Stirling-PDF/src/main/java/stirling/software/SPDF/controller/RearrangePagesPDFController.java

package stirling.software.SPDF.controller;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.MultipartFile;

import stirling.software.SPDF.utils.PdfUtils;

@Controller
public class RearrangePagesPDFController {

    private static final Logger logger = LoggerFactory.getLogger(RearrangePagesPDFController.class);

    @GetMapping("/pdf-organizer")
    public String pageOrganizer(Model model) {
        model.addAttribute("currentPage", "pdf-organizer");
        return "pdf-organizer";
    }

    @GetMapping("/remove-pages")
    public String pageDeleter(Model model) {
        model.addAttribute("currentPage", "remove-pages");
        return "remove-pages";
    }

    @PostMapping("/remove-pages")
    public ResponseEntity<byte[]> deletePages(@RequestParam("fileInput") MultipartFile pdfFile, @RequestParam("pagesToDelete") String pagesToDelete) throws IOException {

        PDDocument document = PDDocument.load(pdfFile.getBytes());

        // Split the page order string into an array of page numbers or range of numbers
        String[] pageOrderArr = pagesToDelete.split(",");

        List<Integer> pagesToRemove = pageOrderToString(pageOrderArr, document.getNumberOfPages());

        for (int i = pagesToRemove.size() - 1; i >= 0; i--) {
            int pageIndex = pagesToRemove.get(i);
            document.removePage(pageIndex);
        }

        return PdfUtils.pdfDocToWebResponse(document, pdfFile.getName() + "_removed_pages.pdf");

    }

    private List<Integer> pageOrderToString(String[] pageOrderArr, int totalPages) {
        List<Integer> newPageOrder = new ArrayList<>();
        // loop through the page order array
        for (String element : pageOrderArr) {
            // check if the element contains a range of pages
            if (element.contains("-")) {
                // split the range into start and end page
                String[] range = element.split("-");
                int start = Integer.parseInt(range[0]);
                int end = Integer.parseInt(range[1]);
                // check if the end page is greater than total pages
                if (end > totalPages) {
                    end = totalPages;
                }
                // loop through the range of pages
                for (int j = start; j <= end; j++) {
                    // print the current index
                    newPageOrder.add(j - 1);
                }
            } else {
                // if the element is a single page
                newPageOrder.add(Integer.parseInt(element) - 1);
            }
        }

        return newPageOrder;
    }

    @PostMapping("/rearrange-pages")
    public ResponseEntity<byte[]> rearrangePages(@RequestParam("fileInput") MultipartFile pdfFile, @RequestParam("pageOrder") String pageOrder) {
        try {
            // Load the input PDF
            PDDocument document = PDDocument.load(pdfFile.getInputStream());

            // Split the page order string into an array of page numbers or range of numbers
            String[] pageOrderArr = pageOrder.split(",");
            // int[] newPageOrder = new int[pageOrderArr.length];
            int totalPages = document.getNumberOfPages();

            List<Integer> newPageOrder = pageOrderToString(pageOrderArr, totalPages);

            // Create a new list to hold the pages in the new order
            List<PDPage> newPages = new ArrayList<>();
            for (int i = 0; i < newPageOrder.size(); i++) {
                newPages.add(document.getPage(newPageOrder.get(i)));
            }

            // Remove all the pages from the original document
            for (int i = document.getNumberOfPages() - 1; i >= 0; i--) {
                document.removePage(i);
            }

            // Add the pages in the new order
            for (PDPage page : newPages) {
                document.addPage(page);
            }

            return PdfUtils.pdfDocToWebResponse(document, pdfFile.getName() + "_rearranged.pdf");
        } catch (IOException e) {

            logger.error("Failed rearranging documents", e);
            return null;
        }
    }

}