#include "engine.h"
#include "context.h"

#include "objects/scene.h"

using namespace Mauri;

auto View::center_scale_viewport() -> void
{
    Render::set_viewport(this->camera_pos[0], this->camera_pos[1],
        this->ortho_width / this->scale, this->ortho_height / this->scale);
}

auto View::center_viewport(f32 buffer_width, f32 buffer_height) -> void
{
    Render::set_viewport((this->width - buffer_width) / -2,
        (this->height - buffer_height) / -2, buffer_width, buffer_height);
}

auto View::default_viewport(f32 buffer_width, f32 buffer_height) -> void
{
    Render::set_viewport(0, 0, buffer_width, buffer_height);
}

auto View::center(f32 buffer_width, f32 buffer_height) -> void
{
    f32 w_scale = this->width / buffer_width;
    f32 h_scale = this->height / buffer_height;

    this->scale = (w_scale <= h_scale) ? w_scale : h_scale;

    f32 scaled_width = this->width / this->scale;
    f32 scaled_height = this->height / this->scale;

    this->camera_pos[0] = ((scaled_width - buffer_width) / -2.f);
    this->camera_pos[1] = ((scaled_height - buffer_height) / -2.f);
}

Engine::Engine(Scene *scene, f32 rate, bool audio)
    : scene(scene), rate(rate), audio_enabled(audio)
{
    this->view.width = scene->width;
    this->view.height = scene->height;
    this->view.ortho_width = scene->width;
    this->view.ortho_height = scene->height;

    this->view.texel_size[0] = 1.f / this->view.width;
    this->view.texel_size[1] = 1.f / this->view.height;

    this->view.texel_half_size[0] = .5f / this->view.width;
    this->view.texel_half_size[1] = .5f / this->view.height;

    this->view.center(context()->width(), context()->height());
    this->view.camera_pos[0] += scene->cam.offset[0];
    this->view.camera_pos[1] += scene->cam.offset[1];

    // No audio for now.
    this->audio_enabled = false;

    this->shader = get_shader("hdr_downsample");
    this->render_shader = this->shader->compile({});

    this->create_framebuffer(COMBINE_BUFFER, this->view.width, this->view.height, 1.f);
    this->combine_buffer = this->get_framebuffer(COMBINE_BUFFER);
    this->create_framebuffer(MIPMAPPED_BUFFER, this->view.width, this->view.height, 1.f);

    this->default_mat = glm::ortho(-1.f, 1.f, -1.f, 1.f, -3.f, 1.f);
    this->default_mat = glm::scale(this->default_mat, vec3{1.f, 1.f, 0.001f});
    this->default_mat_inverse = glm::inverse(this->default_mat);

    this->default_object = new RenderObject(DEFAULT);
    this->flipped_object = new RenderObject(DEFAULT_FLIPPED);
    this->fullscreen_object = new RenderObject(FULLSCREEN);
}

auto Engine::create_framebuffer(const std::string &name, f32 width, f32 height, f32 scale) -> void
{
    this->framebuffers.emplace_back(new Framebuffer(name, width, height, scale));
}

auto Engine::get_framebuffer(const std::string &name) -> Framebuffer *
{
    for (Framebuffer *buffer : this->framebuffers)
    {
        if (buffer->name == name) return buffer;
    }
    return nullptr;
}

auto Engine::get_framebuffer_texture(const std::string &name) -> Texture *
{
    Framebuffer *buffer = this->get_framebuffer(name);
    return ((buffer) ? buffer->texture : nullptr);
}

auto Engine::update() -> void
{
    this->view.cursor_pos[0] = (f32)context()->pointer_x;
    this->view.cursor_pos[1] = (f32)context()->pointer_y;

    this->view.cursor_pos[0] -= this->view.camera_pos[0];
    this->view.cursor_pos[1] -= this->view.camera_pos[1];

    this->view.cursor_pos[0] *= this->view.scale;
    this->view.cursor_pos[1] *= this->view.scale;

    this->view.cursor_pos[1] = this->view.height - this->view.cursor_pos[1];
}

auto Engine::draw() -> void
{
    if (this->scene->clear_enabled)
    {
        this->combine_buffer->buffer->clear(this->scene->clear_color);
    }

    this->scene->draw(this);

    Render::bind_framebuffer(0);
    this->shader->bind(this->render_shader, this, nullptr, &this->default_mat, nullptr);

    this->combine_buffer->texture->bind(0);

    this->view.center_scale_viewport();

    this->flipped_object->bind();
    this->flipped_object->draw();
}

auto Engine::run() -> void
{
    while (!context()->should_close_window())
    {
        this->time = context()->current_time();
        context()->poll();
        this->update();
        this->draw();
        context()->swap_buffers();
    }
}

Engine::~Engine()
{
    for (Framebuffer *buffer : this->framebuffers)
    {
        delete buffer;
    }

    delete this->shader;

    delete this->default_object;
    delete this->flipped_object;
    delete this->fullscreen_object;
}