#include "LightSolver.hpp"
#include "Lightmap.hpp"
#include "content/Content.hpp"
#include "voxels/Chunks.hpp"
#include "voxels/Chunk.hpp"
#include "voxels/voxel.hpp"
#include "voxels/Block.hpp"

#include <assert.h>

LightSolver::LightSolver(const ContentIndices& contentIds, Chunks& chunks, int channel) 
    : blockDefs(contentIds.blocks.getDefs()),
      chunks(chunks), 
      channel(channel) {
}

void LightSolver::add(int x, int y, int z, int emission) {
    if (emission <= 1) {
        return;
    }
    Chunk* chunk = chunks.getChunkByVoxel(x, y, z);
    if (chunk == nullptr) {
        return;
    }
    assert(chunk->lightmap != nullptr);
    auto& lightmap = *chunk->lightmap;

    ubyte light = lightmap.get(x-chunk->x*CHUNK_W, y, z-chunk->z*CHUNK_D, channel);
    if (emission < light) return;

    addqueue.push(lightentry {x, y, z, ubyte(emission)});

    chunk->flags.modified = true;
    lightmap.set(x-chunk->x*CHUNK_W, y, z-chunk->z*CHUNK_D, channel, emission);
}

void LightSolver::add(int x, int y, int z) {
    add(x,y,z, chunks.getLight(x,y,z, channel));
}

void LightSolver::remove(int x, int y, int z) {
    Chunk* chunk = chunks.getChunkByVoxel(x, y, z);
    if (chunk == nullptr) {
        return;
    }
    assert(chunk->lightmap != nullptr);
    auto& lightmap = *chunk->lightmap;

    ubyte light = lightmap.get(x-chunk->x*CHUNK_W, y, z-chunk->z*CHUNK_D, channel);
    if (light == 0) {
        return;
    }
    remqueue.push(lightentry {x, y, z, light});
    lightmap.set(x-chunk->x*CHUNK_W, y, z-chunk->z*CHUNK_D, channel, 0);
}

void LightSolver::solve(Chunk* prevailingChunk) {
    const int coords[] = {
            0, 0, 1,
            0, 0,-1,
            0, 1, 0,
            0,-1, 0,
            1, 0, 0,
           -1, 0, 0
    };

    while (!remqueue.empty()){
        lightentry entry = std::move(remqueue.front());
        remqueue.pop();

        for (int i = 0; i < 6; i++) {
            int imul3 = i * 3;
            int x = entry.x+coords[imul3];
            int y = entry.y+coords[imul3+1];
            int z = entry.z+coords[imul3+2];
            
            Chunk* chunk = prevailingChunk;
            if (chunk == nullptr || !chunk->isBlockInside(x, z)) {
                chunk = chunks.getChunkByVoxel(x,y,z);
                if (chunk == nullptr) {
                    continue;
                }
            } else if (y < 0 || y >= CHUNK_H) {
                continue;
            }

            int lx = x - chunk->x * CHUNK_W;
            int lz = z - chunk->z * CHUNK_D;
            chunk->flags.modified = true;

            assert(chunk->lightmap != nullptr);
            auto& lightmap = *chunk->lightmap;

            ubyte light = lightmap.get(lx,y,lz, channel);
            if (light != 0 && light == entry.light-1) {
                voxel* vox = chunks.get(x, y, z);
                if (vox && vox->id != 0) {
                    const Block* block = blockDefs[vox->id];
                    if (uint8_t emission = block->emission[channel]) {
                        addqueue.push(lightentry {x, y, z, emission});
                        lightmap.set(lx, y, lz, channel, emission);
                    }
                    else lightmap.set(lx, y, lz, channel, 0);
                }
                else lightmap.set(lx, y, lz, channel, 0);
                remqueue.push(lightentry {x, y, z, light});
            }
            else if (light >= entry.light) {
                addqueue.push(lightentry {x, y, z, light});
            }
        }
    }

    while (!addqueue.empty()){
        lightentry entry = std::move(addqueue.front());
        addqueue.pop();

        for (int i = 0; i < 6; i++) {
            int imul3 = i*3;
            int x = entry.x+coords[imul3];
            int y = entry.y+coords[imul3+1];
            int z = entry.z+coords[imul3+2];

            Chunk* chunk = prevailingChunk;
            if (chunk == nullptr || !chunk->isBlockInside(x, z)) {
                chunk = chunks.getChunkByVoxel(x,y,z);
                if (chunk == nullptr) {
                    continue;
                }
            } else if (y < 0 || y >= CHUNK_H) {
                continue;
            }

            assert(chunk->lightmap != nullptr);
            auto& lightmap = *chunk->lightmap;
            int lx = x - chunk->x * CHUNK_W;
            int lz = z - chunk->z * CHUNK_D;
            chunk->flags.modified = true;

            ubyte light = lightmap.get(lx, y, lz, channel);
            voxel& v = chunk->voxels[vox_index(lx, y, lz)];
            const Block* block = blockDefs[v.id];
            if (block->lightPassing && light+2 <= entry.light){
                lightmap.set(
                    x-chunk->x*CHUNK_W, y, z-chunk->z*CHUNK_D, 
                    channel, 
                    entry.light-1);
                addqueue.push(lightentry {x, y, z, ubyte(entry.light-1)});
            }
        }
    }
}