# Copyright (c) 2006, Mathieu Fenniak
# Copyright (c) 2007, Ashish Kulkarni <kulkarni.ashish@gmail.com>
# Copyright (c) 2024, Pubpub-ZZ
#
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
# * The name of the author may not be used to endorse or promote products
# derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.

import struct
from abc import ABC, abstractmethod
from collections.abc import Generator, Iterable, Iterator, Mapping, Sequence
from datetime import datetime
from typing import (
    Any,
    NoReturn,
    Optional,
    Union,
    cast,
)

from ._encryption import Encryption
from ._page import PageObject, _VirtualList
from ._page_labels import index2label as page_index2page_label
from ._utils import (
    _TraversalState,
    deprecation_with_replacement,
    logger_warning,
    parse_iso8824_date,
)
from .constants import CatalogAttributes as CA
from .constants import (
    CheckboxRadioButtonAttributes,
    Core,
    GoToActionArguments,
    PagesAttributes,
    UserAccessPermissions,
)
from .constants import DocumentInformationAttributes as DI
from .constants import FieldDictionaryAttributes as FA
from .constants import PageAttributes as PG
from .errors import LimitReachedError, PdfReadError, PyPdfError
from .filters import _decompress_with_limit
from .generic import (
    ArrayObject,
    BooleanObject,
    ByteStringObject,
    Destination,
    DictionaryObject,
    EncodedStreamObject,
    Field,
    Fit,
    FloatObject,
    IndirectObject,
    NameObject,
    NullObject,
    NumberObject,
    PdfObject,
    TextStringObject,
    TreeObject,
    ViewerPreferences,
    create_string_object,
    is_null_or_none,
)
from .generic._files import EmbeddedFile
from .types import OutlineType, PagemodeType
from .xmp import XmpInformation

# TODO: Make configurable.
OUTLINE_MAX_ENTRIES = 100_000
OUTLINE_MAX_DEPTH = 100


def convert_to_int(d: bytes, size: int) -> Union[int, tuple[Any, ...]]:
    if size > 8:
        raise PdfReadError("Invalid size in convert_to_int")
    d = b"\x00\x00\x00\x00\x00\x00\x00\x00" + d
    d = d[-8:]
    return cast(int, struct.unpack(">Q", d)[0])


class DocumentInformation(DictionaryObject):
    """
    A class representing the basic document metadata provided in a PDF File.
    This class is accessible through
    :py:class:`PdfReader.metadata<pypdf.PdfReader.metadata>`.

    All text properties of the document metadata have
    *two* properties, e.g. author and author_raw. The non-raw property will
    always return a ``TextStringObject``, making it ideal for a case where the
    metadata is being displayed. The raw property can sometimes return a
    ``ByteStringObject``, if pypdf was unable to decode the string's text
    encoding; this requires additional safety in the caller and therefore is not
    as commonly accessed.
    """

    def __init__(self) -> None:
        DictionaryObject.__init__(self)

    def _get_text(self, key: str) -> Optional[str]:
        retval = self.get(key, None)
        if isinstance(retval, TextStringObject):
            return retval
        if isinstance(retval, ByteStringObject):
            return str(retval)
        return None

    @property
    def title(self) -> Optional[str]:
        """
        Read-only property accessing the document's title.

        Returns a ``TextStringObject`` or ``None`` if the title is not
        specified.
        """
        return (
            self._get_text(DI.TITLE) or self.get(DI.TITLE).get_object()  # type: ignore[union-attr]
            if self.get(DI.TITLE)
            else None
        )

    @property
    def title_raw(self) -> Optional[str]:
        """The "raw" version of title; can return a ``ByteStringObject``."""
        return self.get(DI.TITLE)

    @property
    def author(self) -> Optional[str]:
        """
        Read-only property accessing the document's author.

        Returns a ``TextStringObject`` or ``None`` if the author is not
        specified.
        """
        return self._get_text(DI.AUTHOR)

    @property
    def author_raw(self) -> Optional[str]:
        """The "raw" version of author; can return a ``ByteStringObject``."""
        return self.get(DI.AUTHOR)

    @property
    def subject(self) -> Optional[str]:
        """
        Read-only property accessing the document's subject.

        Returns a ``TextStringObject`` or ``None`` if the subject is not
        specified.
        """
        return self._get_text(DI.SUBJECT)

    @property
    def subject_raw(self) -> Optional[str]:
        """The "raw" version of subject; can return a ``ByteStringObject``."""
        return self.get(DI.SUBJECT)

    @property
    def creator(self) -> Optional[str]:
        """
        Read-only property accessing the document's creator.

        If the document was converted to PDF from another format, this is the
        name of the application (e.g. OpenOffice) that created the original
        document from which it was converted. Returns a ``TextStringObject`` or
        ``None`` if the creator is not specified.
        """
        return self._get_text(DI.CREATOR)

    @property
    def creator_raw(self) -> Optional[str]:
        """The "raw" version of creator; can return a ``ByteStringObject``."""
        return self.get(DI.CREATOR)

    @property
    def producer(self) -> Optional[str]:
        """
        Read-only property accessing the document's producer.

        If the document was converted to PDF from another format, this is the
        name of the application (for example, macOS Quartz) that converted it to
        PDF. Returns a ``TextStringObject`` or ``None`` if the producer is not
        specified.
        """
        return self._get_text(DI.PRODUCER)

    @property
    def producer_raw(self) -> Optional[str]:
        """The "raw" version of producer; can return a ``ByteStringObject``."""
        return self.get(DI.PRODUCER)

    @property
    def creation_date(self) -> Optional[datetime]:
        """Read-only property accessing the document's creation date."""
        return parse_iso8824_date(self._get_text(DI.CREATION_DATE))

    @property
    def creation_date_raw(self) -> Optional[str]:
        """
        The "raw" version of creation date; can return a ``ByteStringObject``.

        Typically in the format ``D:YYYYMMDDhhmmss[+Z-]hh'mm`` where the suffix
        is the offset from UTC.
        """
        return self.get(DI.CREATION_DATE)

    @property
    def modification_date(self) -> Optional[datetime]:
        """
        Read-only property accessing the document's modification date.

        The date and time the document was most recently modified.
        """
        return parse_iso8824_date(self._get_text(DI.MOD_DATE))

    @property
    def modification_date_raw(self) -> Optional[str]:
        """
        The "raw" version of modification date; can return a
        ``ByteStringObject``.

        Typically, in the format ``D:YYYYMMDDhhmmss[+Z-]hh'mm`` where the suffix
        is the offset from UTC.
        """
        return self.get(DI.MOD_DATE)

    @property
    def keywords(self) -> Optional[str]:
        """
        Read-only property accessing the document's keywords.

        Returns a ``TextStringObject`` or ``None`` if keywords are not
        specified.
        """
        return self._get_text(DI.KEYWORDS)

    @property
    def keywords_raw(self) -> Optional[str]:
        """The "raw" version of keywords; can return a ``ByteStringObject``."""
        return self.get(DI.KEYWORDS)


class PdfDocCommon(ABC):
    """
    Common functions from PdfWriter and PdfReader objects.

    This root class is strongly abstracted.
    """

    strict: bool = False  # default

    flattened_pages: Optional[list[PageObject]] = None

    _encryption: Optional[Encryption] = None

    _readonly: bool = False

    @property
    @abstractmethod
    def root_object(self) -> DictionaryObject:
        ...  # pragma: no cover

    @property
    @abstractmethod
    def pdf_header(self) -> str:
        ...  # pragma: no cover

    @abstractmethod
    def get_object(
        self, indirect_reference: Union[int, IndirectObject]
    ) -> Optional[PdfObject]:
        ...  # pragma: no cover

    @abstractmethod
    def _replace_object(self, indirect: IndirectObject, obj: PdfObject) -> PdfObject:
        ...  # pragma: no cover

    @property
    @abstractmethod
    def _info(self) -> Optional[DictionaryObject]:
        ...  # pragma: no cover

    @property
    def metadata(self) -> Optional[DocumentInformation]:
        """
        Retrieve the PDF file's document information dictionary, if it exists.

        Note that some PDF files use metadata streams instead of document
        information dictionaries, and these metadata streams will not be
        accessed by this function.
        """
        retval = DocumentInformation()
        if self._info is None:
            return None
        retval.update(self._info)
        return retval

    @property
    @abstractmethod
    def xmp_metadata(self) -> Optional[XmpInformation]:
        ...  # pragma: no cover

    @property
    def viewer_preferences(self) -> Optional[ViewerPreferences]:
        """Returns the existing ViewerPreferences as an overloaded dictionary."""
        o = self.root_object.get(CA.VIEWER_PREFERENCES, None)
        if o is None:
            return None
        o = o.get_object()
        if not isinstance(o, ViewerPreferences):
            o = ViewerPreferences(o)
            if hasattr(o, "indirect_reference") and o.indirect_reference is not None:
                self._replace_object(o.indirect_reference, o)
            else:
                self.root_object[NameObject(CA.VIEWER_PREFERENCES)] = o
        return o

    def get_num_pages(self) -> int:
        """
        Calculate the number of pages in this PDF file.

        Returns:
            The number of pages of the parsed PDF file.

        Raises:
            PdfReadError: If restrictions prevent this action.

        """
        # Flattened pages will not work on an encrypted PDF;
        # the PDF file's page count is used in this case. Otherwise,
        # the original method (flattened page count) is used.
        if self.is_encrypted:
            return self.root_object["/Pages"]["/Count"]  # type: ignore[no-any-return, index]
        if self.flattened_pages is None:
            self._flatten(self._readonly)
        assert self.flattened_pages is not None
        return len(self.flattened_pages)

    def get_page(self, page_number: int) -> PageObject:
        """
        Retrieve a page by number from this PDF file.
        Most of the time ``.pages[page_number]`` is preferred.

        Args:
            page_number: The page number to retrieve
                (pages begin at zero)

        Returns:
            A :class:`PageObject<pypdf._page.PageObject>` instance.

        """
        if self.flattened_pages is None:
            self._flatten(self._readonly)
        assert self.flattened_pages is not None, "mypy"
        return self.flattened_pages[page_number]

    def _get_page_in_node(
        self,
        page_number: int,
    ) -> tuple[DictionaryObject, int]:
        """
        Retrieve the node and position within the /Kids containing the page.
        If page_number is greater than the number of pages, it returns the top node, -1.
        """
        top = cast(DictionaryObject, self.root_object["/Pages"])
        visited: set[int] = set()

        def recursive_call(
            _node: DictionaryObject, mi: int
        ) -> tuple[Optional[PdfObject], int]:
            _node_id = id(_node)
            if _node_id in visited:
                raise LimitReachedError("Detected cycle in /Pages hierarchy when retrieving page.")
            visited.add(_node_id)
            ma = cast(int, _node.get("/Count", 1))  # default 1 for /Page types
            if _node.get("/Type") == "/Page":
                if page_number == mi:
                    return _node, -1
                return None, mi + 1
            if (page_number - mi) >= ma:  # not in nodes below
                if _node == top:
                    return top, -1
                return None, mi + ma
            for _idx, kid in enumerate(cast(ArrayObject, _node["/Kids"])):
                kid = cast(DictionaryObject, kid.get_object())
                n, i = recursive_call(kid, mi)
                if n is not None:  # page has just been found ...
                    if i < 0:  # ... just below!
                        return _node, _idx
                    # ... at lower levels
                    return n, i
                mi = i
            raise PyPdfError("Unexpectedly cannot find the node.")

        node, idx = recursive_call(top, 0)
        assert isinstance(node, DictionaryObject), "mypy"
        return node, idx

    @property
    def named_destinations(self) -> dict[str, Destination]:
        """A read-only dictionary which maps names to destinations."""
        return self._get_named_destinations()

    def get_named_dest_root(self) -> ArrayObject:
        named_dest = ArrayObject()
        if CA.NAMES in self.root_object and isinstance(
            self.root_object[CA.NAMES], DictionaryObject
        ):
            names = cast(DictionaryObject, self.root_object[CA.NAMES])
            if CA.DESTS in names and isinstance(names[CA.DESTS], DictionaryObject):
                # §3.6.3 Name Dictionary (PDF spec 1.7)
                dests = cast(DictionaryObject, names[CA.DESTS])
                dests_ref = dests.indirect_reference
                if CA.NAMES in dests:
                    # §7.9.6, entries in a name tree node dictionary
                    named_dest = cast(ArrayObject, dests[CA.NAMES])
                else:
                    named_dest = ArrayObject()
                    dests[NameObject(CA.NAMES)] = named_dest
            elif hasattr(self, "_add_object"):
                dests = DictionaryObject()
                dests_ref = self._add_object(dests)
                names[NameObject(CA.DESTS)] = dests_ref
                dests[NameObject(CA.NAMES)] = named_dest

        elif hasattr(self, "_add_object"):
            names = DictionaryObject()
            names_ref = self._add_object(names)
            self.root_object[NameObject(CA.NAMES)] = names_ref
            dests = DictionaryObject()
            dests_ref = self._add_object(dests)
            names[NameObject(CA.DESTS)] = dests_ref
            dests[NameObject(CA.NAMES)] = named_dest

        return named_dest

    ## common
    def _get_named_destinations(
        self,
        *,
        tree: Union[TreeObject, None] = None,
        retval: Optional[dict[str, Destination]] = None,
        visited: Optional[set[int]] = None,
    ) -> dict[str, Destination]:
        """
        Retrieve the named destinations present in the document.

        Args:
            tree: The current tree.
            retval: The previously retrieved destinations for nested calls.
            visited: Already known/visited objects.

        Returns:
            A dictionary which maps names to destinations.

        """
        if visited is None:
            visited = set()
        if retval is None:
            retval = {}
            catalog = self.root_object

            # get the name tree
            if CA.DESTS in catalog:
                tree = cast(TreeObject, catalog[CA.DESTS])
            elif CA.NAMES in catalog:
                names = cast(DictionaryObject, catalog[CA.NAMES])
                if CA.DESTS in names:
                    tree = cast(TreeObject, names[CA.DESTS])

        if is_null_or_none(tree):
            return retval
        assert tree is not None, "mypy"

        tree_id = id(tree)
        if tree_id in visited:
            logger_warning("Detected cycle in destination tree.", source=__name__)
            return retval
        visited.add(tree_id)

        if PagesAttributes.KIDS in tree:
            # recurse down the tree
            for kid in cast(ArrayObject, tree[PagesAttributes.KIDS]):
                self._get_named_destinations(tree=kid.get_object(), retval=retval, visited=visited)
        # §7.9.6, entries in a name tree node dictionary
        elif CA.NAMES in tree:  # /Kids and /Names are exclusives (§7.9.6)
            names = cast(DictionaryObject, tree[CA.NAMES])
            i = 0
            while i < len(names):
                key = names[i].get_object()
                i += 1
                if not isinstance(key, (bytes, str)):
                    continue
                try:
                    value = names[i].get_object()
                except IndexError:
                    break
                i += 1
                if isinstance(value, DictionaryObject):
                    if "/D" in value:
                        value = value["/D"]
                    else:
                        continue
                dest = self._build_destination(key, value)
                if dest is not None:
                    retval[cast(str, dest["/Title"])] = dest
                    # Remain backwards-compatible.
                    retval[str(key)] = dest
        else:  # case where /Dests is in the document's catalog dictionary (PDF 1.7 specs, §2 about PDF 1.1)
            for k__, v__ in tree.items():
                val = v__.get_object()
                if isinstance(val, DictionaryObject):
                    if "/D" in val:
                        val = val["/D"].get_object()
                    else:
                        continue
                dest = self._build_destination(k__, val)
                if dest is not None:
                    retval[k__] = dest
        return retval

    # A select group of relevant field attributes. For the complete list,
    # see §12.3.2 of the PDF 1.7 or PDF 2.0 specification.

    def get_fields(
        self,
        tree: Optional[TreeObject] = None,
        retval: Optional[dict[Any, Any]] = None,
        fileobj: Optional[Any] = None,
        stack: Optional[list[PdfObject]] = None,
    ) -> Optional[dict[str, Any]]:
        """
        Extract field data if this PDF contains interactive form fields.

        The *tree*, *retval*, *stack* parameters are for recursive use.

        Args:
            tree: Current object to parse.
            retval: In-progress list of fields.
            fileobj: A file object (usually a text file) to write
                a report to on all interactive form fields found.
            stack: List of already parsed objects.

        Returns:
            A dictionary where each key is a field name, and each
            value is a :class:`Field<pypdf.generic.Field>` object. By
            default, the mapping name is used for keys.
            ``None`` if form data could not be located.

        """
        field_attributes = FA.attributes_dict()
        field_attributes.update(CheckboxRadioButtonAttributes.attributes_dict())
        if retval is None:
            retval = {}
            catalog = self.root_object
            stack = []
            # get the AcroForm tree
            if CA.ACRO_FORM in catalog:
                tree = cast(Optional[TreeObject], catalog[CA.ACRO_FORM])
            else:
                return None
        if tree is None:
            return retval
        assert stack is not None
        if "/Fields" in tree:
            fields = cast(ArrayObject, tree["/Fields"])
            for f in fields:
                field = f.get_object()
                self._build_field(field, retval, fileobj, field_attributes, stack)
        elif any(attr in tree for attr in field_attributes):
            # Tree is a field
            self._build_field(tree, retval, fileobj, field_attributes, stack)
        return retval

    def _get_qualified_field_name(
            self,
            *,
            parent: DictionaryObject,
            visited: Optional[set[int]] = None
    ) -> str:
        if visited is None:
            visited = set()
        parent_id = id(parent)
        if parent_id in visited:
            raise LimitReachedError("Detected cycle in /Parent hierarchy when retrieving qualified field name.")
        visited.add(parent_id)

        if "/TM" in parent:
            return cast(str, parent["/TM"])
        if "/Parent" in parent:
            return (
                self._get_qualified_field_name(
                    parent=cast(DictionaryObject, parent["/Parent"]),
                    visited=visited,
                )
                + "."
                + cast(str, parent.get("/T", ""))
            )
        return cast(str, parent.get("/T", ""))

    @staticmethod
    def _normal_appearance(appearance: Any) -> DictionaryObject:
        """Return the /N normal-appearance sub-dictionary of an /AP entry."""
        appearance = appearance.get_object()
        if not isinstance(appearance, DictionaryObject):
            raise PdfReadError(f"Expected appearance dictionary, got {appearance!r}")
        normal = appearance.get("/N")
        if normal is not None:
            normal = normal.get_object()
        if not isinstance(normal, DictionaryObject):
            raise PdfReadError(f"Expected /N appearance dictionary, got {normal!r}")
        return normal

    def _build_field(
        self,
        field: Union[TreeObject, DictionaryObject],
        retval: dict[Any, Any],
        fileobj: Any,
        field_attributes: Any,
        stack: list[PdfObject],
    ) -> None:
        if all(attr not in field for attr in ("/T", "/TM")):
            return
        key = self._get_qualified_field_name(parent=field)
        if fileobj:
            self._write_field(fileobj, field, field_attributes)
            fileobj.write("\n")
        retval[key] = Field(field)
        obj = retval[key].indirect_reference.get_object()  # to get the full object
        if obj.get(FA.FT, "") == "/Ch" and obj.get(NameObject(FA.Opt)):
            retval[key][NameObject("/_States_")] = obj[NameObject(FA.Opt)]
        if obj.get(FA.FT, "") == "/Btn" and "/AP" in obj:
            #  Checkbox
            normal = self._normal_appearance(obj["/AP"])
            retval[key][NameObject("/_States_")] = ArrayObject(list(normal.keys()))
            if "/Off" not in retval[key]["/_States_"]:
                retval[key][NameObject("/_States_")].append(NameObject("/Off"))
        elif obj.get(FA.FT, "") == "/Btn" and obj.get(FA.Ff, 0) & FA.FfBits.Radio != 0:
            states: list[str] = []
            retval[key][NameObject("/_States_")] = ArrayObject(states)
            for k in obj.get(FA.Kids, {}):
                k = k.get_object()
                if "/AP" not in k:
                    raise PdfReadError(f"Button field kid missing /AP: {k!r}")
                normal = self._normal_appearance(k["/AP"])
                for s in list(normal.keys()):
                    if s not in states:
                        states.append(s)
                retval[key][NameObject("/_States_")] = ArrayObject(states)
            if (
                obj.get(FA.Ff, 0) & FA.FfBits.NoToggleToOff != 0
                and "/Off" in retval[key]["/_States_"]
            ):
                del retval[key]["/_States_"][retval[key]["/_States_"].index("/Off")]
        # at last for order
        self._check_kids(field, retval, fileobj, stack)

    def _check_kids(
        self,
        tree: Union[TreeObject, DictionaryObject],
        retval: Any,
        fileobj: Any,
        stack: list[PdfObject],
    ) -> None:
        if tree in stack:
            logger_warning(
                "%(field_name)s already parsed",
                source=__name__,
                field_name=self._get_qualified_field_name(parent=tree),
            )
            return
        stack.append(tree)
        if PagesAttributes.KIDS in tree:
            # recurse down the tree
            for kid in tree[PagesAttributes.KIDS]:  # type: ignore[attr-defined]
                kid = kid.get_object()
                self.get_fields(kid, retval, fileobj, stack)

    def _write_field(self, fileobj: Any, field: Any, field_attributes: Any) -> None:
        field_attributes_tuple = FA.attributes()
        field_attributes_tuple = (
            field_attributes_tuple + CheckboxRadioButtonAttributes.attributes()
        )

        for attr in field_attributes_tuple:
            if attr in (
                FA.Kids,
                FA.AA,
            ):
                continue
            attr_name = field_attributes[attr]
            try:
                if attr == FA.FT:
                    # Make the field type value clearer
                    types = {
                        "/Btn": "Button",
                        "/Tx": "Text",
                        "/Ch": "Choice",
                        "/Sig": "Signature",
                    }
                    if field[attr] in types:
                        fileobj.write(f"{attr_name}: {types[field[attr]]}\n")
                elif attr == FA.Parent:
                    # Let's just write the name of the parent
                    try:
                        name = field[attr][FA.TM]
                    except KeyError:
                        name = field[attr][FA.T]
                    fileobj.write(f"{attr_name}: {name}\n")
                else:
                    fileobj.write(f"{attr_name}: {field[attr]}\n")
            except KeyError:
                # Field attribute is N/A or unknown, so don't write anything
                pass

    def get_form_text_fields(self, full_qualified_name: bool = False) -> dict[str, Any]:
        """
        Retrieve form fields from the document with textual data.

        Args:
            full_qualified_name: to get full name

        Returns:
            A dictionary. The key is the name of the form field,
            the value is the content of the field.

            If the document contains multiple form fields with the same name, the
            second and following will get the suffix .2, .3, ...

        """

        def indexed_key(k: str, fields: dict[Any, Any]) -> str:
            if k not in fields:
                return k
            return (
                k
                + "."
                + str(sum(1 for kk in fields if kk.startswith(k + ".")) + 2)
            )

        # Retrieve document form fields
        form_fields = self.get_fields()
        if form_fields is None:
            return {}
        ff = {}
        for field, value in form_fields.items():
            if value.get("/FT") == "/Tx":
                if full_qualified_name:
                    ff[field] = value.get("/V")
                else:
                    ff[indexed_key(cast(str, value.get("/T", field)), ff)] = value.get("/V")
        return ff

    def get_pages_showing_field(
        self, field: Union[Field, PdfObject, IndirectObject]
    ) -> list[PageObject]:
        """
        Provides list of pages where the field is called.

        Args:
            field: Field Object, PdfObject or IndirectObject referencing a Field

        Returns:
            List of pages:
                - Empty list:
                    The field has no widgets attached
                    (either hidden field or ancestor field).
                - Single page list:
                    Page where the widget is present
                    (most common).
                - Multi-page list:
                    Field with multiple kids widgets
                    (example: radio buttons, field repeated on multiple pages).

        """
        try:
            # to cope with all types
            field = cast(DictionaryObject, field.indirect_reference.get_object())  # type: ignore[union-attr]
        except Exception as exc:
            raise ValueError("Field type is invalid") from exc
        if is_null_or_none(field.get_inherited(key="/FT", default=None)):
            raise ValueError("Field is not valid")
        ret = []
        if field.get("/Subtype", "") == "/Widget":
            if "/P" in field:
                ret = [field["/P"].get_object()]
            else:
                ret = [
                    p
                    for p in self.pages
                    if field.indirect_reference in p.get("/Annots", "")
                ]
        else:
            kids = field.get("/Kids", ())
            for k in kids:
                k = k.get_object()
                if (k.get("/Subtype", "") == "/Widget") and ("/T" not in k):
                    # Kid that is just a widget, not a field:
                    if "/P" in k:
                        ret += [k["/P"].get_object()]
                    else:
                        ret += [
                            p
                            for p in self.pages
                            if k.indirect_reference in p.get("/Annots", "")
                        ]
        return [
            x
            if isinstance(x, PageObject)
            else (self.pages[self._get_page_number_by_indirect(x.indirect_reference)])  # type: ignore[index, union-attr]
            for x in ret
        ]

    @property
    def open_destination(
        self,
    ) -> Union[Destination, TextStringObject, ByteStringObject, None]:
        """
        Property to access the opening destination (``/OpenAction`` entry in
        the PDF catalog). It returns ``None`` if the entry does not exist
        or is not set.

        Raises:
            Exception: If a destination is invalid.

        """
        if "/OpenAction" not in self.root_object:
            return None
        oa: Any = self.root_object["/OpenAction"]
        if isinstance(oa, bytes):  # pragma: no cover
            oa = oa.decode()
        if isinstance(oa, str):
            return create_string_object(oa)
        if isinstance(oa, ArrayObject):
            try:
                page, typ, *array = oa
                fit = Fit(typ, tuple(array))
                return Destination("OpenAction", page, fit)
            except Exception as exc:
                raise Exception(f"Invalid Destination {oa}: {exc}")
        else:
            return None

    @open_destination.setter
    def open_destination(self, dest: Union[str, Destination, PageObject, None]) -> None:
        raise NotImplementedError("No setter for open_destination")

    @property
    def outline(self) -> OutlineType:
        """
        Read-only property for the outline present in the document
        (i.e., a collection of 'outline items' which are also known as
        'bookmarks').
        """
        return self._get_outline()

    def _get_outline(
        self,
        *,
        node: Optional[DictionaryObject] = None,
        outline: Optional[Any] = None,
        visited: Optional[set[int]] = None,
        depth: int = 0,
        traversal_state: Optional[_TraversalState] = None
    ) -> OutlineType:
        if traversal_state is None:
            traversal_state = _TraversalState()

        if outline is None:
            outline = []
            catalog = self.root_object

            # get the outline dictionary and named destinations
            if Core.OUTLINES in catalog:
                lines = cast(DictionaryObject, catalog[Core.OUTLINES])

                if isinstance(lines, NullObject):
                    return outline

                # §12.3.3 Document outline, entries in the outline dictionary
                if not is_null_or_none(lines) and "/First" in lines:
                    node = cast(DictionaryObject, lines["/First"])
            self._named_destinations = self._get_named_destinations()

        if node is None:
            return outline

        if depth > OUTLINE_MAX_DEPTH:
            raise LimitReachedError(f"Maximum outline depth reached: {depth} > {OUTLINE_MAX_DEPTH}.")

        # see if there are any more outline items
        if visited is None:
            visited = set()
        while True:
            node_id = id(node)
            if node_id in visited:
                logger_warning("Detected cycle in outline structure for %(node)s", source=__name__, node=node)
                break
            visited.add(node_id)
            traversal_state.entry_count += 1
            if traversal_state.entry_count > OUTLINE_MAX_ENTRIES:
                raise LimitReachedError(
                    f"Maximum outline entry limit reached: {traversal_state.entry_count} > {OUTLINE_MAX_ENTRIES}."
                )

            outline_obj = self._build_outline_item(node)
            if outline_obj:
                outline.append(outline_obj)

            # check for sub-outline
            if "/First" in node:
                sub_outline: list[Any] = []
                # Pass a copy to allow multiple outer entries to reference the same inner one.
                inner_visited = visited.copy()
                self._get_outline(
                    node=cast(DictionaryObject, node["/First"]),
                    outline=sub_outline,
                    visited=inner_visited,
                    depth=depth + 1,
                    traversal_state=traversal_state,
                )
                if sub_outline:
                    outline.append(sub_outline)

            if "/Next" not in node:
                break
            node = cast(DictionaryObject, node["/Next"])

        return outline

    @property
    def threads(self) -> Optional[ArrayObject]:
        """
        Read-only property for the list of threads.

        See §12.4.3 from the PDF 1.7 or 2.0 specification.

        It is an array of dictionaries with "/F" (the first bead in the thread)
        and "/I" (a thread information dictionary containing information about
        the thread, such as its title, author, and creation date) properties or
        None if there are no articles.

        Since PDF 2.0 it can also contain an indirect reference to a metadata
        stream containing information about the thread, such as its title,
        author, and creation date.
        """
        catalog = self.root_object
        if Core.THREADS in catalog:
            return cast("ArrayObject", catalog[Core.THREADS])
        return None

    @abstractmethod
    def _get_page_number_by_indirect(
        self, indirect_reference: Union[int, NullObject, IndirectObject, None]
    ) -> Optional[int]:
        ...  # pragma: no cover

    def get_page_number(self, page: PageObject) -> Optional[int]:
        """
        Retrieve page number of a given PageObject.

        Args:
            page: The page to get page number. Should be
                an instance of :class:`PageObject<pypdf._page.PageObject>`

        Returns:
            The page number or None if page is not found

        """
        return self._get_page_number_by_indirect(page.indirect_reference)

    def get_destination_page_number(self, destination: Destination) -> Optional[int]:
        """
        Retrieve page number of a given Destination object.

        Args:
            destination: The destination to get page number.

        Returns:
            The page number or None if page is not found

        """
        return self._get_page_number_by_indirect(destination.page)

    def _build_destination(
        self,
        title: Union[str, bytes],
        array: Optional[
            list[
                Union[NumberObject, IndirectObject, NullObject, DictionaryObject, None]
            ]
        ],
    ) -> Destination:
        page, typ = None, None
        # handle outline items with missing or invalid destination
        if (
            isinstance(array, (NullObject, str))
            or (isinstance(array, ArrayObject) and len(array) < 2)
            or array is None
        ):
            page = NullObject()
            return Destination(title, page, Fit.fit())
        page, typ, *array = array  # type: ignore[assignment]
        try:
            return Destination(title, page, Fit(fit_type=typ, fit_args=array))  # type: ignore[arg-type]
        except PdfReadError:
            logger_warning("Unknown destination: %(title)r %(array)s", source=__name__, title=title, array=array)
            if self.strict:
                raise
            # create a link to first Page
            tmp = self.pages[0].indirect_reference
            indirect_reference = NullObject() if tmp is None else tmp
            return Destination(title, indirect_reference, Fit.fit())

    def _build_outline_item(self, node: DictionaryObject) -> Optional[Destination]:
        dest, title, outline_item = None, None, None

        # title required for valid outline
        # §12.3.3, entries in an outline item dictionary
        try:
            title = cast("str", node["/Title"])
        except KeyError:
            if self.strict:
                raise PdfReadError(f"Outline Entry Missing /Title attribute: {node!r}")
            title = ""

        if "/A" in node:
            # Action, PDF 1.7 and PDF 2.0 §12.6 (only type GoTo supported)
            action = cast(DictionaryObject, node["/A"])
            action_type = cast(NameObject, action[GoToActionArguments.S])
            if action_type == "/GoTo":
                if GoToActionArguments.D in action:
                    dest = action[GoToActionArguments.D]
                elif self.strict:
                    raise PdfReadError(f"Outline Action Missing /D attribute: {node!r}")
        elif "/Dest" in node:
            # Destination, PDF 1.7 and PDF 2.0 §12.3.2
            dest = node["/Dest"]
            # if array was referenced in another object, will be a dict w/ key "/D"
            if isinstance(dest, DictionaryObject) and "/D" in dest:
                dest = dest["/D"]

        if isinstance(dest, ArrayObject):
            outline_item = self._build_destination(title, dest)
        elif isinstance(dest, str):
            # named destination, addresses NameObject Issue #193
            # TODO: Keep named destination instead of replacing it?
            try:
                outline_item = self._build_destination(
                    title, self._named_destinations[dest].dest_array
                )
            except KeyError:
                # named destination not found in Name Dict
                outline_item = self._build_destination(title, None)
        elif dest is None:
            # outline item not required to have destination or action
            # PDFv1.7 Table 153
            outline_item = self._build_destination(title, dest)
        else:
            if self.strict:
                raise PdfReadError(f"Unexpected destination {dest!r}")
            logger_warning(
                "Removed unexpected destination %(dest)r from destination",
                source=__name__,
                dest=dest,
            )
            outline_item = self._build_destination(title, None)

        # if outline item created, add color, format, and child count if present
        if outline_item:
            if "/C" in node:
                # Color of outline item font in (R, G, B) with values ranging 0.0-1.0
                color = node["/C"]
                if isinstance(color, list):
                    outline_item[NameObject("/C")] = ArrayObject(FloatObject(c) for c in color)
                else:
                    logger_warning(
                        "Ignoring non-array outline color %(color)r",
                        source=__name__,
                        color=color,
                    )
            if "/F" in node:
                # specifies style characteristics bold and/or italic
                # with 1=italic, 2=bold, 3=both
                outline_item[NameObject("/F")] = node["/F"]
            if "/Count" in node:
                # absolute value = num. visible children
                # with positive = open/unfolded, negative = closed/folded
                outline_item[NameObject("/Count")] = node["/Count"]
            #  if count is 0 we will consider it as open (to have available is_open)
            outline_item[NameObject("/%is_open%")] = BooleanObject(
                node.get("/Count", 0) >= 0
            )
        outline_item.node = node
        try:
            outline_item.indirect_reference = node.indirect_reference
        except AttributeError:
            pass
        return outline_item

    @property
    def pages(self) -> Sequence[PageObject]:
        """
        Property that emulates a list of :class:`PageObject<pypdf._page.PageObject>`.
        This property allows to get a page or a range of pages.

        The returned object supports indexing, slicing, ``len()``, iteration and
        (for PdfWriter) ``del``, but it is not a :class:`list` - pages are looked
        up on demand rather than materialised up front, so list-only operations
        such as ``append()`` or concatenation with ``+`` are not available.

        Note:
            For PdfWriter only: Provides the capability to remove a page/range of
            page from the list (using the del operator). Remember: Only the page
            entry is removed, as the objects beneath can be used elsewhere. A
            solution to completely remove them - if they are not used anywhere - is
            to write to a buffer/temporary file and then load it into a new
            PdfWriter.

        """
        return _VirtualList(self.get_num_pages, self.get_page)

    @property
    def page_labels(self) -> list[str]:
        """
        A list of labels for the pages in this document.

        This property is read-only. The labels are in the order that the pages
        appear in the document.
        """
        return [page_index2page_label(self, i) for i in range(len(self.pages))]

    @property
    def page_layout(self) -> Optional[str]:
        """
        Get the page layout currently being used.

        .. list-table:: Valid ``layout`` values
           :widths: 50 200

           * - /NoLayout
             - Layout explicitly not specified
           * - /SinglePage
             - Show one page at a time
           * - /OneColumn
             - Show one column at a time
           * - /TwoColumnLeft
             - Show pages in two columns, odd-numbered pages on the left
           * - /TwoColumnRight
             - Show pages in two columns, odd-numbered pages on the right
           * - /TwoPageLeft
             - Show two pages at a time, odd-numbered pages on the left
           * - /TwoPageRight
             - Show two pages at a time, odd-numbered pages on the right
        """
        try:
            return cast(NameObject, self.root_object[CA.PAGE_LAYOUT])
        except KeyError:
            return None

    @property
    def page_mode(self) -> Optional[PagemodeType]:
        """
        Get the page mode currently being used.

        .. list-table:: Valid ``mode`` values
           :widths: 50 200

           * - /UseNone
             - Do not show outline or thumbnails panels
           * - /UseOutlines
             - Show outline (aka bookmarks) panel
           * - /UseThumbs
             - Show page thumbnails panel
           * - /FullScreen
             - Fullscreen view
           * - /UseOC
             - Show Optional Content Group (OCG) panel
           * - /UseAttachments
             - Show attachments panel
        """
        try:
            return self.root_object["/PageMode"]  # type: ignore[return-value]
        except KeyError:
            return None

    def _flatten(
        self,
        list_only: bool = False,
        pages: Union[DictionaryObject, PageObject, None] = None,
        inherit: Optional[dict[str, Any]] = None,
        indirect_reference: Optional[IndirectObject] = None,
        visited: Optional[set[int]] = None,
    ) -> None:
        """
        Process the document pages to ease searching.

        Attributes of a page may inherit from ancestor nodes
        in the page tree. Flattening means moving
        any inheritance data into descendant nodes,
        effectively removing the inheritance dependency.

        Note: It is distinct from another use of "flattening" applied to PDFs.
        Flattening a PDF also means combining all the contents into one single layer
        and making the file less editable.

        Args:
            list_only: Will only list the pages within _flatten_pages.
            pages:
            inherit:
            indirect_reference: Used recursively to flatten the /Pages object.
            visited: Set of id() values of /Pages nodes already visited during
                traversal. Detects multi-hop cycles such as A→B→C→A that the
                single-parent check misses.

        """
        inheritable_page_attributes = (
            NameObject(PG.RESOURCES),
            NameObject(PG.MEDIABOX),
            NameObject(PG.CROPBOX),
            NameObject(PG.ROTATE),
        )
        if inherit is None:
            inherit = {}
        if visited is None:
            visited = set()
        if is_null_or_none(pages):
            # Fix issue 327: set flattened_pages attribute only for
            # decrypted file
            catalog = self.root_object
            pages = catalog.get("/Pages").get_object()  # type: ignore[union-attr]
            if not isinstance(pages, DictionaryObject):
                raise PdfReadError("Invalid object in /Pages")
            self.flattened_pages = []
        assert pages is not None, "mypy"

        if PagesAttributes.TYPE in pages:
            t = cast(str, pages[PagesAttributes.TYPE])
        # if the page tree node has no /Type, consider as a page if /Kids is also missing
        elif PagesAttributes.KIDS not in pages:
            # Without /Type, only accept it as a page if it carries a structural page key.
            if self.strict and not any(
                key in pages for key in (PG.CONTENTS, PG.MEDIABOX, PG.PARENT)
            ):
                raise PdfReadError(f"Non-page object reached through /Kids: {pages!r}")
            t = "/Page"
        else:
            t = "/Pages"

        if t == "/Pages":
            for attr in inheritable_page_attributes:
                if attr in pages:
                    inherit[attr] = pages[attr]
            pages_reference = getattr(pages, "indirect_reference", object())
            kids = pages.get(PagesAttributes.KIDS, ArrayObject()).get_object()
            if isinstance(kids, NullObject):
                kids = ArrayObject()
            elif not isinstance(kids, ArrayObject):
                raise PdfReadError(
                    f"Expected /Kids to be an array, got {type(kids).__name__}."
                )
            for page in kids:
                if getattr(page, "indirect_reference", object()) == pages_reference:
                    raise PdfReadError("Detected cyclic page references.")

                additional_arguments = {}
                if isinstance(page, IndirectObject):
                    additional_arguments["indirect_reference"] = page
                obj = page.get_object()
                if obj:
                    # damaged file may have invalid child in /Pages
                    obj_id = id(obj)
                    if obj_id in visited:
                        raise PdfReadError("Detected cyclic page references.")
                    visited.add(obj_id)
                    self._flatten(list_only, obj, inherit, visited=visited, **additional_arguments)
        elif t == "/Page":
            for attr_in, value in inherit.items():
                # if the page has its own value, it does not inherit the
                # parent's value
                if attr_in not in pages:
                    pages[attr_in] = value
            page_obj = PageObject(self, indirect_reference)
            if not list_only:
                page_obj.update(pages)

            # TODO: Could flattened_pages be None at this point?
            self.flattened_pages.append(page_obj)  # type: ignore[union-attr]

    def remove_page(
        self,
        page: Union[int, PageObject, IndirectObject],
        clean: bool = False,
    ) -> None:
        """
        Remove page from pages list.

        Args:
            page:
                * :class:`int`: Page number to be removed.
                * :class:`~pypdf._page.PageObject`: page to be removed. If the page appears many times
                  only the first one will be removed.
                * :class:`~pypdf.generic.IndirectObject`: Reference to page to be removed.

            clean: replace PageObject with NullObject to prevent annotations
                or destinations to reference a detached page.

        """
        if self.flattened_pages is None:
            self._flatten(self._readonly)
        assert self.flattened_pages is not None
        if isinstance(page, IndirectObject):
            p = page.get_object()
            if not isinstance(p, PageObject):
                logger_warning("IndirectObject is not referencing a page", source=__name__)
                return
            page = p

        if not isinstance(page, int):
            try:
                page = self.flattened_pages.index(page)
            except ValueError:
                logger_warning("Cannot find page in pages", source=__name__)
                return
        if not (0 <= page < len(self.flattened_pages)):
            logger_warning("Page number is out of range", source=__name__)
            return

        ind = self.pages[page].indirect_reference
        # `pages` is typed as a Sequence because it is not a list, but the
        # concrete _VirtualList does implement deletion.
        del cast(_VirtualList, self.pages)[page]
        if clean and ind is not None:
            self._replace_object(ind, NullObject())

    def _get_indirect_object(self, num: int, gen: int) -> Optional[PdfObject]:
        """
        Used to ease development.

        This is equivalent to generic.IndirectObject(num,gen,self).get_object()

        Args:
            num: The object number of the indirect object.
            gen: The generation number of the indirect object.

        Returns:
            A PdfObject

        """
        return IndirectObject(num, gen, self).get_object()

    def decode_permissions(
        self, permissions_code: int
    ) -> NoReturn:  # pragma: no cover
        """Take the permissions as an integer, return the allowed access."""
        deprecation_with_replacement(
            old_name="decode_permissions",
            new_name="user_access_permissions",
            removed_in="5.0.0",
        )

    @property
    def user_access_permissions(self) -> Optional[UserAccessPermissions]:
        """
        Get the user access permissions for encrypted documents.
        Returns None if not encrypted.

        .. warning::

            For AES-256 encrypted documents (R=5/R=6), the returned
            permissions are derived from the ``/P`` field, which is
            only trustworthy if the ``/Perms`` integrity check passed.
            Check :attr:`are_permissions_valid` to verify.
        """
        if self._encryption is None:
            return None
        return UserAccessPermissions(self._encryption.P)

    @property
    def are_permissions_valid(self) -> Optional[bool]:
        """
        Whether the ``/Perms`` integrity check passed for this document.

        For AES-256 encrypted documents (R=5/R=6), the ``/Perms`` field
        is an encrypted copy of the permissions that can be verified
        independently. Returns ``False`` if this check fails (the ``/P``
        permissions may have been tampered with).

        Returns ``None`` if the document is not encrypted or has not yet
        been decrypted via :meth:`decrypt()<pypdf.PdfReader.decrypt>`.
        Returns ``True`` for non-AES-256 encryption (no ``/Perms`` to check).
        """
        if self._encryption is None:
            return None
        if not self._encryption.is_decrypted():
            return None
        return self._encryption._are_permissions_valid

    @property
    @abstractmethod
    def is_encrypted(self) -> bool:
        """
        Read-only boolean property showing whether this PDF file is encrypted.

        Note that this property, if true, will remain true even after the
        :meth:`decrypt()<pypdf.PdfReader.decrypt>` method is called.
        """
        ...  # pragma: no cover

    @property
    def xfa(self) -> Optional[dict[str, Any]]:
        retval: dict[str, Any] = {}
        catalog = self.root_object

        if "/AcroForm" not in catalog or not catalog["/AcroForm"]:
            return None

        tree = cast(TreeObject, catalog["/AcroForm"])

        if "/XFA" in tree:
            fields = cast(ArrayObject, tree["/XFA"])
            i = iter(fields)
            for f in i:
                tag = f
                f = next(i)
                if isinstance(f, IndirectObject):
                    field = cast(Optional[EncodedStreamObject], f.get_object())
                    if field:
                        es = _decompress_with_limit(field._data)
                        retval[tag] = es
        return retval

    @property
    def attachments(self) -> Mapping[str, list[bytes]]:
        """Mapping of attachment filenames to their content."""
        return LazyDict(
            {
                name: (self._get_attachment_list, name)
                for name in self._list_attachments()
            }
        )

    @property
    def attachment_list(self) -> Generator[EmbeddedFile, None, None]:
        """Iterable of attachment objects."""
        yield from EmbeddedFile._load(self.root_object)

    def _list_attachments(self) -> list[str]:
        """
        Retrieves the list of filenames of file attachments.

        Returns:
            list of filenames

        """
        names = []
        for entry in self.attachment_list:
            names.append(entry.name)
            if (name := entry.alternative_name) != entry.name and name:
                names.append(name)
        return names

    def _get_attachment_list(self, name: str) -> list[bytes]:
        out = self._get_attachments(name)[name]
        if isinstance(out, list):
            return out
        return [out]

    def _get_attachments(
        self, filename: Optional[str] = None
    ) -> dict[str, Union[bytes, list[bytes]]]:
        """
        Retrieves all or selected file attachments of the PDF as a dictionary of file names
        and the file data as a bytestring.

        Args:
            filename: If filename is None, then a dictionary of all attachments
                will be returned, where the key is the filename and the value
                is the content. Otherwise, a dictionary with just a single key
                - the filename - and its content will be returned.

        Returns:
            dictionary of filename -> Union[bytestring or List[ByteString]]
            If the filename exists multiple times a list of the different versions will be provided.

        """
        attachments: dict[str, Union[bytes, list[bytes]]] = {}
        for entry in self.attachment_list:
            names = set()
            alternative_name = entry.alternative_name
            if filename is not None:
                if filename in {entry.name, alternative_name}:
                    name = entry.name if filename == entry.name else alternative_name
                    names.add(name)
                else:
                    continue
            else:
                names = {entry.name, alternative_name}

            for name in names:
                if name is None:
                    continue
                if name in attachments:
                    if not isinstance(attachments[name], list):
                        attachments[name] = [attachments[name]]  # type:ignore
                    attachments[name].append(entry.content)  # type:ignore
                else:
                    attachments[name] = entry.content
        return attachments

    @abstractmethod
    def _repr_mimebundle_(
        self,
        include: Union[Iterable[str], None] = None,
        exclude: Union[Iterable[str], None] = None,
    ) -> dict[str, Any]:
        """
        Integration into Jupyter Notebooks.

        This method returns a dictionary that maps a mime-type to its
        representation.

        .. seealso::

            https://ipython.readthedocs.io/en/stable/config/integrating.html
        """
        ...  # pragma: no cover


class LazyDict(Mapping[Any, Any]):
    def __init__(self, *args: Any, **kwargs: Any) -> None:
        self._raw_dict = dict(*args, **kwargs)

    def __getitem__(self, key: str) -> Any:
        func, arg = self._raw_dict.__getitem__(key)
        return func(arg)

    def __iter__(self) -> Iterator[Any]:
        return iter(self._raw_dict)

    def __len__(self) -> int:
        return len(self._raw_dict)

    def __str__(self) -> str:
        return f"LazyDict(keys={list(self.keys())})"
