/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   get_next_line.c                                    :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: vvobis <marvin@42.fr>                      +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2024/04/18 20:20:17 by vvobis            #+#    #+#             */
/*   Updated: 2024/05/27 17:44:59 by vvobis           ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "get_next_line.h"

void    *buffer_extend(void *ptr_old, size_t size_new, size_t size_old)
{
    void    *ptr_new;
    void    *ptr_back;
    void    *ptr_old_free;

    ptr_new = g_calloc(size_new + 1, 1);
    if (!ptr_new)
        return (free(ptr_old), ptr_old = NULL, NULL);
    ptr_back = ptr_new;
    ptr_old_free = ptr_old;
    while (size_old--)
        *(char *)ptr_new++ = *(char *)ptr_old++;
    return (free(ptr_old_free), ptr_old_free = NULL, ptr_back);
}

char    *handle_no_nl(char **buf, char **left)
{
    if (left)
    {
        free(*left);
        *left = NULL;
    }
    if (!buf)
        return (NULL);
    if (g_strlen(*buf))
        return (*buf);
    free(*buf);
    *buf = NULL;
    return (NULL);
}

char    *line_extract(char **buf_joined, char **left, size_t line_len)
{
    char    *line;

    line = g_substr(*buf_joined, 0, line_len);
    if (!line)
        return (free(*buf_joined), *buf_joined = NULL, NULL);
    *left = g_substr(*buf_joined, line_len, g_strlen(*buf_joined) - line_len);
    free(*buf_joined);
    *buf_joined = NULL;
    if (!*left)
        return (free(line), line = NULL, NULL);
    return (line);
}

char    *line_handle(char **buf_fetch)
{
    char        *buf_joined;
    size_t        line_len;
    static char    *left;

    if (!buf_fetch)
        return (free(left), NULL);
    buf_joined = g_strjoin(left, *buf_fetch);
    free(*buf_fetch);
    *buf_fetch = NULL;
    free(left);
    left = NULL;
    if (!buf_joined)
        return (NULL);
    line_len = find_newline(buf_joined);
    if (line_len)
        return (line_extract(&buf_joined, &left, line_len));
    return (handle_no_nl(&buf_joined, &left));
}

char    *get_next_line(int fd)
{
    char        *buf;
    ssize_t        bytes_read;
    size_t        buf_size_cur;
    size_t        buf_size_prev;

    if (fd < 0)
        return (line_handle(NULL), NULL);
    buf = g_calloc(sizeof(*buf), BUFFER_SIZE + 1);
    buf_size_prev = 0;
    buf_size_cur = BUFFER_SIZE;
    while (1)
    {
        if (!buf)
            return (line_handle(NULL));
        bytes_read = read(fd, buf + buf_size_prev, BUFFER_SIZE);
        if (bytes_read < 0)
            return (free(buf), buf = NULL, line_handle(NULL));
        if (find_newline(buf) || bytes_read == 0)
            break ;
        buf_size_prev = buf_size_cur;
        buf_size_cur += BUFFER_SIZE;
        buf = buffer_extend(buf, buf_size_cur, buf_size_prev);
    }
    return (line_handle(&buf));
}