/* mshell - a job manager */

#include <stdio.h>
#include <signal.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>

#include "jobs.h"

#define BOLD "\033[00;01m"
#define NORM "\033[00;00m"

void do_help()
{
	printf("available commands are:\n");
	printf(" exit - cause the shell to exit\n");
	printf(BOLD "\t exit\n" NORM);
	printf(" jobs - display status of jobs in the current session\n");
	printf(BOLD "\t jobs\n" NORM);
	printf
	    (" fg   - run a job identified by its pid or job id in the foreground\n");
	printf(BOLD "\t fg " NORM "pid" BOLD "|" NORM "jobid \n");
	printf
	    (" bg   - run a job identified by its pid or job id in the background\n");
	printf(BOLD "\t bg " NORM "pid" BOLD "|" NORM "jobid \n");
	printf(" stop - stop a job identified by its pid or job id\n");
	printf(BOLD "\t stop " NORM "pid" BOLD "|" NORM "jobid \n");
	printf(" kill - kill a job identified by its pid or job id\n");
	printf(BOLD "\t kill " NORM "pid" BOLD "|" NORM "jobid \n");
	printf(" help - print this message\n");
	printf(BOLD "\t help\n" NORM);
	printf("\n");
	printf
	    ("ctrl-z and ctrl-c can be used to send a SIGTSTP and a SIGINT, respectively\n\n");
}

/* treat_argv - Determine pid or jobid and return the associated job structure */
struct job_t *treat_argv(char **argv)
{
	struct job_t *jobp = NULL;

	/* Ignore command if no argument */
	if (argv[1] == NULL) {
		printf("%s command requires PID or %%jobid argument\n",
		       argv[0]);
		return NULL;
	}

	/* Parse the required PID or %JID arg */
	if (isdigit((int)argv[1][0])) {
		pid_t pid = atoi(argv[1]);
		if (!(jobp = jobs_getjobpid(pid))) {
			printf("(%d): No such process\n", (int)pid);
			return NULL;
		}
	} else if (argv[1][0] == '%') {
		int jid = atoi(&argv[1][1]);
		if (!(jobp = jobs_getjobjid(jid))) {
			printf("%s: No such job\n", argv[1]);
			return NULL;
		}
	} else {
		printf("%s: argument must be a PID or %%jobid\n", argv[0]);
		return NULL;
	}

	return jobp;
}

/* do_bg - Execute the builtin bg command */
void do_bg(char **argv)
{
	struct job_t *job;

	if (verbose) {
		printf("do_bg: entering");
	}

	job = treat_argv(argv);

	if (job == NULL) {
		unix_error("do_bg: No such job");
	}

	if (kill(job->jb_pid, SIGCONT) == -1) {
		unix_error("do_bg: kill");
	}

	job->jb_state = BG;

	if (verbose) {
		printf("do_bg: exiting");
	}

	return;
}

/* waitfg - Block until process pid is no longer the foreground process */
void waitfg(pid_t pid)
{
	sigset_t set, oset;

	if (verbose) {
		printf("waitfg: entering\n");
	}

	sigemptyset(&set);
	sigaddset(&set, SIGCHLD);
	sigprocmask(SIG_BLOCK, &set, &oset);

	while (pid == jobs_fgpid()) {
		sigsuspend(&oset);
	}

	sigprocmask(SIG_SETMASK, &oset, NULL);

	if (verbose) {
		printf("waitfg: exting\n");
	}

	return;
}

/* do_fg - Execute the builtin fg command */
void do_fg(char **argv)
{
	struct job_t *job;

	if (verbose) {
		printf("do_fg: entering");
	}

	job = treat_argv(argv);

	if (job == NULL) {
		unix_error("do_fg: No such job");
	}

	if (kill(job->jb_pid, SIGCONT) == -1) {
		unix_error("do_fg: kill");
	}

	job->jb_state = FG;

	waitfg(job->jb_pid);

	if (verbose) {
		printf("do_fg: exiting");
	}

	return;
}

/* do_stop - Execute the builtin stop command */
void do_stop(char **argv)
{
	struct job_t *job;

	if (verbose) {
		printf("do_stop: entering\n");
	}

	job = treat_argv(argv);

	if (job == NULL) {
		unix_error("do_stop: No such job");
	}

	if (kill(job->jb_pid, SIGSTOP) == -1) {
		unix_error("do_stop: kill");
	}

	job->jb_state = ST;

	if (verbose) {
		printf("do_stop: exiting\n");
	}

	return;
}

/* do_kill - Execute the builtin kill command */
void do_kill(char **argv)
{
	struct job_t *job;

	if (verbose) {
		printf("do_kill: entering\n");
	}

	job = treat_argv(argv);

	if (job == NULL) {
		unix_error("do_kill: No such job\n");
	}

	if (kill(job->jb_pid, SIGKILL) == -1) {
		unix_error("do_kill: kill");
	}

	if (verbose) {
		printf("do_kill: exiting\n");
	}

	return;
}

/* do_exit - Execute the builtin exit command */
void do_exit()
{
	if (verbose) {
		printf("do_exit: entering\n");
	}

	if (jobs_getstoppedjob() == 0) {
		/* kill mshell */
		if (kill(getpid(), SIGKILL) == -1) {
			unix_error("do_exit: kill");
		}
	} else {
		printf("There are stopped jobs.\n");
	}

	if (verbose) {
		printf("do_exit: exiting\n");
	}

	return;
}

/* do_jobs - Execute the builtin fg command */
void do_jobs()
{
	if (verbose) {
		printf("do_jobs: entering\n");
	}

	jobs_listjobs();

	if (verbose) {
		printf("do_jobs: exiting\n");
	}

	return;
}