feat: helper function for generating LLM responses

Controllers/GeneralUseHelperFunctions.cs

@@ -1,5 +1,7 @@
 using Microsoft.EntityFrameworkCore;
 using Microsoft.IdentityModel.Tokens;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
 using QuotifyBE.Data;
 using QuotifyBE.Entities;
 using System.IdentityModel.Tokens.Jwt;
@@ -132,4 +134,108 @@ public class GeneralUseHelpers(ApplicationDbContext db, IConfiguration appsettin
 
         return new JwtSecurityTokenHandler().WriteToken(token);
     }
+
+    public async Task<JObject?> GenerateLLMResponse(string? prompt, string? model, float? temp, int? includedCategory, bool? includeCategorySample)
+    {
+
+        string           _model = model ?? _appsettings.GetSection("LlmIntegration")["DefaultModel"] ?? "deepclaude";
+        float             _temp = temp ?? 0.6f; // sane default
+        string _included_sample = string.Empty;
+        string          _prompt = prompt ?? _appsettings.GetSection("LlmIntegration")["DefaultPrompt"] ??
+                                    "Cześć, czy jesteś w stanie wymyślić i stworzyć jeden oryginalny cytat? " +
+                                    "Zastanów się nad jego puentą, a kiedy będziesz gotów - zwróć sam cytat. " +
+                                    "Nie pytaj mnie co o nim sądzę, ani nie używaj emotikonów (emoji). " +
+                                    "Pamiętaj, że dobre cytaty są krótkie, zwięzłe.";
+
+        if (includedCategory != null)
+        {
+            // Check if category to be included is present.
+            Category? cat = await _db.Categories.FirstOrDefaultAsync(c => c.Id == includedCategory.Value);
+            // It isn't?
+            if (cat == null) return null;
+            // It is?
+            _prompt += $" Niech należy on do kategorii o nazwie \"{cat.Name}\" ({cat.Description}).";
+        }
+
+        // Sanity check
+        if (includeCategorySample != null && includeCategorySample == true)
+        {
+            if (includedCategory == null)
+            {
+                // Can't append something that we're not given.
+                return null;
+            }
+            else
+            {
+                // Try to find the category in question.
+                Category? cat = await _db.Categories.FirstOrDefaultAsync(c => c.Id == includedCategory.Value);
+                // Failed?
+                if (cat == null)
+                {
+                    return null;
+                }
+                else
+                {
+                    IQueryable<Quote> query = _db.Quotes
+                                        .Include(q => q.QuoteCategories!)
+                                        .Where(q => q.QuoteCategories
+                                            .Any(qc => qc.Category == cat)
+                                        );
+                    int totalQuotes = await query.CountAsync();
+                    if (totalQuotes > 0) {
+
+                        Random random = new();
+                        int skip = random.Next(0, totalQuotes);
+
+                        Quote? quote = await query
+                            .Skip(skip)
+                            .Take(1)
+                            .FirstOrDefaultAsync();
+
+                        if (quote != null) {
+                            _prompt += $" Przykładowy cytat z tej kategorii brzmi: \"{quote.Text} ~ {quote.Author}\".\n";
+                        }
+                    }
+                }
+            }
+        }
+
+        List<Dictionary<string, string>> promptMessages = 
+        [
+            new() { { "role", "user" }, {"content", _prompt } }
+        ];
+
+        // Will throw error if not present
+        string apiUrl = _appsettings.GetSection("LlmIntegration")["ApiUrl"] + "/chat/completions"
+            ?? throw new MissingFieldException("API URL missing in LlmIntegration section of appsettings.json!");
+        string apiKey = _appsettings.GetSection("LlmIntegration")["ApiKey"]
+            ?? throw new MissingFieldException("API key missing in LlmIntegration section of appsettings.json!");
+
+        using (var client = new HttpClient())
+        {
+            // Not the best practice if we want reusable connections
+            // https://stackoverflow.com/a/40707446
+            client.DefaultRequestHeaders.Add("Authorization", $"Bearer {apiKey}");
+            var json = JsonConvert.SerializeObject(new
+            {
+                model = _model,
+                temperature = _temp,
+                max_tokens = (includeCategorySample ?? false) ? 2000 : 1000,
+                messages = promptMessages
+            });
+            var content = new StringContent(json, Encoding.UTF8, "application/json");
+            var response = await client.PostAsync(apiUrl, content);
+            if (response.IsSuccessStatusCode)
+            {
+                string receivedResponse = await response.Content.ReadAsStringAsync();
+                return JObject.Parse(receivedResponse);
+            }
+            else
+            {
+                // Handle the error
+                Console.WriteLine($"[QuotifyBE] Error: response status code from API was {response.StatusCode}.");
+                return null;
+            }
+        }
+    }
 }