init: initial commit

internal/parser/pdf_parser.go

@@ -0,0 +1,76 @@
+package parser
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/ledongthuc/pdf"
+)
+
+// PDFParser extracts plain text from PDF files using ledongthuc/pdf (open source).
+type PDFParser struct{}
+
+func (p *PDFParser) SupportedExtensions() []string {
+	return []string{".pdf"}
+}
+
+func (p *PDFParser) ParseToMarkdown(path string) (string, error) {
+	f, r, err := pdf.Open(path)
+	if err != nil {
+		return "", fmt.Errorf("open pdf: %w", err)
+	}
+	defer f.Close()
+
+	var sb strings.Builder
+	totalPages := r.NumPage()
+
+	for i := 1; i <= totalPages; i++ {
+		page := r.Page(i)
+		if page.V.IsNull() {
+			continue
+		}
+		text, err := page.GetPlainText(nil)
+		if err != nil {
+			continue
+		}
+		content := strings.TrimSpace(text)
+		if content != "" {
+			sb.WriteString(fmt.Sprintf("## Page %d\n\n%s\n\n", i, content))
+		}
+	}
+
+	if sb.Len() == 0 {
+		// Fallback: try reading entire content at once
+		content, err := readPDFPlainText(path)
+		if err == nil && content != "" {
+			return content, nil
+		}
+		return "", fmt.Errorf("no text content extracted from PDF")
+	}
+
+	return sb.String(), nil
+}
+
+func readPDFPlainText(path string) (string, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+	stat, _ := f.Stat()
+	reader, err := pdf.NewReader(f, stat.Size())
+	if err != nil {
+		return "", err
+	}
+	var sb strings.Builder
+	for i := 1; i <= reader.NumPage(); i++ {
+		page := reader.Page(i)
+		if page.V.IsNull() {
+			continue
+		}
+		text, _ := page.GetPlainText(nil)
+		sb.WriteString(text)
+	}
+	return sb.String(), nil
+}