/*-
 * main.c
 * Copyright (c) 1993-1999, Francisco Rosales <frosal@fi.upm.es>
 *
 * Minishell C source
 * Show how to use "obtain_order" input interface function
 *
 * THIS FILE IS TO BE MODIFIED
 */

#include <stddef.h>         /* NULL */
#include <stdio.h>          /* setbuf, printf */
#include <unistd.h>
#include <stdlib.h>
#include <paths.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>

#define STDIN_FILENO 0
#define STDOUT_FILENO 1
#define STDERR_FILENO 2

extern int obtain_order();      /* See parser.y for description */

int old_in, old_out, old_err;

// This function operates on redirection of STDIN, STDOUT, STDERR
void redirection( char **fileC){
    int fp;

    //Check if we have request the STDIN
    if (fileC[0] != NULL) {

        //Open the file descriptor and open the file
        fp=open(fileC[0],O_RDONLY,0666);

        //Close the STDIN
        close(STDIN_FILENO);

        // I do a copy of STDIN on fp
        dup(fp);
    }
    //Check if we have request the STDUOT
    if (fileC[1] != NULL) {

        //Open the file descriptor and open and creat the file
        fp=open(fileC[1], O_CREAT | O_TRUNC | O_WRONLY, 0666);

        //Close the STDOUT
        close(STDOUT_FILENO);

        // I do a copy of STDOUT on fp
        dup(fp);
    }
    //Check if we have request the STDERR
    if (fileC[2] != NULL) {

        //Open the file descriptor and open and creat the file
        fp=open(fileC[2], O_CREAT | O_TRUNC | O_WRONLY, 0666);

        //Close the STDERR
        close(STDERR_FILENO);

        // I do a copy of STDERR on fp
        dup(fp);

    }
}

//With this function I copy the first position of standard INPUT, OUTPUT, ERROR
void copyFileDescriptor()
{
    old_in = dup(STDIN_FILENO);
    old_out = dup(STDOUT_FILENO);
    old_err = dup(STDERR_FILENO);

}

//Reposition the three standard in old position
void setupFiledescriptor()
{
    close(STDIN_FILENO);
    dup(old_in);
    close(STDOUT_FILENO);
    dup(old_out);
    close(STDERR_FILENO);
    dup(old_err);
}

void welcomeScreen()

{
    printf("\n-------------------------------------------------\n");
    printf("\tWelcome to MINI-shell  \n");
    printf("\tAuthor :Giovanni Formisano Francesco D'Alia\n");
    printf("-------------------------------------------------\n");
    printf("\n\n");
}

void shellPrompt(char *currentDirectory)
{
    printf("%s :> ",getcwd(currentDirectory, 1024));
}


int main(void)
{
    char* currentDirectory;
    char ***argvv;
    int argvc;
    char **argv;
    char *filev[3];
    int bg;
    int err;
    int ret,pid,status,pid2,pid3;
    int fp[2],fp2[2];


    setbuf(stdout, NULL);           /* Unbuffered */
    setbuf(stdin, NULL);

    copyFileDescriptor();

    welcomeScreen();

    currentDirectory = (char*) calloc(1024, sizeof(char));

    while (1) {

        shellPrompt(currentDirectory);
        //fprintf(stderr, "%s", "msh> ");   /* Prompt */

        ret = obtain_order(&argvv, filev, &bg);
        if (ret == 0) break;        /* EOF */



        if (ret == -1) continue;    /* Syntax error */
        argvc = ret - 1;        /* Line */
        if (argvc == 0) continue;   /* Empty line */


    //This variable args count how many command the user put on the shell
    int args =0;

    //This FOR count count how many command the user put on the shell
    for (argvc = 0; (argv = argvv[argvc]); argvc++)

        args++;

        for (argvc = 0; (argv = argvv[argvc]); argvc++) {

            // First of all I check how many command I have insert, in this case with only one command
            //I creat the fork to execution of that command while the father wait the child that it's finish
            if (args == 1) {

                redirection(filev);

                //Create a fork
                pid = fork();

                //Check the error
                if ( pid < 0 ){

                    printf("error create fork!!!!");
                    exit(1);
                }
                //This is child
                if ( pid == 0 ){

                        //This command exe the command that find inside /bin/bash
                        err = execvp((char *)argvv[argvc][0],argvv[argvc]);

                        //Check the error of exevp
                        if (err < 0)
                            perror("errore execvp");
                    exit(0);

                }else {
                    //This is the father and than with check (!bg) the programm control if there is or no
                    // the command in background
                    if(!bg) {

                        //Wait the termination of child
                        wait(&status);
                    }

                    else {
                        printf("[%d]\n",pid);
                        }
                   }
            }

            //Recall the function setupFileDescriptor to rearrange the STANDARD INPUT OUTPU ERR
            setupFiledescriptor();

            // First of all I check how many command I have insert, in this case with only two command
            //Than I create a pipe to connect the two process. To do this I must create two fork, because the idea is
            //one fork() for each process
            if (args == 2) {

                redirection(filev);

                //Create the first fork()
                pid = fork();

                //Check the error
                if ( pid < 0 ){

                    printf("error create fork!!!!");
                    exit(1);
                }
                if ( pid == 0 ){

                    //Create a pipe for the connection and use two file descriptor
                    pipe(fp);

                    //I creat the second fork()
                    pid2 = fork();

                    if ( pid2 == 0 )

                    {
                        //Here close the file descriptor STDOUTPUT
                        close(STDOUT_FILENO);

                        //Redirection the STDOUT on OUTPUT of pipe
                        dup2(fp[1],STDOUT_FILENO);

                        //Close the INPUT of pipe because must close the file descriptor that pipe don't use
                        close(fp[0]);

                        //This command exe the command that find inside /bin/bash
                        err = execvp((char *)argvv[argvc][0],argvv[argvc]);

                        //Check the error of exevp
                        if (err < 0)
                            perror("errore execvp");
                        exit(0);
                    }
                    //Wait the termination of child
                    wait(&status);

                    //Close the INPUT
                    close(STDIN_FILENO);

                    //Redirection the STDINPUT on INPUT of pipe
                    dup2(fp[0],STDIN_FILENO);

                    //Close the OUTPUT of pipe because must close the file descriptor that pipe don't use
                    close(fp[1]);

                    //This command exe the second commad that user insert
                    err = execvp((char *)argvv[argvc+1][0],argvv[argvc+1]);

                    //Check the error of exevp
                    if (err < 0)
                        perror("errore execvp");
                    exit(0);

                }else{

                    //This is the father and than with check (!bg) the programm control if there is or no
                    // the command in background
                    if(!bg) {

                        //Wait the termination of child
                        wait(&status);
                        argvc++;
                    }

                    else {
                        printf("[%d]\n",pid);
                    }
                }
            }

            //Recall the function setupFileDescriptor to rearrange the STANDARD INPUT OUTPU ERR
            setupFiledescriptor();

            // First of all I check how many command I have insert, in this case with only three command
            //Than I create two pipe to connect three process. To do this I must create three fork, because the idea is
            //one fork() for each process.
            //The idea is the fork many inside exec the first command, the second fork exec the second command,
            // and the firs fork exec the last command.
            if (args == 3) {

                redirection(filev);

                //Create the first fork()
                pid = fork();

                //Check the error
                if ( pid < 0 ){

                    printf("error create fork!!!!");
                    exit(1);

                }

                if ( pid == 0 ){

                    //Create a pipe for the connection and use two file descriptor
                    pipe(fp);

                    //Create the second fork()
                    pid2 = fork();

                    //Chech error of second fork()
                    if ( pid2 < 0 ){

                        printf("error create fork!!!!");
                        exit(1);
                    }

                    if ( pid2 == 0 )

                    {
                        //I create the second pipe
                        pipe(fp2);

                        //I creat the third fork()
                        pid3 = fork();

                        //Check the error of third fork()
                        if ( pid3 < 0 ){

                            printf("error create fork!!!!");
                            exit(1);
                        }
                        if ( pid3 == 0){

                            //Close the INPUT
                            close(fp2[0]);

                            //Redirection the STDOUT on OUTPUT of pipe
                            dup2(fp2[1],STDOUT_FILENO);

                            //Close the INPUT of pipe because must close the file descriptor that pipe don't use
                            close(fp2[1]);

                            //This command exe the first command
                            err = execvp((char *)argvv[argvc][0],argvv[argvc]);

                            //Check error of execvp
                            if (err < 0)
                                perror("errore execvp");
                            exit(0);

                        }else {

                            //Wait the termination of child
                            wait(&status);

                            //Close the INPUT
                            close (fp2[1]);

                            //With this two function dup there is the connection of second command with
                            //third command exchanging the INPUT of one with OUTPUT of the other one
                            dup2(fp2[0],STDIN_FILENO);
                            dup2(fp[1],STDOUT_FILENO);

                            ////Close the INPUT of pipe one because must close the file descriptor that pipe don't use
                            close (fp[0]);

                            //Close the OUTPUT of pipe two because must close the file descriptor that pipe don't use
                            close(fp2[1]);

                            //This command exe the second command
                            err = execvp((char *)argvv[argvc+1][0],argvv[argvc+1]);

                            //Check error of execvp
                            if (err < 0)
                                perror("errore execvp");
                            exit(0);

                        }

                    }

                    //Wait the termination of child
                    wait(&status);

                    //Close the STDIN
                    close(STDIN_FILENO);

                    //Redirection the STDINPUT on INPUT of pipe
                    dup2(fp[0],STDIN_FILENO);

                    //Close the OUTPUT of pipe two because must close the file descriptor
                    close(fp[1]);

                    //This command exe the third command
                    err = execvp((char *)argvv[argvc+2][0],argvv[argvc+2]);


                    if (err < 0)
                        perror("errore execvp");
                    exit(0);

                }else{

                    //This is the father and than with check (!bg) the programm control if there is or no
                    // the command in background
                    if(!bg) {

                        //Wait the termination of child
                        wait(&status);

                        argvc = argvc + 2;
                    }

                    else {
                        printf("[%d]\n",pid);
                    }
                }
            }

            //Recall the function setupFileDescriptor to rearrange the STANDARD INPUT OUTPU ERR
            setupFiledescriptor();
        }
        setupFiledescriptor();
    }
    return 0;
}