feat(api): add rest embed channel handler

lib/api/src/channel/rest_embed.rs

@@ -0,0 +1,91 @@
+use std::time::Duration;
+
+use actix_web::{HttpResponse, web};
+use serde::{Deserialize, Serialize};
+
+use crate::channel::ChannelBus;
+
+const CACHE_KEY_PREFIX: &str = "oembed:twitter:";
+const CACHE_TTL: Duration = Duration::from_secs(30 * 24 * 60 * 60);
+
+#[derive(Debug, Deserialize)]
+pub struct OEmbedQuery {
+    pub url: String,
+}
+
+#[derive(Debug, Clone, Deserialize, Serialize)]
+pub struct OEmbedResponse {
+    pub author_name: String,
+    pub author_url: String,
+    pub provider_name: String,
+    pub html: String,
+    pub width: Option<i32>,
+    pub height: Option<i32>,
+}
+
+/// Proxy endpoint for fetching oEmbed data from Twitter/X.
+/// Responses are cached via AppCache for 30 days (tweets are immutable).
+pub async fn twitter_oembed(
+    bus: web::Data<ChannelBus>,
+    query: web::Query<OEmbedQuery>,
+) -> Result<HttpResponse, actix_web::Error> {
+    let tweet_url = &query.url;
+
+    // Validate it's actually a Twitter/X URL
+    if !tweet_url.starts_with("https://twitter.com/")
+        && !tweet_url.starts_with("https://x.com/")
+        && !tweet_url.starts_with("http://twitter.com/")
+        && !tweet_url.starts_with("http://x.com/")
+    {
+        return Ok(HttpResponse::BadRequest().json(serde_json::json!({
+            "error": "URL must be a Twitter/X link"
+        })));
+    }
+
+    let cache = &bus.inner.cache;
+    let cache_key = format!("{CACHE_KEY_PREFIX}{tweet_url}");
+
+    // Check cache first
+    if let Ok(Some(cached)) = cache.get::<OEmbedResponse>(&cache_key).await {
+        return Ok(HttpResponse::Ok().json(cached));
+    }
+
+    let data = match fetch_oembed(tweet_url).await {
+        Ok(data) => data,
+        Err(err) => {
+            return Ok(HttpResponse::InternalServerError()
+                .json(serde_json::json!({ "error": err })));
+        }
+    };
+
+    // Store in cache with 30-day TTL
+    let _ = cache.set_with_ttl(&cache_key, &data, CACHE_TTL).await;
+
+    Ok(HttpResponse::Ok().json(data))
+}
+
+async fn fetch_oembed(tweet_url: &str) -> Result<OEmbedResponse, String> {
+    let oembed_url = format!(
+        "https://publish.twitter.com/oembed?url={}&omit_script=true&dnt=true",
+        urlencoding::encode(tweet_url)
+    );
+
+    let client = reqwest::Client::new();
+    let resp = client
+        .get(&oembed_url)
+        .header("User-Agent", "GitDataAI/1.0")
+        .send()
+        .await
+        .map_err(|e| format!("Failed to fetch from Twitter: {e}"))?;
+
+    if !resp.status().is_success() {
+        return Err(format!(
+            "Twitter returned status {}",
+            resp.status().as_u16()
+        ));
+    }
+
+    resp.json::<OEmbedResponse>()
+        .await
+        .map_err(|e| format!("Failed to parse oEmbed response: {e}"))
+}