use memmap2::{Mmap, MmapOptions};
use std::{
	fs::File,
	io::{Read, stdin},
	path::PathBuf,
};

use crate::error::Result;

#[derive(Debug, PartialEq)]
pub(crate) enum Source {
	Stdin,
	File(PathBuf),
}

impl Source {
	pub(crate) fn from_paths(paths: Vec<PathBuf>) -> Vec<Self> {
		paths.into_iter().map(Self::File).collect()
	}

	pub(crate) fn from_stdin() -> Vec<Self> {
		vec![Self::Stdin]
	}

	pub(crate) fn display(&self) -> String {
		match self {
			Self::Stdin => "STDIN".to_string(),
			Self::File(path) => format!("FILE {}", path.display()),
		}
	}
}

// TODO: memmap2 docs state that users should implement proper
// procedures to avoid problems the `unsafe` keyword indicate.
// This would be in a later PR.
pub(crate) unsafe fn make_mmap(path: &PathBuf) -> Result<Mmap> {
	unsafe { Ok(Mmap::map(&File::open(path)?)?) }
}

pub(crate) fn make_mmap_stdin() -> Result<Mmap> {
	let mut handle = stdin().lock();
	let mut buf = Vec::new();
	handle.read_to_end(&mut buf)?;
	let mut mmap = MmapOptions::new().len(buf.len()).map_anon()?;
	mmap.copy_from_slice(&buf);
	let mmap = mmap.make_read_only()?;
	Ok(mmap)
}
