#pragma once

#include "../../GFX/Mesh.hpp"
#include "../../GFX/Util/MeshBuilder.hpp"
#include "../Chunk.hpp"

namespace MC::World::Generation::ChunkMeshing {

struct ChunkNeighbors {
    Chunk *north, *east, *south, *west;
    Chunk *north_east, *south_east, *south_west, *north_west;
};

struct ChunkMesh { GFX::Mesh land_mesh, water_mesh; };
ChunkMesh mesh_chunk(Chunk& chunk, const ChunkNeighbors& neighbors);

namespace Detail {

using Vertex = Vector<3, F32>;
using Normal = Vector<3, F32>;
using TexCoord = Vector<2, F32>;
using AO = F32;

template <typename T>
using Face = std::array<T, 4>;

template <typename Decisions>
GFX::Mesh create_mesh(Chunk& chunk, const ChunkNeighbors& neighbors) {
    GFX::Util::MeshBuilder<Normal, TexCoord, AO> builder;

    for (Int x = 0; x < Chunk::Width; x++) {
        for (Int y = 0; y < Chunk::Height; y++) {
            for (Int z = 0; z < Chunk::Width; z++) {
                auto block = chunk.get(x, y, z);
                if (Decisions::should_ignore_block(block))
                    continue;

                for (auto side: BlockSide::all()) {
                    if (!Decisions::is_face_visible(chunk, neighbors, x, y, z, side))
                        continue;

                    U32 s = builder.vertex_count();

                    builder.positions(Decisions::face_positions(side, x, y, z));
                    builder.attributes<0>(Decisions::face_normals(side));
                    builder.attributes<1>(Decisions::face_tex_coords(block.type, side));
                    builder.attributes<2>(Decisions::face_ao_values(chunk, neighbors, x, y, z, side));
                    builder.indices(std::array{ s + 0, s + 1, s + 2, s + 2, s + 3, s + 0 });
                }
            }
        }
    }

    return builder.mesh();
}

class DefaultMeshDecisions {
public:
    static Face<Vertex> face_positions(BlockSide side, U32 x, U32 y, U32 z);
    static Face<TexCoord> face_tex_coords(BlockType type, BlockSide side);
    static Face<Normal> face_normals(BlockSide side);
    static Face<AO> face_ao_values(Chunk& chunk, const ChunkNeighbors& neighbors, U32 x, U32 y, U32 z, BlockSide side);

    static Chunk::BlockData get_block_wrapping(const Chunk& chunk, const ChunkNeighbors& neighbors, Vector<3, I32> pos);
    static Vector<3, I32> get_face_normal(BlockSide side);

    static Bool is_face_visible(Chunk& chunk, const ChunkNeighbors& neighbors, U32 x, U32 y, U32 z, BlockSide side);
    static Bool should_ignore_block(Chunk::BlockData block);
};

class WaterMeshDecisions final : public DefaultMeshDecisions {
public:
    static Bool is_face_visible(Chunk& chunk, const ChunkNeighbors& neighbors, U32 x, U32 y, U32 z, BlockSide side);
    static Bool should_ignore_block(Chunk::BlockData block);
};

}
}