/* $Id$

This file is part of libmspgl
Copyright © 2010  Mikko Rasa, Mikkosoft Productions
Distributed under the LGPL
*/

#include <cmath>
#include <msp/core/application.h>
#include <msp/fs/utils.h>
#include <msp/gbase/simplewindow.h>
#include <msp/gl/blend.h>
#include <msp/gl/camera.h>
#include <msp/gl/framebuffer.h>
#include <msp/gl/light.h>
#include <msp/gl/lighting.h>
#include <msp/gl/mesh.h>
#include <msp/gl/object.h>
#include <msp/gl/tests.h>
#include <msp/io/print.h>

using namespace std;
using namespace Msp;

class Viewer: public Application
{
private:
	Graphics::SimpleGLWindow window;
	GL::Object *object;
	GL::Mesh *mesh;
	GL::Light light;
	GL::Lighting lighting;
	GL::Camera camera;
	float yaw;
	float pitch;
	float distance;
	float light_yaw;
	float light_pitch;
	unsigned dragging;
	int pointer_x;
	int pointer_y;

	static Application::RegApp<Viewer> reg;

public:
	Viewer(int, char **);
	~Viewer();

	virtual int main();
private:
	virtual void tick();

	void button_press(int, int, unsigned, unsigned);
	void button_release(int, int, unsigned, unsigned);
	void pointer_motion(int, int);
	void key_press(unsigned, unsigned, wchar_t);

	void update_camera();
	void update_light();

public:
	static void usage(const char *, const char *, bool);
};


Application::RegApp<Viewer> Viewer::reg;

Viewer::Viewer(int argc, char **argv):
	window(1024, 768, false),
	object(0),
	mesh(0),
	yaw(0),
	pitch(0),
	distance(10),
	light_yaw(0),
	light_pitch(0),
	dragging(0),
	pointer_x(0),
	pointer_y(0)
{
	if(argc<2)
		throw UsageError("Filename must be provided");

	string fn = argv[1];
	string ext = FS::extpart(fn);

	if(ext==".mesh")
	{
		mesh = new GL::Mesh;
		DataFile::load(*mesh, fn);
	}
	else if(ext==".object")
	{
		object = new GL::Object;
		DataFile::load(*object, fn);
	}
	else
		throw UsageError("Don't know how to view this file");

	window.signal_close.connect(sigc::bind(sigc::mem_fun(this, &Viewer::exit), 0));
	window.signal_button_press.connect(sigc::mem_fun(this, &Viewer::button_press));
	window.signal_button_release.connect(sigc::mem_fun(this, &Viewer::button_release));
	window.signal_pointer_motion.connect(sigc::mem_fun(this, &Viewer::pointer_motion));
	window.signal_key_press.connect(sigc::mem_fun(this, &Viewer::key_press));

	light.set_position(GL::Vector4(0, 0, 1, 0));
	lighting.attach(0, light);

	camera.set_up_direction(GL::Vector3(0, 0, 1));
	update_camera();
}

Viewer::~Viewer()
{
	delete object;
	delete mesh;
}

int Viewer::main()
{
	window.show();
	return Application::main();
}

void Viewer::tick()
{
	window.tick();

	GL::Framebuffer::system().clear(GL::COLOR_BUFFER_BIT|GL::DEPTH_BUFFER_BIT);

	camera.apply();

	GL::Bind bind_lighting(lighting);
	GL::Bind bind_depth(GL::DepthTest::lequal());
	GL::Bind bind_blend(GL::Blend::alpha());
	if(object)
		object->render();
	else if(mesh)
		mesh->draw();

	window.swap_buffers();
}

void Viewer::usage(const char *err, const char *argv0, bool)
{
	if(err)
		IO::print("%s\n", err);
	IO::print("Usage: %s <filename>\n", argv0);
}

void Viewer::button_press(int x, int y, unsigned btn, unsigned)
{
	if(btn==1)
	{
		dragging = 1;
		pointer_x = x;
		pointer_y = y;
	}
	else if(btn==3)
	{
		dragging = 3;
		pointer_motion(x, y);
	}
	else if(btn==4)
	{
		distance *= 0.9;
		update_camera();
	}
	else if(btn==5)
	{
		distance *= 1.1;
		update_camera();
	}
}

void Viewer::button_release(int, int, unsigned btn, unsigned)
{
	if(btn==dragging)
		dragging = 0;
}

void Viewer::pointer_motion(int x, int y)
{
	if(dragging==1)
	{
		int dx = x-pointer_x;
		int dy = pointer_y-y;

		yaw -= dx*M_PI*2/window.get_width();
		while(yaw>M_PI)
			yaw -= M_PI*2;
		while(yaw<-M_PI)
			yaw += M_PI*2;

		pitch += dy*M_PI/window.get_height();
		if(pitch>M_PI*0.49)
			pitch = M_PI*0.49;
		if(pitch<-M_PI*0.49)
			pitch = -M_PI*0.49;

		update_camera();

		pointer_x = x;
		pointer_y = y;
	}
	else if(dragging==3)
	{
		int dx = x-window.get_width()/2;
		int dy = window.get_height()/2-y;

		light_yaw = yaw+dx*M_PI/window.get_width();
		light_pitch = pitch-dy*M_PI/window.get_height();

		update_light();
	}
}

void Viewer::key_press(unsigned, unsigned, wchar_t)
{
}

void Viewer::update_camera()
{
	float cy = cos(yaw);
	float sy = sin(yaw);
	float cp = cos(pitch);
	float sp = sin(pitch);
	camera.set_position(GL::Vector3(-cy*cp*distance, -sy*cp*distance, -sp*distance));
	camera.set_depth_clip(distance*0.02, distance*50);
	camera.look_at(GL::Vector3(0, 0, 0));
}

void Viewer::update_light()
{
	float cy = cos(light_yaw);
	float sy = sin(light_yaw);
	float cp = cos(light_pitch);
	float sp = sin(light_pitch);
	light.set_position(GL::Vector4(-cy*cp, -sy*cp, -sp, 0));
}