Add confirmation prompts for modifications of lots of tasks

cli/src/invocation/cmd/modify.rs

@@ -1,15 +1,58 @@
 use crate::argparse::{Filter, Modification};
-use crate::invocation::{apply_modification, filtered_tasks, summarize_task};
+use crate::invocation::util::{confirm, summarize_task};
+use crate::invocation::{apply_modification, filtered_tasks};
+use crate::settings::Settings;
 use taskchampion::Replica;
 use termcolor::WriteColor;
 
+/// confirm modification of more than `modificationt_count_prompt` tasks, defaulting to 3
+fn check_modification<W: WriteColor>(
+    w: &mut W,
+    settings: &Settings,
+    affected_tasks: usize,
+) -> Result<bool, crate::Error> {
+    let setting = settings.modification_count_prompt.unwrap_or(3);
+    if setting == 0 || affected_tasks <= setting as usize {
+        return Ok(true);
+    }
+
+    let prompt = format!("Operation will modify {} tasks; continue?", affected_tasks,);
+    if confirm(&prompt)? {
+        return Ok(true);
+    }
+
+    writeln!(w, "Cancelled")?;
+
+    // only show this help if the setting is not set
+    if settings.modification_count_prompt.is_none() {
+        writeln!(
+            w,
+            "Set the `modification_count_prompt` setting to avoid this prompt:"
+        )?;
+        writeln!(
+            w,
+            "    ta config set modification_count_prompt {}",
+            affected_tasks + 1
+        )?;
+        writeln!(w, "Set it to 0 to disable the prompt entirely")?;
+    }
+    Ok(false)
+}
+
 pub(crate) fn execute<W: WriteColor>(
     w: &mut W,
     replica: &mut Replica,
+    settings: &Settings,
     filter: Filter,
     modification: Modification,
 ) -> Result<(), crate::Error> {
-    for task in filtered_tasks(replica, &filter)? {
+    let tasks = filtered_tasks(replica, &filter)?;
+
+    if !check_modification(w, settings, tasks.size_hint().0)? {
+        return Ok(());
+    }
+
+    for task in tasks {
         let mut task = task.into_mut(replica);
 
         apply_modification(&mut task, &modification)?;
@@ -34,6 +77,7 @@ mod test {
     fn test_modify() {
         let mut w = test_writer();
         let mut replica = test_replica();
+        let settings = Settings::default();
 
         let task = replica
             .new_task(Status::Pending, s!("old description"))
@@ -46,7 +90,7 @@ mod test {
             description: DescriptionMod::Set(s!("new description")),
             ..Default::default()
         };
-        execute(&mut w, &mut replica, filter, modification).unwrap();
+        execute(&mut w, &mut replica, &settings, filter, modification).unwrap();
 
         // check that the task appeared..
         let task = replica.get_task(task.get_uuid()).unwrap().unwrap();

cli/src/invocation/mod.rs

@@ -2,13 +2,14 @@
 
 use crate::argparse::{Command, Subcommand};
 use crate::settings::Settings;
-use taskchampion::{Replica, Server, ServerConfig, StorageConfig, Task, Uuid};
+use taskchampion::{Replica, Server, ServerConfig, StorageConfig, Uuid};
 use termcolor::{ColorChoice, StandardStream};
 
 mod cmd;
 mod filter;
 mod modify;
 mod report;
+mod util;
 
 #[cfg(test)]
 mod test;
@@ -60,7 +61,7 @@ pub(crate) fn invoke(command: Command, settings: Settings) -> Result<(), crate::
                     modification,
                 },
             ..
-        } => return cmd::modify::execute(&mut w, &mut replica, filter, modification),
+        } => return cmd::modify::execute(&mut w, &mut replica, &settings, filter, modification),
 
         Command {
             subcommand:
@@ -149,14 +150,3 @@ fn get_writer() -> StandardStream {
         ColorChoice::Never
     })
 }
-
-/// Summarize a task in a single line
-fn summarize_task(replica: &mut Replica, task: &Task) -> anyhow::Result<String> {
-    let ws = replica.working_set()?;
-    let uuid = task.get_uuid();
-    if let Some(id) = ws.by_uuid(uuid) {
-        Ok(format!("{} - {}", id, task.get_description()))
-    } else {
-        Ok(format!("{} - {}", uuid, task.get_description()))
-    }
-}

cli/src/invocation/util.rs

@@ -0,0 +1,22 @@
+use dialoguer::Confirm;
+use taskchampion::{Replica, Task};
+
+/// Print the prompt and ask the user to answer yes or no.  If input is not from a terminal, the
+/// answer is assumed to be true.
+pub(super) fn confirm<S: Into<String>>(prompt: S) -> anyhow::Result<bool> {
+    if !atty::is(atty::Stream::Stdin) {
+        return Ok(true);
+    }
+    Ok(Confirm::new().with_prompt(prompt).interact()?)
+}
+
+/// Summarize a task in a single line
+pub(super) fn summarize_task(replica: &mut Replica, task: &Task) -> anyhow::Result<String> {
+    let ws = replica.working_set()?;
+    let uuid = task.get_uuid();
+    if let Some(id) = ws.by_uuid(uuid) {
+        Ok(format!("{} - {}", id, task.get_description()))
+    } else {
+        Ok(format!("{} - {}", uuid, task.get_description()))
+    }
+}