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    // Copyright 2015-2017 Parity Technologies (UK) Ltd.
    // This file is part of Parity.

    // Parity 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.

    // Parity 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 Parity.  If not, see <http://www.gnu.org/licenses/>.

    use rustc_serialize::json::Json;
    use std::thread;
    use std::io::Read;
    use std::time::Duration;
    use std::str::FromStr;
    use std::sync::mpsc;
    use hyper::client::{Handler, Request, Response, Client};
    use hyper::{Url, Next, Encoder, Decoder};
    use hyper::net::HttpStream;

    #[derive(Debug)]
    pub struct PriceInfo {
    	pub ethusd: f32,
    }

    pub struct SetPriceHandler<F> {
    	set_price: F,
    	channel: mpsc::Sender<()>,
    }

    impl<F> Drop for SetPriceHandler<F> {
    	fn drop(&mut self) {
    		let _ = self.channel.send(());
    	}
    }

    impl<F: Fn(PriceInfo) + Sync + Send + 'static> Handler<HttpStream> for SetPriceHandler<F> {
    	fn on_request(&mut self, _: &mut Request) -> Next { Next::read().timeout(Duration::from_secs(3)) }
    	fn on_request_writable(&mut self, _: &mut Encoder<HttpStream>) -> Next { Next::read().timeout(Duration::from_secs(3)) }
    	fn on_response(&mut self, _: Response) -> Next { Next::read().timeout(Duration::from_secs(3)) }

    	fn on_response_readable(&mut self, r: &mut Decoder<HttpStream>) -> Next {
    		let mut body = String::new();
    		let info = r.read_to_string(&mut body)
    			.map_err(|e| format!("Unable to read response: {:?}", e))
    			.and_then(|_| self.process_response(&body));

    		if let Err(e) = info {
    			warn!("Failed to auto-update latest ETH price: {:?}", e);
    		}
    		Next::end()
    	}
    }

    impl<F: Fn(PriceInfo) + Sync + Send + 'static> SetPriceHandler<F> {
    	fn process_response(&self, body: &str) -> Result<(), String> {
    		let json = Json::from_str(body).map_err(|e| format!("Invalid JSON returned: {:?}", e))?;
    		let obj = json.find_path(&["result", "ethusd"]).ok_or("USD price not found".to_owned())?;
    		let ethusd = match *obj {
    			Json::String(ref s) => FromStr::from_str(s).ok(),
    			_ => None,
    		}.ok_or("Unexpected price format.".to_owned())?;

    		(self.set_price)(PriceInfo {
    			ethusd: ethusd,
    		});
    		Ok(())
    	}
    }

    impl PriceInfo {
    	pub fn get<F: Fn(PriceInfo) + Sync + Send + 'static>(set_price: F) {
    		thread::spawn(move || {
    			let url = FromStr::from_str("http://api.etherscan.io/api?module=stats&action=ethprice")
    				.expect("string known to be a valid URL; qed");

    			if let Err(e) = Self::request(url, set_price) {
    				warn!("Failed to auto-update latest ETH price: {:?}", e);
    			}
    		});
    	}

    	fn request<F: Fn(PriceInfo) + Send + Sync + 'static>(url: Url, set_price: F) -> Result<(), String> {
    		let (tx, rx) = mpsc::channel();
    		let client = Client::new().map_err(|e| format!("Unable to start client: {:?}", e))?;

    		client.request(
    			url,
    			SetPriceHandler {
    				set_price: set_price,
    				channel: tx,
    			},
    		).map_err(|_| "Request failed.".to_owned())?;

    		// Wait for exit
    		let _ = rx.recv().map_err(|e| format!("Request interrupted: {:?}", e))?;
    		client.close();

    		Ok(())
    	}
    }

    #[test] #[ignore]
    fn should_get_price_info() {
    	use std::sync::Arc;
    	use std::time::Duration;
    	use util::log::init_log;
    	use util::{Condvar, Mutex};

    	init_log();
    	let done = Arc::new((Mutex::new(PriceInfo { ethusd: 0f32 }), Condvar::new()));
    	let rdone = done.clone();

    	PriceInfo::get(move |price| { let mut p = rdone.0.lock(); *p = price; rdone.1.notify_one(); });
    	let mut p = done.0.lock();
    	let t = done.1.wait_for(&mut p, Duration::from_millis(10000));
    	assert!(!t.timed_out());
    	assert!(p.ethusd != 0f32);
    }

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