//go:build never
// +build never

package documents

import (
	"fmt"
	"os"
	"path/filepath"

	api "github.com/pdfcpu/pdfcpu/pkg/api"
)

// finalizeWithTerms tries to append the standard Terms & Conditions PDF
// to the generated document. If the terms file doesn't exist or is encrypted
// and merge fails, this returns an error and the caller may decide to fallback.
//
// outputDir: directory where PDFs live (e.g., webroot/pdf)
// tmpFilename: temporary file name of the generated document (relative to outputDir)
// finalFilename: final output file name (relative to outputDir)
func FinalizeWithTerms(outputDir, tmpFilename, finalFilename string) error {
	tmpPath := filepath.Join(outputDir, tmpFilename)
	finalPath := filepath.Join(outputDir, finalFilename)

	// Standard T&C file used by legacy PHP flow
	termsPath := filepath.Join(outputDir, "CMC_terms_and_conditions2006_A4.pdf")

	if _, err := os.Stat(termsPath); err != nil {
		// Terms file missing: just rename tmp to final
		return FallbackFinalize(outputDir, tmpFilename, finalFilename)
	}

	// Merge tmp (first) + terms (second) into final
	inputs := []string{tmpPath, termsPath}
	if err := api.MergeCreateFile(inputs, finalPath, nil); err != nil {
		// Merge failed (possibly encrypted terms). Return error so caller can fallback
		return fmt.Errorf("pdf merge failed: %w", err)
	}

	// Cleanup tmp file on success
	_ = os.Remove(tmpPath)
	return nil
}

// finalizeWithTermsAndExtras is like finalizeWithTerms but allows appending additional PDFs.
// extras should be absolute or relative to outputDir. Non-existent extras are ignored.
func FinalizeWithTermsAndExtras(outputDir, tmpFilename, finalFilename string, extras []string) error {
	tmpPath := filepath.Join(outputDir, tmpFilename)
	finalPath := filepath.Join(outputDir, finalFilename)

	// Base inputs: generated document
	inputs := []string{tmpPath}

	// Optional terms
	termsPath := filepath.Join(outputDir, "CMC_terms_and_conditions2006_A4.pdf")
	if _, err := os.Stat(termsPath); err == nil {
		inputs = append(inputs, termsPath)
	}

	// Append any extra files (if they exist)
	for _, p := range extras {
		ap := p
		if !filepath.IsAbs(ap) {
			ap = filepath.Join(outputDir, p)
		}
		if _, err := os.Stat(ap); err == nil {
			inputs = append(inputs, ap)
		}
	}

	// If we only have the tmp file, just rename
	if len(inputs) == 1 {
		return FallbackFinalize(outputDir, tmpFilename, finalFilename)
	}

	if err := api.MergeCreateFile(inputs, finalPath, nil); err != nil {
		return fmt.Errorf("pdf merge failed: %w", err)
	}
	_ = os.Remove(tmpPath)
	return nil
}

// fallbackFinalize renames the tmp file to the final filename, overwriting if needed.
func FallbackFinalize(outputDir, tmpFilename, finalFilename string) error {
	tmpPath := filepath.Join(outputDir, tmpFilename)
	finalPath := filepath.Join(outputDir, finalFilename)

	// Remove any existing final file
	_ = os.Remove(finalPath)
	return os.Rename(tmpPath, finalPath)
}