feat: per-repo issue tracker, Gitea support, PR review pipeline (#10)

compliance-agent/src/webhooks/gitea.rs

@@ -0,0 +1,138 @@
+use std::sync::Arc;
+
+use axum::body::Bytes;
+use axum::extract::{Extension, Path};
+use axum::http::{HeaderMap, StatusCode};
+use hmac::{Hmac, Mac};
+use sha2::Sha256;
+
+use compliance_core::models::ScanTrigger;
+
+use crate::agent::ComplianceAgent;
+
+type HmacSha256 = Hmac<Sha256>;
+
+pub async fn handle_gitea_webhook(
+    Extension(agent): Extension<Arc<ComplianceAgent>>,
+    Path(repo_id): Path<String>,
+    headers: HeaderMap,
+    body: Bytes,
+) -> StatusCode {
+    // Look up the repo to get its webhook secret
+    let oid = match mongodb::bson::oid::ObjectId::parse_str(&repo_id) {
+        Ok(oid) => oid,
+        Err(_) => return StatusCode::NOT_FOUND,
+    };
+    let repo = match agent
+        .db
+        .repositories()
+        .find_one(mongodb::bson::doc! { "_id": oid })
+        .await
+    {
+        Ok(Some(repo)) => repo,
+        _ => {
+            tracing::warn!("Gitea webhook: repo {repo_id} not found");
+            return StatusCode::NOT_FOUND;
+        }
+    };
+
+    // Verify HMAC-SHA256 signature using the per-repo secret
+    if let Some(secret) = &repo.webhook_secret {
+        let signature = headers
+            .get("x-gitea-signature")
+            .and_then(|v| v.to_str().ok())
+            .unwrap_or("");
+
+        if !verify_signature(secret, &body, signature) {
+            tracing::warn!("Gitea webhook: invalid signature for repo {repo_id}");
+            return StatusCode::UNAUTHORIZED;
+        }
+    }
+
+    let event = headers
+        .get("x-gitea-event")
+        .and_then(|v| v.to_str().ok())
+        .unwrap_or("");
+
+    let payload: serde_json::Value = match serde_json::from_slice(&body) {
+        Ok(v) => v,
+        Err(e) => {
+            tracing::warn!("Gitea webhook: invalid JSON: {e}");
+            return StatusCode::BAD_REQUEST;
+        }
+    };
+
+    match event {
+        "push" => {
+            let agent_clone = (*agent).clone();
+            let repo_id = repo_id.clone();
+            tokio::spawn(async move {
+                tracing::info!("Gitea push webhook: triggering scan for {repo_id}");
+                if let Err(e) = agent_clone.run_scan(&repo_id, ScanTrigger::Webhook).await {
+                    tracing::error!("Webhook-triggered scan failed: {e}");
+                }
+            });
+            StatusCode::OK
+        }
+        "pull_request" => handle_pull_request(agent, &repo_id, &payload).await,
+        _ => {
+            tracing::debug!("Gitea webhook: ignoring event '{event}'");
+            StatusCode::OK
+        }
+    }
+}
+
+async fn handle_pull_request(
+    agent: Arc<ComplianceAgent>,
+    repo_id: &str,
+    payload: &serde_json::Value,
+) -> StatusCode {
+    let action = payload["action"].as_str().unwrap_or("");
+    if action != "opened" && action != "synchronized" {
+        return StatusCode::OK;
+    }
+
+    let pr_number = payload["pull_request"]["number"].as_u64().unwrap_or(0);
+    let head_sha = payload["pull_request"]["head"]["sha"]
+        .as_str()
+        .unwrap_or("");
+    let base_sha = payload["pull_request"]["base"]["sha"]
+        .as_str()
+        .unwrap_or("");
+
+    if pr_number == 0 || head_sha.is_empty() || base_sha.is_empty() {
+        tracing::warn!("Gitea PR webhook: missing required fields");
+        return StatusCode::BAD_REQUEST;
+    }
+
+    let repo_id = repo_id.to_string();
+    let head_sha = head_sha.to_string();
+    let base_sha = base_sha.to_string();
+    let agent_clone = (*agent).clone();
+    tokio::spawn(async move {
+        tracing::info!("Gitea PR webhook: reviewing PR #{pr_number} on {repo_id}");
+        if let Err(e) = agent_clone
+            .run_pr_review(&repo_id, pr_number, &base_sha, &head_sha)
+            .await
+        {
+            tracing::error!("PR review failed for #{pr_number}: {e}");
+        }
+    });
+
+    StatusCode::OK
+}
+
+fn verify_signature(secret: &str, body: &[u8], signature: &str) -> bool {
+    // Gitea sends raw hex (no sha256= prefix)
+    let sig_bytes = match hex::decode(signature) {
+        Ok(b) => b,
+        Err(_) => return false,
+    };
+
+    let mut mac = match HmacSha256::new_from_slice(secret.as_bytes()) {
+        Ok(m) => m,
+        Err(_) => return false,
+    };
+    mac.update(body);
+    mac.verify_slice(&sig_bytes).is_ok()
+}