#include <unistd.h>
#include <errno.h>
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "io.h"

static struct settings_s {
	size_t fetchpos;
	size_t fetchto;
	char *filein;
	char *fileout;
	int mode;
} settings = {0};

static struct stream file_in = {.fd = -1};
static struct stream file_out = {.fd = -1};

static int parseargs(int argc, char **argv, struct settings_s * settings);
void printhelp(const char * const name);

int main(int argc, char **argv)
{
	int ret = 0;

	if ((ret = parseargs(argc, argv, &settings))) {
		goto out;
	}

	file_in.name = settings.filein;
	file_in.stride = 0; /* TODO */

	if ((ret = openstream(&file_in))) {
		goto out;
	}

	file_out.name = settings.fileout ? settings.fileout : settings.filein;
	file_out.out = 1;
	file_out.n = file_in.n;
	file_out.stride = 0; /* TODO */

	if ((ret = openstream(&file_out))) {
		goto out;
	}

out:
	close(file_in.fd);
	close(file_out.fd);
	return ret;
}

static int parseargs(int argc, char **argv, struct settings_s * settings)
{
	struct settings_s s = {0};
	ssize_t i;
	int ret = 0;

	if (argc < 2) {
		goto err;
	}

	for (i = 1; i < argc - 1; ++i) {
		if (!(strcmp(argv[i], "--sort"))) {
			s.mode &= ~1;
		} else if (!(strcmp(argv[i], "--fetch"))) {
			s.mode |= 1;
		} else if (!(strncmp(argv[i], "--position=", 11))) {
			if (strlen(argv[i]) > 11) {
				s.fetchpos = strtoul(argv[i] + 11, NULL, 10);
			} else {
				goto err;
			}
		} else if (!(strncmp(argv[i], "--num=", 6))) {
			if (strlen(argv[i]) > 6) {
				s.fetchto = strtoul(argv[i] + 11, NULL, 10);
			} else {
				goto err;
			}
		} else if (!(strncmp(argv[i], "--out=", 6))) {
			if (strlen(argv[i]) > 6) {
				s.fileout = argv[i] + 6;
			} else {
				goto err;
			}
		} else {
			goto err;
		}
	}

	if (!strncmp(argv[i], "--", 2)) {
		goto err;
	} else {
		s.filein = argv[i];
	}

	if (!s.fileout) {
		s.fileout = s.filein;
	}

	s.fetchto = s.fetchpos + s.fetchto;

	*settings = s;

	if (0) {
err:
		ret = EINVAL;
		printhelp(*argv);
	}

	return ret;
}

void printhelp(const char * const name)
{
	printf(	"This is a mergesort program and such\n"
		"\n"
		"usage:\t%s [options]\n FILE"
		"\n"
		"Options:\n"
		" --sort              sort mode (default)\n"
		" --fetch             fetch element\n"
		" --position=<num>    fetch element from position <num>\n"
		" --num=<num>         <num> of elements to fetch\n"
		" --out=<name>        write output to <name> file\n"
		"\n"
		"In case more than one same option is provided, the last one take precedence\n"
		"\n",
			name);
	return;
}