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public class GeminiAI { // --- Constants --- // Base URL is constant private const string ApiUrlBase = "https://generativelanguage.googleapis.com/v1beta/models/"; // --- Instance Fields --- // API Key and Model Name are specific to the instance, passed in constructor private readonly string apiKey; private readonly string modelName; // Conversation history is specific to the instance private readonly List<Content> chatHistory; // Concurrency flag specific to chat operations on this instance private bool isSending = false; // --- Static Fields --- // HttpClient can be static and shared for performance (ensure TLS is configured elsewhere) private static readonly HttpClient httpClient = new HttpClient(); #region Gemini API Data Classes // Nested or separate, these classes define the API contract // Added initializers '= null!;' or Array.Empty to satisfy CS8618 without full nullable context public class GeminiRequest { [JsonProperty("contents")] public Content[] Contents { get; set; } = Array.Empty<Content>(); } public class Content { [JsonProperty("role")] public string Role { get; set; } = "user"; [JsonProperty("parts")] public Part[] Parts { get; set; } = Array.Empty<Part>(); } public class Part { [JsonProperty("text")] public string Text { get; set; } = null!; } // Or string.Empty public class GeminiResponse { [JsonProperty("candidates")] public Candidate[] Candidates { get; set; } = Array.Empty<Candidate>(); [JsonProperty("promptFeedback")] public PromptFeedback PromptFeedback { get; set; } = null!; } public class Candidate { [JsonProperty("content")] public Content Content { get; set; } = null!; [JsonProperty("finishReason")] public string FinishReason { get; set; } = null!; [JsonProperty("index")] public int Index { get; set; } [JsonProperty("safetyRatings")] public SafetyRating[] SafetyRatings { get; set; } = Array.Empty<SafetyRating>(); } public class SafetyRating { [JsonProperty("category")] public string Category { get; set; } = null!; [JsonProperty("probability")] public string Probability { get; set; } = null!; } public class PromptFeedback { [JsonProperty("safetyRatings")] public SafetyRating[] SafetyRatings { get; set; } = Array.Empty<SafetyRating>(); } #endregion // Gemini API Data Classes /// <summary> /// Creates a new instance of the Gemini Chat Client. /// </summary> /// <param name="apiKey">Your Google API Key.</param> /// <param name="modelNameInput">The specific Gemini model to use (e.g., "gemini-1.5-pro-latest"). Uses default if null/empty.</param> /// <exception cref="ArgumentNullException">Thrown if apiKey is null or empty.</exception> public GeminiAI(string apiKey, string modelNameInput = "gemini-2.5-pro-preview-03-25") // Default to a stable model //gemini-1.5-pro-latest { if (string.IsNullOrEmpty(apiKey)) { throw new ArgumentNullException(nameof(apiKey), "API Key cannot be null or empty."); } this.apiKey = apiKey; // Assign constructor arg to instance field // Use the input model name, or the default if input is invalid if (string.IsNullOrEmpty(modelNameInput)) { this.modelName = "gemini-2.5-pro-preview-03-25"; // Use the default from parameter signature Debug.WriteLine($"Warning: Model name was empty, defaulting to {this.modelName}"); } else { this.modelName = modelNameInput; // Assign constructor arg to instance field } this.chatHistory = new List<Content>(); // Optional: Configure static HttpClient defaults once if needed // Consider thread safety if modifying static properties after startup // if (httpClient.Timeout == TimeSpan.Zero) { httpClient.Timeout = TimeSpan.FromSeconds(120); } } /// <summary> /// Sends a message as part of the ongoing conversation, maintaining history. /// </summary> /// <param name="userMessage">The user's message.</param> /// <returns>The model's response text as a Task<string?>, or null if an error occurred.</returns> public async Task<string?> SendChatMessageAsync(string userMessage) // Return nullable string { if (isSending) { Debug.WriteLine("Error: SendChatMessageAsync called while another request is in progress."); return null; } if (string.IsNullOrWhiteSpace(userMessage)) { Debug.WriteLine("Error: User message cannot be empty."); return null; } isSending = true; try { chatHistory.Add(new Content { Role = "user", Parts = new[] { new Part { Text = userMessage } } }); // Use instance field modelName string apiUrl = $"{ApiUrlBase}{this.modelName}:generateContent?key={this.apiKey}"; var requestPayload = new GeminiRequest { Contents = chatHistory.ToArray() }; string jsonPayload = JsonConvert.SerializeObject(requestPayload, new JsonSerializerSettings { NullValueHandling = NullValueHandling.Ignore }); Debug.WriteLine($"Sending chat request to {this.modelName} with {chatHistory.Count} history items..."); using (StringContent httpContent = new StringContent(jsonPayload, Encoding.UTF8, "application/json")) { HttpResponseMessage response = await httpClient.PostAsync(apiUrl, httpContent); string jsonResponse = await response.Content.ReadAsStringAsync(); if (response.IsSuccessStatusCode) { // --- Change variable type to nullable --- GeminiResponse? geminiResponse = JsonConvert.DeserializeObject<GeminiResponse>(jsonResponse); // ---------------------------------------- // Your existing null-conditional checks handle the rest correctly string? responseText = geminiResponse?.Candidates?.FirstOrDefault()? .Content?.Parts?.FirstOrDefault()?.Text; if (!string.IsNullOrEmpty(responseText)) { // ... rest of success logic ... chatHistory.Add(new Content { Role = "model", Parts = new[] { new Part { Text = responseText } } }); return responseText.Trim(); } else { Debug.WriteLine($"Warning: Gemini returned null or empty inference response object/text. Raw JSON:\n{jsonResponse}"); return string.Empty; } } // ... rest of method ... else { Debug.WriteLine($"API Error: {(int)response.StatusCode} - {response.ReasonPhrase}\nResponse: {jsonResponse}"); if (chatHistory.Any() && chatHistory.Last().Role == "user") { chatHistory.RemoveAt(chatHistory.Count - 1); } return null; } } } catch (HttpRequestException httpEx) { Debug.WriteLine($"Network Error sending chat: {httpEx.ToString()}"); if (chatHistory.Any() && chatHistory.Last().Role == "user") { chatHistory.RemoveAt(chatHistory.Count - 1); } return null; } catch (JsonException jsonEx) { Debug.WriteLine($"JSON Error processing chat response: {jsonEx.ToString()}"); return null; } // Use fully qualified name if needed, but removing the other using should fix ambiguity catch (Exception ex) { Debug.WriteLine($"Unexpected Error sending chat: {ex.ToString()}"); if (chatHistory.Any() && chatHistory.Last().Role == "user") { chatHistory.RemoveAt(chatHistory.Count - 1); } return null; } finally { isSending = false; } } /// <summary> /// Sends a single message for inference without using or modifying the conversation history. /// </summary> /// <param name="userMessage">The user's message/prompt.</param> /// <returns>The model's response text as a Task<string?>, or null if an error occurred.</returns> public async Task<string?> InferAsync(string userMessage) // Return nullable string { if (string.IsNullOrWhiteSpace(userMessage)) { Debug.WriteLine("Error: User message for inference cannot be empty."); return null; } try { // Use instance field modelName string apiUrl = $"{ApiUrlBase}{this.modelName}:generateContent?key={this.apiKey}"; var requestPayload = new GeminiRequest { Contents = new[] { new Content { Role = "user", Parts = new[] { new Part { Text = userMessage } } } } }; string jsonPayload = JsonConvert.SerializeObject(requestPayload, new JsonSerializerSettings { NullValueHandling = NullValueHandling.Ignore }); Debug.WriteLine($"Sending inference request to {this.modelName}..."); using (StringContent httpContent = new StringContent(jsonPayload, Encoding.UTF8, "application/json")) { HttpResponseMessage response = await httpClient.PostAsync(apiUrl, httpContent); string jsonResponse = await response.Content.ReadAsStringAsync(); if (response.IsSuccessStatusCode) { // --- Change variable type to nullable --- GeminiResponse? geminiResponse = JsonConvert.DeserializeObject<GeminiResponse>(jsonResponse); // ---------------------------------------- // Your existing null-conditional checks handle the rest correctly string? responseText = geminiResponse?.Candidates?.FirstOrDefault()? .Content?.Parts?.FirstOrDefault()?.Text; if (!string.IsNullOrEmpty(responseText)) { // ... rest of success logic ... return responseText.Trim(); } else { // Handle case where deserialization might have worked but responseText is still null/empty // Or if geminiResponse itself was null Debug.WriteLine($"Warning: Gemini returned null or empty response object/text. Raw JSON:\n{jsonResponse}"); if (chatHistory.Any() && chatHistory.Last().Role == "user") { chatHistory.RemoveAt(chatHistory.Count - 1); } return string.Empty; } } // ... rest of method ... else { Debug.WriteLine($"API Error during inference: {(int)response.StatusCode} - {response.ReasonPhrase}\nResponse: {jsonResponse}"); return null; } } } catch (HttpRequestException httpEx) { Debug.WriteLine($"Network Error during inference: {httpEx.ToString()}"); return null; } catch (JsonException jsonEx) { Debug.WriteLine($"JSON Error processing inference response: {jsonEx.ToString()}"); return null; } // Use fully qualified name if needed catch (Exception ex) { Debug.WriteLine($"Unexpected Error during inference: {ex.ToString()}"); return null; } } /// <summary> /// Clears the internal conversation history for this client instance. /// </summary> public void ClearHistory() { this.chatHistory.Clear(); Debug.WriteLine("Chat history cleared."); } // Optional: Add method to get current history if needed public IReadOnlyList<Content> GetHistory() => chatHistory.AsReadOnly(); } // End of GeminiAI class |