api: auto-detect Greader API path for Miniflux and FreshRSS

Miniflux serves the Greader API at the server root while FreshRSS uses
/api/greader.php. Instead of hardcoding the FreshRSS suffix, try the
URL as-is first (works for Miniflux) and fall back to appending
/api/greader.php (works for FreshRSS). The user just enters the server
URL without needing to know the API path.

README.md

@@ -1,7 +1,9 @@
 # FeedTheMonkey
 
 FeedTheMonkey is a desktop client for any server that implements the
-[Greader API](https://github.com/theoldreader/api) (such as FreshRSS or Miniflux). It doesn't work as a standalone feed reader —
+[Greader API](https://github.com/theoldreader/api), such as
+[FreshRSS](https://freshrss.org) or [Miniflux](https://miniflux.app).
+Just enter your server URL — the app detects the API path automatically. It doesn't work as a standalone feed reader —
 it connects to a server to fetch articles and sync read state.
 
 This is version 3, rewritten in Rust with GTK4 and libadwaita.

src/api.rs

@@ -42,14 +42,18 @@ struct Summary {
 
 use crate::model::Article;
 
-fn normalize_base_url(server_url: &str) -> String {
+/// Return the candidate base URLs to try in order.
+/// Miniflux serves the Greader API at the server root;
+/// FreshRSS serves it at /api/greader.php.
+fn candidate_base_urls(server_url: &str) -> Vec<String> {
     let base = server_url.trim_end_matches('/');
-    // If the user entered just a host (or host/path) without the FreshRSS
-    // API suffix, append it automatically.
     if base.ends_with("/api/greader.php") {
-        base.to_string()
+        vec![base.to_string()]
     } else {
-        format!("{base}/api/greader.php")
+        vec![
+            base.to_string(),
+            format!("{base}/api/greader.php"),
+        ]
     }
 }
 
@@ -59,47 +63,49 @@ impl Api {
         username: &str,
         password: &str,
     ) -> Result<Self, String> {
-        let base = normalize_base_url(server_url);
         let client = Client::new();
+        let candidates = candidate_base_urls(server_url);
+        let mut last_err = String::new();
+
+        for base in candidates {
             let url = format!("{base}/accounts/ClientLogin");
-        let resp = client
+            let resp = match client
                 .post(&url)
                 .form(&[("Email", username), ("Passwd", password)])
                 .send()
                 .await
-            .map_err(|e| e.to_string())?;
+            {
+                Ok(r) => r,
+                Err(e) => { last_err = e.to_string(); continue; }
+            };
 
             let status = resp.status();
             let body = resp.text().await.map_err(|e| e.to_string())?;
 
             if !status.is_success() {
-            let msg = human_error(&body, status.as_u16());
-            return Err(format!("Login failed ({}): {}", status.as_u16(), msg));
+                last_err = format!("Login failed ({}): {}", status.as_u16(), human_error(&body, status.as_u16()));
+                continue;
             }
 
-        let auth_token = body
-            .lines()
-            .find_map(|l| l.strip_prefix("Auth="))
-            .ok_or_else(|| {
-                // The server returned 200 but not the expected API response —
-                // most likely the URL points to a web page, not a FreshRSS API.
-                if looks_like_html(&body) {
+            let auth_token = match body.lines().find_map(|l| l.strip_prefix("Auth=")) {
+                Some(t) => t.to_string(),
+                None => {
+                    last_err = if looks_like_html(&body) {
                         format!(
-                        "The server at {} does not appear to be a FreshRSS \
-                         Google Reader API endpoint. Check your server URL.",
-                        base
+                            "The server at {base} does not appear to be a \
+                             Greader API endpoint. Check your server URL."
                         )
                     } else {
                         format!("Unexpected response from server: {}", body.trim())
+                    };
+                    continue;
                 }
-            })?
-            .to_string();
+            };
 
-        Ok(Self {
-            client,
-            server_url: base,
-            auth_token,
-        })
+            return Ok(Self { client, server_url: base, auth_token });
+        }
+
+        Err(last_err)
     }
 
     pub async fn fetch_write_token(&self) -> Result<String, String> {