Improva error messages when missing cmd line args.

1 files changed, 31 insertions, 10 deletions

diff --git a/src/main.rs b/src/main.rs
index 060dd84..f9c9685 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -17,8 +17,10 @@
 use ical;
 use chrono::{DateTime, TimeZone, Utc};
 use regex::RegexBuilder;
+use std::error::Error;
 use std::fs::File;
 use std::io::BufReader;
+use std::path::{Path, PathBuf};
 
 fn parse_datetime(datetime: Option<String>) -> Option<DateTime<Utc>> {
     if let Some(mut dt) = datetime {
@@ -56,7 +58,7 @@ fn print_event(event: &ical::parser::ical::component::IcalEvent) {
         summary);
 }
 
-fn read_icalendar_from_file(filename: &str) -> std::io::Result<Vec<ical::parser::ical::component::IcalCalendar>> {
+fn read_icalendar_from_file(filename: &Path) -> std::io::Result<Vec<ical::parser::ical::component::IcalCalendar>> {
     let buf = BufReader::new(File::open(filename)?);
     Ok(ical::IcalParser::new(buf)
         .filter_map(|c| c.ok())
@@ -121,16 +123,35 @@ fn match_events_regardless_of_case() {
     assert_eq!(1, events.len());
 }
 
-fn main() {
+struct IcaltoolArgs {
+    filename: PathBuf,
+    pattern: String,
+}
+
+fn parse_args() -> Result<IcaltoolArgs, Box<dyn Error>> {
     let mut args = std::env::args().skip(1);
-    let filename = args.next().unwrap();
-    let pattern = args.next().unwrap();
-    let calendars = read_icalendar_from_file(&filename).unwrap();
-    println!("Found {} calendard in file...", calendars.len());
-
-    for c in calendars {
-        for e in c.events.iter().filter(|e| match_event(&e, &pattern)) {
-            print_event(&e);
+
+    let filename = args.next().ok_or("Missing filename")?.into();
+    let pattern = args.next().ok_or("Missing pattern.")?;
+
+    Ok(IcaltoolArgs{ filename, pattern })
+}
+
+fn main() {
+    match parse_args() {
+        Ok(args) => {
+            let calendars = read_icalendar_from_file(&args.filename).unwrap();
+            println!("Found {} calendard in file...", calendars.len());
+
+            for c in calendars {
+                for e in c.events.iter().filter(|e| match_event(&e, &args.pattern)) {
+                    print_event(&e);
+                }
+            }
+        },
+        Err(e) => {
+            println!("[-] Error: {}", e);
+            println!("Usage: icaltool <filename> <patterns>");
         }
     }
 }