/* noshmore
 * an extended version of nosh,
 * the minimal POSIX C shell.
 * -> generally: adds some functionality.
 *
 * von czjstmax, <jstmaxlol at disroot dot org>
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <stdbool.h>
#include <wordexp.h>
#include <sys/wait.h>
#include <readline/readline.h>
#include <readline/history.h>

void handlecc(int sig);
void FreeAll();

char *line = NULL;
wordexp_t p;

int main(void)
{
    signal(SIGINT, handlecc);
    char *USER = getenv("USER");
    if (!USER)
        USER = "god";

    while (true) {
        char prompt[strlen(USER) + strlen("$ ") + 1];
        snprintf(prompt, sizeof(prompt), "%s$ ", USER);

        line = readline(prompt);

        if (!line)
            break;
        if (*line)
            add_history(line);

        if (wordexp(line, &p, 0) != 0) {
            fprintf(stderr, "nsh+! parse error\n");
            free(line);
            continue;
        }

        // built-ins
        if (p.we_wordc == 0) {
            FreeAll();
            continue;
        }
        if (strcmp(p.we_wordv[0], ":q") == 0 || strcmp(p.we_wordv[0], "exit") == 0) {
            FreeAll();
            return 0;
        }
        else if (strcmp(p.we_wordv[0], "echo") == 0) {
            for (size_t i = 1; i < p.we_wordc; i++)
                printf("%s ", p.we_wordv[i]);
            if (p.we_wordc >= 2) {
                if (strcmp(p.we_wordv[1], "-c") != 0)
                    printf("\n");
                else continue;
            }
        }
        else if (strcmp(p.we_wordv[0], "cd") == 0) {
            if (p.we_wordc <= 1) {
                printf("nsh+! cd: no arguments were given.\n");
                FreeAll();
                continue;
            }
            if (chdir(p.we_wordv[1]))
                perror("nsh+! ERROR: failed to change directory");
        }
        else if (strcmp(p.we_wordv[0], "clear") == 0) {
            printf("\033[2J\033[H\033[3J");
            fflush(stdout);
        }
        else if (strcmp(p.we_wordv[0], "help") == 0) {
            printf(
                "noshmore\n"
                "an extended version of nosh, the minimal POSIX C shell.\n"
                "\n"
                "built-ins:\n"
                "echo  -> outputs a string of text, doesn't need \" enclosure.\n"
                "         supports '-c' for output without '\\n'"
                "clear -> clears screen (and scrollback)\n"
                "cd    -> change working directory\n"
                "help  -> prints this screen\n"
                "\ngithub repo: github.com/jstmaxlol/noshmore\n"
            );
        }
        else {
            pid_t pid = fork();
            char **argv = p.we_wordv; // pray with me now
            if (pid == 0) {
                execvp(p.we_wordv[0], argv);
                perror("nsh+! ERROR: failed to execvp()");
                FreeAll();
                _exit(1);
            }
            else if (pid > 0) {
                int status;
                waitpid(pid, &status, 0);
            }
            else {
                fprintf(stderr, "nsh+! ERROR: couldn't execute %s\n", p.we_wordv[0]);
            }
        }
    }
}

void handlecc(int sig)
{
    (void)sig;
    rl_replace_line("", 0);
    printf("\n");
    rl_on_new_line();
    rl_redisplay();
}

void FreeAll()
{
    wordfree(&p);
    free(line);
    line = NULL;
}