Changes

api/Services/Rag/CvRagService.cs

@@ -0,0 +1,169 @@
+using Api.Models.Rag;
+using Api.Settings;
+using Microsoft.Extensions.Options;
+using System.Text.Json;
+
+namespace Api.Services.Rag;
+
+public interface ICvRagService
+{
+    Task<CvIngestResponse> IngestCvAsync(IFormFile file, bool gdprConsent, CancellationToken ct);
+    Task<JobMatchResponse> MatchJobAsync(JobMatchRequest request, CancellationToken ct);
+}
+
+public sealed class CvRagService : ICvRagService
+{
+    private readonly IPdfTextExtractor _pdfTextExtractor;
+    private readonly ITextChunker _textChunker;
+    private readonly IOpenAiRagClient _openAi;
+    private readonly ICvVectorStore _store;
+    private readonly IJobTextExtractor _jobTextExtractor;
+    private readonly RagSettings _settings;
+    private readonly ILogger<CvRagService> _logger;
+
+    public CvRagService(
+        IPdfTextExtractor pdfTextExtractor,
+        ITextChunker textChunker,
+        IOpenAiRagClient openAi,
+        ICvVectorStore store,
+        IJobTextExtractor jobTextExtractor,
+        IOptions<RagSettings> options,
+        ILogger<CvRagService> logger)
+    {
+        _pdfTextExtractor = pdfTextExtractor;
+        _textChunker = textChunker;
+        _openAi = openAi;
+        _store = store;
+        _jobTextExtractor = jobTextExtractor;
+        _settings = options.Value;
+        _logger = logger;
+    }
+
+    public async Task<CvIngestResponse> IngestCvAsync(IFormFile file, bool gdprConsent, CancellationToken ct)
+    {
+        if (!gdprConsent) throw new InvalidOperationException("GDPR consent is required.");
+        if (file.Length == 0) throw new InvalidOperationException("CV PDF is empty.");
+        if (file.Length > _settings.MaxPdfSizeMb * 1024L * 1024L) throw new InvalidOperationException($"PDF is too large. Max size is {_settings.MaxPdfSizeMb} MB.");
+        if (!string.Equals(Path.GetExtension(file.FileName), ".pdf", StringComparison.OrdinalIgnoreCase)) throw new InvalidOperationException("Only PDF files are accepted.");
+
+        await using var stream = file.OpenReadStream();
+        var text = _pdfTextExtractor.ExtractText(stream);
+        if (text.Length < 80) throw new InvalidOperationException("Could not extract enough text from this PDF.");
+
+        var documentId = $"cv_{Guid.NewGuid():N}";
+        var expiresAt = DateTimeOffset.UtcNow.AddMinutes(Math.Max(10, _settings.CvTtlMinutes));
+        var chunks = _textChunker.Chunk(text, _settings.ChunkSize, _settings.ChunkOverlap);
+
+        var stored = new List<StoredCvChunk>();
+        for (var i = 0; i < chunks.Count; i++)
+        {
+            ct.ThrowIfCancellationRequested();
+            stored.Add(new StoredCvChunk
+            {
+                Id = Guid.NewGuid().ToString("N"),
+                DocumentId = documentId,
+                Text = chunks[i],
+                Embedding = await _openAi.CreateEmbeddingAsync(chunks[i], ct),
+                ChunkIndex = i,
+                ExpiresAt = expiresAt
+            });
+        }
+
+        _store.Save(documentId, stored);
+        var summary = await SummarizeCvAsync(text, ct);
+        return new CvIngestResponse(documentId, stored.Count, text.Length, summary);
+    }
+
+    public async Task<JobMatchResponse> MatchJobAsync(JobMatchRequest request, CancellationToken ct)
+    {
+        if (!request.GdprConsent) throw new InvalidOperationException("GDPR consent is required.");
+        if (string.IsNullOrWhiteSpace(request.CvDocumentId)) throw new InvalidOperationException("Missing CV document id.");
+
+        var cvChunks = _store.Get(request.CvDocumentId);
+        if (cvChunks.Count == 0) throw new InvalidOperationException("CV context was not found or has expired. Upload the CV again.");
+
+        var jobText = await _jobTextExtractor.ExtractAsync(request.JobUrl, request.JobDescription, ct);
+        if (jobText.Length < 80) throw new InvalidOperationException("Could not extract enough job text. Paste the job description manually.");
+
+        var jobEmbedding = await _openAi.CreateEmbeddingAsync(jobText, ct);
+        var retrieved = _store.Search(request.CvDocumentId, jobEmbedding, _settings.TopK);
+        var cvContext = string.Join("\n\n", retrieved.Select(x => $"CV chunk {x.ChunkIndex} | similarity {x.Score:0.000}:\n{x.Text}"));
+
+        var systemPrompt = "You are a strict senior technical recruiter and AI CV matcher. Return only valid JSON. Do not invent candidate experience. Use only the supplied CV context and job text.";
+        var userPrompt = $$"""
+Compare the candidate CV context with the job description.
+Return this JSON shape exactly:
+{
+  "score": 0,
+  "summary": "short direct assessment",
+  "strengths": ["strength 1"],
+  "gaps": ["gap 1"],
+  "recommendations": ["action 1"],
+  "evidence": ["short CV evidence quote or paraphrase"]
+}
+Score must be 0-100.
+
+CV CONTEXT:
+{{cvContext}}
+
+JOB DESCRIPTION:
+{{jobText}}
+""";
+
+        var content = await _openAi.CreateChatCompletionAsync(systemPrompt, userPrompt, ct);
+        var response = ParseMatchResponse(content);
+        if (response.Evidence.Count == 0)
+        {
+            response.Evidence = retrieved.Select(x => x.Text.Length > 280 ? x.Text[..280] + "..." : x.Text).ToList();
+        }
+        return response;
+    }
+
+    private async Task<string> SummarizeCvAsync(string cvText, CancellationToken ct)
+    {
+        try
+        {
+            var shortened = cvText.Length > 8000 ? cvText[..8000] : cvText;
+            var content = await _openAi.CreateChatCompletionAsync(
+                "Return only valid JSON.",
+                $$"""
+Summarize this CV in one concise sentence. Return JSON: { "summary": "..." }
+
+CV:
+{{shortened}}
+""",
+                ct);
+            using var doc = JsonDocument.Parse(content);
+            return doc.RootElement.TryGetProperty("summary", out var summary) ? summary.GetString() ?? "CV indexed." : "CV indexed.";
+        }
+        catch (Exception ex)
+        {
+            _logger.LogWarning(ex, "CV summary failed");
+            return "CV indexed.";
+        }
+    }
+
+    private static JobMatchResponse ParseMatchResponse(string content)
+    {
+        try
+        {
+            var response = JsonSerializer.Deserialize<JobMatchResponse>(content, new JsonSerializerOptions { PropertyNameCaseInsensitive = true }) ?? new JobMatchResponse();
+            response.Score = Math.Clamp(response.Score, 0, 100);
+            response.Strengths ??= [];
+            response.Gaps ??= [];
+            response.Recommendations ??= [];
+            response.Evidence ??= [];
+            return response;
+        }
+        catch
+        {
+            return new JobMatchResponse
+            {
+                Score = 0,
+                Summary = "The AI response could not be parsed. Check logs and prompt output.",
+                Gaps = ["Invalid JSON returned by the model."],
+                Evidence = []
+            };
+        }
+    }
+}