WIP

2026-06-25 12:38:13 -07:00
parent a89e936f4d
commit bdccb79029
11 changed files with 416 additions and 103 deletions
@@ -0,0 +1,124 @@
+using System.Net.Http.Json;
+using System.Text.Json;
+using Microsoft.Extensions.Options;
+using ROLAC.API.Data;
+
+namespace ROLAC.API.Services.Ai;
+
+/// <summary>
+/// Translates and classifies an expense via the Anthropic Claude Messages API. It forces a single
+/// tool call (<c>tool_choice</c> → <c>classify_expense</c>) whose <c>input_schema</c> matches our
+/// answer shape, so the model returns structured JSON in a <c>tool_use</c> block. The catalog,
+/// prompt, and id validation come from <see cref="ExpenseAiServiceBase"/>; this class only owns the
+/// Claude HTTP call + parse. Forced tool use works on every Claude model, so the configured
+/// <see cref="ClaudeOptions.Model"/> can be swapped (e.g. to a cheaper model) without code changes.
+/// </summary>
+public sealed class ClaudeExpenseAiService : ExpenseAiServiceBase
+{
+    private readonly HttpClient _http;
+    private readonly ClaudeOptions _options;
+    private readonly ILogger<ClaudeExpenseAiService> _logger;
+
+    public ClaudeExpenseAiService(
+        HttpClient http,
+        IOptions<ClaudeOptions> options,
+        AppDbContext db,
+        ILogger<ClaudeExpenseAiService> logger)
+        : base(db)
+    {
+        _http = http;
+        _options = options.Value;
+        _logger = logger;
+    }
+
+    protected override async Task<ModelAnswer?> CallModelAsync(string prompt, CancellationToken ct)
+    {
+        if (string.IsNullOrWhiteSpace(_options.ApiKey))
+        {
+            _logger.LogWarning("Claude API key is not configured; expense AI assist is disabled.");
+            return null;
+        }
+
+        try
+        {
+            var payload = new
+            {
+                model = _options.Model,
+                max_tokens = 1024,
+                tools = new[]
+                {
+                    new
+                    {
+                        name = "classify_expense",
+                        description = "Record the English translation and the chosen expense category ids for the expense.",
+                        input_schema = new
+                        {
+                            type = "object",
+                            properties = new
+                            {
+                                chineseDescription = new { type = "string" },
+                                englishDescription = new { type = "string" },
+                                groupId = new { type = "integer" },
+                                subCategoryId = new { type = "integer" },
+                                confidence = new { type = "number" },
+                            },
+                            required = new[] { "chineseDescription", "englishDescription", "groupId", "subCategoryId", "confidence" },
+                        },
+                    },
+                },
+                tool_choice = new { type = "tool", name = "classify_expense" },
+                messages = new[]
+                {
+                    new { role = "user", content = prompt },
+                },
+            };
+
+            var url = $"{_options.BaseUrl}/messages";
+            using var request = new HttpRequestMessage(HttpMethod.Post, url)
+            {
+                Content = JsonContent.Create(payload),
+            };
+            request.Headers.Add("x-api-key", _options.ApiKey);
+            request.Headers.Add("anthropic-version", _options.AnthropicVersion);
+
+            using var response = await _http.SendAsync(request, ct);
+            if (!response.IsSuccessStatusCode)
+            {
+                var body = await response.Content.ReadAsStringAsync(ct);
+                _logger.LogWarning("Claude returned {Status}: {Body}", (int)response.StatusCode, body);
+                return null;
+            }
+
+            // The forced tool call lands in content[] as a tool_use block; its `input` is our object.
+            using var doc = JsonDocument.Parse(await response.Content.ReadAsStreamAsync(ct));
+            foreach (var block in doc.RootElement.GetProperty("content").EnumerateArray())
+            {
+                if (block.GetProperty("type").GetString() != "tool_use") continue;
+
+                var parsed = block.GetProperty("input").Deserialize<ClaudeAnswer>(
+                    new JsonSerializerOptions { PropertyNameCaseInsensitive = true });
+                if (parsed is null) return null;
+
+                return new ModelAnswer(parsed.EnglishDescription, parsed.ChineseDescription, parsed.GroupId, parsed.SubCategoryId, parsed.Confidence);
+            }
+
+            _logger.LogWarning("Claude response contained no tool_use block.");
+            return null;
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Claude expense AI assist failed.");
+            return null;
+        }
+    }
+
+    /// <summary>Shape of the classify_expense tool input the model fills in.</summary>
+    private sealed class ClaudeAnswer
+    {
+        public string? EnglishDescription { get; set; }
+        public string? ChineseDescription { get; set; }
+        public int     GroupId            { get; set; }
+        public int     SubCategoryId      { get; set; }
+        public double  Confidence         { get; set; }
+    }
+}