#include "Generator.hpp"
#include "../Math/Interpolation.hpp"
#include "../Math/Sigmoid.hpp"

namespace MC::World {

Chunk Generator::generate(int64_t chunk_x, int64_t chunk_y) {
    Chunk chunk(chunk_x, chunk_y);

    auto landmass_map = generate_landmass_map(chunk_x, chunk_y);
    auto hill_map = generate_hill_map(chunk_x, chunk_y);
    auto height_map = generate_height_map(landmass_map, hill_map, chunk_x, chunk_y);

    auto biome_map = generate_biome_map(landmass_map, hill_map, height_map, chunk_x, chunk_y);
    auto terrain_map = generate_terrain(height_map, chunk_x, chunk_y);

    decorate_soil(chunk, biome_map, terrain_map);

    chunk.set_details({{landmass_map.map}, {hill_map.map}, {biome_map.map}});

    return chunk;
}

Generator::ChunkMap2D<float> Generator::generate_landmass_map(int64_t chunk_x, int64_t chunk_y) {
    ChunkMap2D<float> landmass_map{};

    for (uint x = 0; x < Chunk::Width; x++) {
        for (uint y = 0; y < Chunk::Width; y++) {
            landmass_map.set(x, y, get_landmass(chunk_position_to_world_vector(chunk_x, chunk_y, x, y)));
        }
    }

    return landmass_map;
}

Generator::ChunkMap2D<float> Generator::generate_hill_map(int64_t chunk_x, int64_t chunk_y) {
    ChunkMap2D<float> hill_map{};

    for (uint x = 0; x < Chunk::Width; x++) {
        for (uint y = 0; y < Chunk::Width; y++) {
            hill_map.set(x, y, get_hill(chunk_position_to_world_vector(chunk_x, chunk_y, x, y)));
        }
    }

    return hill_map;
}

Generator::ChunkMap2D<float> Generator::generate_height_map(ChunkMap2D<float>& landmass_map, ChunkMap2D<float>& hill_map, int64_t chunk_x, int64_t chunk_y) {
    ChunkMap2D<float> height_map{};

    for (uint x = 0; x < Chunk::Width; x++) {
        for (uint y = 0; y < Chunk::Width; y++) {
            auto landmass_effect = landmass_map.get(x, y);
            auto hill_effect = hill_map.get(x, y);

            auto hill = hill_effect * landmass_effect * 1.4 - 0.4;
            auto landmass = landmass_effect * 0.6 + 0.4;

            auto height = (hill + landmass) / 2.0f;

            height_map.set(x, y, height);
        }
    }

    return height_map;
}

Generator::ChunkMap2D<BiomeType> Generator::generate_biome_map(ChunkMap2D<float>& landmass_map, ChunkMap2D<float>& hill_map, ChunkMap2D<float>& height_map, int64_t chunk_x, int64_t chunk_y) {
    ChunkMap2D<BiomeType> biome_map{};

    for (uint x = 0; x < Chunk::Width; x++) {
        for (uint y = 0; y < Chunk::Width; y++) {
            float landmass = landmass_map.get(x, y);
            float hill = hill_map.get(x, y);

            auto world_pos = chunk_position_to_world_vector(chunk_x, chunk_y, x, y);
            float temperature = get_temperature(world_pos);
            float humidity = get_humidity(world_pos);

            HillSlice hill_slice;
            if (hill > 0.9) { hill_slice = HillSlice::Mountain; }
            else if (hill > 0.33) { hill_slice = HillSlice::Middle; }
            else { hill_slice = HillSlice::Valley; }

            LandmassSlice landmass_slice;
            if (landmass > 0.8) { landmass_slice = LandmassSlice::Land; }
            else if (landmass > 0.45) { landmass_slice = LandmassSlice::Beach; }
            else { landmass_slice = LandmassSlice::Ocean; }

            TemperatureZone temparature_zone;
            if (temperature > 0.66) { temparature_zone = TemperatureZone::Hot; }
            else if (temperature > 0.33) { temparature_zone = TemperatureZone::Fair; }
            else { temparature_zone = TemperatureZone::Cold; }

            HumidityZone humidity_zone;
            if (humidity > 0.66) { humidity_zone = HumidityZone::Wet; }
            else if (humidity > 0.33) { humidity_zone = HumidityZone::Temperate; }
            else { humidity_zone = HumidityZone::Dry; }

            auto biome = lookup_biome(hill_slice, landmass_slice, temparature_zone, humidity_zone);
            biome_map.set(x, y, biome);
        }
    }

    return biome_map;
}

Generator::ChunkMap3D<bool> Generator::generate_terrain(ChunkMap2D<float>& height_map, int64_t chunk_x, int64_t chunk_y) {
    float jaggedness = 0.10f;

    ChunkMap3D<bool> terrain_map{};
    for (uint x = 0; x < Chunk::Width; x++) {
        for (uint z = 0; z < Chunk::Width; z++) {
            auto height = height_map.get(x, z);

            for (uint y = 0; y < Chunk::Height; y++) {
                float density = get_density({Chunk::Width * chunk_x + (float)x, (float)y, Chunk::Width * chunk_y + (float)z});
                float threshold = Math::sigmoid(((float)y / (Chunk::Height * height * 2) - 0.5f) / jaggedness);

                if (density > threshold) {
                    terrain_map.set(x, y, z, true);
                }
            }
        }
    }

    return terrain_map;
}

void Generator::decorate_soil(Chunk& chunk, ChunkMap2D<BiomeType>& biome_map, ChunkMap3D<bool>& terrain_map) {
    constexpr uint dirt_depth = 4;
    constexpr uint water_height = 39;

    for (uint x = 0; x < Chunk::Width; x++) {
        for (uint z = 0; z < Chunk::Width; z++) {
            auto biome = biome_map.get(x, z);

            BlockType top_block{};
            BlockType soil_block{};
            switch (biome) {
            case BiomeType::Beach:
            case BiomeType::Desert:
                top_block = BlockType::Sand;
                soil_block = BlockType::Sand;
                break;
            case BiomeType::Jungle:
            case BiomeType::Forest:
            case BiomeType::Plains:
            case BiomeType::River:
            case BiomeType::Ocean:
                top_block = BlockType::Grass;
                soil_block = BlockType::Dirt;
                break;
            case BiomeType::Alpine:
                top_block = BlockType::Snow;
                soil_block = BlockType::Dirt;
                break;
            }

            auto column_depth = 0;
            for (uint y = Chunk::Height - 1; y > 0; y--) {
                auto block = terrain_map.get(x, y, z);
                if (block) {
                    if (column_depth == 0 && y >= water_height - 1) {
                        chunk.set(x, y, z, {top_block});
                    } else if (column_depth < dirt_depth) {
                        chunk.set(x, y, z, {soil_block});
                    } else {
                        chunk.set(x, y, z, {BlockType::Stone});
                    }
                    column_depth++;
                } else {
                    if (y < water_height) {
                        chunk.set(x, y, z, {BlockType::Water});
                    }
                    column_depth = 0;
                }
            }
        }
    }
}

#define CURVE_START(y) constexpr auto lerp = Math::linear_interpolation; float _py = y; float _px = 0.0f;
#define CURVE_POINT(x, y) if (v < x) return lerp({_py, y}, _px, x, v); _py = y; _px = x
#define CURVE_END(y) return lerp({_py, y}, _px, 1.0f, v);

float Generator::get_landmass(Vector<2> pos) const {
    auto v = m_landmass_noise.at(pos);

    CURVE_START(1.0f);
    CURVE_POINT(0.1f, 0.8f);
    CURVE_POINT(0.3f, 0.8f);
    CURVE_POINT(0.37f, 0.125f);
    CURVE_POINT(0.4f, 0.4f);
    CURVE_POINT(0.46f, 0.45f);
    CURVE_POINT(0.47f, 0.875f);
    CURVE_POINT(0.48f, 0.9f);
    CURVE_POINT(0.55f, 0.95f);
    CURVE_END(1.0f);
}

float Generator::get_hill(Vector<2> pos) const {
    auto v = m_hill_noise.at(pos);

    CURVE_START(0.33f);
    CURVE_POINT(0.25f, 1.0f);

    CURVE_POINT(0.49f, 0.1f);
    CURVE_POINT(0.5f, 0.0f);
    CURVE_POINT(0.51f, 0.1f);

    CURVE_POINT(0.75f, 1.0f);
    CURVE_END(0.33f);
}

float Generator::get_humidity(Vector<2> pos) const {
    auto v = m_humidity_noise.at(pos);
    return v;
}

float Generator::get_temperature(Vector<2> pos) const {
    auto v = m_temperature_noise.at(pos);
    return v;
}

float Generator::get_density(Vector<3> pos) const {
    auto v = m_density_noise.at(pos);
    return v;
}

Vector<2> Generator::chunk_position_to_world_vector(int64_t chunk_x, int64_t chunk_y, uint x, uint y) {
    return {(float)x + chunk_x * Chunk::Width, (float)y + chunk_y * Chunk::Width};
}

std::array<BiomeType, Generator::biome_lookup_table_size> Generator::create_biome_lookup_table() {
    std::array<BiomeType, biome_lookup_table_size> table{};

    auto inc = [](auto& x) { x = (std::remove_reference_t<decltype(x)>)((uint)x + 1); };
    auto cmp = [](auto x, auto s) { return (uint)x < (uint)s; };

    for (HillSlice hill_slice{}; cmp(hill_slice, HillSliceSize); inc(hill_slice)) {
        for (LandmassSlice landmass_slice{}; cmp(landmass_slice, LandmassSliceSize); inc(landmass_slice)) {
            for (TemperatureZone temperature_zone{}; cmp(temperature_zone, TemperatureZoneSize); inc(temperature_zone)) {
                for (HumidityZone humidity_zone{}; cmp(humidity_zone, HumidityZoneSize); inc(humidity_zone)) {
                    BiomeType biome{};
                    if (landmass_slice == LandmassSlice::Ocean) {
                        biome = BiomeType::Ocean;
                        goto set;
                    }
                    if (landmass_slice == LandmassSlice::Beach) {
                        biome = BiomeType::Beach;
                        goto set;
                    }

                    if (hill_slice == HillSlice::Valley) {
                        biome = BiomeType::River;
                        goto set;
                    }
                    if (hill_slice == HillSlice::Mountain) {
                        if (temperature_zone == TemperatureZone::Hot) {
                            biome = BiomeType::Desert;
                        } else {
                            biome = BiomeType::Alpine;
                        }
                        goto set;
                    }

                    switch (temperature_zone) {
                    case TemperatureZone::Hot:
                        biome = BiomeType::Desert;
                        break;
                    case TemperatureZone::Fair:
                        switch (humidity_zone) {
                        case HumidityZone::Wet:
                            biome = BiomeType::Jungle;
                            break;
                        case HumidityZone::Lush:
                            biome = BiomeType::Forest;
                            break;
                        case HumidityZone::Temperate:
                        case HumidityZone::Dry:
                            biome = BiomeType::Plains;
                            break;
                        }
                        break;
                    case TemperatureZone::Cold:
                        switch (humidity_zone) {
                        case HumidityZone::Wet:
                        case HumidityZone::Lush:
                            biome = BiomeType::Alpine;
                            break;
                        case HumidityZone::Temperate:
                        case HumidityZone::Dry:
                            biome = BiomeType::Plains;
                            break;
                        }
                        break;
                    }

                    set:
                    table[biome_lookup_table_index(hill_slice, landmass_slice, temperature_zone, humidity_zone)] = biome;
                }
            }
        }
    }

    return table;
}

size_t Generator::biome_lookup_table_index(HillSlice hill_slice, LandmassSlice landmass_slice, TemperatureZone temperature_zone, HumidityZone humidity_zone) {
    auto hs = (uint8_t)hill_slice; auto ls = (uint8_t)landmass_slice; auto tz = (uint8_t)temperature_zone; auto hz = (uint8_t)humidity_zone;
    auto LS_S = (uint8_t)LandmassSliceSize; auto TZ_S = (uint8_t)TemperatureZoneSize; auto HZ_S = (uint8_t)HumidityZoneSize;
    return (hs * LS_S * TZ_S * HZ_S) + (ls * TZ_S * HZ_S) + (tz * HZ_S) + hz;
}

BiomeType Generator::lookup_biome(HillSlice hill_slice, LandmassSlice landmass_slice, TemperatureZone temperature_zone, HumidityZone humidity_zone) {
    return biome_lookup_table.at(biome_lookup_table_index(hill_slice, landmass_slice, temperature_zone, humidity_zone));
}

}