simplify date and time parsing

src/calendar.rs

@@ -46,10 +46,6 @@ pub fn create_timetable<TzLocal: TimeZone, TzTarget: TimeZone>(
     Ok(create_timetable_vecs(&time_in_timezone.time(), padding_hrs))
 }
 
-pub fn get_todays_date() -> String {
-    Local::now().format("%d-%m-%Y").to_string()
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;

src/cli.rs

@@ -1,9 +1,10 @@
-use super::calendar::{create_timetable, get_todays_date};
+use super::calendar::create_timetable;
 
 use chrono::Local;
 use chrono::NaiveDate;
 use chrono::NaiveTime;
 use chrono::TimeZone;
+use chrono_tz::TZ_VARIANTS;
 use chrono_tz::Tz;
 use clap::Parser;
 use colored::Colorize;
@@ -28,7 +29,10 @@ pub struct Args {
     #[arg(short, long, default_value = "Local")]
     pub local: String,
 
-    pub time: String,
+    #[arg(long)]
+    pub list: bool,
+
+    pub time: Option<String>,
 }
 
 #[derive(PartialEq, Debug)]
@@ -58,30 +62,30 @@ impl fmt::Display for CliError {
 
 impl Error for CliError {}
 
-// struct Timetable {
-//     pub name: String,
-//     pub values: Vec<NaiveTime>,
-// }
-
 pub fn print_timezones(
     timezones: &Vec<String>,
-    time: &String,
+    time: Option<&String>,
     date: Option<&String>,
     local_timezone: &String,
     padding_hours: i8,
 ) -> Result<(), CliError> {
-    let todays_date = &get_todays_date();
+    let parsed_time = if let Some(t) = time {
-    let date = date.unwrap_or(todays_date);
+        if let Ok(hour) = t.parse::<u32>() {
-
+            NaiveTime::from_hms_opt(hour, 0, 0).ok_or(CliError::CouldNotParseTime)?
-    let parsed_time = if let Ok(hour) = time.parse::<u32>() {
+        } else {
-        NaiveTime::from_hms_opt(hour, 0, 0).ok_or(CliError::CouldNotParseTime)?
+            NaiveTime::parse_from_str(t, "%H:%M").map_err(|_| CliError::CouldNotParseTime)?
+        }
     } else {
-        NaiveTime::parse_from_str(time, "%H:%M").map_err(|_| CliError::CouldNotParseTime)?
+        Local::now().naive_local().time()
     };
 
-    let parsed_date = NaiveDate::parse_from_str(date, "%d-%m-%Y")
+    let parsed_date = if let Some(d) = date {
-        .or_else(|_| NaiveDate::parse_from_str(date, "%d-%m"))
+        NaiveDate::parse_from_str(d, "%d-%m-%Y")
-        .map_err(|_| CliError::CouldNotParseDate)?;
+            .or_else(|_| NaiveDate::parse_from_str(d, "%d-%m"))
+            .map_err(|_| CliError::CouldNotParseDate)?
+    } else {
+        Local::now().naive_local().date()
+    };
 
     if local_timezone == "Local" {
         print_calendar(
@@ -199,3 +203,9 @@ fn print_timetable(name: &String, name_padding_len: u32, timetable: &Vec<NaiveTi
 
     println!("{}:{}\t{}", name, name_padding, formatted.join("\t"));
 }
+
+pub fn list_timezones() {
+    for tz in TZ_VARIANTS {
+        println!("{}", tz.name())
+    }
+}

src/main.rs

@@ -4,13 +4,17 @@ mod cli;
 use clap::Parser;
 use cli::{Args, print_timezones};
 
+use crate::cli::list_timezones;
+
 fn main() {
     let args = Args::parse();
 
-    if args.timezone.len() > 0 {
+    if args.list {
+        list_timezones();
+    } else if args.timezone.len() > 0 {
         let res = print_timezones(
             &args.timezone,
-            &args.time,
+            args.time.as_ref(),
             args.date.as_ref(),
             &args.local,
             5,