extern crate gcd;
extern crate iron;
extern crate router;
extern crate urlencoded;
#[macro_use] extern crate mime;

use gcd::gcd;
use iron::prelude::*;
use iron::status;
use router::Router;
use std::str::FromStr;
use urlencoded::UrlEncodedBody;

fn main() {
    let mut router = Router::new();
    router.get("/", get_form, "root");
    router.post("/gcd", post_gcd, "gcd");

    println!("Serving on http://localhost:3000...");

    Iron::new(router).http("localhost:3000").unwrap();
}

fn get_form(_request: &mut Request) -> IronResult<Response> {
    let mut response = Response::new();

    response.set_mut(status::Ok);
    response.set_mut(mime!(Text/Html; Charset=Utf8));
    response.set_mut(r#"
        <title>GCD Calculator</title>
        <form action="/gcd" method="post">
            <input type="number" min="0" name="n" />
            <input type="number" min="0" name="n" />
            <button type="submit">Compute GCD</button>
        </form>
    "#);

    Ok(response)
}

fn post_gcd(request: &mut Request) -> IronResult<Response> {
    let mut response = Response::new();

    let form_data = match request.get_ref::<UrlEncodedBody>() {
        Err(e) => {
            response.set_mut(status::BadRequest);
            response.set_mut(format!("Error parsing form data: {:?}\n", e));
            return Ok(response)
        },
        Ok(map) => map,
    };

    let unparsed_numbers = match form_data.get("n") {
        None => {
            response.set_mut(status::BadRequest);
            response.set_mut(format!("form data has no 'n' parameter\n"));
            return Ok(response);
        },
        Some(nums) => nums,
    };

    let mut numbers = Vec::new();

    for unparsed in unparsed_numbers {
        match u64::from_str(&unparsed) {
            Err(_) => {
                response.set_mut(status::BadRequest);
                response.set_mut(format!("Value for 'n' parameter not a number: {:?}\n", unparsed));
                return Ok(response);
            },
            Ok(n) => {
                numbers.push(n);
            },
        }
    }

    let mut d = numbers[0];
    for m in &numbers[1..] {
        d = gcd(d, *m);
    }

    response.set_mut(status::Ok);
    response.set_mut(mime!(Text/Html; Charset=Utf8));
    response.set_mut(
        format!("The greatest common divisor of the numbers {:?} is <B>{}</b>\n", numbers, d)
    );

    Ok(response)
}