Added last.fm support

src/lastfm.rs

@@ -0,0 +1,89 @@
+use std::collections::HashMap;
+
+use serde::Deserialize;
+
+const BASE_URL: &str = "https://ws.audioscrobbler.com/2.0/";
+
+pub struct LastfmClient {
+    api_key: String,
+    artist_cache: HashMap<String, Vec<SimilarArtist>>,
+}
+
+pub struct SimilarArtist {
+    pub name: String,
+    pub mbid: Option<String>,
+    pub match_score: f64,
+}
+
+// Last.fm returns {"error": N, "message": "..."} on failure
+#[derive(Deserialize)]
+struct ApiError {
+    error: u32,
+    message: String,
+}
+
+// Deserialization structs for the Last.fm API responses
+
+#[derive(Deserialize)]
+struct SimilarArtistsResponse {
+    similarartists: SimilarArtistsWrapper,
+}
+
+#[derive(Deserialize)]
+struct SimilarArtistsWrapper {
+    artist: Vec<ArtistEntry>,
+}
+
+#[derive(Deserialize)]
+struct ArtistEntry {
+    name: String,
+    mbid: Option<String>,
+    #[serde(rename = "match")]
+    match_score: String,
+}
+
+impl LastfmClient {
+    pub fn new(api_key: String) -> Self {
+        Self {
+            api_key,
+            artist_cache: HashMap::new(),
+        }
+    }
+
+    pub fn get_similar_artists(
+        &mut self,
+        artist_mbid: &str,
+    ) -> Result<&[SimilarArtist], Box<dyn std::error::Error>> {
+        if !self.artist_cache.contains_key(artist_mbid) {
+            let url = format!(
+                "{}?method=artist.getSimilar&mbid={}&api_key={}&format=json",
+                BASE_URL, artist_mbid, self.api_key
+            );
+            let body: String = ureq::get(&url).call()?.body_mut().read_to_string()?;
+
+            let artists = if let Ok(err) = serde_json::from_str::<ApiError>(&body) {
+                eprintln!("  Last.fm: {}", err.message);
+                Vec::new()
+            } else {
+                let resp: SimilarArtistsResponse = serde_json::from_str(&body)?;
+                resp.similarartists
+                    .artist
+                    .into_iter()
+                    .map(|a| {
+                        let mbid = a.mbid.filter(|s| !s.is_empty());
+                        SimilarArtist {
+                            name: a.name,
+                            mbid,
+                            match_score: a.match_score.parse().unwrap_or(0.0),
+                        }
+                    })
+                    .collect()
+            };
+
+            self.artist_cache.insert(artist_mbid.to_string(), artists);
+        }
+
+        Ok(self.artist_cache.get(artist_mbid).unwrap())
+    }
+
+}