fix(date): fix the date

Date didn't work out of the box.
Refactor it a bit to match other programs

src/uu/date/src/date.rs

@@ -4,16 +4,20 @@
  * This file is part of the uutils coreutils package.
  *
  * (c) Anthony Deschamps <anthony.j.deschamps@gmail.com>
+ * (c) Sylvestre Ledru <sylvestre@debian.org>
  *
  * For the full copyright and license information, please view the LICENSE
  * file that was distributed with this source code.
  */
 
 extern crate chrono;
-#[macro_use]
+
 extern crate clap;
+#[macro_use]
 extern crate uucore;
 
+use clap::{App, Arg};
+
 use chrono::offset::Utc;
 use chrono::{DateTime, FixedOffset, Local, Offset};
 use std::fs::File;
@@ -25,8 +29,27 @@ const DATE: &str = "date";
 const HOURS: &str = "hours";
 const MINUTES: &str = "minutes";
 const SECONDS: &str = "seconds";
+const HOUR: &str = "hour";
+const MINUTE: &str = "minute";
+const SECOND: &str = "second";
 const NS: &str = "ns";
 
+const NAME: &str = "date";
+const VERSION: &str = env!("CARGO_PKG_VERSION");
+const ABOUT: &str = "print or set the system date and time";
+
+const OPT_DATE: &str = "date";
+const OPT_FORMAT: &str = "format";
+const OPT_FILE: &str = "file";
+const OPT_DEBUG: &str = "debug";
+const OPT_ISO_8601: &str = "iso-8601";
+const OPT_RFC_EMAIL: &str = "rfc-email";
+const OPT_RFC_3339: &str = "rfc-3339";
+const OPT_SET: &str = "set";
+const OPT_REFERENCE: &str = "reference";
+const OPT_UNIVERSAL: &str = "universal";
+const OPT_UNIVERSAL_2: &str = "utc";
+
 // Help strings
 
 static ISO_8601_HELP_STRING: &str = "output date/time in ISO 8601 format.
@@ -35,7 +58,7 @@ static ISO_8601_HELP_STRING: &str = "output date/time in ISO 8601 format.
  for date and time to the indicated precision.
  Example: 2006-08-14T02:34:56-06:00";
 
-static RFC_2822_HELP_STRING: &str = "output date and time in RFC 2822 format.
+static RFC_5322_HELP_STRING: &str = "output date and time in RFC 5322 format.
  Example: Mon, 14 Aug 2006 02:34:56 -0600";
 
 static RFC_3339_HELP_STRING: &str = "output date/time in RFC 3339 format.
@@ -54,7 +77,7 @@ struct Settings {
 /// Various ways of displaying the date
 enum Format {
     Iso8601(Iso8601Format),
-    Rfc2822,
+    Rfc5322,
     Rfc3339(Rfc3339Format),
     Custom(String),
     Default,
@@ -78,9 +101,9 @@ enum Iso8601Format {
 impl<'a> From<&'a str> for Iso8601Format {
     fn from(s: &str) -> Self {
         match s {
-            HOURS => Iso8601Format::Hours,
+            HOURS | HOUR => Iso8601Format::Hours,
-            MINUTES => Iso8601Format::Minutes,
+            MINUTES | MINUTE => Iso8601Format::Minutes,
-            SECONDS => Iso8601Format::Seconds,
+            SECONDS | SECOND => Iso8601Format::Seconds,
             NS => Iso8601Format::Ns,
             DATE => Iso8601Format::Date,
             // Should be caught by clap
@@ -99,7 +122,7 @@ impl<'a> From<&'a str> for Rfc3339Format {
     fn from(s: &str) -> Self {
         match s {
             DATE => Rfc3339Format::Date,
-            SECONDS => Rfc3339Format::Seconds,
+            SECONDS | SECOND => Rfc3339Format::Seconds,
             NS => Rfc3339Format::Ns,
             // Should be caught by clap
             _ => panic!("Invalid format: {}", s),
@@ -108,7 +131,108 @@ impl<'a> From<&'a str> for Rfc3339Format {
 }
 
 pub fn uumain(args: Vec<String>) -> i32 {
-    let settings = parse_cli(args);
+    let syntax = format!(
+        "{0} [OPTION]... [+FORMAT]...
+ {0} [OPTION]... [MMDDhhmm[[CC]YY][.ss]]",
+        NAME
+    );
+    let matches = App::new(executable!())
+        .version(VERSION)
+        .about(ABOUT)
+        .usage(&syntax[..])
+        .arg(
+            Arg::with_name(OPT_DATE)
+                .short("d")
+                .long(OPT_DATE)
+                .takes_value(true)
+                .help("display time described by STRING, not 'now'"),
+        )
+        .arg(
+            Arg::with_name(OPT_FILE)
+                .short("f")
+                .long(OPT_FILE)
+                .takes_value(true)
+                .help("like --date; once for each line of DATEFILE"),
+        )
+        .arg(
+            Arg::with_name(OPT_ISO_8601)
+                .short("I")
+                .long(OPT_ISO_8601)
+                .takes_value(true)
+                .help(ISO_8601_HELP_STRING),
+        )
+        .arg(
+            Arg::with_name(OPT_RFC_EMAIL)
+                .short("R")
+                .long(OPT_RFC_EMAIL)
+                .help(RFC_5322_HELP_STRING),
+        )
+        .arg(
+            Arg::with_name(OPT_RFC_3339)
+                .long(OPT_RFC_3339)
+                .takes_value(true)
+                .help(RFC_3339_HELP_STRING),
+        )
+        .arg(
+            Arg::with_name(OPT_DEBUG)
+                .long(OPT_DEBUG)
+                .help("annotate the parsed date, and warn about questionable usage to stderr"),
+        )
+        .arg(
+            Arg::with_name(OPT_REFERENCE)
+                .short("r")
+                .long(OPT_REFERENCE)
+                .takes_value(true)
+                .help("display the last modification time of FILE"),
+        )
+        .arg(
+            Arg::with_name(OPT_SET)
+                .short("s")
+                .long(OPT_SET)
+                .takes_value(true)
+                .help("set time described by STRING"),
+        )
+        .arg(
+            Arg::with_name(OPT_UNIVERSAL)
+                .short("u")
+                .long(OPT_UNIVERSAL)
+                .alias(OPT_UNIVERSAL_2)
+                .help("print or set Coordinated Universal Time (UTC)"),
+        )
+        .arg(Arg::with_name(OPT_FORMAT).multiple(true))
+        .get_matches_from(&args);
+
+    let format = if let Some(form) = matches.value_of(OPT_FORMAT) {
+        let form = form[1..].into();
+        Format::Custom(form)
+    } else if let Some(fmt) = matches
+        .values_of(OPT_ISO_8601)
+        .map(|mut iter| iter.next().unwrap_or(DATE).into())
+    {
+        Format::Iso8601(fmt)
+    } else if matches.is_present(OPT_RFC_EMAIL) {
+        Format::Rfc5322
+    } else if let Some(fmt) = matches.value_of(OPT_RFC_3339).map(Into::into) {
+        Format::Rfc3339(fmt)
+    } else {
+        Format::Default
+    };
+
+    let date_source = if let Some(date) = matches.value_of(OPT_DATE) {
+        DateSource::Custom(date.into())
+    } else if let Some(file) = matches.value_of(OPT_FILE) {
+        DateSource::File(file.into())
+    } else {
+        DateSource::Now
+    };
+
+    let settings = Settings {
+        utc: matches.is_present(OPT_UNIVERSAL),
+        format,
+        date_source,
+        // TODO: Handle this option:
+        set_to: None,
+    };
 
     if let Some(_time) = settings.set_to {
         unimplemented!();
@@ -174,81 +298,6 @@ pub fn uumain(args: Vec<String>) -> i32 {
     0
 }
 
-/// Handle command line arguments.
-fn parse_cli(args: Vec<String>) -> Settings {
-    let matches = clap_app!(
-        date =>
-            (@group dates =>
-             (@arg date: -d --date [STRING]
-              "display time described by STRING, not 'now'")
-             (@arg file: -f --file [DATEFILE]
-              "like --date; once for each line of DATEFILE"))
-
-            (@group format =>
-             (@arg iso_8601: -I --("iso-8601") <FMT>
-              possible_value[date hours minutes seconds ns]
-              #{0, 1}
-              ISO_8601_HELP_STRING)
-             (@arg rfc_2822: -R --("rfc-2822")
-              RFC_2822_HELP_STRING)
-             (@arg rfc_3339: --("rfc-3339") <FMT>
-              possible_value[date seconds ns]
-              RFC_3339_HELP_STRING)
-             (@arg custom_format: +takes_value {
-                 |s| if s.starts_with('+') {
-                        Ok(())
-                     } else {
-                        Err(String::from("Date formats must start with a '+' character"))
-                     }
-             }))
-
-            (@arg debug: --debug
-             "annotate the parsed date, and warn about questionable usage to stderr")
-            (@arg reference: -r --reference [FILE]
-             "display the last modification time of FILE")
-            (@arg set: -s --set [STRING]
-             "set time described by STRING")
-            (@arg utc: -u --utc --universal
-             "print or set Coordinated Universal Time (UTC)"))
-    // TODO: Decide whether this is appropriate.
-    //   The GNU date command has an explanation of all formatting options,
-    //   but the `chrono` crate has a few differences (most notably, the %Z option)
-    // (after_help: include_str!("usage.txt")))
-    .get_matches_from(args);
-
-    let format = if let Some(form) = matches.value_of("custom_format") {
-        let form = form[1..].into();
-        Format::Custom(form)
-    } else if let Some(fmt) = matches
-        .values_of("iso_8601")
-        .map(|mut iter| iter.next().unwrap_or(DATE).into())
-    {
-        Format::Iso8601(fmt)
-    } else if matches.is_present("rfc_2822") {
-        Format::Rfc2822
-    } else if let Some(fmt) = matches.value_of("rfc_3339").map(Into::into) {
-        Format::Rfc3339(fmt)
-    } else {
-        Format::Default
-    };
-
-    let date_source = if let Some(date) = matches.value_of("date") {
-        DateSource::Custom(date.into())
-    } else if let Some(file) = matches.value_of("file") {
-        DateSource::File(file.into())
-    } else {
-        DateSource::Now
-    };
-
-    Settings {
-        utc: matches.is_present("utc"),
-        format,
-        date_source,
-        // TODO: Handle this option:
-        set_to: None,
-    }
-}
-
 /// Return the appropriate format string for the given settings.
 fn make_format_string(settings: &Settings) -> &str {
     match settings.format {
@@ -259,7 +308,7 @@ fn make_format_string(settings: &Settings) -> &str {
             Iso8601Format::Seconds => "%FT%T%:z",
             Iso8601Format::Ns => "%FT%T,%f%:z",
         },
-        Format::Rfc2822 => "%a, %d %h %Y %T %z",
+        Format::Rfc5322 => "%a, %d %h %Y %T %z",
         Format::Rfc3339(ref fmt) => match *fmt {
             Rfc3339Format::Date => "%F",
             Rfc3339Format::Seconds => "%F %T%:z",