Extract review logic into bot_actions module

Move `exec_review`, `download_git_diff`, and review formatting
to a new `bot_actions::review` module. Update the review flow to
post inline review comments via the Gitea API and simplify the
comment markdown to a summary. Add diff formatting that
preprocesses added lines with line numbers for the LLM prompt.

src/bot.rs

@@ -1,14 +1,9 @@
-use futures_util::stream::TryStreamExt;
 use serde::Deserialize;
 use std::time::Duration;
-use tokio::io::AsyncReadExt;
-use tokio_util::io::StreamReader;
 
 use crate::{
-    consts::{BOT_PROCESS_MSG, MAX_DIFF_SIZE, REVIEW_PROMPT},
     env::EnvConfig,
-    errors::AppError,
-    gitea::{GiteaAPI, ReviewPayload, WebhookType},
+    gitea::{GiteaAPI, WebhookType},
     open_router::OpenRouterClient,
 };
 
@@ -104,7 +99,13 @@ impl Bot {
 
     pub async fn exec(&self, webhook: WebhookType) {
         let exec_result = match webhook {
-            WebhookType::Review(review_payload) => self.exec_review(review_payload),
+            WebhookType::Review(review_payload) => crate::bot_actions::review::exec_review(
+                &self.gitea_api,
+                &self.open_router_client,
+                &self.http_client,
+                &self.config.open_router_model,
+                review_payload,
+            ),
         }
         .await;
 
@@ -113,104 +114,4 @@ impl Bot {
             Err(err) => println!("{}", err),
         }
     }
-
-    pub async fn exec_review(&self, review_payload: ReviewPayload) -> Result<(), AppError> {
-        let new_comment = self
-            .gitea_api
-            .comment(
-                &BOT_PROCESS_MSG.replace("{model}", &self.config.open_router_model),
-                &review_payload.repository.full_name,
-                review_payload.pull_request.number,
-            )
-            .await?;
-
-        let bot_result: Result<ReviewResult, anyhow::Error> = async {
-            let git_diff = self
-                .download_git_diff(&review_payload.pull_request.diff_url)
-                .await?;
-
-            let bot_request = REVIEW_PROMPT
-                .replace("{subject}", &review_payload.pull_request.title)
-                .replace("{comment}", &review_payload.comment.body)
-                .replace("{diff}", &git_diff);
-
-            let chat_result = self.open_router_client.chat(&bot_request).await?;
-            let mut review_result = serde_json::from_str::<ReviewResult>(&chat_result.message)?;
-
-            review_result.cost = chat_result.cost;
-
-            Ok(review_result)
-        }
-        .await;
-
-        let edit_msg = match bot_result {
-            Ok(bot_result) => self.review_result_to_markdown(&bot_result),
-            Err(e) => format!("Error while reviewing: {}", e),
-        };
-
-        self.gitea_api
-            .edit_comment(
-                &edit_msg,
-                &review_payload.repository.full_name,
-                new_comment.id,
-            )
-            .await?;
-
-        Ok(())
-    }
-
-    fn review_result_to_markdown(&self, review_result: &ReviewResult) -> String {
-        if review_result.reviews.is_empty() {
-            return String::from("No issues found. ✅");
-        }
-
-        let mut md = String::from("## Review Feedback\n\n");
-        for (i, item) in review_result.reviews.iter().enumerate() {
-            if i > 0 {
-                md.push_str("\n---\n\n");
-            }
-            md.push_str(&format!("### `{}`\n\n", item.filename));
-            if let Some(line) = item.line {
-                md.push_str(&format!("> **Line {}**\n\n", line));
-            }
-            if !item.code.is_empty() {
-                let lang = lang_from_filename(&item.filename);
-                md.push_str(&format!("```{}\n{}\n```\n\n", lang, item.code));
-            }
-            md.push_str(&item.message);
-            md.push('\n');
-        }
-
-        if !review_result.comment.is_empty() {
-            md.push_str("\n---\n\n");
-            md.push_str("### Summary\n\n");
-            md.push_str(&review_result.comment);
-            md.push('\n');
-        }
-
-        if let Some(cost) = review_result.cost {
-            md.push_str("\n---\n\n");
-            md.push_str(&format!("### Cost: ${}", cost));
-            md.push('\n');
-        }
-
-        md
-    }
-
-    async fn download_git_diff(&self, url: &str) -> anyhow::Result<String> {
-        let response = self.http_client.get(url).send().await?;
-        let stream = response.bytes_stream().map_err(std::io::Error::other);
-
-        let mut buf = Vec::with_capacity(MAX_DIFF_SIZE);
-        StreamReader::new(stream)
-            .take((MAX_DIFF_SIZE + 1) as u64)
-            .read_to_end(&mut buf)
-            .await?;
-
-        if buf.len() > MAX_DIFF_SIZE {
-            anyhow::bail!("Git diff exceeds the maximum allowed size of 1 Mo");
-        }
-
-        Ok(String::from_utf8_lossy(&buf).into_owned())
-    }
 }