feat(expense-categories): AI 建議 for group/sub name + 990 line

Add an AI assist button to the Edit/New Group (大項) and Subcategory (小項) dialogs: the user enters a Chinese name, and the model refines the Chinese, translates it to English, and suggests the matching IRS Form 990 Part IX line. Suggestions surface in a confirm card; Apply fills the Chinese name, English name, and 990 line fields. Backend mirrors the existing expense-classification AI family but over the Form 990 line catalog: IExpenseCategoryAiService + base (catalog load, prompt, id validation) + Claude/Gemini providers + factory that picks the provider from ChurchProfile.AiProvider. New write-gated POST api/expense-categories/ai-suggest endpoint; sub-category requests pass the parent group + its 990 line to bias the choice. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-06-25 14:18:09 -07:00
parent c5b1a9372a
commit 73077295a4
14 changed files with 682 additions and 11 deletions
@@ -0,0 +1,119 @@
+using System.Net.Http.Json;
+using System.Text.Json;
+using ROLAC.API.Data;
+
+namespace ROLAC.API.Services.Ai;
+
+/// <summary>
+/// Refines, translates, and maps an expense category to a Form 990 line via the Google Gemini
+/// <c>generateContent</c> API, using Gemini's structured-output mode (<c>responseSchema</c>). The
+/// catalog, prompt, and id validation come from <see cref="ExpenseCategoryAiServiceBase"/>; this class
+/// only owns the Gemini HTTP call + parse.
+/// </summary>
+public sealed class GeminiExpenseCategoryAiService : ExpenseCategoryAiServiceBase
+{
+    private const string BaseUrl = "https://generativelanguage.googleapis.com/v1beta";
+
+    private readonly HttpClient _http;
+    private readonly IChurchAiConfigProvider _config;
+    private readonly ILogger<GeminiExpenseCategoryAiService> _logger;
+
+    public GeminiExpenseCategoryAiService(
+        HttpClient http,
+        IChurchAiConfigProvider config,
+        AppDbContext db,
+        ILogger<GeminiExpenseCategoryAiService> logger)
+        : base(db)
+    {
+        _http = http;
+        _config = config;
+        _logger = logger;
+    }
+
+    protected override async Task<ModelAnswer?> CallModelAsync(string prompt, CancellationToken ct)
+    {
+        var cfg = await _config.GetAsync(ct);
+        if (string.IsNullOrWhiteSpace(cfg.GeminiApiKey))
+        {
+            _logger.LogWarning("Gemini API key is not configured; category AI assist is disabled.");
+            return null;
+        }
+
+        try
+        {
+            var payload = new
+            {
+                contents = new[]
+                {
+                    new { parts = new[] { new { text = prompt } } },
+                },
+                generationConfig = new
+                {
+                    responseMimeType = "application/json",
+                    responseSchema = new
+                    {
+                        type = "object",
+                        properties = new
+                        {
+                            chineseName = new { type = "string" },
+                            englishName = new { type = "string" },
+                            form990LineId = new { type = "integer" },
+                            confidence = new { type = "number" },
+                        },
+                        required = new[] { "chineseName", "englishName", "form990LineId", "confidence" },
+                    },
+                },
+            };
+
+            var url = $"{BaseUrl}/models/{cfg.GeminiModel}:generateContent";
+            using var request = new HttpRequestMessage(HttpMethod.Post, url)
+            {
+                Content = JsonContent.Create(payload),
+            };
+            request.Headers.Add("X-goog-api-key", cfg.GeminiApiKey);
+
+            using var response = await _http.SendAsync(request, ct);
+            if (!response.IsSuccessStatusCode)
+            {
+                var body = await response.Content.ReadAsStringAsync(ct);
+                _logger.LogWarning("Gemini returned {Status}: {Body}", (int)response.StatusCode, body);
+                return null;
+            }
+
+            // Navigate candidates[0].content.parts[0].text — the model's JSON answer as a string.
+            using var doc = JsonDocument.Parse(await response.Content.ReadAsStreamAsync(ct));
+            var text = doc.RootElement
+                .GetProperty("candidates")[0]
+                .GetProperty("content")
+                .GetProperty("parts")[0]
+                .GetProperty("text")
+                .GetString();
+
+            if (string.IsNullOrWhiteSpace(text))
+            {
+                _logger.LogWarning("Gemini response contained no text part.");
+                return null;
+            }
+
+            var parsed = JsonSerializer.Deserialize<GeminiAnswer>(
+                text, new JsonSerializerOptions { PropertyNameCaseInsensitive = true });
+            if (parsed is null) return null;
+
+            return new ModelAnswer(parsed.ChineseName, parsed.EnglishName, parsed.Form990LineId, parsed.Confidence);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Gemini category AI assist failed.");
+            return null;
+        }
+    }
+
+    /// <summary>Shape of Gemini's JSON answer (constrained by responseSchema).</summary>
+    private sealed class GeminiAnswer
+    {
+        public string? ChineseName   { get; set; }
+        public string? EnglishName   { get; set; }
+        public int?    Form990LineId { get; set; }
+        public double  Confidence    { get; set; }
+    }
+}