poe2-bot/src/Roboto.Memory/Objects/Terrain.cs

using Roboto.Memory;
using Serilog;
using TerrainStruct = Roboto.GameOffsets.States.Terrain;

namespace Roboto.Memory.Objects;

/// <summary>
/// Reads terrain walkability grid from AreaInstance.
/// RemoteObject wrapping the previous TerrainReader logic.
/// Update(areaInstanceAddr) to read terrain.
/// </summary>
public sealed class Terrain : RemoteObject
{
    private uint _cachedTerrainAreaHash;
    private WalkabilityGrid? _cachedTerrain;
    private bool _wasLoading;

    public WalkabilityGrid? Grid { get; private set; }
    public int TerrainWidth { get; private set; }
    public int TerrainHeight { get; private set; }
    public int TerrainCols { get; private set; }
    public int TerrainRows { get; private set; }
    public int WalkablePercent { get; private set; }

    /// <summary>Set before Update() to indicate current loading/area state.</summary>
    public bool IsLoading { get; set; }
    public uint AreaHash { get; set; }

    public Terrain(MemoryContext ctx) : base(ctx) { }

    public void InvalidateCache()
    {
        _cachedTerrain = null;
        _cachedTerrainAreaHash = 0;
    }

    protected override bool ReadData()
    {
        var mem = Ctx.Memory;
        var offsets = Ctx.Offsets;

        if (!offsets.TerrainInline)
        {
            var terrainListPtr = mem.ReadPointer(Address + offsets.TerrainListOffset);
            if (terrainListPtr == 0) return true;

            var terrainPtr = mem.ReadPointer(terrainListPtr);
            if (terrainPtr == 0) return true;

            var dimsPtr = mem.ReadPointer(terrainPtr + offsets.TerrainDimensionsOffset);
            if (dimsPtr == 0) return true;

            TerrainCols = mem.Read<int>(dimsPtr);
            TerrainRows = mem.Read<int>(dimsPtr + 4);
            if (TerrainCols > 0 && TerrainCols < 1000 &&
                TerrainRows > 0 && TerrainRows < 1000)
            {
                TerrainWidth = TerrainCols * offsets.SubTilesPerCell;
                TerrainHeight = TerrainRows * offsets.SubTilesPerCell;
            }
            else
            {
                TerrainCols = 0;
                TerrainRows = 0;
            }
            return true;
        }

        // Inline mode
        var terrainBase = Address + offsets.TerrainListOffset;
        var t = mem.Read<TerrainStruct>(terrainBase);

        var cols = (int)t.Dimensions.X;
        var rows = (int)t.Dimensions.Y;

        if (cols <= 0 || cols >= 1000 || rows <= 0 || rows >= 1000)
            return true;

        TerrainCols = cols;
        TerrainRows = rows;
        TerrainWidth = cols * offsets.SubTilesPerCell;
        TerrainHeight = rows * offsets.SubTilesPerCell;

        if (IsLoading)
        {
            _cachedTerrain = null;
            _cachedTerrainAreaHash = 0;
            Grid = null;
            return true;
        }

        if (_wasLoading)
        {
            _cachedTerrain = null;
            _cachedTerrainAreaHash = 0;
        }

        if (_cachedTerrain != null && _cachedTerrainAreaHash == AreaHash)
        {
            Grid = _cachedTerrain;
            WalkablePercent = CalcWalkablePercent(_cachedTerrain);
            return true;
        }

        var gridBegin = t.WalkableGrid.First;
        var gridEnd = t.WalkableGrid.Last;
        if (gridBegin == 0 || gridEnd <= gridBegin)
            return true;

        var gridDataSize = (int)(gridEnd - gridBegin);
        if (gridDataSize <= 0 || gridDataSize > 16 * 1024 * 1024)
            return true;

        var bytesPerRow = t.BytesPerRow;
        if (bytesPerRow <= 0 || bytesPerRow > 0x10000)
            return true;

        var gridWidth = cols * offsets.SubTilesPerCell;
        var gridHeight = rows * offsets.SubTilesPerCell;

        var rawData = mem.ReadBytes(gridBegin, gridDataSize);
        if (rawData is null)
            return true;

        var data = new byte[gridWidth * gridHeight];
        for (var row = 0; row < gridHeight; row++)
        {
            var rowStart = row * bytesPerRow;
            for (var col = 0; col < gridWidth; col++)
            {
                var byteIndex = rowStart + col / 2;
                if (byteIndex >= rawData.Length) break;

                data[row * gridWidth + col] = (col % 2 == 0)
                    ? (byte)(rawData[byteIndex] & 0x0F)
                    : (byte)((rawData[byteIndex] >> 4) & 0x0F);
            }
        }

        var grid = new WalkabilityGrid(gridWidth, gridHeight, data);
        Grid = grid;
        WalkablePercent = CalcWalkablePercent(grid);

        _cachedTerrain = grid;
        _cachedTerrainAreaHash = AreaHash;

        Log.Information("Terrain grid read: {W}x{H} ({Cols}x{Rows} cells), {Pct}% walkable",
            gridWidth, gridHeight, cols, rows, WalkablePercent);

        return true;
    }

    /// <summary>Update loading edge state. Call after ReadData().</summary>
    public void UpdateLoadingEdge(bool isLoading)
    {
        _wasLoading = isLoading;
    }

    protected override void Clear()
    {
        Grid = null;
        TerrainWidth = 0;
        TerrainHeight = 0;
        TerrainCols = 0;
        TerrainRows = 0;
        WalkablePercent = 0;
    }

    public static int CalcWalkablePercent(WalkabilityGrid grid)
    {
        var walkable = 0;
        for (var i = 0; i < grid.Data.Length; i++)
            if (grid.Data[i] != 0) walkable++;
        return grid.Data.Length > 0 ? (int)(100L * walkable / grid.Data.Length) : 0;
    }
}