42-Alcu/src/get_next_line.c

/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   get_next_line.c                                    :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: lud-adam <lud-adam@student.42.fr>          +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2026/03/28 15:07:17 by lud-adam          #+#    #+#             */
/*   Updated: 2026/03/28 15:13:54 by lud-adam         ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "get_next_line.h"
#include "../libft/libft.h"

size_t ft_strlen_with_c(char *str, char c) {
  size_t i;

  i = 0;
  if (!str)
    return (0);
  while (str[i] && str[i] != c)
    i++;
  return (i);
}

size_t detect_newline(char *str) {
  size_t i;

  i = 0;
  if (!str)
    return (0);
  while (str[i]) {
    if (str[i] == '\n')
      return (1);
    i++;
  }
  return (0);
}

static void fill_line(char *line, char *c_remaining, char *src, size_t *index) {
  size_t i;
  size_t j;

  i = 0;
  j = 0;
  while (c_remaining && c_remaining[i]) {
    line[i] = c_remaining[i];
    i++;
  }
  while (src[j] && src[j] != '\n') {
    line[i + j] = src[j];
    src[j] = 0;
    j++;
  }
  if (src[j] == '\n')
    line[i + j] = '\n';
  *index = j;
}

char *build_line(char *src, char *c_remaining, size_t *index) {
  char *line;
  size_t size;
  size_t is_jump;

  is_jump = detect_newline(src);
  size = ft_strlen_with_c(src, '\n') + ft_strlen_with_c(c_remaining, '\0') +
         is_jump + 1;
  line = ft_calloc(size, sizeof(char));
  if (!line) {
    free(c_remaining);
    return (NULL);
  }
  if (!src)
    return (NULL);
  fill_line(line, c_remaining, src, index);
  if (c_remaining)
    free(c_remaining);
  return (line);
}

static void read_file(int fd, char *buffer, ssize_t *nb_read) {
  *nb_read = read(fd, buffer, BUFFER_SIZE);
  if (*nb_read < 0)
    return;
  buffer[*nb_read] = '\0';
}

static char *get_the_line(int fd, char *buffer) {
  char *line;
  size_t i;
  ssize_t nb_read;

  i = 0;
  nb_read = 0;
  line = NULL;
  if (buffer[0] != '\0') {
    line = build_line(buffer, NULL, &i);
    if (!line)
      return (NULL);
    ft_memcpy(buffer, buffer + i + 1, ft_strlen_with_c(buffer + i, '\0'));
  }
  while (detect_newline(line) == 0) {
    read_file(fd, buffer, &nb_read);
    if (nb_read < 0)
      return (free(line), NULL);
    if (nb_read == 0)
      break;
    line = build_line(buffer, line, &i);
    ft_memcpy(buffer, buffer + i + 1, ft_strlen_with_c(buffer + i, '\0'));
  }
  return (line);
}

char *get_next_line(int fd) {
  static char buffer[BUFFER_SIZE + 1] = "";
  char *line;

  if (fd < 0 || BUFFER_SIZE <= 0)
    return (NULL);
  line = get_the_line(fd, buffer);
  if (!line)
    return (NULL);
  return (line);
}