Changes

Apis/rag-api/Services/DocumentClassifier.cs

@@ -0,0 +1,65 @@
+using System.Text.RegularExpressions;
+using Api.Services.Contracts;
+using Rag.Models;
+
+namespace Api.Services;
+
+public sealed class DocumentClassifier : IDocumentClassifier
+{
+    private static readonly HashSet<string> KnownTypes = new(StringComparer.OrdinalIgnoreCase)
+    {
+        "cv", "job", "article", "contract", "invoice", "product", "documentation", "unknown"
+    };
+
+    public Task<DocumentClassification> ClassifyAsync(string text, string? providedType, string? providedTitle, CancellationToken ct)
+    {
+        if (!string.IsNullOrWhiteSpace(providedType))
+        {
+            var normalized = NormalizeType(providedType);
+            return Task.FromResult(new DocumentClassification
+            {
+                DocumentType = normalized,
+                Confidence = KnownTypes.Contains(normalized) && normalized != "unknown" ? 1.0 : 0.6,
+                Title = BuildTitle(providedTitle, text, normalized)
+            });
+        }
+
+        var lower = text.ToLowerInvariant();
+        var scores = new Dictionary<string, int>(StringComparer.OrdinalIgnoreCase)
+        {
+            ["cv"] = Count(lower, "curriculum vitae", "resume", "work experience", "professional experience", "education", "skills", "technologies", "linkedin", "github"),
+            ["job"] = Count(lower, "job description", "requirements", "responsibilities", "qualifications", "apply", "we are looking", "salary", "benefits", "remote", "hybrid"),
+            ["contract"] = Count(lower, "agreement", "contract", "party", "parties", "liability", "termination", "confidentiality", "governing law"),
+            ["invoice"] = Count(lower, "invoice", "vat", "subtotal", "total", "amount due", "due date", "billing"),
+            ["documentation"] = Count(lower, "api", "endpoint", "configuration", "install", "usage", "parameters", "response", "request"),
+            ["product"] = Count(lower, "features", "pricing", "sku", "product", "specification", "warranty")
+        };
+
+        var best = scores.OrderByDescending(x => x.Value).First();
+        var type = best.Value <= 0 ? "unknown" : best.Key;
+        var confidence = best.Value <= 0 ? 0.25 : Math.Min(0.95, 0.45 + best.Value * 0.08);
+
+        return Task.FromResult(new DocumentClassification
+        {
+            DocumentType = type,
+            Confidence = confidence,
+            Title = BuildTitle(providedTitle, text, type)
+        });
+    }
+
+    private static int Count(string lower, params string[] terms) => terms.Count(term => lower.Contains(term));
+
+    private static string NormalizeType(string value)
+    {
+        var cleaned = Regex.Replace(value.Trim().ToLowerInvariant(), "[^a-z0-9_-]", "-");
+        return string.IsNullOrWhiteSpace(cleaned) ? "unknown" : cleaned;
+    }
+
+    private static string BuildTitle(string? providedTitle, string text, string documentType)
+    {
+        if (!string.IsNullOrWhiteSpace(providedTitle)) return providedTitle.Trim();
+        var firstLine = text.Split('.', '\n', '\r').Select(x => x.Trim()).FirstOrDefault(x => x.Length > 20);
+        if (!string.IsNullOrWhiteSpace(firstLine)) return firstLine.Length <= 120 ? firstLine : firstLine[..120];
+        return $"{documentType} document";
+    }
+}