/**
 * Module for matching adapters to files based on file name or mime type
 */
use crate::adapters::*;

use failure::*;

use regex::{Regex, RegexSet};

use std::iter::Iterator;

use std::rc::Rc;

#[derive(Clone)]
pub enum FastMatcher {
	// MimeType(Regex),
	/**
	 * without the leading dot, e.g. "jpg" or "tar.gz". Matched as /.*\.ext$/
	 *
	 */
	FileExtension(String),
	// todo: maybe add others, e.g. regex on whole filename or even paths
	// todo: maybe allow matching a directory (e.g. /var/lib/postgres)
}

#[derive(Clone)]
pub enum SlowMatcher {
	/// any type of fast matcher
	Fast(FastMatcher),
	///
	/// match by exact mime type extracted using tree_magic
	/// TODO: allow match ignoring suffix etc?
	MimeType(String),
}

pub struct FileMeta {
	// filename is not actually a utf8 string, but since we can't do regex on OsStr and can't get a &[u8] from OsStr either,
	// and since we probably only want to do only matching on ascii stuff anyways, this is the filename as a string with non-valid bytes removed
	pub lossy_filename: String,
	// only given when slow matching is enabled
	pub mimetype: Option<String>,
}

pub fn extension_to_regex(extension: &str) -> Regex {
	Regex::new(&format!("\\.{}$", &regex::escape(extension))).expect("we know this regex compiles")
}

pub fn adapter_matcher<T: AsRef<str>>(
	adapter_names: &[T],
	slow: bool,
) -> Fallible<impl Fn(FileMeta) -> Option<(Rc<dyn FileAdapter>, SlowMatcher)>> {
	let adapters = get_adapters_filtered(adapter_names)?;
	// need order later
	let adapter_names: Vec<String> = adapters.iter().map(|e| e.metadata().name.clone()).collect();
	let mut fname_regexes = vec![];
	let mut mime_regexes = vec![];
	for adapter in adapters.into_iter() {
		let metadata = adapter.metadata();
		use SlowMatcher::*;
		for matcher in metadata.get_matchers(slow) {
			match matcher.as_ref() {
				MimeType(re) => {
					mime_regexes.push((re.clone(), adapter.clone(), MimeType(re.clone())))
				}
				Fast(FastMatcher::FileExtension(re)) => fname_regexes.push((
					extension_to_regex(re),
					adapter.clone(),
					Fast(FastMatcher::FileExtension(re.clone())),
				)),
			};
		}
	}
	let fname_regex_set = RegexSet::new(fname_regexes.iter().map(|p| p.0.as_str()))?;
	let mime_regex_set = RegexSet::new(mime_regexes.iter().map(|p| p.0.as_str()))?;
	Ok(move |meta: FileMeta| {
		let fname_matches: Vec<_> = fname_regex_set
			.matches(&meta.lossy_filename)
			.into_iter()
			.collect();
		let mime_matches: Vec<_> = if slow {
			mime_regex_set
				.matches(&meta.mimetype.expect("No mimetype?"))
				.into_iter()
				.collect()
		} else {
			vec![]
		};
		if fname_matches.len() + mime_matches.len() > 1 {
			// get first according to original priority list...
			// todo: kinda ugly
			let fa = fname_matches
				.iter()
				.map(|e| (fname_regexes[*e].1.clone(), fname_regexes[*e].2.clone()));
			let fb = mime_matches
				.iter()
				.map(|e| (mime_regexes[*e].1.clone(), mime_regexes[*e].2.clone()));
			let mut v = vec![];
			v.extend(fa);
			v.extend(fb);
			v.sort_by_key(|e| {
				adapter_names
					.iter()
					.position(|r| r == &e.0.metadata().name)
					.expect("impossib7")
			});
			eprintln!(
				"Warning: found multiple adapters for {}:",
				meta.lossy_filename
			);
			for mmatch in v.iter() {
				eprintln!(" - {}", mmatch.0.metadata().name);
			}
			return Some(v[0].clone());
		}
		if mime_matches.is_empty() {
			if fname_matches.is_empty() {
				None
			} else {
				let (_, adapter, matcher) = &fname_regexes[fname_matches[0]];
				Some((adapter.clone(), matcher.clone()))
			}
		} else {
			let (_, adapter, matcher) = &mime_regexes[mime_matches[0]];
			Some((adapter.clone(), matcher.clone()))
		}
	})
}