using System.Collections.Generic;
using System.IO;
using System.Linq;
using AcDream.Content.Pak;
using DatReaderWriter;
using DatReaderWriter.DBObjs;
using DatReaderWriter.Options;

namespace AcDream.Content.Tests;

/// <summary>
/// MP1b Task 6: dat-gated live-vs-pak equivalence suite. Runs MeshExtractor
/// LIVE and bakes the SAME ids to a temp pak, reads the pak back, and deep-
/// compares field-by-field via the Task 3 comparator. Because the bake tool
/// and the live client drive the identical MeshExtractor code (MP1a), this
/// test is proving the pak ROUND-TRIP (serialize/deserialize) preserves
/// what extraction actually produces on real content — not re-verifying the
/// extraction algorithm itself (that's the existing Conformance suite's job).
///
/// Skips cleanly when the real dats are absent (CI), matching
/// DatConcurrencyStressTests' convention.
/// </summary>
public sealed class PakEquivalenceTests {
    // Known-tricky GfxObj ids reused from existing conformance fixtures:
    // 0x010002B4 / 0x010008A8 — #119 "[up-null] upload returned null" dump
    //   targets (Issue119UpNullGfxObjDumpTests).
    // 0x010014C3 — the #113-saga Holtburg meeting-hall shell
    //   (Issue119UpNullGfxObjDumpTests.ShellModel_NoTexturedPolyIsDropped).
    private static readonly uint[] KnownTrickyGfxObjIds = { 0x010002B4u, 0x010008A8u, 0x010014C3u };

    // Setup ids reused from existing physics/conformance fixtures:
    // 0x020019FF — the door setup (DoorBugTrajectoryReplayTests,
    //   DoorSetupGfxObjInspectionTests, DoorCollisionApparatusTests).
    // 0x020005D8 / 0x020003F2 — Issue119TowerDumpTests fixtures.
    private static readonly uint[] SetupIds = { 0x020019FFu, 0x020005D8u, 0x020003F2u };

    private const uint HoltburgLandblock = 0xA9B40000u; // ConformanceDats.HoltburgLandblock

    [Fact]
    public void LiveExtraction_MatchesPakRoundTrip_OnFixtureIdSet() {
        var datDir = ContentConformanceDats.ResolveDatDir();
        if (datDir is null) return; // dats absent (CI) — skip, matching suite convention

        using var dats = new DatCollection(datDir, DatAccessType.Read);
        using var datReaderWriter = new ContentTestDatCollectionAdapter(dats);
        var logger = new TestConsoleLogger();

        var sideStaged = new List<ObjectMeshData>();
        var extractor = new MeshExtractor(datReaderWriter, logger, data => sideStaged.Add(data));

        var gfxObjIds = BuildGfxObjIdSet(dats);
        var setupIds = SetupIds.ToList();
        var envCellIds = BuildEnvCellIdSet(dats, HoltburgLandblock, minCount: 5);

        Assert.True(gfxObjIds.Count >= 10, $"fixture GfxObj id set unexpectedly small ({gfxObjIds.Count})");
        Assert.True(setupIds.Count >= 3, $"fixture Setup id set unexpectedly small ({setupIds.Count})");
        Assert.True(envCellIds.Count >= 5, $"fixture EnvCell id set unexpectedly small ({envCellIds.Count})");

        var work = new List<(PakAssetType Type, uint FileId, ulong ExtractorId, bool IsSetup)>();
        work.AddRange(gfxObjIds.Select(id => (PakAssetType.GfxObjMesh, id, (ulong)id, false)));
        work.AddRange(setupIds.Select(id => (PakAssetType.SetupMesh, id, (ulong)id, true)));
        work.AddRange(envCellIds.Select(id => (PakAssetType.EnvCellMesh, id, id | 0x1_0000_0000UL, true)));

        // ---- LIVE extraction (golden) ----
        var golden = new Dictionary<(PakAssetType, uint), ObjectMeshData>();
        var extractionFailures = new List<string>();
        foreach (var (type, fileId, extractorId, isSetup) in work) {
            var data = extractor.PrepareMeshData(extractorId, isSetup);
            if (data is null) {
                extractionFailures.Add($"{type} 0x{fileId:X8}: live extraction returned null");
                continue;
            }
            golden[(type, fileId)] = data;
        }

        Assert.True(extractionFailures.Count == 0,
            $"{extractionFailures.Count} fixture ids failed LIVE extraction (fixture assumption broke): " +
            string.Join(" | ", extractionFailures));

        // ---- bake the SAME ids to a temp pak ----
        var pakPath = Path.Combine(Path.GetTempPath(), $"acdream-equivtest-{System.Guid.NewGuid():N}.pak");
        try {
            var header = new PakHeader {
                FormatVersion = 1,
                PortalIteration = (uint)dats.Portal.Iteration!.CurrentIteration,
                CellIteration = (uint)dats.Cell.Iteration!.CurrentIteration,
                HighResIteration = (uint)dats.HighRes.Iteration!.CurrentIteration,
                LanguageIteration = (uint)dats.Local.Iteration!.CurrentIteration,
                BakeToolVersion = 1,
            };
            using (var writer = new PakWriter(pakPath, header)) {
                foreach (var ((type, fileId), data) in golden) {
                    writer.AddBlob(PakKey.Compose(type, fileId), data);
                }
                writer.Finish();
            }

            // ---- read back and deep-compare ----
            using var reader = new PakReader(pakPath);
            var mismatches = new List<string>();
            foreach (var ((type, fileId), expected) in golden) {
                var key = PakKey.Compose(type, fileId);
                if (!reader.TryReadObjectMeshData(key, out var actual)) {
                    mismatches.Add($"{type} 0x{fileId:X8}: pak read failed (missing or CRC mismatch)");
                    continue;
                }
                try {
                    ObjectMeshDataEquality.AssertEqual(expected, actual);
                }
                catch (Xunit.Sdk.XunitException ex) {
                    mismatches.Add($"{type} 0x{fileId:X8}: {ex.Message}");
                }
            }

            Assert.True(mismatches.Count == 0,
                $"{mismatches.Count}/{golden.Count} fixture ids mismatched between live extraction and pak round-trip:\n" +
                string.Join("\n", mismatches));
        }
        finally {
            if (File.Exists(pakPath)) File.Delete(pakPath);
        }
    }

    /// <summary>
    /// Known-tricky ids (#119/#113 dump fixtures) plus enough additional
    /// GfxObjs (deterministically, the first N ids in dat order after the
    /// tricky set) to reach at least 10 total.
    /// </summary>
    private static List<uint> BuildGfxObjIdSet(DatCollection dats) {
        var ids = new List<uint>(KnownTrickyGfxObjIds);
        var seen = new HashSet<uint>(ids);

        foreach (var id in dats.GetAllIdsOfType<GfxObj>()) {
            if (ids.Count >= 10) break;
            if (seen.Add(id)) ids.Add(id);
        }
        return ids;
    }

    /// <summary>Walks the Holtburg landblock's LandBlockInfo.NumCells range (mirrors StipplingSurfaceEquivalenceTests' enumeration) to get at least <paramref name="minCount"/> real EnvCell ids.</summary>
    private static List<uint> BuildEnvCellIdSet(DatCollection dats, uint landblockId, int minCount) {
        var ids = new List<uint>();
        var lbInfo = dats.Get<LandBlockInfo>(landblockId | 0xFFFEu);
        Assert.True(lbInfo is not null, $"LandBlockInfo for landblock 0x{landblockId:X8} not found — fixture assumption broke");
        Assert.True(lbInfo!.NumCells >= minCount,
            $"landblock 0x{landblockId:X8} has only {lbInfo.NumCells} cells — fixture assumption broke (need >= {minCount})");

        uint firstCellId = landblockId | 0x0100u;
        for (uint offset = 0; offset < lbInfo.NumCells && ids.Count < minCount; offset++) {
            uint envCellId = firstCellId + offset;
            if (dats.Get<EnvCell>(envCellId) is not null) ids.Add(envCellId);
        }
        return ids;
    }
}