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

void register_child_signal(){

}

void execute_command(char** args){
    int pid;
    int status;
    pid = fork();
    if(pid == 0){
        execvp(args[0], args);
        printf("Error! Command not found\n");
        exit(0);
    }
    else if(pid < 0){
        printf("Error forking!\n");
    }
    else{
        do{
            waitpid(pid, &status, 0);
        }
        while(!WIFEXITED(status) && !WIFSIGNALED(status));
    }
}

void execute_shell_builtin(char** command_array){
    if(!strcmp("cd", command_array[0])){

    }
    else if(!strcmp("echo", command_array[0])){

    }
    else if(!strcmp("export", command_array[0])){

    }
}

int evaluate_command(char** command_array){
    if(!strcmp("cd", command_array[0]) || !strcmp("echo", command_array[0]) || !strcmp("export", command_array[0])){
        return 0;
    }
    else if(!strcmp("exit", command_array[0])){
        return -1;
    }
    else{
        return 1;
    }
}

char** parse_command(char input[]){
    static char* strings[100];
    int index = 0;
    char* token = strtok(input, " \n"); // split string by space and newline
    while (token != NULL){
        strings[index++] = token ;
        token = strtok(NULL, " \n");
    }
    strings[index] = NULL;
    return strings;
}

void shell_loop(){
    int status = 1;
    do {
        printf("%s", "$ ");
        char input_command[100] ;
        fgets(input_command, 100, stdin);
        char** command_array = parse_command(input_command);  // parse array of char to array of strings seperated by space and ended with null
        int type = evaluate_command(command_array); // 0: shell builtin, 1: executable or error, -1: exit
        switch (type) {
            case 0:
                execute_shell_builtin(command_array);
                break;
            case 1:
                execute_command(command_array);
                break;
            default:
                status = 0;
                break;
        }
    }
    while(status);
}

void setup_environment(){
    /*cd(Current_Working_Directory)*/
}

void on_child_exit(){
    /*reap_child_zombie()
    write_to_log_file("Child terminated")*/
}

void parent_main(){
    /*register_child_signal(on_child_exit());*/
    setup_environment();
    shell_loop();
}

int main() {
    shell_loop();
    return 0;
}