add --rfc3339-to-unix command to parse a datetime in rfc3339 and display it as unix timestamp

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "utcnow"
-version = "1.1.0"
+version = "1.2.0"
 authors = ["Jonathan Strong <jonathan.strong@gmail.com>"]
 edition = "2018"
 

src/main.rs

@@ -1,6 +1,6 @@
 #![allow(unused)]
 use std::str::FromStr;
-use chrono::{DateTime, Utc, NaiveDateTime};
+use chrono::{DateTime, Utc, NaiveDateTime, TimeZone};
 
 const ONE_SECOND: u64 = 1_000_000_000_u64;
 
@@ -68,18 +68,26 @@ fn main() {
             .help("terminate displayed time with null character instead of newline")
             .takes_value(false)
             .required(false))
-        .arg(clap::Arg::with_name("unix-to-utc")
-            .long("unix-to-utc")
-            .help("convert integer unix timestamp (nanoseconds precision) to iso datetime")
+        .arg(clap::Arg::with_name("unix-to-rfc3339")
+            .long("unix-to-rfc3339")
+            .alias("unix-to-utc")
+            .help("convert integer unix timestamp (nanoseconds precision) to datetime in rfc3339 format")
             .takes_value(true)
             .required(false)
             .conflicts_with_all(&["unix", "seconds"]))
+        .arg(clap::Arg::with_name("rfc3339-to-unix")
+            .long("rfc3339-to-unix")
+            .alias("utc-to-unix")
+            .help("parse rfc3339 timestamp and display it as a unix timestamp")
+            .takes_value(true)
+            .required(false)
+            .conflicts_with_all(&["unix", "unix-to-rfc3339", "rfc2822", "timespec"]))
         .get_matches();
 
     
     let (sec, nsec): (i64, i32) =
 
-        if let Some(ts_str) = args.value_of("unix-to-utc") {                            // either parse --unix-to-utc input
+        if let Some(ts_str) = args.value_of("unix-to-rfc3339") {                        // either parse --unix-to-rfc3339 input
             match u64::from_str(ts_str) {
                 Ok(nanos) => nanos_to_timespec(nanos),
 
@@ -88,6 +96,18 @@ fn main() {
                     std::process::exit(1);
                 }
             }
+
+        } else if let Some(rfc_str) = args.value_of("rfc3339-to-unix") {                // or --rfc3339-to-unix
+            //match DateTime::<Utc>::parse_from_rfc3339(rfc_str) {
+            match rfc_str.parse::<DateTime<Utc>>() {
+                Ok(utc) => nanos_to_timespec(nanos(utc)),
+
+                Err(e) => {
+                    eprintln!("failed to parse timestamp (expected integer): {}", e);
+                    std::process::exit(1);
+                }
+            }
+
         } else {                                                                        // or else get current time
             get_time()
         };
@@ -100,7 +120,7 @@ fn main() {
         print!("{},{}{}", sec, nsec, endline);
 
 
-    } else if args.is_present("unix") {                                                 // display unix
+    } else if args.is_present("unix") || args.is_present("rfc3339-to-unix") {           // display unix
 
         if args.is_present("seconds") {                                                 // unix seconds
             print!("{}{}", sec, endline);