#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/wait.h>
#define RED   "\x1B[31m"
#define RESET "\x1B[0m"

char* varNames[1000];
char* varValues[1000];
int varCount = 0;
int varIndex = 0;

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])){
        if(command_array[1] == NULL || !strcmp("~", command_array[1])){
            chdir(getenv("HOME"));
        }
        else if(!strcmp("..", command_array[1])){
            chdir("..");
        }
        else{
            chdir(command_array[1]);
            if (chdir(command_array[1]) == -1){
                printf("Error! Directory not found\n");
            }
        }
    }
    else if(!strcmp("echo", command_array[0])){
        if(command_array[1] == NULL){
            printf("\n");
        }
        else{
            int j = 1;
            while(command_array[j] != NULL){
                if(command_array[j][0] == '$'){
                    char** x = varNames;
                    char* varName = command_array[1] + 1;
                    for(int i = 0; i < varIndex; i++){
                        if(!strcmp(varName, varNames[i])){
                            printf("%s\n", varValues[i]);
                            return;
                        }
                    }
                    printf("Error! Variable not found\n");
                }
                else{
                    for(int i = 1; command_array[i] != NULL; i++){
                        printf("%s ", command_array[i]);
                    }
                    printf("\n");
                }
                j++;
            }
        }
    }
    else if(!strcmp("export", command_array[0])){
        char* token = strtok(command_array[1], "=");
        varNames[varIndex] = token;
        token = strtok(NULL, "=");
        varValues[varIndex] = token;
        varIndex++;
    }
    int len = sizeof(varNames) / sizeof(varNames[0]);
    for (int i = 0; i < len ; i++) {
        printf("%s\n", varNames[i]);
    }
    for (int i = 0; i < len ; i++) {
        printf("%s\n", varValues[i]);
    }
}

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 if(!strcmp(" ", command_array[0]) || !strcmp("", command_array[0])){
        return 10;
    }
    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 {
        if(!strcmp(getenv("HOME"), getcwd(NULL, 0))){
            printf(RED "%s", "ubuntu@Armia-PC:");
            printf( "%s", "~$ " RESET);
        }
        else{
            printf(RED "%s", "ubuntu@Armia-PC:");
            printf("%s", getcwd(NULL, 0));
            printf("%s", "$ " RESET);
        }
        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;
            case -1:
                status = 0;
                break;
            default:
                break;
        }

    }
    while(status);
}

void setup_environment(){
    chdir(getenv("HOME"));
}

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

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