chg-shell/main.rs

use std::env;
use std::path::Path;
use std::io::Write;
use std::io::Result as IoResult;
use inquire::{Text, validator::Validation};
use inquire::{Select, Confirm};
use inquire::ui::{RenderConfig, Styled};
use regex::Regex;
use std::io::{Error, ErrorKind};
use std::process::{Command, Output};
use std::ffi::CString;
use libc::{c_char, execvp, fork, waitpid, WIFEXITED, WEXITSTATUS};

static AUTHOR_STRING: &str = r#"
    Author: Spencer
    Description: A shell to promote proper system changes!
    Ask for the source code!
"#;

fn cd(path: &str) -> Result<(), std::io::Error> {
    env::set_current_dir(Path::new(path))
}

fn execute_command(command: &str) -> IoResult<String> {
    // Checking to see if the command is a builtin
    match command.split_whitespace().next() {
        Some(first_word) if first_word == "cd" => {
            let path: String = command.split_whitespace().skip(1).collect::<Vec<&str>>().join(" ");
            match cd(&path) {
                Ok(_) => return Ok("".to_string()),
                Err(e) => return Err(e),
            }
        },
        Some(first_word) if first_word == "author" => {
            println!("{}", AUTHOR_STRING);
            return Ok("".to_string())
        }
        Some(_) => (),
        None => (),
    };

    // Split the command into arguments
    let args: Vec<&str> = command.split_whitespace().collect();
    if args.is_empty() {
        return Err(Error::new(ErrorKind::Other, "No command provided"));
    }

    // Convert command and arguments to CStrings
    let c_args: Vec<CString> = args.iter()
                                   .map(|s| CString::new(*s).expect("CString::new failed"))
                                   .collect();

    // Create an array of pointers to the CStrings
    let mut argv: Vec<*const c_char> = c_args.iter()
                                             .map(|s| s.as_ptr())
                                             .chain(std::iter::once(std::ptr::null()))
                                             .collect();

    // Fork and exec
    unsafe {
        match fork() {
            -1 => return Err(Error::last_os_error()),
            0 => { // Child process
                if execvp(c_args[0].as_ptr(), argv.as_mut_ptr()) == -1 {
                    let e = Error::last_os_error();
                    std::process::exit(e.raw_os_error().unwrap_or(1));
                } else {
                    Err(Error::last_os_error())
                }
            },
            pid => { // Parent process
                let mut status: i32 = 0;
                if waitpid(pid, &mut status, 0) == -1 {
                    return Err(Error::last_os_error());
                }

                if WIFEXITED(status) && WEXITSTATUS(status) == 0 {
                    Ok(String::new())
                } else {
                    let exit_status = WEXITSTATUS(status);
                    Err(Error::new(ErrorKind::Other, format!("Command exited with status {}", exit_status)))
                }
            },
        }
    }
}

fn prompt(name: &str) -> String {
    let mut line = String::new();
    print!("{}", name);
    std::io::stdout().flush().unwrap();
    std::io::stdin().read_line(&mut line).expect("Error: Could not read a line");

    return line.trim().to_string()
}

fn generate_prompt() -> IoResult<String> {
    let command = r#"echo -n "[${USER}@${HOSTNAME} ${PWD##*/}]$ ""#;
    let output: Output = Command::new("bash")
        .arg("-c")
        .arg(command)
        .output()?;

    if output.status.success() {
        // Convert the stdout of the command to a String
        Ok(String::from_utf8_lossy(&output.stdout).to_string())
    } else {
        // Handle errors by converting stderr to a String and returning an Err variant
        let error_message = String::from_utf8_lossy(&output.stderr);
        Err(std::io::Error::new(
            std::io::ErrorKind::Other,
            format!("Command failed with error: {}", error_message),
        ))
    }
}

fn main() {
    // RenderConfig for inquire
    let mut empty_render_config: RenderConfig = RenderConfig::default();
    empty_render_config = empty_render_config.with_prompt_prefix(Styled::new(""));
    empty_render_config = empty_render_config.with_answered_prompt_prefix(Styled::new(""));
    empty_render_config = empty_render_config.with_canceled_prompt_indicator(Styled::new(""));

    // Change type options
    let options: Vec<&str> = vec!["File change", "Package Update", "Package Removal",
                                  "File Removal", "Misc. Command"];

    // Change request input validator
    let re = Regex::new(r"CHG[0-9]{6}$").unwrap();
    let change_validator = move |input: &str| if input.chars().count() == 0 {
        Ok(Validation::Invalid("Change request cannot be empty".into()))
    } else if re.is_match(input) {
        Ok(Validation::Valid)
    } else {
        Ok(Validation::Invalid("Invalid change request (e.g: CHGXXXXXX)".into()))
    };

    let mut bypass_change = false;
    loop {
        let prompt_command = match generate_prompt() {
            Ok(output) => {
                let prompt_output = prompt(&output);
                if prompt_output.chars().count() == 0 {
                    continue;
                } else if prompt_output.starts_with("runme ") || prompt_output == "runme" {
                    bypass_change = true;
                    if prompt_output.len() > 6 {
                        match execute_command(prompt_output.split_at(6).1) {
                            Ok(output) => print!("{}", output),
                            Err(e) => eprintln!("Command failed: {}", e),
                        }
                    }
                    continue;
                } else {
                    prompt_output
                }
            },
            Err(_) => return
        };

        if !bypass_change {
            let change_request = match Text::new("(e.g. CHGXXXXXX) Enter change request: ")
                .with_render_config(empty_render_config.clone())
                .with_validator(change_validator.clone())
                .prompt() {
                    Ok(input) => input,
                    Err(_) => continue,
                };
            println!("Change request validated: {}", change_request);

            let _change_type = Select::new("Change Type?", options.clone())
                .with_render_config(empty_render_config.clone())
                .prompt();

            let ans = Confirm::new("Are you within the change window?")
                .with_default(false)
                .with_help_message("Ensure you are running commands within the change time window")
                .prompt();

            match ans {
                Ok(true) => {
                    match execute_command(&prompt_command) {
                        Ok(output) => print!("{}", output),
                        Err(e) => eprintln!("Command failed: {}", e),
                    }
                }
                Ok(false) =>  {
                    continue
                }
                Err(_) => println!("not running command..."),
            }
        } else {
            match execute_command(&prompt_command) {
                Ok(output) => print!("{}", output),
                Err(e) => eprintln!("Command failed: {}", e)
            }
        }
    }
}