenderingDiagnostics.DumpWalkTranscriptEnabled = previous;
        }
    }
}