use std::{
    ops,
    path::{
	PathBuf,
	Path
    },
    fmt,
};
use lazy_static::lazy_static;

pub mod error;

#[derive(Debug, PartialEq, Eq, Hash)]
pub struct TempFile(PathBuf);

const FILENAME_LEN_BYTES: usize = 16;
const PREFIX: &'static str = "lolistealer-";

lazy_static! {
    pub static ref LOCATION: &'static Path = {
	Box::leak(std::env::temp_dir().into_boxed_path())
    };
}

/// Generate a new random byte string for a filename.
fn generate_filename(mut to: impl fmt::Write) -> Result<(), error::Error>
{
    let mut buffer = [0u8; FILENAME_LEN_BYTES];
    getrandom::getrandom(&mut buffer[..])?;

    write!(to, "{}", PREFIX)?;
    for byte in buffer.iter() {
	write!(to, "{:02x}", *byte)?;
    }

    Ok(())
}

impl TempFile
{
    /// Create a new temp file path
    pub fn new() -> Self
    {
	let mut buffer = String::with_capacity((FILENAME_LEN_BYTES*2) + PREFIX.len());
	generate_filename(&mut buffer).expect("tf fatal");
	Self(LOCATION.join(buffer))
    }
    /// Try to create a new temp file path
    pub fn try_new() -> Result<Self, error::Error>
    {
	let mut buffer = String::with_capacity((FILENAME_LEN_BYTES*2) + PREFIX.len());
	generate_filename(&mut buffer)?;
	Ok(Self(LOCATION.join(buffer)))
    }

    /// Consume the `TempFile` and return the raw path, performing no cleanup.
    pub fn into_pathbuf(mut self) -> PathBuf
    {
	let pb = std::mem::replace(&mut self.0, PathBuf::default());
	std::mem::forget(self);
	pb
    }
}

impl ops::Drop for TempFile
{
    fn drop(&mut self)
    {
	if self.0.exists() {
	    if self.0.is_file() {
		let _ = std::fs::remove_file(&self.0);
	    } else {
		let _ = std::fs::remove_dir_all(&self.0);
	    }
	}
    }
}

impl AsRef<Path> for TempFile
{
    fn as_ref(&self) -> &Path
    {
	self.0.as_ref()
    }
}

impl ops::Deref for TempFile
{
    type Target = Path;
    fn deref(&self) -> &Self::Target
    {
	self.0.as_ref()
    }
}