hive-forge: pr review-reply answers an inline review comment in its conversation

hive-forge/src/main.rs

@@ -85,7 +85,7 @@ enum Verb {
     View(verbs::view::Args),
     /// Issue-scoped commands: `issue <show|create|edit|view|comment|comments|close|reopen|labels|assign|dependency|reaction|timeline> …`.
     Issue(verbs::issue_cmd::Args),
-    /// PR-scoped commands: `pr <show|status|create|merge|reviews|assign-reviewer|commits|diff|view|edit|comment|comments|close|reopen|labels|assign-committer|dependency|reaction|timeline> …`.
+    /// PR-scoped commands: `pr <show|status|create|merge|reviews|review-reply|assign-reviewer|commits|diff|view|edit|comment|comments|close|reopen|labels|assign-committer|dependency|reaction|timeline> …`.
     Pr(verbs::pr_cmd::Args),
     /// Post a comment on an issue or PR.
     #[command(hide = true)]

hive-forge/src/verbs/mod.rs

@@ -36,6 +36,7 @@ pub mod pr_commits;
 pub mod pr_create;
 pub mod pr_edit;
 pub mod pr_merge;
+pub mod pr_review_reply;
 pub mod pr_reviews;
 pub mod pr_status;
 pub mod reaction;

hive-forge/src/verbs/pr_cmd.rs

@@ -33,6 +33,8 @@ enum Cmd {
     Merge(verbs::pr_merge::Args),
     /// List a PR's reviews, or submit one.
     Reviews(verbs::pr_reviews::Args),
+    /// Answer an inline review comment, in its conversation.
+    ReviewReply(verbs::pr_review_reply::Args),
     /// Request (or withdraw with `--remove`) a review from a user.
     AssignReviewer(verbs::pr_assign_reviewer::Args),
     /// Print the PR's unified diff.
@@ -73,6 +75,7 @@ pub fn run(client: &Client, args: Args) -> Result<()> {
         Cmd::Status(a) => verbs::pr_status::run(client, a),
         Cmd::Merge(a) => verbs::pr_merge::run(client, a),
         Cmd::Reviews(a) => verbs::pr_reviews::run(client, a),
+        Cmd::ReviewReply(a) => verbs::pr_review_reply::run(client, a),
         Cmd::AssignReviewer(a) => verbs::pr_assign_reviewer::run(client, a),
         Cmd::Diff(a) => verbs::diff::run(client, a),
         // Generics shared with `issue` — verify the number is a PR first.

hive-forge/src/verbs/pr_review_reply.rs

@@ -0,0 +1,165 @@
+//! `pr review-reply <number> <comment-id>` - answer an inline review comment.
+//!
+//! Forgejo's API has no reply endpoint, so the reply is a one-comment
+//! `COMMENT` review anchored at the same path and line as the comment it
+//! answers; the forge shows comments with one anchor as one conversation.
+
+use anyhow::{Result, bail};
+use clap::Args as ClapArgs;
+use forgejo_api::structs::{CreatePullReviewComment, CreatePullReviewOptions};
+use serde_json::{Value, json};
+
+use crate::body;
+use crate::client::{Client, index};
+use crate::verbs::pr_reviews::{comment_location, fetch_inline_comments};
+use crate::verbs::{all_pages, print_json};
+
+#[derive(ClapArgs)]
+pub struct Args {
+    /// PR number.
+    number: u64,
+    /// Id of the inline comment to answer: the `#id` that `pr reviews` shows.
+    comment_id: i64,
+    /// Inline body text.
+    #[arg(long, conflicts_with = "body_file")]
+    body: Option<String>,
+    /// Read body from a file. `-` means stdin.
+    #[arg(long = "body-file")]
+    body_file: Option<String>,
+}
+
+/// Where a reply has to be anchored to land in the same conversation.
+#[derive(Debug, PartialEq, Eq)]
+struct Anchor {
+    path: String,
+    line: i64,
+    extra_lines: i64,
+}
+
+/// The anchor of `comment`, or an error when it has none to reuse.
+///
+/// Forgejo drops `position` when a push moved the line out of the diff, and
+/// then there is nothing to anchor a reply to.
+fn anchor_of(comment: &Value) -> Result<Anchor> {
+    let line = comment
+        .get("position")
+        .and_then(Value::as_i64)
+        .filter(|&l| l > 0);
+    let path = comment
+        .get("path")
+        .and_then(Value::as_str)
+        .filter(|p| !p.is_empty());
+    let (Some(line), Some(path)) = (line, path) else {
+        bail!(
+            "comment at {} has no line position (a push moved it out of the diff), so a reply \
+             cannot be anchored to it; post a normal PR comment instead",
+            comment_location(comment)
+        );
+    };
+    Ok(Anchor {
+        path: path.to_owned(),
+        line,
+        extra_lines: comment
+            .get("extra_lines_count")
+            .and_then(Value::as_i64)
+            .unwrap_or(0),
+    })
+}
+
+/// Find the inline comment with `id` among the PR's reviews.
+fn find_comment(client: &Client, number: u64, id: i64) -> Result<Value> {
+    let (owner, name) = client.owner_repo()?;
+    let reviews = all_pages(|page, size| {
+        let (_, batch) = client
+            .api()
+            .repo_list_pull_reviews(owner, name, index(number)?)
+            .page(page)
+            .page_size(size)
+            .send()?;
+        Ok(batch)
+    })?;
+    for review in reviews {
+        let Some(review_id) = review.id.filter(|&r| r > 0) else {
+            continue;
+        };
+        let found = fetch_inline_comments(client, number, review_id)
+            .into_iter()
+            .find(|c| c.get("id").and_then(Value::as_i64) == Some(id));
+        if let Some(c) = found {
+            return Ok(c);
+        }
+    }
+    bail!("no inline review comment #{id} on PR #{number}; `pr reviews {number}` lists their ids")
+}
+
+/// # Errors
+///
+/// Fails when the comment is not on this PR, has no line position to anchor
+/// to, or the body is empty; propagates transport errors from the forge.
+pub fn run(client: &Client, args: Args) -> Result<()> {
+    let text = body::resolve_required(
+        args.body.as_deref(),
+        args.body_file.as_deref(),
+        "pr review-reply",
+    )?;
+    let target = find_comment(client, args.number, args.comment_id)?;
+    let anchor = anchor_of(&target)?;
+    let (owner, name) = client.owner_repo()?;
+    let review = client
+        .api()
+        .repo_create_pull_review(
+            owner,
+            name,
+            index(args.number)?,
+            CreatePullReviewOptions {
+                body: Some(String::new()),
+                comments: Some(vec![CreatePullReviewComment {
+                    body: Some(text),
+                    extra_lines_count: Some(anchor.extra_lines),
+                    new_position: Some(anchor.line),
+                    old_position: Some(0),
+                    path: Some(anchor.path),
+                }]),
+                commit_id: target
+                    .get("commit_id")
+                    .and_then(Value::as_str)
+                    .map(str::to_owned),
+                event: Some("COMMENT".to_owned()),
+            },
+        )
+        .send()?;
+    print_json(&json!({
+        "review": review.id,
+        "in_reply_to": args.comment_id,
+        "at": comment_location(&target),
+    }))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn anchor_reuses_path_line_and_span() {
+        let c = json!({"path": "src/a.rs", "position": 42, "extra_lines_count": 2});
+        assert_eq!(
+            anchor_of(&c).unwrap(),
+            Anchor {
+                path: "src/a.rs".into(),
+                line: 42,
+                extra_lines: 2
+            }
+        );
+    }
+
+    #[test]
+    fn anchor_refuses_a_comment_without_position() {
+        let c = json!({"path": "src/a.rs", "position": 0});
+        let err = anchor_of(&c).unwrap_err().to_string();
+        assert!(
+            err.contains("src/a.rs") && err.contains("no line position"),
+            "{err}"
+        );
+        assert!(anchor_of(&json!({"position": 3})).is_err());
+    }
+}