package documents

import (
	"fmt"

	"github.com/pdfcpu/pdfcpu/pkg/api"
	"github.com/pdfcpu/pdfcpu/pkg/pdfcpu/color"
	"github.com/pdfcpu/pdfcpu/pkg/pdfcpu/model"
	"github.com/pdfcpu/pdfcpu/pkg/pdfcpu/types"
)

// AddPageNumbers adds page numbers to a PDF file
// This should be called after all merging is complete to show accurate page counts
func AddPageNumbers(pdfPath string) error {
	// Read the PDF to get page count
	pageCount, err := api.PageCountFile(pdfPath)
	if err != nil {
		return fmt.Errorf("failed to get page count: %w", err)
	}

	// Create watermark configuration for page numbers
	// Position: bottom right, slightly above footer
	wm := &model.Watermark{
		TextString: fmt.Sprintf("Page $p of %d", pageCount),
		FontName:   "Helvetica",
		FontSize:   9,
		ScaleAbs:   true,
		Color:      color.Black,
		Pos:        types.BottomRight,
		Dx:         -15, // 15mm from right
		Dy:         25,  // 25mm from bottom
		Rotation:   0,
	}

	// Apply watermark (page numbers) to all pages
	if err := api.AddWatermarksFile(pdfPath, pdfPath, nil, wm, nil); err != nil {
		return fmt.Errorf("failed to add page numbers: %w", err)
	}

	return nil
}