#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
#include <time.h>


#include "Model.h"

body* bodies; //vector that contains all the bodies in the system

void setBody(body* b, double mass, double pos[3], double vel[3]){
		
	b->mass = mass;
	memcpy(b->pos, pos, 3 * sizeof(double));
	memcpy(b->vel, vel, 3 * sizeof(double));
}


void initializeNBody(int n){
	int i;
	double mass = 0;
	double pos[3] = {0, 0, 0};
	double vel[3] = {0, 0, 0};
	
	
	for (i = 0; i < n; i++){
		setBody(&bodies[i], mass, pos, vel);
		//printf("%f %f\n", bodies[i].mass, bodies[i].pos[2]);
	}
	
}

//generate random float number between [low, high)
double frand(double low, double high)
{
	double temp;

	/* swap low & high around if the user makes no sense */
	if (low > high){
		temp = low;
		low = high;
		high = temp;
	}

	/* calculate the random number & return it */
	temp = (rand() / ( RAND_MAX + 1.0))
		* (high - low) + low;
	return temp;
}



void mkplummer(int n, unsigned int seed){
	int i;
	double mass;
	double pos[3];
	double vel[3];
	double radius, theta, phi;
	double x, y;
	double velocity;

	if(seed == 0)
		srand(time(NULL)); //different succession of results in the subsequent calls to rand
	else srand(seed);   //used for debugging

	initializeNBody(n);
	
	
	for(i = 0;i < n; i++){
		mass = 1.0 / n;
		radius = 1.0 / sqrt(pow(frand(0, 1),-(2.0 / 3.0)) - 1.0);
		theta = acos(frand(-1, 1));
		phi = frand(0, 2 * PI);
		pos[0] = radius * sin(theta) * cos(phi);
		pos[1] = radius * sin(theta) * sin(phi);
		pos[2] = radius * cos(theta);
		x = 0.0;
		y = 0.1;
		while( y > x * x * pow (1.0 - x*x, 3.5)){
			x = frand(0, 1);
			y = frand(0, 0.1);
		}
		velocity = x * sqrt(2.0) * pow(1.0 + radius * radius, -0.25);
		theta = acos(frand(-1, 1));
		phi = frand(0, 2 * PI);
		vel[0] = velocity * sin(theta) * cos(phi);
		vel[1] = velocity * sin(theta) * sin(phi);
		vel[2] = velocity * cos(theta);
		setBody(&bodies[i], mass, pos, vel);
	}

	

}

void writeData(int n){
	char line[256];
	int i;	
	FILE *f = fopen(FILE_NAME, "w+");
	if(f == NULL){
		printf("Error opening file\n");
		return;
	}
	sprintf(line, "%d\n", n);
	fputs(line, f);
	sprintf(line, "%d\n", 0);
	fputs(line, f);
	for(i = 0; i < n; i++){
		//printf("here\n");
		sprintf(line, "%f %f %f %f %f %f %f\n", 
			bodies[i].mass,
			bodies[i].pos[0], bodies[i].pos[1], bodies[i].pos[2],
			bodies[i].vel[0], bodies[i].vel[1], bodies[i].vel[2]);
		fputs(line, f);
	}
	fclose(f);

}

int main(int argv, char** argc){
	int n;
	unsigned int seed;
	if(argv != 3){
		printf("usage ./Model nr_bodies seed\n");
		return 0;
	}

	n = atoi(argc[1]);
	seed = atoi(argc[2]);

	bodies = (body*) malloc(n * sizeof(body));
	mkplummer(n, seed);
	//writeData(n);
	return 1;
}