/*
	C-style program

		use malloc()/realloc()/free(), stdio, and qsort()

	read or generate N strings
	optionally sort them

	- Bjarne Stroustrup - http://www.research.att/~bs
*/

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

int cmp(const void* p, const void* q)
{
	return strcmp(*(char**)p,*(char**)q);
}

void quit()
{
	fprintf(stderr,"memory exhausted\n");
	exit(1);
}


/*
	command line argument handling:

		prog 1		- read from cin and sort 

		prog 0		- read from cin (don't sort)

		prog 1 file	- read from file and sort

		prog 0 file	- read from file (don't sort)

		prog 1 file ofile - read from file, sort, and write to ofile

		prog 0 file ofile - read from file (don't sort) and write to ofile
		
	an optional 4th argument controls preallocation.
*/

int main(int argc, char* argv[])
{
	int max = 0;	// by default: read from cin
	int res = 1000;	// by default: grow incrementally
	bool s = true;	// by default: sort
	char* file = 0;
	char* ofile = 0;

	switch (argc) {	// s { max | file } ofile res
	case 5:
		res = atoi(argv[4]);
	case 4:
		ofile = argv[3];
	case 3:
		max = atoi(argv[2]);
		if (max == 0) file = argv[2];
	case 2:
		s = atoi(argv[1]);
		break;
	default:
		fprintf(stderr,"wrong number of arguments\n");
		exit(1);
	} 

	char** buf = (char**)malloc(sizeof(char*)*res);
	if (buf==0) quit();

	const int maxline = 2000;
	char d[maxline];
	int n = 0;	// number of elements

	if (max) {
		printf("generate %d\n",max);
	}
	else if (file) {
		printf("C style read from %s using string buffer\n",file);
		FILE* fin = fopen(file,"r");
		while (fscanf(fin,"%s",&d)==1) {	// read
			char* p = (char*)malloc(strlen(d)+1);	// strdup() isn't standard
			if (p==0) quit();
			strcpy(p,d);

			if (n==res) {
				res += res;
				buf = (char**)realloc(buf,sizeof(char*)*res);
				if (buf==0) quit();
			}
			buf[n++] = p;
		}
	}
	else {
		printf("read stdin\n");
	}

	if (s) {
		printf("qsort(%p,%d,%d,%p)\n",buf, n, sizeof(char*), strcmp);
		qsort(buf, n, sizeof(char*), cmp);
	}

	if (ofile) {
		printf("write %s\n",ofile);
		FILE* fout = fopen(ofile,"w");
		for (int i = 0; i<n; i++) fprintf(fout,"%s\n",buf[i]);
	}

	for (int i = 0; i<n; i++) free(buf[i]);
	free(buf);
}