use std::{ffi::CStr, fs::File, io::{self, Read}};
use toml::Value;
use xcb::x;

pub const BSCREENSAVER_WM_CLASS: &[u8] = b"bscreensaver\0Bscreensaver\0";

pub fn init_logging(env_name: &str) {
    env_logger::builder()
        .format_timestamp_millis()
        .parse_env(env_name)
        .init();
}

pub fn load_configuration() -> anyhow::Result<Option<Value>> {
    match xdg::BaseDirectories::new()?.find_config_file("bscreensaver.toml") {
        None => Ok(None),
        Some(config_path) => {
            let mut f = File::open(config_path)?;
            let mut config = String::new();
            f.read_to_string(&mut config)?;
            drop(f);

            let config_toml = config.parse::<Value>()?;
            Ok(Some(config_toml))
        },
    }
}

pub fn create_atom(conn: &xcb::Connection, name: &[u8]) -> xcb::Result<x::Atom> {
    let cookie = conn.send_request(&x::InternAtom {
        only_if_exists: false,
        name,
    });
    Ok(conn.wait_for_reply(cookie)?.atom())
}

pub fn destroy_gc(conn: &xcb::Connection, gc: x::Gcontext) -> xcb::Result<()> {
    conn.send_and_check_request(&x::FreeGc {
        gc,
    })?;
    Ok(())
}

pub fn destroy_window(conn: &xcb::Connection, window: x::Window) -> xcb::Result<()> {
    conn.send_and_check_request(&x::DestroyWindow {
        window,
    })?;
    Ok(())
}

pub fn get_username() -> io::Result<String> {
    // SAFETY: libc must be sane
    let uid = unsafe { libc::getuid() };
    // SAFETY: libc must be sane
    let pwd = unsafe { libc::getpwuid(uid) };
    // SAFETY: null-check occurs on same line
    if pwd.is_null() || unsafe { *pwd }.pw_name.is_null() {
        Err(io::Error::new(io::ErrorKind::NotFound, "Username not found".to_string()))
    } else {
        // SAFETY: libc must be sane; null checks performed above
        let cstr = unsafe { CStr::from_ptr((*pwd).pw_name) };
        cstr.to_str()
            .map_err(|_| io::Error::new(io::ErrorKind::InvalidData, "Invalid UTF-8 data in username".to_string()))
            .map(|s| s.to_string())
    }
}