#define _DEFAULT_SOURCE
#define _POSIX_C_SOURCE 200809L

#include "utils/env.h"

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include "utils/libstring.h"

void env_set(const char *name, const char *value)
{
    if (setenv(name, value, 1) == -1)
    {
        fprintf(stderr, "env_set: unable to set \'%s\'=\'%s\'.\n", name, value);
    }
}

void env_unset(const char *name)
{
    if (unsetenv(name) == -1)
    {
        fprintf(stderr, "env_unset: unable to unset \'%s\'.\n", name);
    }
}

static void _generate_random(void)
{
    int d = rand() % MAX_RAND;
    char buf[16] = { 0 };
    sprintf(buf, "%d", d);
    env_set("RANDOM", buf);
}

static struct string *_cat_args(void)
{
    int nb_args = atoi(env_get("#"));
    struct string *s = string_create(NULL);
    for (int i = 1; i <= nb_args; i++)
    {
        char buf[16] = { 0 };
        sprintf(buf, "%d", i);
        string_pushstr(s, env_get(buf));
        if (i != nb_args)
        {
            string_pushc(s, ' ');
        }
    }
    return s;
}

char *env_get(const char *name)
{
    if (STRINGS_ARE_EQUAL(name, "RANDOM"))
    {
        _generate_random();
    }
    if (STRINGS_ARE_EQUAL(name, "*"))
    {
        struct string *s = _cat_args();
        env_set("*", s->data);
        string_free(s);
    }
    if (STRINGS_ARE_EQUAL(name, "@"))
    {
        struct string *s = string_create(NULL);
        string_pushc(s, '\"');
        struct string *args = _cat_args();
        string_pushstr(s, args->data);
        string_pushc(s, '\"');
        if (s->length > 2)
        {
            env_set("@", s->data);
        }
        string_free(s);
        string_free(args);
    }
    return getenv(name);
}

void env_clear(void)
{
    if (clearenv())
    {
        fprintf(stderr, "env_clear: unable to clear the environment.\n");
    }
}

static void _set_pwd(void)
{
    char buf[MAX_PATH_SIZE] = { 0 };
    char *path = getcwd(buf, MAX_PATH_SIZE);
    env_set("PWD", path);
    env_set("OLDPWD", path);
}

static void _set_uid(void)
{
    uid_t uid = getuid();
    // Magic value but UID is an integer (POSIX requirement)
    // So it won't be more that 10 chars long
    char buf[16] = { 0 };
    sprintf(buf, "%u", uid);
    env_set("UID", buf);
}

static void _set_pid(void)
{
    pid_t pid = getpid();
    // Magic value but PID is an integer (POSIX requirement)
    // So it won't be more that 10 chars long
    char buf[16] = { 0 };
    sprintf(buf, "%d", pid);
    env_set("$", buf);
}

void env_setup(void)
{
    _set_pwd();
    _set_uid();
    _set_pid();
    env_set("IFS", DEFAULT_IFS);
    env_set("?", "0");
}