//! Date and time utils for HTTP.

//!

//! Multiple HTTP header fields store timestamps.

//! For example a response created on May 15, 2015 may contain the header

//! `Date: Fri, 15 May 2015 15:34:21 GMT`. Since the timestamp does not

//! contain any timezone or leap second information it is equvivalent to

//! writing 1431696861 Unix time. Rust’s `SystemTime` is used to store

//! these timestamps.

//!

//! This crate provides two public functions:

//!

//! * `parse_http_date` to parse a HTTP datetime string to a system time

//! * `fmt_http_date` to format a system time to a IMF-fixdate

//!

//! In addition it exposes the `HttpDate` type that can be used to parse

//! and format timestamps. Convert a sytem time to `HttpDate` and vice versa.

//! The `HttpDate` (8 bytes) is smaller than `SystemTime` (16 bytes) and

//! using the display impl avoids a temporary allocation.

#![forbid(unsafe_code)]

use std::error;

use std::fmt::{self, Display, Formatter};

use std::io;

use std::time::SystemTime;

pub use date::HttpDate;

mod date;

/// An opaque error type for all parsing errors.

#[derive(Debug)]

pub struct Error(());

impl error::Error for Error {}

impl Display for Error {

    fn fmt(&self, f: &mut Formatter) -> Result<(), fmt::Error> {

        f.write_str("string contains no or an invalid date")

    }

}

impl From<Error> for io::Error {

    fn from(e: Error) -> io::Error {

        io::Error::new(io::ErrorKind::Other, e)

    }

}

/// Parse a date from an HTTP header field.

///

/// Supports the preferred IMF-fixdate and the legacy RFC 805 and

/// ascdate formats. Two digit years are mapped to dates between

/// 1970 and 2069.

pub fn parse_http_date(s: &str) -> Result<SystemTime, Error> {

    s.parse::<HttpDate>().map(|d| d.into())

}

/// Format a date to be used in a HTTP header field.

///

/// Dates are formatted as IMF-fixdate: `Fri, 15 May 2015 15:34:21 GMT`.

pub fn fmt_http_date(d: SystemTime) -> String {

    format!("{}", HttpDate::from(d))

}

#[cfg(test)]

mod tests {

    use std::str;

    use std::time::{Duration, UNIX_EPOCH};

    use super::{fmt_http_date, parse_http_date, HttpDate};

    #[test]

    fn test_rfc_example() {

        let d = UNIX_EPOCH + Duration::from_secs(784111777);

        assert_eq!(

            d,

            parse_http_date("Sun, 06 Nov 1994 08:49:37 GMT").expect("#1")

        );

        assert_eq!(

            d,

            parse_http_date("Sunday, 06-Nov-94 08:49:37 GMT").expect("#2")

        );

        assert_eq!(d, parse_http_date("Sun Nov  6 08:49:37 1994").expect("#3"));

    }

    #[test]

    fn test2() {

        let d = UNIX_EPOCH + Duration::from_secs(1475419451);

        assert_eq!(

            d,

            parse_http_date("Sun, 02 Oct 2016 14:44:11 GMT").expect("#1")

        );

        assert!(parse_http_date("Sun Nov 10 08:00:00 1000").is_err());

        assert!(parse_http_date("Sun Nov 10 08*00:00 2000").is_err());

        assert!(parse_http_date("Sunday, 06-Nov-94 08+49:37 GMT").is_err());

    }

    #[test]

    fn test3() {

        let mut d = UNIX_EPOCH;

        assert_eq!(d, parse_http_date("Thu, 01 Jan 1970 00:00:00 GMT").unwrap());

        d += Duration::from_secs(3600);

        assert_eq!(d, parse_http_date("Thu, 01 Jan 1970 01:00:00 GMT").unwrap());

        d += Duration::from_secs(86400);

        assert_eq!(d, parse_http_date("Fri, 02 Jan 1970 01:00:00 GMT").unwrap());

        d += Duration::from_secs(2592000);

        assert_eq!(d, parse_http_date("Sun, 01 Feb 1970 01:00:00 GMT").unwrap());

        d += Duration::from_secs(2592000);

        assert_eq!(d, parse_http_date("Tue, 03 Mar 1970 01:00:00 GMT").unwrap());

        d += Duration::from_secs(31536005);

        assert_eq!(d, parse_http_date("Wed, 03 Mar 1971 01:00:05 GMT").unwrap());

        d += Duration::from_secs(15552000);

        assert_eq!(d, parse_http_date("Mon, 30 Aug 1971 01:00:05 GMT").unwrap());

        d += Duration::from_secs(6048000);

        assert_eq!(d, parse_http_date("Mon, 08 Nov 1971 01:00:05 GMT").unwrap());

        d += Duration::from_secs(864000000);

        assert_eq!(d, parse_http_date("Fri, 26 Mar 1999 01:00:05 GMT").unwrap());

    }

    #[test]

    fn test_fmt() {

        let d = UNIX_EPOCH;

        assert_eq!(fmt_http_date(d), "Thu, 01 Jan 1970 00:00:00 GMT");

        let d = UNIX_EPOCH + Duration::from_secs(1475419451);

        assert_eq!(fmt_http_date(d), "Sun, 02 Oct 2016 14:44:11 GMT");

    }

    #[allow(dead_code)]

    fn testcase(data: &[u8]) {

        if let Ok(s) = str::from_utf8(data) {

            println!("{:?}", s);

            if let Ok(d) = parse_http_date(s) {

                let o = fmt_http_date(d);

                assert!(!o.is_empty());

            }

        }

    }

    #[test]

    fn size_of() {

        assert_eq!(::std::mem::size_of::<HttpDate>(), 8);

    }

    #[test]

    fn test_date_comparison() {

        let a = UNIX_EPOCH + Duration::from_secs(784111777);

        let b = a + Duration::from_secs(30);

        assert!(a < b);

        let a_date: HttpDate = a.into();

        let b_date: HttpDate = b.into();

        assert!(a_date < b_date);

        assert_eq!(a_date.cmp(&b_date), ::std::cmp::Ordering::Less)

    }

    #[test]

    fn test_parse_bad_date() {

        // 1994-11-07 is actually a Monday

        let parsed = "Sun, 07 Nov 1994 08:48:37 GMT".parse::<HttpDate>();

        assert!(parsed.is_err())

    }

}