func loadRequestStream()

in Sources/GoogleAI/GenerativeAIService.swift [56:145]
73 lines of code
10 McCabe index (conditional complexity)

  func loadRequestStream<T: GenerativeAIRequest>(request: T)
    -> AsyncThrowingStream<T.Response, Error> {
    return AsyncThrowingStream { continuation in
      Task {
        let urlRequest: URLRequest
        do {
          urlRequest = try self.urlRequest(request: request)
        } catch {
          continuation.finish(throwing: error)
          return
        }

        #if DEBUG
          printCURLCommand(from: urlRequest)
        #endif

        let stream: URLSession.AsyncBytes
        let rawResponse: URLResponse
        do {
          (stream, rawResponse) = try await urlSession.bytes(for: urlRequest)
        } catch {
          continuation.finish(throwing: error)
          return
        }

        // Verify the status code is 200
        let response: HTTPURLResponse
        do {
          response = try httpResponse(urlResponse: rawResponse)
        } catch {
          continuation.finish(throwing: error)
          return
        }

        // Verify the status code is 200
        guard response.statusCode == 200 else {
          Logging.network
            .error("[GoogleGenerativeAI] The server responded with an error: \(response)")
          var responseBody = ""
          for try await line in stream.lines {
            responseBody += line + "\n"
          }

          Logging.default.error("[GoogleGenerativeAI] Response payload: \(responseBody)")
          continuation.finish(throwing: parseError(responseBody: responseBody))

          return
        }

        // Received lines that are not server-sent events (SSE); these are not prefixed with "data:"
        var extraLines: String = ""

        let decoder = JSONDecoder()
        decoder.keyDecodingStrategy = .convertFromSnakeCase
        for try await line in stream.lines {
          Logging.network.debug("[GoogleGenerativeAI] Stream response: \(line)")

          if line.hasPrefix("data:") {
            // We can assume 5 characters since it's utf-8 encoded, removing `data:`.
            let jsonText = String(line.dropFirst(5))
            let data: Data
            do {
              data = try jsonData(jsonText: jsonText)
            } catch {
              continuation.finish(throwing: error)
              return
            }

            // Handle the content.
            do {
              let content = try parseResponse(T.Response.self, from: data)
              continuation.yield(content)
            } catch {
              continuation.finish(throwing: error)
              return
            }
          } else {
            extraLines += line
          }
        }

        if extraLines.count > 0 {
          continuation.finish(throwing: parseError(responseBody: extraLines))
          return
        }

        continuation.finish(throwing: nil)
      }
    }
  }