#include "app.hpp"
#include <Magnum/GL/DefaultFramebuffer.h>

namespace floormat {

void app::do_camera(double dt)
{
    if (keys[key::camera_reset])
        reset_camera_offset();
    else
    {
        Vector2d dir{};

        if (keys[key::camera_up])
            dir += Vector2d{0, -1};
        else if (keys[key::camera_down])
            dir += Vector2d{0,  1};
        if (keys[key::camera_left])
            dir += Vector2d{-1, 0};
        else if (keys[key::camera_right])
            dir += Vector2d{1,  0};

        if (dir != Vector2d{})
        {
            constexpr double screens_per_second = 1;
            const auto pixels_per_second = windowSize().length() / screens_per_second;
            auto camera_offset = _shader.camera_offset();
            const auto max_camera_offset = Vector2d(windowSize() * 10);

            camera_offset -= dir.normalized() * dt * pixels_per_second;
            camera_offset[0] = std::clamp(camera_offset[0], -max_camera_offset[0], max_camera_offset[0]);
            camera_offset[1] = std::clamp(camera_offset[1], -max_camera_offset[1], max_camera_offset[1]);

            _shader.set_camera_offset(camera_offset);
        }
        else
            return;
    }
    recalc_cursor_tile();
    if (_cursor_tile)
        do_mouse_move(*_cursor_tile);
}

void app::reset_camera_offset()
{
    _shader.set_camera_offset(tile_shader::project({TILE_MAX_DIM*-.5*dTILE_SIZE[0], TILE_MAX_DIM*-.5*dTILE_SIZE[1], 0}));
    recalc_cursor_tile();
}

void app::recalc_cursor_tile()
{
    if (_cursor_pixel && !_cursor_in_imgui)
        _cursor_tile = pixel_to_tile(Vector2d(*_cursor_pixel));
    else
        _cursor_tile = std::nullopt;
}

global_coords app::pixel_to_tile(Vector2d position) const
{
    constexpr Vector2d pixel_size{dTILE_SIZE[0], dTILE_SIZE[1]};
    constexpr Vector2d half{.5, .5};
    const Vector2d px = position - Vector2d{windowSize()}*.5 - _shader.camera_offset()*.5;
    const Vector2d vec = tile_shader::unproject(px) / pixel_size + half;
    const auto x = (std::int32_t)std::floor(vec[0]), y = (std::int32_t)std::floor(vec[1]);
    return { x, y };
}

std::array<std::int16_t, 4> app::get_draw_bounds() const noexcept
{

    using limits = std::numeric_limits<std::int16_t>;
    auto x0 = limits::max(), x1 = limits::min(), y0 = limits::max(), y1 = limits::min();

    for (const auto win = Vector2d(windowSize());
         auto p : {pixel_to_tile(Vector2d{0, 0}).chunk(),
                   pixel_to_tile(Vector2d{win[0]-1, 0}).chunk(),
                   pixel_to_tile(Vector2d{0, win[1]-1}).chunk(),
                   pixel_to_tile(Vector2d{win[0]-1, win[1]-1}).chunk()})
    {
        x0 = std::min(x0, p.x);
        x1 = std::max(x1, p.x);
        y0 = std::min(y0, p.y);
        y1 = std::max(y1, p.y);
    }
    return {x0, x1, y0, y1};
}

} // namespace floormat