Download and keep updated currency conversions

Cargo.toml

@@ -10,11 +10,12 @@ license = "MPL-2.0"
 keywords = ["unit", "math", "conversion", "cli", "tool"]
 
 [features]
-default = ["linefeed", "chrono-humanize", "gpl"]
+default = ["linefeed", "chrono-humanize", "gpl", "currency"]
 ircbot = ["irc", "glob"]
 web = ["hyper", "url", "sandbox"]
 sandbox = ["libc", "ipc-channel"]
 gpl = []
+currency = ["hyper", "xml-rs"]
 
 [dependencies]
 rust-gmp = "0.3.2"
@@ -28,6 +29,7 @@ hyper = { version = "0.9.10", optional = true }
 url = { version = "1.2.0", optional = true }
 libc = { version = "0.2.14", optional = true }
 ipc-channel = { version = "0.5.1", optional = true }
+xml-rs = { version = "0.3.4", optional = true }
 
 [[bin]]
 name = "rink"

definitions.units

@@ -531,6 +531,7 @@ specific_volume         ? volume / mass
 spin                    ? mass area / time
 surface_tension         ? energy / area
 fuel_efficiency         ? area^-1
+specific_energy         ? energy / mass
 
 
 #
@@ -4886,7 +4887,7 @@ Ci                      curie        # emitted by the amount of radon that is
                                      # in equilibrium with 1 gram of radium.
 rutherford              1e6 Bq       #
 
-radiation_dose          ? gray
+radiation_dose          gray
 gray                    J/kg         # Absorbed dose of radiation
 Gy                      gray         #
 rad                     1e-2 Gy      # From Radiation Absorbed Dose

src/currency.rs

@@ -0,0 +1,64 @@
+use std::fs::File;
+use std::time::{SystemTime, Duration};
+use std::fmt::Display;
+use hyper::Client;
+use hyper::status::StatusCode;
+use std::io::{Read, Write};
+use std::path::PathBuf;
+use std::fs::create_dir_all;
+
+static URL: &'static str = "http://www.ecb.europa.eu/stats/eurofxref/eurofxref-daily.xml";
+
+pub type Parsed = Vec<(String, f64)>;
+
+pub fn parse(_f: File) -> Parsed {
+    unimplemented!()
+}
+
+fn path() -> Result<PathBuf, String> {
+    let mut path = try!(::config_dir());
+    path.push("rink/currency.xml");
+    Ok(path)
+}
+
+fn download() -> Result<(), String> {
+    try!(create_dir_all(try!(path()).parent().unwrap()).map_err(|x| format!("{}", x)));
+    let mut f = try!(File::create(try!(path())).map_err(|x| format!("{}", x)));
+
+    let client = Client::new();
+    let mut res = try!(client.get(URL).send().map_err(|x| format!("{}", x)));
+    if res.status != StatusCode::Ok {
+        return Err(format!("Request failed with status code {}", res.status))
+    }
+    let mut buf = vec![0; 8192];
+    loop {
+        match res.read(&mut buf) {
+            Ok(0) => break,
+            Ok(n) => {
+                try!(f.write(&buf[..n]).map_err(|x| format!("{}", x)));
+            },
+            Err(e) => return Err(format!("{}", e))
+        }
+    }
+    try!(f.sync_all().map_err(|x| format!("{}", x)));
+    Ok(())
+}
+
+fn open() -> Result<Parsed, String> {
+    fn ts<T:Display>(x: T) -> String {
+        format!("{}", x)
+    }
+    let f = try!(File::open(try!(path())).map_err(ts));
+    let stats = try!(f.metadata().map_err(ts));
+    let mtime = try!(stats.modified().map_err(ts));
+    let now = SystemTime::now();
+    let elapsed = try!(now.duration_since(mtime).map_err(ts));
+    if elapsed > Duration::from_secs(23*60*60) {
+        return Err(format!("File is out of date"))
+    }
+    Ok(parse(f))
+}
+
+pub fn load() -> Result<Parsed, String> {
+    open().or_else(|_| download().and_then(|()| open()))
+}

src/lib.rs

@@ -39,6 +39,10 @@ extern crate chrono_humanize;
 extern crate libc;
 #[cfg(feature = "sandbox")]
 extern crate ipc_channel;
+#[cfg(feature = "currency")]
+extern crate hyper;
+#[cfg(feature = "currency")]
+extern crate xml;
 
 pub mod text_query;
 pub mod eval;
@@ -49,6 +53,8 @@ pub mod gnu_units;
 pub mod ast;
 pub mod value;
 pub mod reply;
+#[cfg(feature = "currency")]
+pub mod currency;
 
 pub use number::Number;
 pub use eval::Context;
@@ -93,6 +99,20 @@ fn config_dir() -> Result<PathBuf, String> {
         .map(|mut x: PathBuf| { x.push("Library/Application Support"); x})
 }
 
+#[cfg(feature = "currency")]
+fn load_currency() -> Option<Result<ast::Defs, String>> {
+    let res = match currency::load() {
+        Ok(x) => x,
+        Err(e) => return Some(Err(e))
+    };
+    unimplemented!()
+}
+
+#[cfg(not(feature = "currency"))]
+fn load_currency() -> Option<Result<ast::Defs, String>> {
+    None
+}
+
 #[cfg(feature = "gpl")]
 static DEFAULT_FILE: Option<&'static str> = Some(include_str!("../definitions.units"));
 #[cfg(not(feature = "gpl"))]
@@ -138,10 +158,16 @@ pub fn load() -> Result<Context, String> {
     let mut iter = gnu_units::TokenIterator::new(&*units).peekable();
     let units = gnu_units::parse(&mut iter);
     let dates = date::parse_datefile(&*dates);
+    let currency = load_currency();
 
     let mut ctx = eval::Context::new();
     ctx.load(units);
     ctx.load_dates(dates);
+    match currency {
+        Some(Ok(currency)) => ctx.load(currency),
+        Some(Err(e)) => println!("Failed to load currency data: {}", e),
+        None => (),
+    }
     Ok(ctx)
 }