/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   content_expand.c                                   :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: lperrey <lperrey@student.42.fr>            +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2021/11/07 02:01:33 by lperrey           #+#    #+#             */
/*   Updated: 2021/12/21 01:20:40 by lperrey          ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "minishell.h"

static char		*env_var_expansion(char *content, int *i);
static char		*retrieve_var(char *content, int *i);

t_list	*content_expand(char *content, int *i)
{
	t_list	*expand;

	expand = ft_lstnew(NULL);
	if (!expand)
		return (NULL);
	expand->content = env_var_expansion(content, i);
	if (!expand->content)
	{
		free(expand);
		return (NULL);
	}
	return (expand);
}

static char	*env_var_expansion(char *content, int *i)
{
	char	*expansion;

	(*i)++;
	if (content[*i] == '?')
	{
		(*i)++;
		expansion = ft_itoa(get_last_exit_status());
	}
	else if (content[*i] == '_' || ft_isalpha(content[*i]))
		expansion = retrieve_var(content, i);
	else
	{
		expansion = ft_calloc(1 + 1, 1);
		if (!expansion)
			return (NULL);
		expansion[0] = '$';
	}
	return (expansion);
}

static char	*retrieve_var(char *content, int *i)
{
	char	*expansion;
	char	*tmp;
	int		i_exp;

	expansion = ft_calloc(ft_strlen(&content[*i - 1]) + 1, 1);
	if (!expansion)
		return (NULL);
	i_exp = 0;
	while (content[*i] == '_' || ft_isalnum(content[*i]))
		expansion[i_exp++] = content[(*i)++];
	tmp = getenv(expansion);
	ft_free_null(&expansion);
	if (tmp)
		expansion = ft_strdup(tmp);
	else
		expansion = ft_calloc(1, 1);
	return (expansion);
}

/*
environment variables must be POSIX NAME :
	3.235 Name
https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html
#tag_03_235
*/