/*
 * Copyright (C) 2024 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.graphics.pdf;

import static android.graphics.pdf.PdfLinearizationTypes.PDF_DOCUMENT_TYPE_LINEARIZED;
import static android.graphics.pdf.PdfLinearizationTypes.PDF_DOCUMENT_TYPE_NON_LINEARIZED;

import android.annotation.FlaggedApi;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.graphics.Bitmap;
import android.graphics.Matrix;
import android.graphics.Point;
import android.graphics.Rect;
import android.graphics.pdf.content.PdfPageGotoLinkContent;
import android.graphics.pdf.content.PdfPageImageContent;
import android.graphics.pdf.content.PdfPageLinkContent;
import android.graphics.pdf.content.PdfPageTextContent;
import android.graphics.pdf.flags.Flags;
import android.graphics.pdf.models.FormEditRecord;
import android.graphics.pdf.models.FormWidgetInfo;
import android.graphics.pdf.models.PageMatchBounds;
import android.graphics.pdf.models.jni.LoadPdfResult;
import android.graphics.pdf.models.selection.PageSelection;
import android.graphics.pdf.models.selection.SelectionBoundary;
import android.graphics.pdf.utils.Preconditions;
import android.os.ParcelFileDescriptor;
import android.system.ErrnoException;
import android.system.Os;
import android.system.OsConstants;
import android.util.Log;

import java.io.IOException;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;

/**
 * Represents a PDF document processing class.
 *
 * @hide
 */
public class PdfProcessor {
    /** Represents a PDF without form fields */
    public static final int PDF_FORM_TYPE_NONE = 0;

    /** Represents a PDF with form fields specified using the AcroForm spec */
    public static final int PDF_FORM_TYPE_ACRO_FORM = 1;

    /** Represents a PDF with form fields specified using the entire XFA spec */
    public static final int PDF_FORM_TYPE_XFA_FULL = 2;

    /** Represents a PDF with form fields specified using the XFAF subset of the XFA spec */
    public static final int PDF_FORM_TYPE_XFA_FOREGROUND = 3;

    private static final String TAG = "PdfProcessor";
    private static final Object sPdfiumLock = new Object();
    private PdfDocumentProxy mPdfDocument;

    public PdfProcessor() {
        PdfDocumentProxy.loadLibPdf();
    }

    /**
     * Creates an instance of {@link PdfDocumentProxy} on successful loading of the PDF document.
     * This method ensures that an older {@link PdfDocumentProxy} instance is closed and then loads
     * the new document. This method should be run on a {@link android.annotation.WorkerThread} as
     * it is long-running task.
     *
     * @param fileDescriptor {@link ParcelFileDescriptor} for the input PDF document.
     * @param params         instance of {@link LoadParams} which includes the password as well.
     * @throws IOException       if an error occurred during the processing of the PDF document.
     * @throws SecurityException if the password is incorrect.
     */
    @FlaggedApi(Flags.FLAG_ENABLE_PDF_VIEWER)
    public void create(ParcelFileDescriptor fileDescriptor, @Nullable LoadParams params)
            throws IOException {
        Preconditions.checkNotNull(fileDescriptor, "Input FD cannot be null");
        ensurePdfDestroyed();
        try {
            Os.lseek(fileDescriptor.getFileDescriptor(), 0, OsConstants.SEEK_SET);
        } catch (ErrnoException ee) {
            throw new IllegalArgumentException("File descriptor not seekable");
        }

        String password = (params != null) ? params.getPassword() : null;
        synchronized (sPdfiumLock) {
            LoadPdfResult result =
                    PdfDocumentProxy.createFromFd(fileDescriptor.detachFd(), password);
            switch (result.status) {
                case NEED_MORE_DATA, PDF_ERROR, FILE_ERROR ->
                        throw new IOException("Unable to load the document!");
                case REQUIRES_PASSWORD ->
                        throw new SecurityException("Password required to access document");
                case LOADED -> this.mPdfDocument = result.pdfDocument;
                default -> throw new RuntimeException("Unexpected error has occurred!");
            }
        }
    }

    /** Returns the number of pages in the PDF document */
    public int getNumPages() {
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            return mPdfDocument.getNumPages();
        }
    }

    /**
     * Returns the {@link List} of {@link PdfPageTextContent} for the page number specified. In case
     * of the multiple column textual content, the order is not guaranteed and the text is returned
     * as it is seen by the processing library.
     *
     * @param pageNum page number of the document
     * @return list of the textual content encountered on the page.
     */
    @FlaggedApi(Flags.FLAG_ENABLE_PDF_VIEWER)
    public List<PdfPageTextContent> getPageTextContents(int pageNum) {
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            PdfPageTextContent content = new PdfPageTextContent(mPdfDocument.getPageText(pageNum));
            return List.of(content);
        }
    }

    /**
     * Returns the alternate text for each image encountered on the specified page as a
     * {@link List} of {@link PdfPageImageContent}. The primary use case of this method is for
     * accessibility.
     *
     * @param pageNum page number of the document
     * @return list of the alt text for each image on the page.
     */
    @FlaggedApi(Flags.FLAG_ENABLE_PDF_VIEWER)
    public List<PdfPageImageContent> getPageImageContents(int pageNum) {
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            return mPdfDocument.getPageAltText(pageNum).stream()
                    .map(PdfPageImageContent::new)
                    .collect(Collectors.toList());
        }
    }

    /**
     * Returns the width of the given page of the PDF document. It is not guaranteed that all the
     * pages of the document will have the same dimensions
     */
    public int getPageWidth(int pageNum) {
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            return mPdfDocument.getPageWidth(pageNum);
        }
    }

    /**
     * Returns the height of the given page of the PDF document. It is not guaranteed that all the
     * pages of the document will have the same dimensions
     */
    public int getPageHeight(int pageNum) {
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            return mPdfDocument.getPageHeight(pageNum);
        }
    }

    /**
     * Renders a page to a bitmap for the specified page number.
     *
     * <p>Should be invoked on the {@link android.annotation.WorkerThread} as it is a long-running
     * task.
     */
    @FlaggedApi(Flags.FLAG_ENABLE_PDF_VIEWER)
    public void renderPage(
            int pageNum, Bitmap bitmap, Rect destClip, Matrix transform, RenderParams params) {
        Preconditions.checkNotNull(bitmap, "Destination bitmap cannot be null");
        Preconditions.checkNotNull(params, "RenderParams cannot be null");
        Preconditions.checkArgument(bitmap.getConfig() == Bitmap.Config.ARGB_8888,
                "Unsupported pixel format");
        Preconditions.checkArgument(transform == null || transform.isAffine(),
                "Transform not affine");
        int renderMode = params.getRenderMode();
        Preconditions.checkArgument(renderMode == RenderParams.RENDER_MODE_FOR_DISPLAY
                || renderMode == RenderParams.RENDER_MODE_FOR_PRINT, "Unsupported render mode");
        Preconditions.checkArgument(clipInBitmap(destClip, bitmap), "destClip not in bounds");
        final int contentLeft = (destClip != null) ? destClip.left : 0;
        final int contentTop = (destClip != null) ? destClip.top : 0;
        final int contentRight = (destClip != null) ? destClip.right : bitmap.getWidth();
        final int contentBottom = (destClip != null) ? destClip.bottom : bitmap.getHeight();

        // If transform is not set, stretch page to whole clipped area
        if (transform == null) {
            int clipWidth = contentRight - contentLeft;
            int clipHeight = contentBottom - contentTop;
            transform = new Matrix();
            transform.postScale((float) clipWidth / getPageWidth(pageNum),
                    (float) clipHeight / getPageHeight(pageNum));
            transform.postTranslate(contentLeft, contentTop);
        }

        float[] transformArr = new float[9];
        transform.getValues(transformArr);

        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            mPdfDocument.render(
                    pageNum,
                    bitmap,
                    contentLeft,
                    contentTop,
                    contentRight,
                    contentBottom,
                    transformArr,
                    renderMode,
                    params.areAnnotationsDisabled());
        }
    }

    /**
     * Searches the specified page with the specified query. Should be run on the
     * {@link android.annotation.WorkerThread} as it is a long-running task.
     *
     * @param pageNum page number of the document
     * @param query   the search query
     * @return list of {@link PageMatchBounds} that represents the highlighters which can span
     * multiple
     * lines as well.
     */
    @FlaggedApi(Flags.FLAG_ENABLE_PDF_VIEWER)
    public List<PageMatchBounds> searchPageText(int pageNum, String query) {
        Preconditions.checkNotNull(query, "Search query cannot be null");
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            return mPdfDocument.searchPageText(pageNum, query).unflattenToList();
        }
    }

    /**
     * Return a PageSelection which represents the selected content that spans between the
     * two boundaries, both of which can be either exactly defined with text indexes, or
     * approximately defined with points on the page.The resulting Selection will also be
     * exactly defined with both indexes and points.If the start and stop boundary are both
     * the same point, selects the word at that point.
     */
    @FlaggedApi(Flags.FLAG_ENABLE_PDF_VIEWER)
    public PageSelection selectPageText(int pageNum, SelectionBoundary start,
            SelectionBoundary stop) {
        Preconditions.checkNotNull(start, "Start selection boundary cannot be null");
        Preconditions.checkNotNull(stop, "Stop selection boundary cannot be null");
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            android.graphics.pdf.models.jni.PageSelection legacyPageSelection =
                    mPdfDocument.selectPageText(
                            pageNum,
                            android.graphics.pdf.models.jni.SelectionBoundary.convert(start),
                            android.graphics.pdf.models.jni.SelectionBoundary.convert(stop));
            if (legacyPageSelection != null) {
                return legacyPageSelection.convert();
            }
            return null;
        }
    }

    /** Get the bounds and URLs of all the links on the given page. */
    @FlaggedApi(Flags.FLAG_ENABLE_PDF_VIEWER)
    public List<PdfPageLinkContent> getPageLinkContents(int pageNum) {
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            return mPdfDocument.getPageLinks(pageNum).unflattenToList();
        }
    }

    /** Returns bookmarks and other goto links (within the current document) on a page */
    public List<PdfPageGotoLinkContent> getPageGotoLinks(int pageNum) {
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            return mPdfDocument.getPageGotoLinks(pageNum);
        }
    }

    /** Retains object in memory related to a page when that page becomes visible. */
    public void retainPage(int pageNum) {
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            mPdfDocument.retainPage(pageNum);
        }
    }

    /** Releases object in memory related to a page when that page is no longer visible. */
    public void releasePage(int pageNum) {
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            mPdfDocument.releasePage(pageNum);
        }
    }

    /**
     * Returns the linearization flag on the PDF document.
     */
    @PdfLinearizationTypes.PdfLinearizationType
    public int getDocumentLinearizationType() {
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            return mPdfDocument.isPdfLinearized()
                    ? PDF_DOCUMENT_TYPE_LINEARIZED
                    : PDF_DOCUMENT_TYPE_NON_LINEARIZED;
        }
    }

    /**
     * Returns the form type of the loaded PDF
     *
     * @throws IllegalArgumentException if an unrecognized PDF form type is returned
     */
    public int getPdfFormType() {
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            int pdfFormType = mPdfDocument.getFormType();
            return switch (pdfFormType) {
                case PDF_FORM_TYPE_ACRO_FORM,
                                PDF_FORM_TYPE_XFA_FULL,
                                PDF_FORM_TYPE_XFA_FOREGROUND ->
                        pdfFormType;
                default -> PDF_FORM_TYPE_NONE;
            };
        }
    }

    /** Returns true if this PDF prefers to be scaled for printing. */
    public boolean scaleForPrinting() {
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            return mPdfDocument.scaleForPrinting();
        }
    }

    /**
     * Returns information about all form widgets on the page, or an empty list if there are no form
     * widgets on the page.
     *
     * <p>Optionally restricted by {@code types}. If {@code types} is empty, all form widgets on the
     * page will be returned.
     */
    @NonNull
    public List<FormWidgetInfo> getFormWidgetInfos(
            int pageNum, @NonNull @FormWidgetInfo.WidgetType int[] types) {
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            return mPdfDocument.getFormWidgetInfos(pageNum, types);
        }
    }

    /**
     * Returns information about the widget with {@code annotationIndex}.
     *
     * <p>{@code annotationIndex} refers to the index of the annotation within the page's "Annot"
     * array in the PDF document. This info is available on results of previous calls via {@link
     * FormWidgetInfo#getWidgetIndex()}.
     */
    @NonNull
    FormWidgetInfo getFormWidgetInfoAtIndex(int pageNum, int annotationIndex) {
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            FormWidgetInfo result = mPdfDocument.getFormWidgetInfo(pageNum, annotationIndex);
            if (result == null) {
                throw new IllegalArgumentException("No widget found at this index.");
            }
            return result;
        }
    }

    /** Returns information about the widget at the given point. */
    @NonNull
    public FormWidgetInfo getFormWidgetInfoAtPosition(int pageNum, int x, int y) {
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            FormWidgetInfo result = mPdfDocument.getFormWidgetInfo(pageNum, x, y);
            if (result == null) {
                throw new IllegalArgumentException("No widget found at point.");
            }
            return result;
        }

    }

    /**
     * Applies a {@link FormEditRecord} to the PDF.
     *
     * @return a list of rectangular areas invalidated by form widget operation
     * <p>For click type {@link FormEditRecord}s, performs a click on {@link
     * FormEditRecord#getClickPoint()}
     * <p>For set text type {@link FormEditRecord}s, sets the text value of the form widget.
     * <p>For set indices type {@link FormEditRecord}s, sets the {@link
     * FormEditRecord#getSelectedIndices()} as selected and all others as unselected for the
     * form widget indicated by the record.
     */
    @NonNull
    public List<Rect> applyEdit(int pageNum, @NonNull FormEditRecord editRecord) {
        Preconditions.checkNotNull(editRecord, "Edit record cannot be null");
        Preconditions.checkArgument(pageNum >= 0, "Invalid page number");
        if (editRecord.getType() == FormEditRecord.EDIT_TYPE_CLICK) {
            return applyEditTypeClick(pageNum, editRecord);
        } else if (editRecord.getType() == FormEditRecord.EDIT_TYPE_SET_INDICES) {
            return applyEditTypeSetIndices(pageNum, editRecord);
        } else if (editRecord.getType() == FormEditRecord.EDIT_TYPE_SET_TEXT) {
            return applyEditSetText(pageNum, editRecord);
        }
        return Collections.emptyList();
    }

    @FlaggedApi(Flags.FLAG_ENABLE_FORM_FILLING)
    private List<Rect> applyEditTypeClick(int pageNum, @NonNull FormEditRecord editRecord) {
        Preconditions.checkNotNull(editRecord.getClickPoint(),
                "Can't apply click edit record without point");
        Point clickPoint = editRecord.getClickPoint();
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            List<Rect> results = mPdfDocument.clickOnPage(pageNum, clickPoint.x, clickPoint.y);
            if (results == null) {
                throw new IllegalArgumentException("Cannot click on this widget.");
            }
            return results;
        }
    }

    @FlaggedApi(Flags.FLAG_ENABLE_FORM_FILLING)
    private List<Rect> applyEditTypeSetIndices(int pageNum, @NonNull FormEditRecord editRecord) {
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            int[] selectedIndices = editRecord.getSelectedIndices();
            List<Rect> results =
                    mPdfDocument.setFormFieldSelectedIndices(
                            pageNum, editRecord.getWidgetIndex(), selectedIndices);
            if (results == null) {
                throw new IllegalArgumentException("Cannot set selected indices on this widget.");
            }
            return results;
        }
    }

    @FlaggedApi(Flags.FLAG_ENABLE_FORM_FILLING)
    private List<Rect> applyEditSetText(int pageNum, @NonNull FormEditRecord editRecord) {
        Preconditions.checkNotNull(editRecord.getText(),
                "Can't apply set text record without text");
        String text = editRecord.getText();
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            List<Rect> results =
                    mPdfDocument.setFormFieldText(pageNum, editRecord.getWidgetIndex(), text);
            if (results == null) {
                throw new IllegalArgumentException("Cannot set form field text on this widget.");
            }
            return results;
        }
    }

    /** Ensures that any previous {@link PdfDocumentProxy} instance is closed. */
    public void ensurePdfDestroyed() {
        synchronized (sPdfiumLock) {
            if (mPdfDocument != null) {
                try {
                    mPdfDocument.destroy();
                } catch (Throwable t) {
                    Log.e(TAG, "Error closing PdfDocumentProxy", t);
                } finally {
                    mPdfDocument = null;
                }
            }
        }
    }

    /**
     * Saves the current state of the loaded PDF document to the given writable
     * ParcelFileDescriptor.
     */
    public void write(ParcelFileDescriptor destination, boolean removePasswordProtection) {
        Preconditions.checkNotNull(destination, "Destination FD cannot be null");
        if (removePasswordProtection) {
            cloneWithoutSecurity(destination);
        } else {
            saveAs(destination);
        }
    }

    /**
     * Creates a copy of the current document without security, if it is password protected. This
     * may be necessary for the PrintManager which can't handle password-protected files.
     *
     * @param destination points to where pdfclient should make a copy of the pdf without security.
     */
    private void cloneWithoutSecurity(ParcelFileDescriptor destination) {
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            mPdfDocument.cloneWithoutSecurity(destination);
        }
    }

    /**
     * Saves the current document to the given {@link ParcelFileDescriptor}.
     *
     * @param destination where the currently open PDF should be written.
     */
    private void saveAs(ParcelFileDescriptor destination) {
        synchronized (sPdfiumLock) {
            assertPdfDocumentNotNull();
            mPdfDocument.saveAs(destination);
        }
    }

    private boolean clipInBitmap(@Nullable Rect clip, Bitmap destination) {
        if (clip == null) {
            return true;
        }
        return clip.left >= 0 && clip.top >= 0 && clip.right <= destination.getWidth()
                && clip.bottom <= destination.getHeight();
    }

    private void assertPdfDocumentNotNull() {
        Preconditions.checkNotNull(mPdfDocument, "PdfDocumentProxy cannot be null");
    }
}