feat(extract): implement PDF extraction via pdftotext

ingestion/internal/extract/extract_test.go

@@ -3,6 +3,7 @@ package extract
 
 import (
 	"os"
+	"os/exec"
 	"path/filepath"
 	"testing"
 
@@ -38,3 +39,24 @@ func TestText_UnsupportedExtension(t *testing.T) {
 	_, err := Text(path)
 	assert.ErrorContains(t, err, "unsupported")
 }
+
+func TestText_PDF(t *testing.T) {
+	if _, err := exec.LookPath("pdftotext"); err != nil {
+		t.Skip("pdftotext not available")
+	}
+	dir := t.TempDir()
+	pdfPath := filepath.Join(dir, "test.pdf")
+
+	// Minimal valid PDF containing the text "Hello PDF".
+	minimalPDF := "%PDF-1.4\n1 0 obj<</Type/Catalog/Pages 2 0 R>>endobj\n" +
+		"2 0 obj<</Type/Pages/Kids[3 0 R]/Count 1>>endobj\n" +
+		"3 0 obj<</Type/Page/MediaBox[0 0 612 792]/Parent 2 0 R/Contents 4 0 R/Resources<</Font<</F1<</Type/Font/Subtype/Type1/BaseFont/Helvetica>>>>>>>>endobj\n" +
+		"4 0 obj<</Length 44>>\nstream\nBT /F1 12 Tf 100 700 Td (Hello PDF) Tj ET\nendstream\nendobj\n" +
+		"xref\n0 5\n0000000000 65535 f\n0000000009 00000 n\n0000000058 00000 n\n0000000115 00000 n\n0000000310 00000 n\n" +
+		"trailer<</Size 5/Root 1 0 R>>\nstartxref\n406\n%%EOF\n"
+	require.NoError(t, os.WriteFile(pdfPath, []byte(minimalPDF), 0o644))
+
+	got, err := Text(pdfPath)
+	require.NoError(t, err)
+	assert.Contains(t, got, "Hello PDF")
+}

ingestion/internal/extract/pdf.go

@@ -1,8 +1,28 @@
 // ingestion/internal/extract/pdf.go
 package extract
 
-import "fmt"
+import (
+	"bytes"
+	"fmt"
+	"os/exec"
+	"strings"
+)
 
-func extractPDF(_ string) (string, error) {
-	return "", fmt.Errorf("PDF extraction not implemented")
+// extractPDF runs pdftotext on path and returns the extracted text.
+// pdftotext must be installed (package: poppler-utils on Alpine/Debian, poppler on Homebrew).
+func extractPDF(path string) (string, error) {
+	cmd := exec.Command("pdftotext", "-q", path, "-")
+	var stdout, stderr bytes.Buffer
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+
+	if err := cmd.Run(); err != nil {
+		errMsg := strings.TrimSpace(stderr.String())
+		if errMsg == "" {
+			errMsg = err.Error()
+		}
+		return "", fmt.Errorf("pdftotext: %s", errMsg)
+	}
+
+	return strings.TrimSpace(stdout.String()), nil
 }