/*
ft_getline Copyright (C) 2026 yctct

This program 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
(at your option) any later version.

This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.
*/


#include "ft_getline.h"

char	*read_file(int fd, char *buf, char *line, char *stash)
{
	ssize_t	bytes_read;

	bytes_read = read(fd, buf, BUFFER_SIZE);
	if (bytes_read < 0)
	{
		free(line);
		return (NULL);
	}
	buf[bytes_read] = 0;
	if (bytes_read == 0)
	{
		if (line[0] != 0)
		{
			stash[0] = 0;
			return (line);
		}
		else
		{
			free(line);
			return (NULL);
		}
	}
	return (buf);
}



char	*eol_is_in_line(char *pivot, char *stash, char *line)
{
	int		i;
	int		j;
	char	*tmp;

	i = 1;
	j = 0;
	while (pivot[i] != 0)
		stash[j++] = pivot[i++];
	stash[j] = 0;
	pivot[1] = 0;
	tmp = line;
	line = ft_strdup(line); 
	free(tmp);
	return (line);
}

char	*keep_reading(int fd, char *pivot, char *stash, char *line)
{
	char		buf[BUFFER_SIZE + 1];

	while (read_file(fd, buf, line, stash) != 0)
	{
		line = ft_strjoin(line, buf);
		if (!line)
			return (NULL);
		pivot = ft_strchr(line, EOL);
		if (pivot != 0)
			return (eol_is_in_line(pivot, stash, line));
		else if (buf[0] == 0) 
			return (line);
	}
	return (NULL);
}

char	*ft_getline(int fd)
{
	char		*line;
	static char	stash[BUFFER_SIZE] = "\0";
	char		*pivot;

	if ((fd < -1) || (fd > 1024))
		return (NULL);
	line = ft_strdup(stash);
	if (!line)
		return (NULL);
	pivot = ft_strchr(line, EOL);
	if (pivot != 0)
		return (eol_is_in_line(pivot, stash, line));
	else
		return (keep_reading(fd, pivot, stash, line));
	return (NULL);
}