#define _XOPEN_SOURCE

#include <ctype.h>
#include <errno.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include "datetime.h"

static const char *DATETIME_FMTS_[] = {
	"%H:%M:%S",
	"%I:%M:%S %p",
	"%H:%M",
	"%Y-%m-%dT%H:%M:%S",
	"%Y-%m-%d %H:%M:%S",
	"%A %B %d, %Y %H:%M:%S",
	NULL
};

static char *
datetime_normalize_spacing(int argc, const char *argv[])
{
	int   buf_l;
	int   i;
	int   l;
	bool  was_space;
	int   j;
	char *buf;
	int   buf_i;

	buf_l = 0;
	for (i = 0; i < argc; ++i) {
		l = strlen(argv[i]);
		was_space = true;
		for (j = 0; j < l; ++j) {
			if (isspace(argv[i][j]) != 0) {
				if (was_space == false) {
					buf_l++;
					was_space = true;
				}
			} else {
				buf_l++;
				was_space = false;
			}
		}
		++buf_l;
	}

	buf = calloc(buf_l, sizeof(*buf));
	if (buf == NULL) {
		fprintf(stderr, "Failed to allocate buffer: %s\n",
				strerror(errno));
		return NULL;
	}

	buf_i = 0;
	for (i = 0; i < argc; ++i) {
		l = strlen(argv[i]);
		was_space = true;
		for (j = 0; j < l; ++j) {
			if (isspace(argv[i][j]) != 0) {
				if (was_space == false) {
					buf[buf_i++] = ' ';
					was_space = true;
				}
			} else {
				buf[buf_i++] = argv[i][j];
				was_space = false;
			}
		}
		buf[buf_i++] = ' ';
	}
	buf[--buf_i] = '\0';

	return buf;
}

int
datetime_parse(int argc, const char *argv[], struct tm *tm)
{
	int   e   = -1;
	char *buf;
	int   i;
	char *end;

	buf = datetime_normalize_spacing(argc, argv);
	if (buf == NULL) {
		return -1;
	}

	for (i = 0; DATETIME_FMTS_[i] != NULL; ++i) {
		printf("%s =~ %s\n", buf, DATETIME_FMTS_[i]);
		end = strptime(buf, DATETIME_FMTS_[i], tm);
		if (end != NULL && *end == '\0') {
			e = 0;
			break;
		}
	}

	free(buf);
	return e;
}