// fif - File Info Fixer
// Copyright (C) 2021 Lynnesbian
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

mod parameters;

use std::path::{Path};
use walkdir::{WalkDir, DirEntry};
use smartstring::alias::String;
use structopt::StructOpt;
use std::fs::File;
use std::io;
use std::io::Read;
use mime_guess;
use xdg_mime::SharedMimeInfo;
use mime_guess::Mime;
use log::{warn, error};

// TODO: test if this actually works on a windows machine
#[cfg(windows)]
fn is_hidden(entry: &DirEntry) -> bool {
	use std::os::windows::prelude::*;
	use std::fs;
	fs::metadata(entry) // try to get metadata for file
		.map_or(
			false, // if getting metadata/attributes fails, assume it's not hidden
      |f| f.file_attributes() & 0x2 // flag for hidden - https://docs.microsoft.com/en-us/windows/win32/fileio/file-attribute-constants
		)
}

#[cfg(not(windows))]
fn is_hidden(entry: &DirEntry) -> bool {
	entry.file_name().to_str().map_or(false, |f| f.starts_with('.') && f != ".")
}

fn ext_match(args: &parameters::Parameters, entry: &DirEntry) -> bool {
	if !args.scan_hidden && is_hidden(entry) {
		// skip hidden files and directories. this check is performed first because it's very lightweight.
		return false;
	}

	if entry.file_type().is_dir() {
		// always allow directories - there's no point doing file extension matching on something that isn't a file.
		return true;
	}

	let ext = Path::new(entry.file_name()) // create a Path from the entry...
		.extension() // get its extension...
		.map(|e| String::from(e.to_string_lossy())); // and convert it from an OsStr to a String.

	if ext.is_none() { return false } // don't scan files without extensions. TODO - this should be configurable

	if let Some(extensions) = &args.extensions {
		// if the user has specified a list of extensions to check against, make sure this file ends in one of them.
		// TODO - maybe use ascii_lowercase instead?
		return extensions.contains(&ext.unwrap().to_ascii_lowercase().into())
	}
	true
}

fn mime_type(db: &SharedMimeInfo, filepath: &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(filepath)?;

	file.read(&mut buffer)?;

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

fn get_ext_from_mime(mime: &Mime) -> Option<String> {
	match mime_guess::get_mime_extensions(mime) // get a list of possible extensions for this mime type
		.map(|g| g[0]) { // take the first option in the list and return it as a string
		// jpeg files are given the primary extension "jpe", due to the extension list being stored in alphabetical order.
		// to handle this particular case, swap "jpe" out for "jpg", and leave everything else the same, making sure we
		// convert the &strs to Strings.
		Some("jpe") => Some(String::from("jpg")),
		Some(ext) => Some(String::from(ext)),
		None => None
	}
}

fn main() {
	let args = parameters::Parameters::from_args();
	let db = xdg_mime::SharedMimeInfo::new();
	println!("{:#?}", args);
	// println!("{:#?}", args.dirs);
	println!("=====\nIterating directory: {:?}\n=====", args.dirs);

	let stepper = WalkDir::new(&args.dirs).into_iter();
	for entry in stepper.filter_entry(|e| ext_match(&args, e)) {
		let entry = entry.unwrap();
		if !entry.file_type().is_file() {
			// println!("{} is not a file", entry.path().display());
			continue
		}

		// let result = tree_magic_mini::from_filepath(entry.path()).unwrap_or("???");
		let result = mime_type(&db, entry.path());
		if let Err(error) = result {
			error!("{}", error);
			continue
		}

		let result = result.unwrap();
		if result.is_none() {
			warn!("Couldn't determine mimetype for {}", entry.path().display());
			continue
		}

		let result = result.unwrap();

		println!(
			"{} has type {}, extension should be {:?}",
			entry.path().display(),
			result,
			get_ext_from_mime(&result)
		);
	}
}