// A program to scan emails for phishing links.
// Copyright (C) 2019  Harald Eilertsen
//
// 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/>.

use phisher;
use clap::{clap_app, crate_name, crate_authors, crate_version, crate_description};
use std::boxed::Box;
use std::error::Error;
use std::fs::{ File, remove_file };
use std::io::{ BufRead, BufReader, Write };
use std::os::unix::net::{ UnixListener, UnixStream };
use std::result::Result;
use std::string::ToString;
use std::sync::Arc;
use std::thread;
use std::time::SystemTime;

fn main() {
    let args = clap_app!(app =>
        (name: crate_name!())
        (version: crate_version!())
        (author: crate_authors!())
        (about: crate_description!())
        (@arg PHISHTANK: --phishtank +required +takes_value "The phishtank json data file to use.")
    ).get_matches();

    let start_time = SystemTime::now();
    let filename = args.value_of("PHISHTANK").unwrap();
    if let Ok(file) = File::open(filename) {
        let tank = Arc::new(phisher::load_phistank(BufReader::new(file)).unwrap());

        println!("Loaded {} phishes in {} seconds!",
            tank.phishes.len(),
            start_time.elapsed().unwrap().as_secs());

        match run_server(tank) {
            Ok(_) => println!("Exiting."),
            Err(e) => eprintln!("Error: {}, terminating.", e.to_string())
        };
    }
    else {
        eprintln!("Could not open file {}.\nIs the filename correct?", filename);
    }
}

fn run_server(tank: Arc<phisher::PhishTank>) -> Result<(), Box<dyn Error>> {
    let bind_address = "/tmp/phisher";
    let listener = UnixListener::bind(&bind_address)?;

    println!("Listening for connections on {}...", &bind_address);

    for stream in listener.incoming() {
        match stream {
            Ok(stream) => {
                let t = Arc::clone(&tank);
                thread::spawn(move || {
                    if let Err(e) = handle_connection(stream, t) {
                        eprintln!("Client was disconnected: {}", e.to_string());
                    }
                });
            }
            Err(e) => {
                eprintln!("Received error: {}", e.to_string());
                break;
            }
        }
    }

    Ok(remove_file("/tmp/phisher")?)
}

// Handle a connected client.
//
// Once a client is connected, it can request the status of multiple
// URLs before closing the connection. Each URL must be passed in on
// a separate line, and the results are returned in the same order
// as the URLs were passed in.
//
fn handle_connection(mut stream: UnixStream, tank: Arc<phisher::PhishTank>)
    -> Result<(), Box<dyn Error>>
{
    // Clone the stream so we get another ref to the underlying socket,
    // then wrap it in a BufReader, so we can use read_line on it.
    let mut bufreader = BufReader::new(stream.try_clone()?);

    loop {
        let mut buffer = String::new();
        bufreader.read_line(&mut buffer)?;

        let input = buffer.trim_end();

        if input == "bye" {
            stream.write(b"bye.")?;
            break;
        }

        if tank.is_phish(&input) {
            stream.write(b"it's a phish!\n")?;
        }
        else {
            stream.write(b"good url.\n")?;
        }
    }

    Ok(())
}