/*
* Copyright (c) 2010 Jice
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*     * Redistributions of source code must retain the above copyright
*       notice, this list of conditions and the following disclaimer.
*     * Redistributions in binary form must reproduce the above copyright
*       notice, this list of conditions and the following disclaimer in the
*       documentation and/or other materials provided with the distribution.
*     * The name of Jice may not be used to endorse or promote products
*       derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY JICE ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL JICE BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <stdio.h>
#include <math.h>
#include "main.hpp"

// gas simulation
// based on Jos Stam, "Real-Time Fluid Dynamics for Games". Proceedings of the Game Developer Conference, March 2003.
// http://www.dgp.toronto.edu/people/stam/reality/Research/pub.html

#define WIDTH 50
#define HEIGHT 50

#define WIDTHx2 (WIDTH*2)
#define HEIGHTx2 (HEIGHT*2)
// use square map
#define N MIN(WIDTHx2,HEIGHTx2)
// store a 2D map in a 1D array
#define SIZE (N+2)*(N+2)
// convert x,y to array index
#define IX(i,j) ((i)+(N+2)*(j))
#define SWAP(x0,x) {float *tmp=x0;x0=x;x=tmp;}  

// 2D velocity maps (current and previous)
float u[SIZE],v[SIZE], u_prev[SIZE], v_prev[SIZE];
// density maps (current and previous)
float dens[SIZE], dens_prev[SIZE];
TCODImage img(WIDTHx2,HEIGHTx2);

float visc=1E-6f;
float diff=1E-5f;
float force=40.0f;
float source=5000.0f;
float stepDelay=0.0f;

int playerx=N/4,playery=N/4;

// set boundary conditions
void set_bnd ( int b, float * x ) { 
	for ( int i=1 ; i<=N ; i++ ) {
		// west and east walls 
		x[IX(0,i)] = b == 1 ? -x[IX(1,i)] : x[IX(1,i)];
		x[IX(N+1,i)] = b == 1 ? -x[IX(N,i)] : x[IX(N,i)];
		// boundary doesn't work on north and south walls...
		// dunno why...
		x[IX(i,0)] = b == 1 ? -x[IX(i,1)] : x[IX(i,1)];
		x[IX(i,N+1)] = b == 1 ? -x[IX(i,N)] : x[IX(i,N)];
	} 
	// boundary conditions at corners
	x[IX(0  ,0  )] = 0.5f*(x[IX(1,0  )]+x[IX(0  ,1)]); 
	x[IX(0  ,N+1)] = 0.5f*(x[IX(1,N+1)]+x[IX(0  ,N )]); 
	x[IX(N+1,0  )] = 0.5f*(x[IX(N,0  )]+x[IX(N+1,1)]); 
	x[IX(N+1,N+1)] = 0.5f*(x[IX(N,N+1)]+x[IX(N+1,N )]); 
} 


// update density map according to density sources
// x : density map
// s : density source map
// dt : elapsed time
void add_source(float *x, float *s, float dt) {
	for (int i=0; i < SIZE; i++) {
		x[i] += dt*s[i];
	}
}

// update density or velocity map for diffusion
// b : boundary width
// x : current density map
// x0 : previous density map
// diff : diffusion coef
// dt : elapsed time
void diffuse( int b, float *x, float *x0, float diff, float dt) {
	float a = diff*dt*N*N;
	for (int k=0; k < 20; k++) {
		for ( int i=1; i <= N; i++ ) {
			for (int j=1; j<= N; j++) {
				x[IX(i,j)] = (x0[IX(i,j)] + a*(x[IX(i-1,j)]+x[IX(i+1,j)]
											+x[IX(i,j-1)]+x[IX(i,j+1)]))/(1+4*a);
			}
 		}
		set_bnd(b,x);
	}
}

// update density map according to velocity map
// b : boundary width
// d : current density map
// d0 : previous density map
// u,v : current velocity map
// dt : elapsed time
void advect ( int b, float * d, float * d0, float * u, float * v, float dt ) { 
	int i0, j0, i1, j1; 
	float x, y, s0, t0, s1, t1, dt0; 

	dt0 = dt*N; 
	for ( int i=1 ; i<=N ; i++ ) { 
		for ( int j=1 ; j<=N ; j++ ) {       
			x = i-dt0*u[IX(i,j)]; 
			y = j-dt0*v[IX(i,j)]; 
			if (x<0.5) x=0.5; 
			if (x>N+0.5) x=N+ 0.5; 
			i0=(int)x; 
			i1=i0+1; 
			if (y<0.5) y=0.5; 
			if (y>N+0.5) y=N+ 0.5; 
			j0=(int)y; 
			j1=j0+1; 
			s1 = x-i0; 
			s0 = 1-s1; 
			t1 = y-j0; 
			t0 = 1-t1; 
			d[IX(i,j)] = s0*(t0*d0[IX(i0,j0)]+t1*d0[IX(i0,j1)])+ 
				s1*(t0*d0[IX(i1,j0)]+t1*d0[IX(i1,j1)]); 
		} 
	} 
	set_bnd ( b, d ); 
} 

void project ( float * u, float * v, float * p, float * div ) { 
	float h = 1.0f/N; 
	for ( int i=1 ; i<=N ; i++ ) { 
		for ( int j=1 ; j<=N ; j++ ) { 
			div[IX(i,j)] = -0.5f*h*(u[IX(i+1,j)]-u[IX(i-1,j)]+ 
							v[IX(i,j+1)]-v[IX(i,j-1)]); 
			p[IX(i,j)] = 0; 
		} 
	} 
	set_bnd ( 0, div ); set_bnd ( 0, p ); 

	for ( int k=0 ; k<20 ; k++ ) { 
		for ( int i=1 ; i<=N ; i++ ) { 
			for ( int j=1 ; j<=N ; j++ ) { 
				p[IX(i,j)] = (div[IX(i,j)]+p[IX(i-1,j)]+p[IX(i+1,j)]+ 
							p[IX(i,j-1)]+p[IX(i,j+1)])/4; 
			} 
		} 
		set_bnd ( 0, p ); 
	} 

	for ( int i=1 ; i<=N ; i++ ) { 
		for ( int j=1 ; j<=N ; j++ ) { 
			u[IX(i,j)] -= 0.5f*(p[IX(i+1,j)]-p[IX(i-1,j)])/h; 
			v[IX(i,j)] -= 0.5f*(p[IX(i,j+1)]-p[IX(i,j-1)])/h; 
		} 
	} 
	set_bnd ( 1, u ); set_bnd ( 2, v );  
} 

// do all three density steps
void update_density ( float * x, float * x0,  float * u, float * v, float diff,  float dt ) { 
  add_source ( x, x0, dt ); 
  SWAP ( x0, x ); diffuse ( 0, x, x0, diff, dt ); 
  SWAP ( x0, x ); advect ( 0, x, x0, u, v, dt ); 
} 

void update_velocity( float * u, float * v, float * u0, float * v0,  float visc, float dt ) { 
	add_source ( u, u0, dt ); 
	add_source ( v, v0, dt ); 
	SWAP ( u0, u ); diffuse ( 1, u, u0, visc, dt ); 
	SWAP ( v0, v ); diffuse ( 2, v, v0, visc, dt ); 
	project ( u, v, u0, v0 ); 
	SWAP ( u0, u ); SWAP ( v0, v ); 
	advect ( 1, u, u0, u0, v0, dt ); advect ( 2, v, v0, u0, v0, dt ); 
	project ( u, v, u0, v0 ); 
} 

void init() {
	memset(u,0,sizeof(float)*SIZE);
	memset(v,0,sizeof(float)*SIZE);
	memset(u_prev,0,sizeof(float)*SIZE);
	memset(v_prev,0,sizeof(float)*SIZE);
	for (int i=0;i < SIZE; i++) dens[i]=0.0f;
	memcpy(dens_prev,dens,sizeof(float)*SIZE);
}

void get_from_UI ( float * d, float * u, float * v, float elapsed, TCOD_key_t k,TCOD_mouse_t mouse ) {
	int i,j;
	float vx=0.0f,vy=0.0f;

	stepDelay -= elapsed;
	if ( stepDelay < 0.0f ) {
		if ( TCODConsole::isKeyPressed(TCODK_UP) && playery > 0 ) {
			playery--;
			vy -= force;
		} 
		if ( TCODConsole::isKeyPressed(TCODK_DOWN) && playery < N/2-1 ) {
			playery++;
			vx += force;
		} 
		if ( TCODConsole::isKeyPressed(TCODK_LEFT) && playerx > 0 ) {
			playerx--;
			vx -= force;
		}
		if ( TCODConsole::isKeyPressed(TCODK_RIGHT) && playerx < N/2-1 ) { 
			playerx++;
			vx += force;
		}
		stepDelay=0.2f; // move 5 cells per second
		// try to move smoke when you walk inside it. doesn't seem to work...
		u[IX(playerx*2,playery*2)] = 5*vx;
		v[IX(playerx*2,playery*2)] = 5*vy;
	}

	for ( i=0 ; i<SIZE; i++ ) {
		u[i] = v[i] = d[i] = 0.0f;
	}

	if ( !mouse.lbutton && !mouse.rbutton ) return;

	i = mouse.cx*2;
	j = mouse.cy*2;
	if ( i<1 || i>N || j<1 || j>N ) return;

	if ( mouse.lbutton ) {
		float dx,dy,l;
		dx=(float)(mouse.cx-playerx);
		dy=(float)(mouse.cy-playery);
		l=sqrtf(dx*dx+dy*dy);
		if ( l > 0 ) {
			l = 1.0f/l;
			dx*=l;
			dy*=l;
			u[IX(playerx*2,playery*2)] = force * dx;
			v[IX(playerx*2,playery*2)] = force * dy;
			d[IX(playerx*2,playery*2)] = source;
		}
	}

}

void update(float elapsed, TCOD_key_t k, TCOD_mouse_t mouse) {
	get_from_UI(dens_prev,u_prev,v_prev,elapsed,k,mouse);
	update_velocity(u,v,u_prev,v_prev,visc,elapsed);
	update_density(dens,dens_prev,u,v,diff,elapsed);
}

void render() {
	static TCODColor deepBlue = TCODColor::darkestFlame;
	static TCODColor highBlue = TCODColor::lightestYellow;
	for (int x=0;x <= N; x++) {
		for (int y=0; y <= N; y++ ) {
			float coef=(float)(dens[IX(x,y)]/128.0f);
			coef=CLAMP(0.0f,1.0f,coef);
			img.putPixel(x,y,TCODColor::lerp(deepBlue,highBlue,coef ));
		}
	}
	img.blit2x(TCODConsole::root,0,0);
	TCODConsole::root->print(2,HEIGHT-2,"%4d fps", TCODSystem::getFps());
	TCODConsole::root->setDefaultForeground(TCODColor::white);
	TCODConsole::root->putChar(playerx,playery,'@');
}

int main (int argc, char *argv[]) {
	// initialize the game window
	TCODConsole::initRoot(WIDTH,HEIGHT,"pyromancer flame spell v" VERSION, false,TCOD_RENDERER_SDL);
	TCODSystem::setFps(25);
	TCODMouse::showCursor(true);
	
	bool endCredits=false;
	init();
	
	while (! TCODConsole::isWindowClosed()) {
		TCOD_key_t k;
		TCOD_mouse_t mouse;

		TCODSystem::checkForEvent(TCOD_EVENT_KEY|TCOD_EVENT_MOUSE, &k, &mouse);
/*
		v_prev[IX(N/2,0)] = 1.0f;
		u_prev[IX(N/3,N/3)]=1.0f;
		dens_prev[IX(N/2,0)] = 128.0f;
*/
		if ( k.vk == TCODK_PRINTSCREEN ) {
			// screenshot
			if (! k.pressed ) TCODSystem::saveScreenshot(NULL);
			k.vk=TCODK_NONE;
		} else if ( k.lalt && (k.vk == TCODK_ENTER || k.vk == TCODK_KPENTER) ) {
			// switch fullscreen
			if (! k.pressed ) TCODConsole::setFullscreen(!TCODConsole::isFullscreen());
			k.vk=TCODK_NONE;
		}
		// update the game
		update(TCODSystem::getLastFrameLength(),k,mouse);

		// render the game screen
		render();
		TCODConsole::root->print(5,49,"Arrows to move, left mouse button to cast");
		// render libtcod credits
		if (! endCredits ) endCredits = TCODConsole::renderCredits(4,4,true);
		// flush updates to screen
		TCODConsole::root->flush();
	}
	return 0;	
}