/*
 * Copyright 2017 Yann Weber
 * 
 * This file is part of Ttail.
 * 
 * Ttail is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * any later version.
 * 
 * Ttail is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with Ttail.  If not, see <http://www.gnu.org/licenses/>.
 */
#include "ttail_init.h"

void usage()
{
	static struct option opts[] = TTAIL_LONG_OPT;
	static char *help[][2] = TTAIL_OPT_HELP;
	size_t i;
	printf("Usage : ttail -d DATE [OPTIONS] [LOGFILES]\n");
	printf("\t\n");
	printf("Options list\n");
	i=0;
	while(opts[i].name)
	{
		printf("\t-%c, --%s", opts[i].val, opts[i].name);
		if(opts[i].has_arg == required_argument)
		{
			printf("=%s\n",
				help[i][1]?help[i][1]:"ARG");
		}
		else if(opts[i].has_arg == optional_argument)
		{
			printf("[=%s]\n",
				help[i][1]?help[i][1]:"ARG");
		}
		else
		{
			printf("\n");
		}
		printf("\t\t%s\n\n", help[i][0]);
		i++;
	}
	printf(TTAIL_HELP_TEXT);
}

ttail_t *ttail_init(int argc, char **argv)
{
	ttail_t *res;
	int c, opt_i, ret;
	size_t i;
	char *dates[2] = { NULL, NULL };
	char *date;

	res = malloc(sizeof(ttail_t));
	if(!res)
	{
		perror("Unable to allocate memory");
		goto ttail_init_alloc_err;
	}

	opterr = 1;
	optind = 0;
	res->verbose = 0;
	res->fmt = NULL;
	res->flag = 0;
	res->logfile = NULL;
	res->logfile_name = NULL;
	res->logfile_sz = 0;
	res->prefix_sz = 0;
	res->session = NULL;
	ttail_tm_init(&(res->date_min));
	ttail_tm_init(&(res->date_max));

	while(1)
	{
		static struct option long_options[] = TTAIL_LONG_OPT;

		c = getopt_long(argc, argv, TTAIL_SHORT_OPT, long_options, &opt_i);
		if(c == -1)
			break;
		
		switch(c)
		{
			case 'v':
				res->verbose++;
				break;
			case 'r':
				if(ttail_set_prefix(res, optarg))
				{
					goto ttail_init_err;
				}
				break;
			case 'p':
				if(res->flag & TTAIL_FLAG_PREFIX)
				{
					fprintf(stderr, "Preffix allready \
set\n");
					goto ttail_init_err;
				}
				res->flag |= TTAIL_FLAG_PREFIX;
				res->prefix_sz = atoi(optarg);
				if(res->prefix_sz <= 0)
				{
					fprintf(stderr, "Prefix size have \
to be > 0");
					goto ttail_init_err;
				}
				break;
			case 'E':
				if(ttail_set_flag_re_ex(res) < 0)
				{
					goto ttail_init_err;
				}
				break;
			case 'I':
				if(ttail_set_flag_re_ci(res) < 0)
				{
					goto ttail_init_err;
				}
				break;
			case 'f':
				if(res->flag & TTAIL_FLAG_FORMAT)
				{
					fprintf(stderr,"Multiple date format \
given\n");
					goto ttail_init_err;
				}
				if(ttail_set_fmt(res, optarg) < 0)
				{
					goto ttail_init_err;
				}

				break;
			case 'h':
				usage();
				goto ttail_init_err;
			case 'd':
			case 'm':
				date = malloc(sizeof(char)*(strlen(optarg)+1));
				if(!date)
				{
					goto ttail_init_err;
				}
				strcpy(date, optarg);
				dates[c=='d'?0:1] = date;
				break;
			case 'P':
				if(res->flag & TTAIL_FLAG_PERMISSIVE)
				{
					fprintf(stderr, "Warning : looks like \
-P --permissive flag was set more than once\n");
				}
				res->flag |= TTAIL_FLAG_PERMISSIVE;
				break;
			default: /* ? */
				goto ttail_init_err;
				
		}
	}
	
	for(i=optind; i<argc; i++)
	{
		ret = ttail_add_logfile(res, argv[i]);
		if(ret < 0)
		{
			goto ttail_init_err;
		}
	}

	if(ttail_set_dates(res, dates) < 0)
	{
		goto ttail_init_err;
	}

	return res;
	ttail_init_err:
	if(dates[0]) { free(dates[0]); }
	if(dates[1]) { free(dates[1]); }
	ttail_free(res);
	ttail_init_alloc_err:
	return NULL;
}

int ttail_init_check(ttail_t* t)
{
	size_t i, ret;
	if(t->logfile_sz)
	{
		ret = 0;
		for(i=0; i<t->logfile_sz; i++)
		{
			if(t->logfile[i])
			{
				ret = 1;
				break;
			}
		}
		if(!ret)
		{
			fprintf(stderr, "Unable to read from any of the files \
given as argument\n");
			return -1;
		}
	}
	if(!(t->flag & TTAIL_FLAG_DATE_MIN) && !(t->flag & TTAIL_FLAG_DATE_MAX))
	{
		fprintf(stderr, "one of --date-min -d --date-max -m is \
mandatory\n");
		return -1;
	}
	if((t->flag & TTAIL_FLAG_DATE_MIN) && (t->flag & TTAIL_FLAG_DATE_MAX))
	{
		if(ttail_tm_cmp(&(t->date_min), &(t->date_max)) > 0)
		{
			fprintf(stderr, "date-min > date-max.\n");
			return -1;
		}
	}
	return 0;
}

int ttail_add_logfile(ttail_t* res, const char* filename)
{
	void *tmp;
	FILE *fp;
	char *fname;
	int ret, i;

	for(i=0; i<res->logfile_sz; i++)
	{
		if(strcmp(filename, res->logfile_name[i]) == 0)
		{
			fprintf(stderr, "File '%s' allready added\n",
				filename);
			return -1;
		}
	}

	res->logfile_sz++;
	tmp = res->logfile;
	res->logfile = realloc(res->logfile,
		sizeof(FILE*)*res->logfile_sz);
	ret = 0;
	if(!res->logfile)
	{
		perror("Unable to allocate memory for logfiles");
		res->logfile = tmp;
		goto ttail_add_logfile_fpalloc_err;
	}
	fp = fopen(filename, "r");
	if(!fp)
	{
		fprintf(stderr, "Unable to open file : %s\n", filename);
		res->logfile[res->logfile_sz-1] = NULL;
		ret = 1;
	}
	res->logfile[res->logfile_sz-1] = fp;

	tmp = res->logfile_name;
	res->logfile_name = realloc(res->logfile_name,
		sizeof(char*)*res->logfile_sz);
	if(!res->logfile_name)
	{
		perror("Unable to allocate memory for logfiles");
		res->logfile_name = tmp;
		goto ttail_add_logfile_fnalloc_err;

	}
	fname = malloc(sizeof(char)*(strlen(filename)+1));
	if(!fname)
	{
		perror("Unable to allocate memory for logfiles");
		goto ttail_add_logfile_fnalloc_err;
	}
	strcpy(fname, filename);
	res->logfile_name[res->logfile_sz-1] = fname;
	
	return ret;

	ttail_add_logfile_fnalloc_err:
	fclose(res->logfile[res->logfile_sz-2]);
	ttail_add_logfile_fpalloc_err:
	res->logfile_sz--;
	return -1;
}

int ttail_set_prefix(ttail_t* res, const char* regex)
{
	int ret, cflags;
	char *re_errbuff;
	size_t re_errbuff_sz;

	if(res->flag & TTAIL_FLAG_PREFIX)
	{
		fprintf(stderr, "Regex prefix allready set");
		return 1;
	}
	res->flag |= TTAIL_FLAG_PREFIX;
	cflags = 0;
	if(res->flag & TTAIL_FLAG_EXTENDED_RE)
	{
		cflags |= REG_EXTENDED;
	}
	if(res->flag & TTAIL_FLAG_CI_RE)
	{
		cflags |= REG_ICASE;
	}
	ret = regcomp(&res->date_prefix, regex, cflags);
	if(!ret)
	{
		res->prefix_sz = -1;
		return 0;
	}
	/*compilation error */
	res->flag ^= TTAIL_FLAG_PREFIX;
	re_errbuff_sz = regerror(ret,
		&res->date_prefix, NULL, 0);
	re_errbuff = malloc(
		sizeof(char)*re_errbuff_sz);
	if(!re_errbuff)
	{
		perror("Failed to allocate memory for regex compilation \
error message");
		goto ttail_set_prefix_err;
	}
	regerror(ret, &res->date_prefix,
		re_errbuff,
		sizeof(char)*re_errbuff_sz);
	fprintf(stderr, "Regex compilation fails : %s", re_errbuff);

	free(re_errbuff);
	ttail_set_prefix_err:
	return -1;
}

int ttail_set_fmt(ttail_t* t, const char* fmt)
{
	if(t->flag & TTAIL_FLAG_FORMAT)
	{
		return -1;
	}
	t->fmt = strdup(fmt);
	if(!t->fmt)
	{
		return -1;
	}
	t->flag |= TTAIL_FLAG_FORMAT;
	return 0;
}

/**@brief This function is used by bot @ref ttail_set_flag_re_ex() and
 *ttail_set_flag_re_ci() function
 *@param t ttail_t*
 *@return -1 on error else 0
 */
static int _ttail_common_set_flag_re(ttail_t* ttail)
{
	if(ttail->flag & TTAIL_FLAG_PREFIX)
	{
		fprintf(stderr, "Regex flags has to be set BEFORE the \
prefix\n");
		return -1;
	}
	return 0;
}

int ttail_set_flag_re_ex(ttail_t* ttail)
{
	if(_ttail_common_set_flag_re(ttail) < 0)
	{
		return -1;
	}
	ttail->flag |= TTAIL_FLAG_EXTENDED_RE;
	return 0;
}

int ttail_set_flag_re_ci(ttail_t* ttail)
{
	if(_ttail_common_set_flag_re(ttail) < 0)
	{
		return -1;
	}
	ttail->flag |= TTAIL_FLAG_CI_RE;
	return 0;
}

int ttail_set_dates(ttail_t* res, char* dates[2])
{
	int c, ret;
	char *date;

	for(c=0;c<2;c++)
	{
		ttail_tm_init(c==0?&(res->date_min):&(res->date_max));
		if(!dates[c])
		{
			continue;
		}
		date = dates[c];
		if(!strncmp(date, "#-", 2))
		{
			/* relative date */
			ret = _ttail_set_date_relative(res, date, c);
		}
		else
		{
			/* date from format */
			ret = _ttail_set_date_fmt(res, date, c);
		}
		if(ret < 0)
		{
			return -1;
		}
		res->flag |= c?TTAIL_FLAG_DATE_MAX:TTAIL_FLAG_DATE_MIN;
	}

	if(dates[0]) { free(dates[0]); dates[0] = NULL; }
	if(dates[1]) { free(dates[1]); dates[1] = NULL; }

	return 0;
}

int _ttail_set_date_fmt(ttail_t* res, char* date, int c)
{
	int ret;
	char *endp;
	char *fmt[] = TTAIL_DEFAULT_FORMATS;

	if(!(res->flag & TTAIL_FLAG_FORMAT))
	{
		/* no format specified */
		ret = ttail_format_guess(date,
			c==0?&(res->date_min):&(res->date_max));
		if(ret < 0)
		{
			fprintf(stderr, "Unable to guess format for \
date '%s'\n", date);
			return -1;
		}
		res->fmt = malloc(sizeof(char)*(strlen(fmt[ret])+1));
		if(!res->fmt)
		{
			perror("Unable to allocate memory for date format");
			res->flag ^= TTAIL_FLAG_FORMAT;
		}
		strcpy(res->fmt, fmt[ret]);
		res->flag |= TTAIL_FLAG_FORMAT;

		res->flag |= c?TTAIL_FLAG_DATE_MAX:TTAIL_FLAG_DATE_MIN;
		return 0;
	}
	endp = strptime(date, res->fmt, 
		c==0?&(res->date_min):&(res->date_max));
	if(!endp)
	{
		fprintf(stderr, "Unable to parse date-%s '%s' with \
format '%s'\n", c==0?"min":"max", date, res->fmt);
		return -1;
	}
	else if(*endp != '\0')
	{
		fprintf(stderr, "Leading caracters for date-%s : '%s' \
is not matched in '%s'\n",\
			c==0?"min":"max", endp, date);
		return -1;
	}
	return 0;
}
int _ttail_set_date_relative(ttail_t* res, char* date, int c)
{
	time_t now;
	char *unit, str_date[64];
	int value;
	struct tm *tm, *tm_p;
	short mod;
	
	if(strncmp(date, "#-", 2))
	{
		fprintf(stderr, "'%s' is not a relative date\n", date);
		return -1;
	}

	tm = c==0?&(res->date_min):&(res->date_max);
	ttail_tm_init(tm);
	if(time(&now) < 0)
	{
		fprintf(stderr, "Unable to retrieve time using time()\n");
		return -1;
	}
	if(!(tm_p = localtime(&now)))
	{
		fprintf(stderr, "Unable to retrieve localtime using localtime()\n");
		return -1;
	}

	memcpy(tm, tm_p, sizeof(struct tm));

	mod = 0;
	unit = NULL;
	value = (int)strtol(date+2, &unit, 10);
	if(unit == date+2)
	{
		fprintf(stderr, "No value found in format '%s'\n", date);
		return -1;
	}
	if(value < 0)
	{
		fprintf(stderr, "Bad relative format '%s'\n", date);
		return -1;
	}
	switch(*unit)
	{
		case 's':
			if(*(unit+1) == '\0' || !strcmp(unit, "sec"))
			{
				tm->tm_sec -= value;
				if(tm->tm_sec < 0)
				{
					mod = 1;
					value = abs(tm->tm_sec);
					tm->tm_sec = 60 - (value % 60);
					value /= 60;
					value++;
				}
				if(!mod)
				{
					break;
				}
			}
		case 'm':
			if(mod || *(unit+1) == '\0' || !strcmp(unit, "min"))
			{
				mod = 0;
				tm->tm_min -= value;
				if(tm->tm_min < 0)
				{
					mod = 1;
					value = abs(tm->tm_min);
					tm->tm_min = 60 - (value % 60);
					value /= 60;
					value++;
				}
				if(!mod)
				{
					break;
				}
			}
		case 'h':
			if(mod || *(unit+1) == '\0' || !strcmp(unit, "hour"))
			{
				mod = 0;
				tm->tm_hour -= value;
				if(tm->tm_hour < 0)
				{
					mod = 1;
					value = abs(tm->tm_hour);
					tm->tm_hour = 24 - (value % 24);
					value /= 24;
					value++;
				}
				if(!mod)
				{
					break;
				}
			}
		case 'd':
			if(mod || *(unit+1) == '\0' || !strcmp(unit, "day"))
			{
				mod = 0;
				tm->tm_mday -= value;
				if(tm->tm_mday <= 0)
				{
					mod = 1;
					value = abs(tm->tm_mday);
					tm->tm_mday = 31 - (value % 31);
					value /= 31;
					value++;
				}
				if(!mod)
				{
					break;
				}
			}
		case 'M':
			if(mod || *(unit+1) == '\0' || !strcmp(unit, "Month"))
			{
				mod = 0;
				tm->tm_mon -= value;
				if(tm->tm_mon < 0)
				{
					mod = 1;
					value = abs(tm->tm_mon);
					tm->tm_mon = 12 - (value % 12);
					value /= 12;
					value++;
				}
				if(!mod)
				{
					break;
				}
			}
		case 'y':
			if(mod || *(unit+1) == '\0' || !strcmp(unit, "year"))
			{
				tm->tm_year -= value;
				break;
			}
		default:
			fprintf(stderr,"Invalid relative date '%s'\n", date);
			return -1;
	}
	if(res->verbose > 0)
	{
		strftime(str_date, 64, "%c", tm);
		fprintf(stderr, "%s date set to %s\n", 
			c?"stop":"start", str_date);
	}
	return 0;

}

int ttail_norm_dates(ttail_t* ttail)
{
	struct tm *tm_p, tm;
	/* Huge buffer but no way to make a difference between error and
	   buffer too small using strftime */
	char date[4096], *endp;
	size_t date_len;
	time_t now;

	if(time(&now) < 0)
	{
		perror("Unable to retrieve time using time()\n");
		return -1;
	}
	if(!(tm_p = localtime(&now)))
	{
		perror("Unable to retrieve localtime using localtime()\n");
		return -1;
	}
	if(!(date_len = strftime(date, sizeof(date), ttail->fmt, tm_p)))
	{
		fprintf(stderr, "Unable to print the current date using strftime()\n");
		return -1;
	}
	ttail_tm_init(&tm);
	endp = strptime(date, ttail->fmt, &tm);
	if(!endp || *endp != '\0')
	{
		fprintf(stderr, "An error occured, unable to strptime() a date\
we just strftime() !\n");
		exit(EXIT_FAILURE);
	}
	
	TTAIL_NORMDATE(ttail, &tm, tm_sec);
	TTAIL_NORMDATE(ttail, &tm, tm_min);
	TTAIL_NORMDATE(ttail, &tm, tm_hour);
	TTAIL_NORMDATE(ttail, &tm, tm_mday);
	TTAIL_NORMDATE(ttail, &tm, tm_mon);
	TTAIL_NORMDATE(ttail, &tm, tm_year);
	
	return 0;
}

int ttail_format_guess(const char* date_str, struct tm* tm)
{
	int i, res;
	char *res_ret, *ret;
	char *fmt[] = TTAIL_DEFAULT_FORMATS;
	struct tm dte;
	
	memset(&dte, 0, sizeof(struct tm));

	res = -1;
	res_ret = NULL;
	i=0;
	while(fmt[i])
	{
		ret = strptime(date_str, fmt[i], &dte);
		if(ret)
		{
			if(!res_ret || strlen(res_ret) > strlen(ret))
			{
				res_ret = ret;
				res = i;
				if(tm)
				{
					memcpy(tm, &dte, sizeof(struct tm));
				}
			}
		}
		i++;
	}
	if(!res_ret)
	{
		if(tm)
		{
			memset(tm, 0, sizeof(struct tm));
		}
		return -1;
	}
	return res;
}

void ttail_free(ttail_t* t)
{
	size_t i;
	if(t->flag & TTAIL_FLAG_PREFIX && t->prefix_sz < 0)
	{
		regfree(&(t->date_prefix));
	}
	for(i=0; i<t->logfile_sz; i++)
	{
		if(t->logfile[i])
		{
			fclose(t->logfile[i]);
		}
		if(t->logfile_name[i])
		{
			free(t->logfile_name[i]);
		}
	}
	free(t->logfile);
	free(t->logfile_name);
	t->logfile_sz = 0;
	if(t->fmt != NULL)
	{
		free(t->fmt);
	}
	free(t);
	optind=0;
}