#include <cmath>

#include "client/World.h"
#include "client/rendering/Engine.h"
#include "client/rendering/Mesh.h"
#include "common/BlockStorage.h"
#include "rendering/FileTexture.h"
#include "utils/List.h"
#include "utils/Logger.h"
#include "utils/Random.h"

static BlockStorage blocks{7, 7};
static List<Entity*> entities;
static Mesh mesh;
static FileTexture texture;
static bool dirty = true;

bool World::init() {
    mesh.init();
    Error error = texture.load("resources/textures.png", 4);
    if(error.has()) {
        LOG_ERROR(error.message);
    }
    return error.has();
}

void World::addEntity(Entity* e) {
    entities.add(e);
}

void World::removeEntity(Entity* e) {
    for(int i = 0; i < entities.getLength(); i++) {
        if(entities[i] == e) {
            entities.removeBySwap(i);
            return;
        }
    }
}

static List<Box> getBoxes(const Box& box) {
    int minX = floorf(box.getMin()[0]);
    int minY = floorf(box.getMin()[1]);
    int minZ = floorf(box.getMin()[2]);
    int maxX = floorf(box.getMax()[0]);
    int maxY = floorf(box.getMax()[1]);
    int maxZ = floorf(box.getMax()[2]);

    List<Box> boxes;
    for(int x = minX; x <= maxX; x++) {
        for(int y = minY; y <= maxY; y++) {
            for(int z = minZ; z <= maxZ; z++) {
                Block::addBoxes(blocks.get(x, y, z), boxes,
                                Vector3(static_cast<float>(x),
                                        static_cast<float>(y),
                                        static_cast<float>(z)));
            }
        }
    }
    return boxes;
}

static Vector3 limitMove(const Entity& e, Vector3 move) {
    Box box = e.getBox();
    List<Box> boxes = getBoxes(box.expand(move));
    if(boxes.getLength() == 0) {
        return move;
    }
    Vector3 realMove;

    constexpr float step = 0.05f;
    while(move[0] != 0.0f || move[1] != 0.0f || move[2] != 0.0f) {
        for(int i = 0; i < 3; i++) {
            Vector3 old = realMove;
            if(move[i] > step) {
                realMove[i] += step;
                move[i] -= step;
            } else if(move[i] < -step) {
                realMove[i] -= step;
                move[i] += step;
            } else if(move[i] != 0.0f) {
                realMove[i] += move[i];
                move[i] = 0.0f;
            }
            Box moved = box.offset(realMove);
            for(const Box& box : boxes) {
                if(box.collidesWith(moved)) {
                    move[i] = 0.0f;
                    realMove = old;
                    break;
                }
            }
        }
    }
    return realMove;
}

void World::tick() {
    for(Entity* e : entities) {
        e->tick();
        if(!e->skip) {
            Vector3 move = limitMove(*e, e->getVelocity());
            e->move(move);
        }
    }
}

static bool isAir(int x, int y, int z) {
    return blocks.get(x, y, z) == 0;
}

static void addCube(TypedBuffer<Triangle>& buffer, float x, float y, float z) {
    Vector3 v000(x, y, z);
    Vector3 v001(x, y, z + 1);
    Vector3 v010(x, y + 1, z);
    Vector3 v011(x, y + 1, z + 1);
    Vector3 v100(x + 1, y, z);
    Vector3 v101(x + 1, y, z + 1);
    Vector3 v110(x + 1, y + 1, z);
    Vector3 v111(x + 1, y + 1, z + 1);

    Vector2 t1(0.1875f, 0.0f);
    Vector2 t2(0.25f, 0.0f);
    Vector2 t3(0.25f, 0.0625f);
    Vector2 t4(0.1875f, 0.0625f);

    if(isAir(x, y - 1, z)) {
        Vector2 tb(0.125f, 0.0625f);
        buffer.add(Triangle(Vertex(v000, Vector2(0.125f, 0.0f)),
                            Vertex(v100, t1), Vertex(v001, tb)));
        buffer.add(
            Triangle(Vertex(v100, t1), Vertex(v101, t4), Vertex(v001, tb)));
    }
    if(isAir(x, y + 1, z)) {
        Vector2 tt(0.3125f, 0.0f);
        buffer.add(
            Triangle(Vertex(v010, t2), Vertex(v011, t3), Vertex(v110, tt)));
        buffer.add(Triangle(Vertex(v110, tt), Vertex(v011, t3),
                            Vertex(v111, Vector2(0.3125f, 0.0625f))));
    }
    if(isAir(x - 1, y, z)) {
        buffer.add(
            Triangle(Vertex(v000, t4), Vertex(v001, t3), Vertex(v010, t1)));
        buffer.add(
            Triangle(Vertex(v001, t3), Vertex(v011, t2), Vertex(v010, t1)));
    }
    if(isAir(x + 1, y, z)) {
        buffer.add(
            Triangle(Vertex(v100, t3), Vertex(v110, t2), Vertex(v101, t4)));
        buffer.add(
            Triangle(Vertex(v101, t4), Vertex(v110, t2), Vertex(v111, t1)));
    }
    if(isAir(x, y, z + 1)) {
        buffer.add(
            Triangle(Vertex(v001, t4), Vertex(v101, t3), Vertex(v011, t1)));
        buffer.add(
            Triangle(Vertex(v111, t2), Vertex(v011, t1), Vertex(v101, t3)));
    }
    if(isAir(x, y, z - 1)) {
        buffer.add(
            Triangle(Vertex(v000, t3), Vertex(v010, t2), Vertex(v100, t4)));
        buffer.add(
            Triangle(Vertex(v110, t1), Vertex(v100, t4), Vertex(v010, t2)));
    }
}

static void rebuildRenderData() {
    TypedBuffer<Triangle> buffer(100);
    for(int x = 0; x < blocks.getSize(); x++) {
        for(int y = 0; y < blocks.getHeight(); y++) {
            for(int z = 0; z < blocks.getSize(); z++) {
                if(!isAir(x, y, z)) {
                    addCube(buffer, x, y, z);
                }
            }
        }
    }
    mesh.build(buffer);
    LOG_DEBUG("world render update");
}

void World::render() {
    if(dirty) {
        rebuildRenderData();
        dirty = false;
    }
    texture.bindTo(0);
    for(int x = -1; x <= 1; x++) {
        for(int z = -1; z <= 1; z++) {
            Engine::matrix
                .translateTo(blocks.getSize() * x, 0.0f, blocks.getSize() * z)
                .update();
            mesh.draw();
        }
    }
}

int World::getHeight() {
    return blocks.getHeight();
}

void World::setBlock(int x, int y, int z, Block::Id block) {
    dirty = true;
    blocks.set(x, y, z, block);
}