feat(cli/bump): description flag

This allows for optionally specifying a description that can be included
in changelogs.

src/app.rs

@@ -14,7 +14,7 @@ use bomper::{
 use console::{style, Style};
 use gix::refs::transaction::PreviousValue;
 use similar::{ChangeTag, TextDiff};
-use std::{fmt, io::Write, path::PathBuf};
+use std::{fmt, io::Write, path::PathBuf, process::Command};
 
 pub struct App {
     pub args: BaseArgs,
@@ -36,7 +36,19 @@ impl App {
 
         let increment = opts.options.determine_increment(&commits, &tag.version)?;
         let new_version = increment_version(tag.version.clone(), increment);
-        let changelog_entry = generate_changelog_entry(&commits, &new_version.to_string());
+        let version_description = if opts.description {
+            match prompt_for_description()? {
+                Some(description) => Some(description),
+                None => {
+                    println!("Aborting bump due to empty description");
+                    return Ok(());
+                }
+            }
+        } else {
+            None
+        };
+        let changelog_entry =
+            generate_changelog_entry(&commits, &new_version.to_string(), version_description);
 
         let replacement = VersionReplacement {
             old_version: tag.version.to_string(),
@@ -75,13 +87,14 @@ impl App {
                     .ok_or_else(|| Error::VersionNotFound(version.clone()))?;
                 let commits =
                     get_commits_between_tags(&repo, &version_range[1], &version_range[0])?;
-                let changelog_entry = generate_changelog_entry(&commits, &version.to_string());
+                let changelog_entry =
+                    generate_changelog_entry(&commits, &version.to_string(), None);
                 println!("{}", changelog_entry);
             }
             None => {
                 let tag = get_latest_tag(&repo)?;
                 let commits = get_commits_since_tag(&repo, &tag)?;
-                let changelog_entry = generate_changelog_entry(&commits, "unreleased");
+                let changelog_entry = generate_changelog_entry(&commits, "unreleased", None);
                 let path = std::path::PathBuf::from("CHANGELOG.md");
                 if opts.no_decorations {
                     match opts.only_current_version {
@@ -325,3 +338,38 @@ fn print_diff(original: String, new: String, context: String) {
         }
     }
 }
+
+const DESCRIPTION_HELP: &[u8] = br#"
+# Please enter a description for this version change"
+# All lines starting with '#' will be ignored
+# The contents of this file will be inserted into the changelog markdown"#;
+
+fn prompt_for_description() -> Result<Option<String>> {
+    let mut file = tempfile::NamedTempFile::new_in(".")?;
+    file.write_all(DESCRIPTION_HELP)?;
+
+    let editor = std::env::var("EDITOR").map_err(|_| Error::EditorNotSet)?;
+    Command::new(editor)
+        .arg(file.path())
+        .status()
+        .expect("failed to edit changelog description file");
+
+    let description = std::fs::read_to_string(file.path())?;
+    let description = description
+        .lines()
+        .filter(|line| !line.trim().starts_with('#'))
+        .collect::<Vec<_>>()
+        .join("\n");
+
+    if description.is_empty() {
+        Ok(None)
+    } else {
+        // check if the file only contains whitespace
+        let description = description.trim();
+        if description.is_empty() {
+            Ok(None)
+        } else {
+            Ok(Some(description.to_string()))
+        }
+    }
+}

src/changelog.rs

@@ -8,6 +8,7 @@ const TEMPLATE: &str = include_str!("templates/changelog_entry.md");
 pub struct ChangelogEntry<'a> {
     pub version: &'a str,
     pub commits: HashMap<String, Vec<ChangelogCommit>>,
+    pub description: Option<String>,
 }
 
 #[derive(Clone, Debug, serde::Serialize)]
@@ -37,6 +38,7 @@ pub fn display_commit_type(commit_type: &CommitType) -> String {
 pub fn generate_changelog_entry<'a, I: IntoIterator<Item = &'a Commit>>(
     commits: I,
     version: &str,
+    description: Option<String>,
 ) -> String {
     let mut env = minijinja::Environment::new();
     env.add_template("changelog_entry", TEMPLATE).unwrap();
@@ -56,6 +58,7 @@ pub fn generate_changelog_entry<'a, I: IntoIterator<Item = &'a Commit>>(
     let entry = ChangelogEntry {
         version,
         commits: typed_commits,
+        description,
     };
 
     let template = env.get_template("changelog_entry").unwrap();

src/cli.rs

@@ -41,6 +41,10 @@ pub(crate) struct RawBump {
 pub(crate) struct Bump {
     #[clap(flatten)]
     pub options: BumpOptions,
+
+    /// Whether to prompt for a hand-written summary message
+    #[arg(short, long)]
+    pub description: bool,
 }
 
 #[derive(clap::Args, Debug)]

src/error.rs

@@ -55,6 +55,8 @@ pub enum Error {
     #[error("invalid toml: {0}")]
     TomlDeserialize(#[from] toml::de::Error),
 
+    #[error("EDITOR environment variable not set")]
+    EditorNotSet,
     #[error("invalid replacement count: {0}")]
     InvalidReplacementCount(usize),
     #[error("invalid cargo.toml: {0}")]

src/templates/changelog_entry.md

@@ -1,5 +1,8 @@
 ## {{ entry.version }}
-{% for commit_type, commits in entry.commits|items -%}
+{% if entry.description %}
+{{ entry.description }}
+{% endif -%}
+{% for commit_type, commits in entry.commits|items %}
 #### {{ commit_type }}
 {% for commit in commits -%}
 - {{ commit.summary }} - ({{ commit.hash }}) - {{ commit.author }}