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

package stirling.software.SPDF.controller;

import java.io.ByteArrayOutputStream;
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.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
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("/delete-pages")
	public String pageDeleter(Model model) {
		model.addAttribute("currentPage", "delete-pages");
		return "delete-pages";
	}

	@PostMapping("/delete-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<Integer>();
		// 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;
		}
	}

}