use xdg_mime::SharedMimeInfo;
use std::path::Path;
use std::io;
use mime_guess::Mime;
use std::fs::File;
use std::io::Read;
use smartstring::alias::String;
use cached::proc_macro::cached;

pub fn mime_type(db: &SharedMimeInfo, path: &Path) -> io::Result<Option<Mime>, > {
	// attempt to read up to the 256 bytes of the file
	let mut buffer = [0; 256];
	let mut file = File::open(path)?;

	// this can be ignored because it's perfectly okay if the file is less than 256 bytes long - we only care about the
	// first few bytes for the purpose of mime sniffing
	#[allow(clippy::unused_io_amount)]
	file.read(&mut buffer)?;

	Ok(db.get_mime_type_for_data(&buffer).map(|m| m.0))
}

#[cached]
// TODO: avoid cloning mime if possible, although i don't really see how it would be - maybe instead of passing the mime
// object, pass a hash of it?
pub fn mime_extension_lookup(mime: Mime) -> Option<Vec<String>> {
	if mime == mime_guess::mime::IMAGE_JPEG {
		// jpeg files are given the primary extension "jpe", due to the extension list being stored in alphabetical order.
		// to handle this particular case, return a custom vector consisting of just "jpg" and "jpeg".
		return Some(vec![String::from("jpg"), String::from("jpeg")]);
	}
	match mime_guess::get_mime_extensions(&mime) { // get a list of possible extensions for this mime type
		Some(exts) => Some(exts.iter().map(|e| String::from(*e)).collect()),
		None => None
	}
}