// Copyright (C) 2019 Marius Schellenberger

package scan

import (
	"net/http"
	"os"
	"path/filepath"
	"strings"
)

const (
	pdfContentType = "application/pdf"
	maxSniffSize   = 512
)

func isPDF(path string) bool {
	return checkContentType(path) || checkExtension(path)
}

func checkContentType(path string) bool {
	f, err := os.Open(path)
	if err != nil {
		return false
	}
	defer f.Close()
	buf := make([]byte, maxSniffSize)
	_, err = f.Read(buf)
	if err != nil {
		return false
	}
	return http.DetectContentType(buf) == pdfContentType
}

func checkExtension(path string) bool {
	return strings.ToLower(filepath.Ext(path)) == pdfExt
}