#include "pxl8_bsp.h"

#include <string.h>

#include "pxl8_color.h"
#include "pxl8_io.h"
#include "pxl8_log.h"
#include "pxl8_mem.h"

#define BSP_VERSION 29

typedef enum {
    CHUNK_ENTITIES = 0,
    CHUNK_PLANES = 1,
    CHUNK_TEXTURES = 2,
    CHUNK_VERTICES = 3,
    CHUNK_VISIBILITY = 4,
    CHUNK_NODES = 5,
    CHUNK_TEXINFO = 6,
    CHUNK_FACES = 7,
    CHUNK_LIGHTING = 8,
    CHUNK_CLIPNODES = 9,
    CHUNK_LEAFS = 10,
    CHUNK_MARKSURFACES = 11,
    CHUNK_EDGES = 12,
    CHUNK_SURFEDGES = 13,
    CHUNK_MODELS = 14,
    CHUNK_COUNT = 15
} pxl8_bsp_chunk_type;

typedef struct {
    u32 offset;
    u32 size;
} pxl8_bsp_chunk;

typedef struct {
    u32 version;
    pxl8_bsp_chunk chunks[CHUNK_COUNT];
} pxl8_bsp_header;

static inline pxl8_vec3 read_vec3(pxl8_stream* stream) {
    f32 x = pxl8_read_f32(stream);
    f32 y = pxl8_read_f32(stream);
    f32 z = pxl8_read_f32(stream);
    return (pxl8_vec3){x, z, y};
}

static bool validate_chunk(const pxl8_bsp_chunk* chunk, u32 element_size, usize file_size) {
    if (chunk->size == 0) return true;
    if (chunk->offset >= file_size) return false;
    if (chunk->offset + chunk->size > file_size) return false;
    if (chunk->size % element_size != 0) return false;
    return true;
}

static inline bool pxl8_bsp_get_edge_vertex(const pxl8_bsp* bsp, i32 surfedge_idx, u32* out_vert_idx) {
    if (surfedge_idx >= (i32)bsp->num_surfedges) return false;

    i32 edge_idx = bsp->surfedges[surfedge_idx];
    u32 vertex_index;

    if (edge_idx >= 0) {
        if ((u32)edge_idx >= bsp->num_edges) return false;
        vertex_index = 0;
    } else {
        edge_idx = -edge_idx;
        if ((u32)edge_idx >= bsp->num_edges) return false;
        vertex_index = 1;
    }

    *out_vert_idx = bsp->edges[edge_idx].vertex[vertex_index];
    return *out_vert_idx < bsp->num_vertices;
}

pxl8_result pxl8_bsp_load(const char* path, pxl8_bsp* bsp) {
    if (!path || !bsp) return PXL8_ERROR_INVALID_ARGUMENT;

    memset(bsp, 0, sizeof(*bsp));

    u8* file_data = NULL;
    usize file_size = 0;
    pxl8_result result = pxl8_io_read_binary_file(path, &file_data, &file_size);
    if (result != PXL8_OK) {
        pxl8_error("Failed to load BSP file: %s", path);
        return result;
    }

    if (file_size < sizeof(pxl8_bsp_header)) {
        pxl8_error("BSP file too small: %s", path);
        pxl8_free(file_data);
        return PXL8_ERROR_INVALID_FORMAT;
    }

    pxl8_stream stream = pxl8_stream_create(file_data, (u32)file_size);

    pxl8_bsp_header header;
    header.version = pxl8_read_u32(&stream);

    if (header.version != BSP_VERSION) {
        pxl8_error("Invalid BSP version: %u (expected %d)", header.version, BSP_VERSION);
        pxl8_free(file_data);
        return PXL8_ERROR_INVALID_FORMAT;
    }

    for (i32 i = 0; i < CHUNK_COUNT; i++) {
        header.chunks[i].offset = pxl8_read_u32(&stream);
        header.chunks[i].size = pxl8_read_u32(&stream);
    }

    pxl8_bsp_chunk* chunk = &header.chunks[CHUNK_VERTICES];
    if (!validate_chunk(chunk, 12, file_size)) goto error_cleanup;
    bsp->num_vertices = chunk->size / 12;
    if (bsp->num_vertices > 0) {
        bsp->vertices = pxl8_calloc(bsp->num_vertices, sizeof(pxl8_bsp_vertex));
        if (!bsp->vertices) goto error_cleanup;
        pxl8_stream_seek(&stream, chunk->offset);
        for (u32 i = 0; i < bsp->num_vertices; i++) {
            bsp->vertices[i].position = read_vec3(&stream);
        }
    }

    chunk = &header.chunks[CHUNK_EDGES];
    if (!validate_chunk(chunk, 4, file_size)) goto error_cleanup;
    bsp->num_edges = chunk->size / 4;
    if (bsp->num_edges > 0) {
        bsp->edges = pxl8_calloc(bsp->num_edges, sizeof(pxl8_bsp_edge));
        pxl8_stream_seek(&stream, chunk->offset);
        for (u32 i = 0; i < bsp->num_edges; i++) {
            bsp->edges[i].vertex[0] = pxl8_read_u16(&stream);
            bsp->edges[i].vertex[1] = pxl8_read_u16(&stream);
        }
    }

    chunk = &header.chunks[CHUNK_SURFEDGES];
    if (!validate_chunk(chunk, 4, file_size)) goto error_cleanup;
    bsp->num_surfedges = chunk->size / 4;
    if (bsp->num_surfedges > 0) {
        bsp->surfedges = pxl8_calloc(bsp->num_surfedges, sizeof(i32));
        pxl8_stream_seek(&stream, chunk->offset);
        for (u32 i = 0; i < bsp->num_surfedges; i++) {
            bsp->surfedges[i] = pxl8_read_i32(&stream);
        }
    }

    chunk = &header.chunks[CHUNK_PLANES];
    if (!validate_chunk(chunk, 20, file_size)) goto error_cleanup;
    bsp->num_planes = chunk->size / 20;
    if (bsp->num_planes > 0) {
        bsp->planes = pxl8_calloc(bsp->num_planes, sizeof(pxl8_bsp_plane));
        pxl8_stream_seek(&stream, chunk->offset);
        for (u32 i = 0; i < bsp->num_planes; i++) {
            bsp->planes[i].normal = read_vec3(&stream);
            bsp->planes[i].dist = pxl8_read_f32(&stream);
            bsp->planes[i].type = pxl8_read_i32(&stream);
        }
    }

    chunk = &header.chunks[CHUNK_FACES];
    if (!validate_chunk(chunk, 20, file_size)) goto error_cleanup;
    bsp->num_faces = chunk->size / 20;
    if (bsp->num_faces > 0) {
        bsp->faces = pxl8_calloc(bsp->num_faces, sizeof(pxl8_bsp_face));
        pxl8_stream_seek(&stream, chunk->offset);
        for (u32 i = 0; i < bsp->num_faces; i++) {
            bsp->faces[i].plane_id = pxl8_read_u16(&stream);
            bsp->faces[i].side = pxl8_read_u16(&stream);
            bsp->faces[i].first_edge = pxl8_read_u32(&stream);
            bsp->faces[i].num_edges = pxl8_read_u16(&stream);
            bsp->faces[i].material_id = pxl8_read_u16(&stream);
            bsp->faces[i].styles[0] = pxl8_read_u8(&stream);
            bsp->faces[i].styles[1] = pxl8_read_u8(&stream);
            bsp->faces[i].styles[2] = pxl8_read_u8(&stream);
            bsp->faces[i].styles[3] = pxl8_read_u8(&stream);
            bsp->faces[i].lightmap_offset = pxl8_read_u32(&stream);

            bsp->faces[i].aabb_min = (pxl8_vec3){1e30f, 1e30f, 1e30f};
            bsp->faces[i].aabb_max = (pxl8_vec3){-1e30f, -1e30f, -1e30f};
        }
    }

    chunk = &header.chunks[CHUNK_NODES];
    if (!validate_chunk(chunk, 24, file_size)) goto error_cleanup;
    bsp->num_nodes = chunk->size / 24;
    if (bsp->num_nodes > 0) {
        bsp->nodes = pxl8_calloc(bsp->num_nodes, sizeof(pxl8_bsp_node));
        pxl8_stream_seek(&stream, chunk->offset);
        for (u32 i = 0; i < bsp->num_nodes; i++) {
            bsp->nodes[i].plane_id = pxl8_read_u32(&stream);
            bsp->nodes[i].children[0] = pxl8_read_i16(&stream);
            bsp->nodes[i].children[1] = pxl8_read_i16(&stream);
            i16 nx = pxl8_read_i16(&stream);
            i16 ny = pxl8_read_i16(&stream);
            i16 nz = pxl8_read_i16(&stream);
            bsp->nodes[i].mins[0] = nx;
            bsp->nodes[i].mins[1] = nz;
            bsp->nodes[i].mins[2] = ny;
            i16 mx = pxl8_read_i16(&stream);
            i16 my = pxl8_read_i16(&stream);
            i16 mz = pxl8_read_i16(&stream);
            bsp->nodes[i].maxs[0] = mx;
            bsp->nodes[i].maxs[1] = mz;
            bsp->nodes[i].maxs[2] = my;
            bsp->nodes[i].first_face = pxl8_read_u16(&stream);
            bsp->nodes[i].num_faces = pxl8_read_u16(&stream);
        }
    }

    chunk = &header.chunks[CHUNK_LEAFS];
    if (!validate_chunk(chunk, 28, file_size)) goto error_cleanup;
    bsp->num_leafs = chunk->size / 28;
    if (bsp->num_leafs > 0) {
        bsp->leafs = pxl8_calloc(bsp->num_leafs, sizeof(pxl8_bsp_leaf));
        pxl8_stream_seek(&stream, chunk->offset);
        for (u32 i = 0; i < bsp->num_leafs; i++) {
            bsp->leafs[i].contents = pxl8_read_i32(&stream);
            bsp->leafs[i].visofs = pxl8_read_i32(&stream);
            i16 nx = pxl8_read_i16(&stream);
            i16 ny = pxl8_read_i16(&stream);
            i16 nz = pxl8_read_i16(&stream);
            bsp->leafs[i].mins[0] = nx;
            bsp->leafs[i].mins[1] = nz;
            bsp->leafs[i].mins[2] = ny;
            i16 mx = pxl8_read_i16(&stream);
            i16 my = pxl8_read_i16(&stream);
            i16 mz = pxl8_read_i16(&stream);
            bsp->leafs[i].maxs[0] = mx;
            bsp->leafs[i].maxs[1] = mz;
            bsp->leafs[i].maxs[2] = my;
            bsp->leafs[i].first_marksurface = pxl8_read_u16(&stream);
            bsp->leafs[i].num_marksurfaces = pxl8_read_u16(&stream);
            for (u32 j = 0; j < 4; j++) bsp->leafs[i].ambient_level[j] = pxl8_read_u8(&stream);
        }
    }

    chunk = &header.chunks[CHUNK_MARKSURFACES];
    if (!validate_chunk(chunk, 2, file_size)) goto error_cleanup;
    bsp->num_marksurfaces = chunk->size / 2;
    if (bsp->num_marksurfaces > 0) {
        bsp->marksurfaces = pxl8_calloc(bsp->num_marksurfaces, sizeof(u16));
        pxl8_stream_seek(&stream, chunk->offset);
        for (u32 i = 0; i < bsp->num_marksurfaces; i++) {
            bsp->marksurfaces[i] = pxl8_read_u16(&stream);
        }
    }

    chunk = &header.chunks[CHUNK_MODELS];
    if (!validate_chunk(chunk, 64, file_size)) goto error_cleanup;
    bsp->num_models = chunk->size / 64;
    if (bsp->num_models > 0) {
        bsp->models = pxl8_calloc(bsp->num_models, sizeof(pxl8_bsp_model));
        pxl8_stream_seek(&stream, chunk->offset);
        for (u32 i = 0; i < bsp->num_models; i++) {
            f32 minx = pxl8_read_f32(&stream);
            f32 miny = pxl8_read_f32(&stream);
            f32 minz = pxl8_read_f32(&stream);
            bsp->models[i].mins[0] = minx;
            bsp->models[i].mins[1] = minz;
            bsp->models[i].mins[2] = miny;
            f32 maxx = pxl8_read_f32(&stream);
            f32 maxy = pxl8_read_f32(&stream);
            f32 maxz = pxl8_read_f32(&stream);
            bsp->models[i].maxs[0] = maxx;
            bsp->models[i].maxs[1] = maxz;
            bsp->models[i].maxs[2] = maxy;
            bsp->models[i].origin = read_vec3(&stream);
            for (u32 j = 0; j < 4; j++) bsp->models[i].headnode[j] = pxl8_read_i32(&stream);
            bsp->models[i].visleafs = pxl8_read_i32(&stream);
            bsp->models[i].first_face = pxl8_read_i32(&stream);
            bsp->models[i].num_faces = pxl8_read_i32(&stream);
        }
    }

    chunk = &header.chunks[CHUNK_VISIBILITY];
    if (!validate_chunk(chunk, 1, file_size)) goto error_cleanup;
    bsp->visdata_size = chunk->size;
    if (bsp->visdata_size > 0) {
        bsp->visdata = pxl8_malloc(bsp->visdata_size);
        memcpy(bsp->visdata, file_data + chunk->offset, bsp->visdata_size);
    }

    chunk = &header.chunks[CHUNK_LIGHTING];
    if (!validate_chunk(chunk, 1, file_size)) goto error_cleanup;
    bsp->lightdata_size = chunk->size;
    if (bsp->lightdata_size > 0) {
        bsp->lightdata = pxl8_malloc(bsp->lightdata_size);
        memcpy(bsp->lightdata, file_data + chunk->offset, bsp->lightdata_size);
    }

    pxl8_free(file_data);

    for (u32 i = 0; i < bsp->num_faces; i++) {
        pxl8_bsp_face* face = &bsp->faces[i];
        f32 min_x = 1e30f, min_y = 1e30f, min_z = 1e30f;
        f32 max_x = -1e30f, max_y = -1e30f, max_z = -1e30f;

        for (u32 j = 0; j < face->num_edges; j++) {
            i32 surfedge_idx = face->first_edge + j;
            u32 vert_idx;

            if (!pxl8_bsp_get_edge_vertex(bsp, surfedge_idx, &vert_idx)) continue;

            pxl8_vec3 v = bsp->vertices[vert_idx].position;

            if (v.x < min_x) min_x = v.x;
            if (v.x > max_x) max_x = v.x;
            if (v.y < min_y) min_y = v.y;
            if (v.y > max_y) max_y = v.y;
            if (v.z < min_z) min_z = v.z;
            if (v.z > max_z) max_z = v.z;
        }

        face->aabb_min = (pxl8_vec3){min_x, min_y, min_z};
        face->aabb_max = (pxl8_vec3){max_x, max_y, max_z};
    }

    pxl8_debug("Loaded BSP: %u verts, %u faces, %u nodes, %u leafs",
               bsp->num_vertices, bsp->num_faces, bsp->num_nodes, bsp->num_leafs);

    return PXL8_OK;

error_cleanup:
    pxl8_error("BSP chunk validation failed: %s", path);
    pxl8_free(file_data);
    pxl8_bsp_destroy(bsp);
    return PXL8_ERROR_INVALID_FORMAT;
}

void pxl8_bsp_destroy(pxl8_bsp* bsp) {
    if (!bsp) return;

    pxl8_free(bsp->cell_portals);
    pxl8_free(bsp->edges);
    pxl8_free(bsp->faces);
    pxl8_free(bsp->leafs);
    pxl8_free(bsp->lightdata);
    pxl8_free(bsp->lightmaps);
    pxl8_free(bsp->marksurfaces);
    pxl8_free(bsp->models);
    pxl8_free(bsp->nodes);
    pxl8_free(bsp->planes);
    pxl8_free(bsp->surfedges);
    pxl8_free(bsp->vertex_lights);
    pxl8_free(bsp->vertices);
    pxl8_free(bsp->visdata);
    pxl8_free(bsp->heightfield);

    memset(bsp, 0, sizeof(*bsp));
}

i32 pxl8_bsp_find_leaf(const pxl8_bsp* bsp, pxl8_vec3 pos) {
    if (!bsp || bsp->num_nodes == 0) return -1;

    i32 node_id = 0;

    while (node_id >= 0) {
        const pxl8_bsp_node* node = &bsp->nodes[node_id];
        const pxl8_bsp_plane* plane = &bsp->planes[node->plane_id];

        f32 dist = pxl8_vec3_dot(pos, plane->normal) - plane->dist;
        node_id = node->children[dist < 0 ? 1 : 0];
    }

    return -(node_id + 1);
}


bool pxl8_bsp_is_leaf_visible(const pxl8_bsp* bsp, i32 leaf_from, i32 leaf_to) {
    if (!bsp || !bsp->visdata || bsp->visdata_size == 0) return true;
    if (leaf_from < 0 || leaf_to < 0) return true;
    if ((u32)leaf_from >= bsp->num_leafs || (u32)leaf_to >= bsp->num_leafs) return true;

    i32 visofs = bsp->leafs[leaf_from].visofs;
    if (visofs < 0) return true;

    u32 row_size = (bsp->num_leafs + 7) >> 3;
    u32 byte_idx = (u32)leaf_to >> 3;
    u32 bit_idx = (u32)leaf_to & 7;

    u8* vis = bsp->visdata + visofs;
    u8* vis_end = bsp->visdata + bsp->visdata_size;
    u32 out = 0;

    while (out < row_size && vis < vis_end) {
        if (*vis) {
            if (out == byte_idx) {
                return (*vis & (1 << bit_idx)) != 0;
            }
            out++;
            vis++;
        } else {
            vis++;
            if (vis >= vis_end) break;
            u32 count = *vis++;
            if (out + count > byte_idx && byte_idx >= out) {
                return false;
            }
            out += count;
        }
    }

    return out > byte_idx ? false : true;
}

pxl8_bsp_pvs pxl8_bsp_decompress_pvs(const pxl8_bsp* bsp, i32 leaf) {
    pxl8_bsp_pvs pvs = {0};

    u32 row = (bsp->num_leafs + 7) >> 3;
    pvs.data = pxl8_malloc(row);
    pvs.size = row;

    if (!pvs.data) return pvs;

    if (!bsp || leaf < 0 || (u32)leaf >= bsp->num_leafs) {
        memset(pvs.data, 0xFF, row);
        return pvs;
    }

    i32 visofs = bsp->leafs[leaf].visofs;
    if (visofs < 0 || !bsp->visdata || bsp->visdata_size == 0) {
        memset(pvs.data, 0xFF, row);
        return pvs;
    }

    u8* in = bsp->visdata + visofs;
    u8* out = pvs.data;
    u8* out_end = pvs.data + row;

    do {
        if (*in) {
            *out++ = *in++;
        } else {
            in++;
            i32 c = *in++;
            while (c > 0 && out < out_end) {
                *out++ = 0;
                c--;
            }
        }
    } while (out < out_end);

    return pvs;
}

void pxl8_bsp_pvs_destroy(pxl8_bsp_pvs* pvs) {
    if (pvs) {
        pxl8_free(pvs->data);
        pvs->data = NULL;
        pvs->size = 0;
    }
}

bool pxl8_bsp_pvs_is_visible(const pxl8_bsp_pvs* pvs, i32 leaf) {
    if (!pvs || !pvs->data || leaf < 0) return true;
    u32 byte_idx = (u32)leaf >> 3;
    u32 bit_idx = (u32)leaf & 7;
    if (byte_idx >= pvs->size) return true;
    return (pvs->data[byte_idx] & (1 << bit_idx)) != 0;
}

pxl8_bsp_lightmap pxl8_bsp_lightmap_uniform(u8 r, u8 g, u8 b) {
    return (pxl8_bsp_lightmap){
        .color = {r, g, b},
        .height = 0,
        .offset = 0,
        .width = 0,
    };
}

pxl8_bsp_lightmap pxl8_bsp_lightmap_mapped(u8 width, u8 height, u32 offset) {
    return (pxl8_bsp_lightmap){
        .color = {0, 0, 0},
        .height = height,
        .offset = offset,
        .width = width,
    };
}

u8 pxl8_bsp_light_at(const pxl8_bsp* bsp, f32 x, f32 y, f32 z, u8 ambient) {
    if (!bsp || !bsp->vertices || !bsp->vertex_lights) return 255;

    f32 best_dist = FLT_MAX;
    u32 best_idx = 0;

    for (u32 i = 0; i < bsp->num_vertices; i++) {
        f32 dx = bsp->vertices[i].position.x - x;
        f32 dy = bsp->vertices[i].position.y - y;
        f32 dz = bsp->vertices[i].position.z - z;
        f32 dist = dx * dx + dy * dy + dz * dz;
        if (dist < best_dist) {
            best_dist = dist;
            best_idx = i;
        }
    }

    if (best_idx >= bsp->num_vertex_lights) return 255;

    u32 packed = bsp->vertex_lights[best_idx];
    u8 direct = (packed >> 24) & 0xFF;
    u8 ao = (packed >> 16) & 0xFF;
    f32 combined = (f32)direct + ((f32)ambient / 255.0f) * (f32)ao;
    return (u8)(combined > 255.0f ? 255.0f : combined);
}

pxl8_bsp_lightmap_sample pxl8_bsp_sample_lightmap(const pxl8_bsp* bsp, u32 face_idx, f32 u, f32 v) {
    pxl8_bsp_lightmap_sample white = {255, 255, 255};

    if (!bsp || !bsp->lightmaps || face_idx >= bsp->num_lightmaps) {
        return white;
    }

    const pxl8_bsp_lightmap* lm = &bsp->lightmaps[face_idx];

    if (lm->width == 0) {
        return (pxl8_bsp_lightmap_sample){lm->color[2], lm->color[1], lm->color[0]};
    }

    if (!bsp->lightdata || bsp->lightdata_size == 0) {
        return white;
    }

    f32 w = (f32)lm->width;
    f32 h = (f32)lm->height;
    f32 fx = u * w;
    f32 fy = v * h;

    if (fx < 0) fx = 0;
    if (fx > w - 1.001f) fx = w - 1.001f;
    if (fy < 0) fy = 0;
    if (fy > h - 1.001f) fy = h - 1.001f;

    u32 x0 = (u32)fx;
    u32 y0 = (u32)fy;
    u32 x1 = x0 + 1;
    u32 y1 = y0 + 1;
    if (x1 >= lm->width) x1 = lm->width - 1;
    if (y1 >= lm->height) y1 = lm->height - 1;

    f32 frac_x = fx - (f32)x0;
    f32 frac_y = fy - (f32)y0;

    u32 stride = lm->width;
    u32 base = lm->offset;

    u32 idx00 = base + y0 * stride + x0;
    u32 idx10 = base + y0 * stride + x1;
    u32 idx01 = base + y1 * stride + x0;
    u32 idx11 = base + y1 * stride + x1;

    u8 r00, g00, b00, r10, g10, b10, r01, g01, b01, r11, g11, b11;

    if (idx00 < bsp->lightdata_size) pxl8_rgb332_unpack(bsp->lightdata[idx00], &r00, &g00, &b00);
    else { r00 = g00 = b00 = 255; }
    if (idx10 < bsp->lightdata_size) pxl8_rgb332_unpack(bsp->lightdata[idx10], &r10, &g10, &b10);
    else { r10 = g10 = b10 = 255; }
    if (idx01 < bsp->lightdata_size) pxl8_rgb332_unpack(bsp->lightdata[idx01], &r01, &g01, &b01);
    else { r01 = g01 = b01 = 255; }
    if (idx11 < bsp->lightdata_size) pxl8_rgb332_unpack(bsp->lightdata[idx11], &r11, &g11, &b11);
    else { r11 = g11 = b11 = 255; }

    f32 inv_x = 1.0f - frac_x;
    f32 inv_y = 1.0f - frac_y;

    u8 r = (u8)(r00 * inv_x * inv_y + r10 * frac_x * inv_y + r01 * inv_x * frac_y + r11 * frac_x * frac_y);
    u8 g = (u8)(g00 * inv_x * inv_y + g10 * frac_x * inv_y + g01 * inv_x * frac_y + g11 * frac_x * frac_y);
    u8 b = (u8)(b00 * inv_x * inv_y + b10 * frac_x * inv_y + b01 * inv_x * frac_y + b11 * frac_x * frac_y);

    return (pxl8_bsp_lightmap_sample){b, g, r};
}

u32 pxl8_bsp_face_count(const pxl8_bsp* bsp) {
    if (!bsp) return 0;
    return bsp->num_faces;
}

pxl8_vec3 pxl8_bsp_face_normal(const pxl8_bsp* bsp, u32 face_id) {
    pxl8_vec3 up = {0, 1, 0};
    if (!bsp || face_id >= bsp->num_faces) return up;

    const pxl8_bsp_face* face = &bsp->faces[face_id];
    if (face->plane_id >= bsp->num_planes) return up;

    pxl8_vec3 normal = bsp->planes[face->plane_id].normal;
    if (face->side) {
        normal.x = -normal.x;
        normal.y = -normal.y;
        normal.z = -normal.z;
    }
    return normal;
}

void pxl8_bsp_face_set_material(pxl8_bsp* bsp, u32 face_id, u16 material_id) {
    if (!bsp || face_id >= bsp->num_faces) return;
    bsp->faces[face_id].material_id = material_id;
}