Create BearWave macOS radio-first app

Sources/BearWaveCore/Services/StationArtworkLoader.swift

@@ -0,0 +1,78 @@
+import AppKit
+import CryptoKit
+import Foundation
+import Observation
+
+@Observable
+@MainActor
+final class StationArtworkLoader {
+    private let cacheDirectory: URL
+    private var memoryCache: [String: NSImage] = [:]
+    private var inFlight: Set<String> = []
+
+    init(cacheDirectory: URL) {
+        self.cacheDirectory = cacheDirectory.appendingPathComponent("station_artwork")
+    }
+
+    func image(for station: RadioStation?) -> NSImage? {
+        guard let urlString = normalizedArtworkURLString(for: station) else {
+            return BearWaveAssets.image(named: "bearwave")
+        }
+        if let cached = memoryCache[urlString] {
+            return cached
+        }
+        if let diskImage = NSImage(contentsOf: cacheURL(for: urlString)) {
+            memoryCache[urlString] = diskImage
+            return diskImage
+        }
+        load(urlString)
+        return BearWaveAssets.image(named: "bearwave")
+    }
+
+    private func load(_ urlString: String) {
+        guard !inFlight.contains(urlString), let url = URL(string: urlString) else { return }
+        inFlight.insert(urlString)
+
+        Task {
+            defer {
+                Task { @MainActor in self.inFlight.remove(urlString) }
+            }
+            do {
+                var request = URLRequest(url: url)
+                request.timeoutInterval = 10
+                request.setValue("BearWave-macOS/1.0", forHTTPHeaderField: "User-Agent")
+                let (data, response) = try await URLSession.shared.data(for: request)
+                guard let http = response as? HTTPURLResponse, (200..<300).contains(http.statusCode),
+                      let image = NSImage(data: data) else { return }
+
+                try? FileManager.default.createDirectory(at: cacheDirectory, withIntermediateDirectories: true)
+                try? data.write(to: cacheURL(for: urlString), options: .atomic)
+
+                await MainActor.run {
+                    memoryCache[urlString] = image
+                }
+            } catch {
+                return
+            }
+        }
+    }
+
+    private func normalizedArtworkURLString(for station: RadioStation?) -> String? {
+        guard let station else { return nil }
+        let raw = station.favicon.trimmingCharacters(in: .whitespacesAndNewlines)
+        guard !raw.isEmpty else { return nil }
+        if raw.hasPrefix("//") {
+            return "https:\(raw)"
+        }
+        if raw.hasPrefix("http://") || raw.hasPrefix("https://") {
+            return raw
+        }
+        return nil
+    }
+
+    private func cacheURL(for urlString: String) -> URL {
+        let digest = SHA256.hash(data: Data(urlString.utf8))
+        let hash = digest.map { String(format: "%02x", $0) }.joined()
+        return cacheDirectory.appendingPathComponent("\(hash).image")
+    }
+}