handling of CLI flags

src/main.rs

@@ -1,21 +1,48 @@
 use structopt::StructOpt;
+use chrono::{Local, NaiveTime};
+use std::process;
+use std::process::Command;
 
 #[derive(Debug, StructOpt)]
 #[structopt( author, about)]
 struct Cli {
-    #[structopt(short = "k", help="output khal events")]
+    #[structopt(short, long, help="output khal events")]
     khal: bool,
-    #[structopt(short = "t", help="output todos")]
+    #[structopt(short, long, help="output todos")]
     todo: bool,
 }
 
 fn main() {
     let args = Cli::from_args();
 
-    if args.khal && args.todo {
+    if ( !args.khal && !args.todo ) || 
-        println!("khal");
+        ( args.khal && args.todo ) 
+    {
+        eprintln!("Please provide either khal or todo flag.");
+        Cli::clap().print_help();
+        println!();
+        process::exit(1);
+    }
+
+    let now = Local::now().time();
+    let from = now.format("%H:%M").to_string();
+
+    if args.khal {
+        let cmd = Command::new("khal")
+            .arg("list")
+            .arg("-df")
+            .arg("{name}")
+            .arg("-f")
+            .arg("{start-time}")
+            .arg("--notstarted")
+            .arg(&from)
+            .arg("23:59")
+            .output();
+
+        println!("khal output");
+    } else if args.todo {
+        println!("todo output");
     }
 
-    println!("{:?}", args);
 
 }