#define _GNU_SOURCE

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <string.h>
#include <signal.h>
#include <fcntl.h>
#include <errno.h>
#include <setjmp.h>
#include "readcmd.h"
#include "jobs.h"

extern int errno;

struct cmdline *cmd;

int pid_fils, wait_code;

list jobs;

int prompting = 0;
jmp_buf goto_prompt;

char initcd[256], currentcd[256];

int file_in, file_out;

int pipes[256][2];
int sous_fils[256];

void handler_sigchld(int sig_num)
{
    do
    {
        pid_fils = waitpid(-1, &wait_code, WNOHANG | WUNTRACED | WCONTINUED);
        if ((pid_fils == -1) && (errno != ECHILD))
        { // wait fail ?
            fprintf(stderr, "ERROR: waiting for %d failed, (%d) %s\n", pid_fils, errno, strerror(errno));
            exit(errno);
        }

        cell *job = trouver(&jobs, pid_fils);
        if (job != NULL)
        {
            if (prompting)
            {
                printf("\n");
            }

            if (WIFSTOPPED(wait_code))
            {
                printf("[%d] %d stopped: %s\n", job->id, job->pid, job->cmd);
            }
            else if (WIFCONTINUED(wait_code))
            {
                printf("[%d] %d continued: %s\n", job->id, job->pid, job->cmd);
                if (!strcmp(cmd->seq[0][0], "fg"))
                {
                    supprimer(&jobs, job->pid);
                }
            }
            else if (WIFEXITED(wait_code))
            {
                printf("[%d] %d exited: %s\n", job->id, job->pid, job->cmd);
                supprimer(&jobs, job->pid);
            }
            else if (wait_code == SIGKILL)
            {
                printf("[%d] %d killed: %s\n", job->id, job->pid, job->cmd);
                supprimer(&jobs, job->pid);
            }
        }
    } while (pid_fils > 0);

    if (prompting)
    {
        siglongjmp(goto_prompt, sig_num);
    }
}

void handler_sigint(int sig_num)
{
    printf("\n");
    if (!prompting)
    {
        kill(pid_fils, SIGKILL);
        pause();
    }
    siglongjmp(goto_prompt, sig_num);
}

void handler_sigtstp(int sig_num)
{
    printf("\n");
    if (!prompting)
    {
        ajouter(&jobs, pid_fils, *(cmd->seq));
        kill(pid_fils, SIGSTOP);
        pause();
    }
    siglongjmp(goto_prompt, sig_num);
}

int main(int argc, char *argv[])
{
    initialiser(&jobs);
    getcwd(initcd, sizeof(initcd));

    // gestion des signaux
    struct sigaction action;
    sigemptyset(&action.sa_mask);
    action.sa_flags = SA_SIGINFO | SA_RESTART;
    action.sa_handler = handler_sigchld;
    sigaction(SIGCHLD, &action, NULL);
    action.sa_handler = handler_sigint;
    sigaction(SIGINT, &action, NULL);
    action.sa_handler = handler_sigtstp;
    sigaction(SIGTSTP, &action, NULL);

    // main loop
    while (1)
    {
        sigsetjmp(goto_prompt, 1);

        prompting = 1;
        getcwd(currentcd, sizeof(currentcd));
        printf("%s >>> ", currentcd);
        cmd = readcmd();
        prompting = 0;

        // TODO: créer fonction "builtin" ?
        if (cmd == NULL)
        { // EOF
            break;
        }
        else if (cmd->err)
        { // error from readcmd
            fprintf(stderr, "ERROR: readcmd failed, %s\n", cmd->err);
            continue;
        }
        else if (cmd->seq[0] == NULL)
        { // empty
            continue;
        }
        else if (!strcmp(cmd->seq[0][0], "exit"))
        { // "exit"
            break;
        }
        else if (!strcmp(cmd->seq[0][0], "cd"))
        { // "cd"
            int ret = 0;
            if (cmd->seq[0][1] == NULL)
            { // no path
                ret = chdir(initcd);
            }
            else
            { // with path
                ret = chdir(cmd->seq[0][1]);
            }
            if (ret)
            { // wrong path
                fprintf(stderr, "ERROR: cd failed, (%d) %s\n", errno, strerror(errno));
            }
            continue;
        }
        else if (!strcmp(cmd->seq[0][0], "jobs"))
        { // "jobs"
            afficher(&jobs);
            continue;
        }
        else if (!strcmp(cmd->seq[0][0], "bg"))
        { // "bg"
            cell *job;
            if (cmd->seq[0][1] == NULL)
            { // no id
                fprintf(stderr, "ERROR: id missing\n");
                continue;
            }
            else
            { // id specified
                job = trouver_id(&jobs, atoi(cmd->seq[0][1]));
            }
            kill(job->pid, SIGCONT);
            pause();
            continue;
        }
        else if (!strcmp(cmd->seq[0][0], "fg"))
        { // "fg"
            cell *job;
            if (cmd->seq[0][1] == NULL)
            { // no id
                fprintf(stderr, "ERROR: id missing\n");
                continue;
            }
            else
            { // id specified
                job = trouver_id(&jobs, atoi(cmd->seq[0][1]));
                pid_fils = job->pid;
            }
            kill(pid_fils, SIGCONT);
            pause();
            waitpid(pid_fils, NULL, 0);
            continue;
        }
        else if (!strcmp(cmd->seq[0][0], "stop"))
        { // "stop"
            cell *job;
            if (cmd->seq[0][1] == NULL)
            { // no id
                fprintf(stderr, "ERROR: id missing\n");
                continue;
            }
            else
            { // id specified
                job = trouver_id(&jobs, atoi(cmd->seq[0][1]));
            }
            kill(job->pid, SIGSTOP);
            pause();
            continue;
        }
        else if (!strcmp(cmd->seq[0][0], "pid"))
        { // "pid"
            printf("pid=%d\n", getpid());
            continue;
        }

        // compter le nombre de commandes séparées par des pipes
        int nb_pipe = -1;
        char ***cursor = cmd->seq;
        while (*cursor)
        {
            cursor++;
            nb_pipe++;
        }
        if (nb_pipe < 0)
        { // counting failed ?
            fprintf(stderr, "ERROR: counting pipes failed");
            exit(1);
        }

        if ((pid_fils = fork()) == -1)
        { // fork fail ?
            fprintf(stderr, "ERROR: forking failed, (%d) %s\n", errno, strerror(errno));
            exit(errno);
        }
        if (pid_fils == 0)
        { // instructions du fils
            action.sa_handler = SIG_IGN;
            sigaction(SIGTSTP, &action, NULL); // on ignore SIGTSTP
            sigaction(SIGINT, &action, NULL);  // on ignore SIGINT

            if (cmd->in)
            { // "<"
                file_in = open(cmd->in, O_RDONLY);
                dup2(file_in, 0);
            }
            if (cmd->out)
            { // ">"
                file_out = open(cmd->out, O_CREAT | O_TRUNC | O_WRONLY, 0640);
                dup2(file_out, 1);
            }

            if (nb_pipe > 0)
            { // "|" présent(s) dans la commande
                for (int i = 0; i <= nb_pipe; i++)
                { // on crée itérativement nb_pipe fils et pipes
                    if (pipe(pipes[i]) < 0)
                    { // pipe failed ?
                        fprintf(stderr, "ERROR: pipe error, (%d) %s\n", errno, strerror(errno));
                        exit(errno);
                    }

                    if ((sous_fils[i] = fork()) < 0)
                    { // fork failed ?
                        fprintf(stderr, "ERROR: fork error, (%d) %s\n", errno, strerror(errno));
                        exit(errno);
                    }
                    else if (sous_fils[i] == 0)
                    { // instructions des sous-fils

                        if (i == 0)
                        { // premier sous-fils
                            close(pipes[0][0]);
                        }
                        else if (dup2(pipes[i - 1][0], STDIN_FILENO) == -1)
                        { // dup2 fail
                            fprintf(stderr, "ERROR: dup2 error, (%d) %s\n", errno, strerror(errno));
                            exit(errno);
                        }

                        if (i == nb_pipe)
                        { // dernier sous-fils
                            close(pipes[i][1]);
                        }
                        else if (dup2(pipes[i][1], STDOUT_FILENO) == -1)
                        { // dup2 fail
                            fprintf(stderr, "ERROR: dup2 error, (%d) %s\n", errno, strerror(errno));
                            exit(errno);
                        }

                        for (int j = 0; j <= i; j++)
                        { // on ferme les pipes non nécéssaires
                            if (j <= i - 2)
                            { // on ferme tous les pipes que l'on utilise pas
                                close(pipes[j][0]);
                                close(pipes[j][1]);
                            }
                            else if (j == i - 1)
                            { // on ferme l'écriture du pipe précédent
                                close(pipes[j][1]);
                            }
                            else if (j == i)
                            { // on ferme la lecture de son propre pipe
                                close(pipes[j][0]);
                            }
                        }

                        execvp(cmd->seq[i][0], cmd->seq[i]);
                        fprintf(stderr, "ERROR: execvp failed, (%d) %s\n", errno, strerror(errno));
                        exit(errno); // si execvp échoue on exit avec une erreur
                    }
                }
                for (int i = 0; i <= nb_pipe; i++)
                { // on ferme tous les pipes pour le fils
                    close(pipes[i][0]);
                    close(pipes[i][1]);
                }
                for (int i = 0; i <= nb_pipe; i++)
                { // on attend chaque sous-fils
                    pid_t id = waitpid(sous_fils[i], &wait_code, 0);

                    if (id == -1)
                    { // wait fail ?
                        fprintf(stderr, "ERROR: waiting for %d failed, (%d) %s\n", wait_code, errno, strerror(errno));
                        exit(errno);
                    }
                    if (wait_code)
                    { // execvp fail ?
                        fprintf(stderr, "ERROR: child failed, (%d) %s\n", wait_code, strerror(wait_code));
                    }
                }
                exit(0); // on termine le fils
            }
            else
            { // pas de piping
                execvp(cmd->seq[0][0], cmd->seq[0]);
                fprintf(stderr, "ERROR: execvp failed, (%d) %s\n", errno, strerror(errno));
                exit(errno); // si execvp échoue on exit avec une erreur
            }
        }
        else
        { // instructions du père
            if (cmd->backgrounded)
            { // background
                int id_fils = ajouter(&jobs, pid_fils, *(cmd->seq));
                printf("[%d] %d\n", id_fils, pid_fils);
            }
            else
            { // foreground
                pid_t id = waitpid(pid_fils, &wait_code, 0);

                if (id == -1)
                { // wait fail ?
                    fprintf(stderr, "ERROR: waiting for %d failed, (%d) %s\n", wait_code, errno, strerror(errno));
                    exit(errno);
                }
                if (wait_code)
                { // execvp fail ?
                    fprintf(stderr, "ERROR: child failed, (%d) %s\n", wait_code, strerror(wait_code));
                }
            }
        }
    }

    return EXIT_SUCCESS;
}