add an 'info' subcommand

cli/src/cmd/shared.rs

@@ -0,0 +1,38 @@
+use clap::Arg;
+use failure::{format_err, Fallible};
+use taskchampion::{Replica, Task};
+use uuid::Uuid;
+
+pub(super) fn task_arg<'a>() -> Arg<'a, 'a> {
+    Arg::with_name("task")
+        .help("task id or uuid")
+        .required(true)
+}
+
+pub(super) fn get_task<S: AsRef<str>>(replica: &mut Replica, task_arg: S) -> Fallible<Task> {
+    let task_arg = task_arg.as_ref();
+
+    // first try treating task as a working-set reference
+    match task_arg.parse::<u64>() {
+        Ok(i) => {
+            let mut working_set = replica.working_set().unwrap();
+            if i > 0 && i < working_set.len() as u64 {
+                if let Some(task) = working_set[i as usize].take() {
+                    return Ok(task);
+                }
+            }
+        }
+        Err(_) => {}
+    }
+
+    match Uuid::parse_str(task_arg) {
+        Ok(uuid) => {
+            if let Some(task) = replica.get_task(&uuid)? {
+                return Ok(task);
+            }
+        }
+        Err(_) => {}
+    }
+
+    Err(format_err!("Cannot interpret {:?} as a task", task_arg))
+}