#include <iostream>
#include <sys/wait.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <vector>
#include <fcntl.h>

using namespace std;

void ParseCmd(string cmd, vector<string> & line);

int main() {
    //pid_t subproc;
    string cmd;
    string prompt{"DASH > "};
    char * myArgs[10];
         myArgs[0] = NULL;
    char * myEnvp[3];
        myEnvp[0] = strdup("SHELL=DASH");
        myEnvp[1] = strdup("USER=confused");
        myEnvp[2] = NULL; 

    cout << prompt;
    getline(cin, cmd);

    while (cmd !=  "exit") {
        pid_t pid;
        int code;
        size_t argc;
        size_t linePos;
        vector<string> line;
       
        ParseCmd(cmd, line);

        pid = fork();
        if (pid == 0) {
            argc = 0;
            linePos = 0;

            while (argc < 9 and linePos < line.size()) {
                if (line [linePos] == "<") {
                    linePos++;
                    if (linePos < line.size()){
                        close(STDIN_FILENO);
                        open(line[linePos].c_str(), O_RDONLY);
                        linePos++;
                    }
                } else if (line[linePos] == ">") {
                    linePos++;
                    if (linePos < line.size()) {
                        close(STDOUT_FILENO);
                        open(line[linePos].c_str(), 
                                O_WRONLY|O_CREAT|O_TRUNC, S_IRUSR|S_IWUSR);
                        linePos++;
                    }
                } else {
                    myArgs[argc] = strdup(line[linePos].c_str());
                    argc ++;
                    linePos++;
                }
            }

            myArgs[argc] = NULL;

            code = execvpe(line[0].c_str(), myArgs, myEnvp);
            if (code == -1) {
               perror("exec failed");
            }
            return 1;
        } else {
            int status;
            code = wait(&status);
            if (code == -1) {
               if (errno == ECHILD) {
                   cout << " I bet the exec failed" << endl;
               } else {
                   perror("wait failed");
               }
            }
        }

        cout << prompt;
        getline(cin, cmd);
    }

    free (myEnvp[0]);
    free (myEnvp[1]);

    return 0;
}

void ParseCmd(string cmd,  vector<string> &  line) {
    size_t pos;
    pos = cmd.find(' ');
    while (pos != string::npos) {
        string subcmd = cmd.substr(0, pos);

        if (subcmd != "") {

            line.push_back(subcmd);
            if (pos != string::npos) {
               cmd = cmd.substr(pos+1);
            } else {
               cmd = "";
            }
        }
        pos = cmd.find(' ');
    }
     
    if (cmd != "") {
        line.push_back(cmd);
    }
}