/**
 * @file main.c
 * @author Sam Moore (20503628) - 2012
 * @purpose Contains main function, argument handling
 * NOTE: This file is identical for both the single-threaded and multi-threaded versions of the program
 */

#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <signal.h>
#include <string.h> // For parsing arguments

#include "nbody.h"
#include "graphics.h"

// --- Variable definitions --- //
System universe; // global variable declared in "nbody.h" - The universe of bodies
Options options; // global variable declared in "nbody.h" - Options passed to program through arguments


// --- Function forward declarations --- //
void HandleArguments(int argc, char ** argv); //Interprets program arguments and sets up the "options" variable
unsigned IntegerArgument(unsigned * i, int argc, char ** argv, int * store, int * store2); //Helper function to get integer switch
void FloatArgument(unsigned * i, int argc, char ** argv, float * store); //Helper function to get switch value for float
void DisplayStatistics(); //Called on exit of program, displays information about computation time, steps computed, etc
void Interrupt(int dummy); // Interrupt handler function, called when SIGINT (Ctrl-C) is sent to program


// --- Function implementations --- //

/**
 * @function main
 * @purpose The main function. Calls HandleArguments to set up options, 
 *		sets up functions to call at exit, starts simulation and graphics loops
 * @param argc - Number of arguments
 * @param argv - The argument strings
 */
int main(int argc, char** argv)
{
	//Set default options values here
	options.program = argv[0];
	options.input = NULL;
	options.output = NULL;
	options.num_threads = 0;
	options.nested_threads = 0;
	options.num_steps = -1; // Negative values => simulation runs forever unless otherwise specified
	options.timeout = -1;
	options.draw_graphics = true;
	options.pedantic_graphics = false;
	options.print_positions = false;
	options.verbosity = 0;
	options.theta = 0.50;

	//If there are no arguments, print information about usage
	if (argc == 1)
	{
		printf("Usage: %s [OPTIONS] field\n", argv[0]);
		printf("Controls:\n X - exit\n I, J, K, M - rotate\n W, Z, A, S - move to view"
			" point\n ./, - zoom in/out\n +/- - scaled zoom in/out\n");
		exit(EXIT_SUCCESS);
	}

	//Parse the arguments
	HandleArguments(argc, argv);
	
	//Check there is an initial field.
	if (options.input == NULL)
	{
		fprintf(stderr, "Usage: %s [OPTIONS] field\n", argv[0]);
		fprintf(stderr, " (You did not provide a file for the initial field of bodies)\n");
		exit(EXIT_FAILURE);
	}



	signal(SIGINT, Interrupt); //Handle SIGINT signals
	atexit(Universe_Cleanup); //On exit, cleanup universe (and write positions of bodies to file if supplied).
	atexit(DisplayStatistics); //On exit, print information about the computations done
	System_Init(&universe,options.input); //Initialise the universe from the initial field
	
	//Setup the time of day at which the simulation starts
	if (gettimeofday(&(options.start_time), NULL) != 0)
	{
		perror("Couldn't get time of day");
		exit(EXIT_FAILURE);
	}
	
	options.start_clock = clock(); //Get CPU cycles executed before simulation starts
	Simulation_Run(argc, argv); // Start the simulation
	
	//printf("Main thread done!\n");
	
	//pthread_exit(NULL);
	exit(EXIT_SUCCESS); //Should never get to this line
}


/**
 * @function HandleArguments
 * @purpose Fill the "options" variable by parsing command line arguments
 * @param argc - Number of arguments
 * @param argv - Argument strings
 */
void HandleArguments(int argc, char ** argv)
{
	for (unsigned i = 1; i < argc; ++i) //For all arguments
	{
		if (argv[i][0] != '-') //If the argument is not a switch value...
		{
			//Interpret first non switch as input file, and second as output file.
			//If there are too many non switch arguments, give an error.
			if (options.input == NULL) 
				options.input = argv[i];
			else if (options.output == NULL)
				options.output = argv[i];
			else
			{
				fprintf(stderr,"Usage: %s [OPTIONS] field [output]\n", argv[0]);
				fprintf(stderr," (You provided too many file names)\n");
				exit(EXIT_FAILURE);
			}
			continue;
		}
		switch (argv[i][1]) //The argument is a switch if we get here
		{
			case 'n': //Number of threads switch
				IntegerArgument(&i, argc, argv, &(options.num_threads), &(options.nested_threads));
				#ifdef SINGLE_THREADED
				fprintf(stderr, "Warning: -%c switch has no effect in the single-threaded program.\n", 'n');
				
				#else
				if (options.num_threads <= 0)
				{
					fprintf(stderr, "Require at least one thread (-%c %s is invalid).\n",'n', argv[i]);
					exit(EXIT_FAILURE);
				}
				#endif //SINGLE_THREADED
				break;
			case 's': //Number of steps switch
				IntegerArgument(&i, argc, argv, &(options.num_steps), NULL);
				if (options.num_steps < 0)
				{
					fprintf(stderr, "Require zero or more steps to run (-%c %s is invalid).\n", 's', argv[i]);
					exit(EXIT_FAILURE);
				}
				break;
			case 't': //Timeout switch (in seconds)
				IntegerArgument(&i, argc, argv, &(options.timeout), NULL);
				if (options.timeout < 0)
				{
					fprintf(stderr, "Require a timeout greater or equal to zero (-%c %s is invalid).", 't', argv[i]);
					exit(EXIT_FAILURE);
				}				
				break;
			case 'g': //Graphics switch
				options.draw_graphics = !options.draw_graphics;
				break;
			case 'v': //Verbosity switch
				IntegerArgument(&i, argc, argv, &(options.verbosity), NULL);
				break;

			case '-':
				if (strcmp(argv[i]+2, "pedantic-graphics") == 0)
				{
					options.pedantic_graphics = true;
					#ifdef SINGLE_THREADED
					fprintf(stderr, "Warning: %s switch has no effect in the single threaded program.\n", argv[i]);
					#endif //SINGLE_THREADED
				}
				else if (strcmp(argv[i]+2, "fast-graphics") == 0)
				{
					options.pedantic_graphics = false;
					#ifdef SINGLE_THREADED
					fprintf(stderr, "Warning: %s switch has no effect in the single threaded program.\n", argv[i]);
					#endif //SINGLE_THREADED

				}
				else if (strcmp(argv[i]+2, "theta") == 0)
				{
					FloatArgument(&i, argc, argv, &(options.theta));
					#ifndef BARNES_HUT
					fprintf(stderr, "Warning: %s switch only works in Barnes Hut version.\n", argv[i-1]);
					#else
					if (options.theta < 0)
					{
						fprintf(stderr, "Require a theta value greater or equal to zero (%s %s is invalid).\n", argv[i-1], argv[i]);
						exit(EXIT_FAILURE);
					}
					
					#endif //BARNS_HUT
					
				}
				else
				{
					fprintf(stderr, "Unrecognised switch %s\n", argv[i]);
					exit(EXIT_FAILURE);
				}
				break;


			default:
				fprintf(stderr, "Unrecognised switch -%c\n", argv[i][1]);
				exit(EXIT_FAILURE);
				break;
		}
		
	}
}

/**
 * @function IntegerArgument
 * @purpose Helper function to get up to two integers following a argument switch, seperated by ':'
 * @param i - position in the argument array, will be updated after this function
 * @param argc - number of arguments
 * @param argv - argument strings
 * @param store - pointer to unsigned to store result in
 * @param store2 - pointer to second integer (set to NULL if there is only one integer)
 * @returns 1 if store was filled, 2 if both store1 and store2 were filled
 */
unsigned IntegerArgument(unsigned * i, int argc, char ** argv, int * store, int * store2)
{
	if (*i >= argc-1)
	{
		fprintf(stderr,"Supply a positive integer for the -%c switch.\n", argv[*i][1]);
		exit(EXIT_FAILURE);
	}

	char * seperator = strstr(argv[*i+1], ":");
	if (seperator != NULL)
	{
		if (store2 == NULL)
		{
			fprintf(stderr,"Supply a positive integer for the -%c switch.\n", argv[*i][1]);
			exit(EXIT_FAILURE);	
		}
		int val = atoi(seperator+1);
		if (val <= 0)
		{
			fprintf(stderr,"Supply a positive integer for the -%c switch.\n", argv[*i][1]);
			exit(EXIT_FAILURE);	
		}	
		*store2 = (unsigned)val;

		*seperator = '\0';
	}
	
	int val = atoi(argv[*i+1]);
	if (val <= 0 && strcmp("0", argv[*i+1]) != 0)
	{
		fprintf(stderr,"Supply a positive integer for the -%c switch. %s is invalid.\n", argv[*i][1], argv[*i+1]);
		exit(EXIT_FAILURE);
	}
	*store = val;
	*i += 1;

	return (seperator == NULL) ? 1 : 2;
}
/**
 * @function FloatArgument
 * @purpose Helper function to get a float following a argument switch
 * @param i - position in the argument array, will be updated after this function
 * @param argc - number of arguments
 * @param argv - argument strings
 * @param store - pointer to float to store result in
 */
void FloatArgument(unsigned * i, int argc, char ** argv, float * store)
{
	if (*i >= argc-1)
	{
		fprintf(stderr,"Supply a float for the -%c switch.\n", argv[*i][1]);
		exit(EXIT_FAILURE);
	}
	*store = atof(argv[*i+1]);
	if (*store == 0.0 && argv[*i+1][0] != '0')
	{
		fprintf(stderr,"Supply a float for the -%c switch.\n", argv[*i][1]);
		exit(EXIT_FAILURE);
	}
	*i += 1;
}



/**
 * @function Interrupt
 * @purpose Handle SIGINT signal; quit the program gracefully, so that statistics are still displayed
 * @param dummy - a dummy
 */

void Interrupt(int dummy)
{
	QuitProgram(false);
}