#include <onidev.h>

void error_callback(
    GLenum source, GLenum type, GLuint id, GLenum severity,
    GLsizei length, const char* message, const void* user_param)
{
    od::err() << message;
}

int main()
{
    namespace gl = od::gl;

    od::Window win(640, 480, "OpenGL Demo", od::Version(3, 2));

    std::cout << "OpenGL " << od::Extension::get().version().str() << std::endl;

    gl::debugMessageCallback(error_callback, nullptr);
    glEnable(GL_DEBUG_OUTPUT);

    std::string vertex_shader_scr =
        OD_GLSL(140,
            attribute vec2 pos;
            uniform   mat3 transform; // model view projection

            void main()
            {
                gl_Position = vec4(transform * vec3(pos, 1.0), 1.0);
            });

    std::string fragment_shader_scr =
        OD_GLSL(140,
            uniform vec4 col;
            void main()
            {
                gl_FragColor = col;
            });

    enum {
        position_attrib_index
    };
    const std::map<unsigned, std::string> attrib_map = {
        { position_attrib_index, "pos" }
    };

    gl::Program program;
    {
        gl::Shader vertex_shader(gl::Shader::Vertex, vertex_shader_scr);
        gl::Shader fragment_shader(gl::Shader::Fragment, fragment_shader_scr);

        program.attach(vertex_shader);
        program.attach(fragment_shader);
        for(const auto& p: attrib_map) {
            program.bindAttribLocation(p.first, p.second);
        }
        program.link();

        program.detach(vertex_shader);
        program.detach(fragment_shader);
    }

    gl::Vao vao;
    gl::Vbo vbo_shape;
    {
        std::vector<float> data_pos = {
            -10, -10, 10, -10,
            10, -10, 10, 10,
            10, 10, -10, 10,
            -10, 10, -10, -10
        };

        vbo_shape.bind();
        vbo_shape.data(data_pos.size() * sizeof(float), &data_pos[0]);

        vao.bind();
        vao.setVertexAttribf(vbo_shape, position_attrib_index, 2, false, 2 * sizeof(float), 0);
        vao.unbind();
    }

    program.use();
    unsigned uniform_color = gl::getUniformLocation(program.handle(), "col");
    unsigned uniform_transform = gl::getUniformLocation(program.handle(), "transform");
    GLfloat color[4] = {0.2f, 0.7f, 0.7f, 1.f};
    gl::uniform4fv(uniform_color, 1, static_cast<const GLfloat*>(color));
    program.unuse();

    od::Camera camera( Vec2(win.width(), win.height()) );

    while(win.open())
    {
        win.ioHandle();

        if(od::keyPressed(od::vk_escape))
            break;

        od::Vec2 mouse(win.mouse_x(), win.mouse_y());

        od::drawClear();


        glBlendFunc(GL_SRC_ALPHA, GL_ONE);
        glLineWidth(6);

        od::Vec2 m = camera.angle;
        m = m * (6.f / camera.scale.x);

        if(od::keyCheck(od::vk_right)) camera.pos += Vec2(m.y, -m.x);
        if(od::keyCheck(od::vk_left )) camera.pos += Vec2(-m.y, m.x);
        if(od::keyCheck(od::vk_up   )) camera.pos -= m;
        if(od::keyCheck(od::vk_down )) camera.pos += m;

        if(od::keyCheck(od::vk_numpad4)) camera.angle.rotate(-0.05);
        if(od::keyCheck(od::vk_numpad6)) camera.angle.rotate( 0.05);

        if(od::keyCheck(od::vk_add     )) camera.scale *= 1.05;
        if(od::keyCheck(od::vk_subtract)) camera.scale /= 1.05;

        {
            program.use();

            od::Mat3 camera_matrix = camera.matrix();
            GLfloat color1[4] = {0.2f, 0.7f, 0.7f, 1.f};
            gl::uniform4fv(uniform_color, 1, color1);

            for(int i=0; i<4; ++i)
            for(int j=0; j<4; ++j)
            {
                od::Mat3 model(1.f, 0.f, i*32.f,
                               0.f, 1.f, j*32.f,
                               0.f, 0.f, 1.f);

                gl::uniformMatrix(uniform_transform, camera_matrix * model);

                vao.bind();
                glDrawArrays(GL_LINES, 0, 15);
                vao.unbind();
            }

            GLfloat color2[4] = {0.7f, 0.2f, 0.2f, 1.f};
            gl::uniform4fv(uniform_color, 1, color2);

            for(int i=-4; i<0; ++i)
            for(int j=-4; j<0; ++j)
            {
                od::Mat3 model(1.f, 0.f, i*32.f,
                               0.f, 1.f, j*32.f,
                               0.f, 0.f, 1.f);

                gl::uniformMatrix(uniform_transform, camera_matrix * model);

                vao.bind();
                glDrawArrays(GL_LINES, 0, 15);
                vao.unbind();
            }

            {
                GLfloat color3[4] = {0.2f, 0.7f, 0.2f, 1.f};
                gl::uniform4fv(uniform_color, 1, color3);

                Vec2 p = camera.viewToWorld(mouse);
                od::Mat3 model(1.f, 0.f, p.x,
                               0.f, 1.f, p.y,
                               0.f, 0.f, 1.f);

                gl::uniformMatrix(uniform_transform, camera_matrix * model);

                vao.bind();
                glDrawArrays(GL_LINES, 0, 15);
                vao.unbind();
            }

            program.unuse();
        }

        od::framerateUpdate();
        win.screenRefresh();
    }

    return 0;
}