#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>
#define MAX_INPUT_SIZE 1024
#define MAX_TOKEN_SIZE 64
#define MAX_NUM_TOKENS 64
// Tokenizes the input string based on whitespace
void tokenizeInput(char *input, char **tokens, int *numTokens)
{
    char *token = strtok(input, " \t\n");
    *numTokens = 0;
    while (token != NULL && *numTokens < MAX_NUM_TOKENS)
    {
        tokens[*numTokens] = token;
        (*numTokens)++;
        token = strtok(NULL, " \t\n");
    }
}
// Executes the given command and waits for it to finish
void executeCommand(char **tokens, int numTokens, int background)
{
    pid_t pid = fork();
    if (pid == 0)
    { // Child process
        if (background)
        {
            // Ignore SIGINT signal for background processes
            signal(SIGINT, SIG_IGN);
        }
        // Execute the command
        execvp(tokens[0], tokens);
        // If execvp returns, there was an error
        printf("imcsh: command not found: %s\n", tokens[0]);
        exit(1);
    }
    else if (pid > 0)
    { // Parent process
        if (!background)
        {
            // Wait for the child process to finish
            waitpid(pid, NULL, 0);
        }
        else
        {
            // Print the PID of the background process
            printf("Background process PID: %d\n", pid);
        }
    }
    else
    { // Error occurred
        printf("Failed to fork()\n");
        exit(1);
    }
}
// Prints the version of imcsh
void showVersion()
{
    printf("IMCSH Version 1.1 created by me.\n");
}
// Redirects the output to a file
void redirectOutput(char **tokens, int numTokens)
{
    // Find the ">" symbol in the tokens
    int i;
    for (i = 0; i < numTokens; i++)
    {
        if (strcmp(tokens[i], ">") == 0)
        {
            break;
        }
    }
    // If ">" symbol found and there is a file name after it
    if (i < numTokens - 1)
    {
        char *filename = tokens[i + 1];
        // Open the file for writing (create if it doesn't exist, append if it does)
        FILE *file = fopen(filename, "a");
        if (file != NULL)
        {
            // Duplicate the file descriptor of the opened file
            int fd = fileno(file);
            // Redirect the stdout to the file descriptor
            dup2(fd, STDOUT_FILENO);
            fclose(file);
        }
        else
        {
            printf("imcsh: failed to open file: %s\n", filename);
        }
    }
    else
    {
        printf("imcsh: invalid command syntax\n");
    }
}
int main()
{
    char input[MAX_INPUT_SIZE];
    char *tokens[MAX_NUM_TOKENS];
    int numTokens;
    char *username = getlogin();
    if (username == NULL)
    {
        printf("Failed to get username.\n");
    }
    char hostname[1024];
    if (gethostname(hostname, sizeof(hostname)) != 0)
    {
        printf("Failed to get hostname.\n");
        exit(1);
    }
    while (1)
    {
        // Print the command prompt
        // printf("%s@%s> ", username, hostname);
        printf("user@host> ");
        // Read user input
        fgets(input, sizeof(input), stdin);
        // Tokenize the input
        tokenizeInput(input, tokens, &numTokens);
        if (numTokens > 0)
        {
            // Check for internal commands
            if (strcmp(tokens[0], "exec") == 0)
            {
                int background = 0;
                // Check for "&" symbol at the end (for background execution)
                if (numTokens > 1 && strcmp(tokens[numTokens - 1], "&") == 0)
                {
                    background = 1;
                    tokens[numTokens - 1] = NULL; // Remove "&" symbol
                }
                // Execute the command
                executeCommand(tokens + 1, numTokens - 1, background);
            }
            else if (strcmp(tokens[0], "globalusage") == 0)
            {
                showVersion();
            }
            else if (strcmp(tokens[0], "quit") == 0)
            {
                // Check for running processes
                int status;
                pid_t result;
                do
                {
                    result = waitpid(-1, &status, WNOHANG);
                    if (result > 0)
                    {
                        printf("Running process: %d\n", result);
                    }
                } while (result > 0);
                // Prompt for confirmation
                printf("The following processes are running, are you sure you want to quit? [Y/n]: ");
                char confirm[5];
                fgets(confirm, sizeof(confirm), stdin);
                if (confirm[0] == 'Y' || confirm[0] == 'y')
                {
                    // Terminate all running processes and exit the shell
                    kill(0, SIGTERM);
                    break;
                }
            }
            else
            {
                // External command, execute it
                executeCommand(tokens, numTokens, 0);
            }
        }
    }
    return 0;
}

if (gethostname(hostname, sizeof(hostname)) != 0)
    {
        printf("Failed to get hostname.\n");
        exit(1);
    } 

void tokenizeInput(char *input, char **tokens, int *numTokens)
{
    char *token = strtok(input, " \t\n");
    *numTokens = 0;
    while (token != NULL && *numTokens < MAX_NUM_TOKENS - 1)
    {
        tokens[*numTokens] = token;
        (*numTokens)++;
        token = strtok(NULL, " \t\n");
    }
    tokens[*numTokens] = NULL;
}