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

package stirling.software.SPDF.controller.api;

import java.io.IOException;
import io.swagger.v3.oas.annotations.media.Schema;
import stirling.software.SPDF.utils.WebResponseUtils;

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.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RequestPart;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

import io.swagger.v3.oas.annotations.Operation;
import io.swagger.v3.oas.annotations.Parameter;

@RestController
public class RearrangePagesPDFController {

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


    @PostMapping(consumes = "multipart/form-data", value = "/remove-pages")
    @Operation(summary = "Remove pages from a PDF file",
            description = "This endpoint removes specified pages from a given PDF file. Users can provide a comma-separated list of page numbers or ranges to delete.")
    public ResponseEntity<byte[]> deletePages(
            @RequestPart(required = true, value = "fileInput")
            @Parameter(description = "The input PDF file from which pages will be removed")
                    MultipartFile pdfFile,
            @RequestParam("pagesToDelete")
            @Parameter(description = "Comma-separated list of pages or page ranges to delete, e.g., '1,3,5-8'")
                    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 WebResponseUtils.pdfDocToWebResponse(document, pdfFile.getOriginalFilename().replaceFirst("[.][^.]+$", "") + "_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;
    }

    private enum CustomMode {
        REVERSE_ORDER,
        DUPLEX_SORT,
        BOOKLET_SORT,
        ODD_EVEN_SPLIT,
        REMOVE_FIRST,
        REMOVE_LAST,
        REMOVE_FIRST_AND_LAST,
    }

    private List<Integer> removeFirst(int totalPages) {
        if (totalPages <= 1) return new ArrayList<>();
        List<Integer> newPageOrder = new ArrayList<>();
        for (int i = 2; i <= totalPages; i++) {
            newPageOrder.add(i - 1);
        }
        return newPageOrder;
    }

    private List<Integer> removeLast(int totalPages) {
        if (totalPages <= 1) return new ArrayList<>();
        List<Integer> newPageOrder = new ArrayList<>();
        for (int i = 1; i < totalPages; i++) {
            newPageOrder.add(i - 1);
        }
        return newPageOrder;
    }

    private List<Integer> removeFirstAndLast(int totalPages) {
        if (totalPages <= 2) return new ArrayList<>();
        List<Integer> newPageOrder = new ArrayList<>();
        for (int i = 2; i < totalPages; i++) {
            newPageOrder.add(i - 1);
        }
        return newPageOrder;
    }

    
    private List<Integer> reverseOrder(int totalPages) {
        List<Integer> newPageOrder = new ArrayList<>();
        for (int i = totalPages; i >= 1; i--) {
            newPageOrder.add(i - 1);
        }
        return newPageOrder;
    }

    private List<Integer> duplexSort(int totalPages) {
        List<Integer> newPageOrder = new ArrayList<>();
        int half = (totalPages + 1) / 2; // This ensures proper behavior with odd numbers of pages
        for (int i = 1; i <= half; i++) {
            newPageOrder.add(i - 1);
            if (i <= totalPages - half) { // Avoid going out of bounds
                newPageOrder.add(totalPages - i);
            }
        }
        return newPageOrder;
    }


    private List<Integer> bookletSort(int totalPages) {
        List<Integer> newPageOrder = new ArrayList<>();
        for (int i = 0; i < totalPages / 2; i++) {
            newPageOrder.add(i);
            newPageOrder.add(totalPages - i - 1);
        }
        return newPageOrder;
    }

    private List<Integer> oddEvenSplit(int totalPages) {
        List<Integer> newPageOrder = new ArrayList<>();
        for (int i = 1; i <= totalPages; i += 2) {
            newPageOrder.add(i - 1);
        }
        for (int i = 2; i <= totalPages; i += 2) {
            newPageOrder.add(i - 1);
        }
        return newPageOrder;
    }

    private List<Integer> processCustomMode(String customMode, int totalPages) {
        try {
            CustomMode mode = CustomMode.valueOf(customMode.toUpperCase());
            switch (mode) {
                case REVERSE_ORDER:
                    return reverseOrder(totalPages);
                case DUPLEX_SORT:
                    return duplexSort(totalPages);
                case BOOKLET_SORT:
                    return bookletSort(totalPages);
                case ODD_EVEN_SPLIT:
                    return oddEvenSplit(totalPages);
                case REMOVE_FIRST:
                    return removeFirst(totalPages);
                case REMOVE_LAST:
                    return removeLast(totalPages);
                case REMOVE_FIRST_AND_LAST:
                    return removeFirstAndLast(totalPages);
                default:
                    throw new IllegalArgumentException("Unsupported custom mode");
            }
        } catch (IllegalArgumentException e) {
            logger.error("Unsupported custom mode", e);
            return null;
        }
    }

    @PostMapping(consumes = "multipart/form-data", value = "/rearrange-pages")
    @Operation(summary = "Rearrange pages in a PDF file",
            description = "This endpoint rearranges pages in a given PDF file based on the specified page order or custom mode. Users can provide a page order as a comma-separated list of page numbers or page ranges, or a custom mode.")
    public ResponseEntity<byte[]> rearrangePages(
            @RequestPart(required = true, value = "fileInput")
            @Parameter(description = "The input PDF file to rearrange pages")
                    MultipartFile pdfFile,
            @RequestParam(required = false, value = "pageOrder")
            @Parameter(description = "The new page order as a comma-separated list of page numbers or page ranges (e.g., '1,3,5-7')")
                    String pageOrder,
            @RequestParam(required = false, value = "customMode")
            @Parameter(schema = @Schema(implementation = CustomMode.class, description = "The custom mode for page rearrangement. " +
            	    "Valid values are:\n" +
            	    "REVERSE_ORDER: Reverses the order of all pages.\n" +
            	    "DUPLEX_SORT: Sorts pages as if all fronts were scanned then all backs in reverse (1, n, 2, n-1, ...). " +
            	    "BOOKLET_SORT: Arranges pages for booklet printing (last, first, second, second last, ...).\n" +
            	    "ODD_EVEN_SPLIT: Splits and arranges pages into odd and even numbered pages.\n" +
            	    "REMOVE_FIRST: Removes the first page.\n" +
            	    "REMOVE_LAST: Removes the last page.\n" +
            	    "REMOVE_FIRST_AND_LAST: Removes both the first and the last pages.\n"))
                    String customMode) {
        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 != null ? pageOrder.split(",") : new String[0];
            int totalPages = document.getNumberOfPages();
            System.out.println("pageOrder=" + pageOrder);
            System.out.println("customMode length =" + customMode.length());
            List<Integer> newPageOrder;
            if(customMode != null && customMode.length() > 0) {
            	newPageOrder = processCustomMode(customMode, totalPages);
            } else {
            	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 WebResponseUtils.pdfDocToWebResponse(document, pdfFile.getOriginalFilename().replaceFirst("[.][^.]+$", "") + "_rearranged.pdf");
        } catch (IOException e) {
            logger.error("Failed rearranging documents", e);
            return null;
        }
    }


}