Implement Milestone 7.2 offline audio downloads

packages/apple/VelodyNetworking/Sources/VelodyNetworking/VelodyAPIClient.swift

@@ -43,6 +43,11 @@ public protocol VelodyAPIClient: Sendable {
         deviceId: String
     ) async throws -> RemoteLibraryResponseDTO
 
+    func downloadAudioAsset(
+        assetId: String,
+        deviceId: String
+    ) async throws -> Data
+
     func prepareUpload(
         _ payload: UploadPrepareRequest
     ) async throws -> UploadPrepareResponse
@@ -123,6 +128,23 @@ public struct URLSessionVelodyAPIClient: VelodyAPIClient {
         )
     }
 
+    public func downloadAudioAsset(
+        assetId: String,
+        deviceId: String
+    ) async throws -> Data {
+        let request = try buildRequest(
+            method: "GET",
+            pathComponents: ["api", "v1", "assets", assetId, "download"],
+            queryItems: [
+                URLQueryItem(name: "deviceId", value: deviceId),
+            ],
+            bodyData: nil,
+            acceptType: "audio/mpeg"
+        )
+
+        return try await executeData(request)
+    }
+
     public func prepareUpload(
         _ payload: UploadPrepareRequest
     ) async throws -> UploadPrepareResponse {
@@ -236,7 +258,8 @@ public struct URLSessionVelodyAPIClient: VelodyAPIClient {
         pathComponents: [String],
         queryItems: [URLQueryItem],
         bodyData: Data?,
-        contentType: String? = nil
+        contentType: String? = nil,
+        acceptType: String = "application/json"
     ) throws -> URLRequest {
         guard let url = endpointURL(
             pathComponents: pathComponents,
@@ -247,7 +270,7 @@ public struct URLSessionVelodyAPIClient: VelodyAPIClient {
 
         var request = URLRequest(url: url)
         request.httpMethod = method
-        request.setValue("application/json", forHTTPHeaderField: "Accept")
+        request.setValue(acceptType, forHTTPHeaderField: "Accept")
 
         if let bodyData {
             request.httpBody = bodyData
@@ -280,6 +303,20 @@ public struct URLSessionVelodyAPIClient: VelodyAPIClient {
         )
     }
 
+    private func executeData(_ request: URLRequest) async throws -> Data {
+        let data: Data
+        let response: URLResponse
+
+        do {
+            (data, response) = try await session.data(for: request)
+        } catch {
+            throw VelodyAPIError.requestFailed(error.localizedDescription)
+        }
+
+        try validate(response: response, data: data)
+        return data
+    }
+
     private func decodeResponse<Response: Decodable>(
         data: Data,
         response: URLResponse,
@@ -401,6 +438,18 @@ public struct StubVelodyAPIClient: VelodyAPIClient {
         )
     }
 
+    public func downloadAudioAsset(
+        assetId: String,
+        deviceId: String
+    ) async throws -> Data {
+        _ = assetId
+        _ = deviceId
+
+        return Data([
+            0x49, 0x44, 0x33, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x21,
+        ])
+    }
+
     public func prepareUpload(
         _ payload: UploadPrepareRequest
     ) async throws -> UploadPrepareResponse {