feat(reader): add PDF reading support with outline chapters, CLI blocks, and noise filtering (task 7)

app/vendor/pypdf/generic/_link.py

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+# 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.
+
+
+# This module contains code used by _writer.py to track links in pages
+# being added to the writer until the links can be resolved.
+
+from typing import TYPE_CHECKING, Optional, Union, cast
+
+from .._utils import logger_warning
+from . import ArrayObject, DictionaryObject, IndirectObject, PdfObject, TextStringObject, is_null_or_none
+
+if TYPE_CHECKING:
+    from .._page import PageObject
+    from .._reader import PdfReader
+    from .._writer import PdfWriter
+
+
+class NamedReferenceLink:
+    """Named reference link being preserved until we can resolve it correctly."""
+
+    def __init__(self, reference: TextStringObject, source_pdf: "PdfReader") -> None:
+        """reference: TextStringObject with named reference"""
+        self._reference = reference
+        self._source_pdf = source_pdf
+
+    def find_referenced_page(self) -> Union[IndirectObject, None]:
+        destination = self._source_pdf.named_destinations.get(str(self._reference))
+        return destination.page if destination else None
+
+    def patch_reference(self, target_pdf: "PdfWriter", new_page: IndirectObject) -> None:
+        """target_pdf: PdfWriter which the new link went into"""
+        # point named destination in new PDF to the new page
+        if str(self._reference) not in target_pdf.named_destinations:
+            target_pdf.add_named_destination(str(self._reference), new_page.page_number)
+
+
+class DirectReferenceLink:
+    """Direct reference link being preserved until we can resolve it correctly."""
+
+    def __init__(self, reference: ArrayObject) -> None:
+        """reference: an ArrayObject whose first element is the Page indirect object"""
+        self._reference = reference
+
+    def find_referenced_page(self) -> Union[IndirectObject, None]:
+        if not self._reference:
+            return None
+        return cast(IndirectObject, self._reference[0])
+
+    def patch_reference(self, target_pdf: "PdfWriter", new_page: IndirectObject) -> None:
+        """target_pdf: PdfWriter which the new link went into"""
+        self._reference[0] = new_page
+
+
+ReferenceLink = Union[NamedReferenceLink, DirectReferenceLink]
+
+
+def extract_links(new_page: "PageObject", old_page: "PageObject") -> list[tuple[ReferenceLink, ReferenceLink]]:
+    """Extracts links from two pages on the assumption that the two pages are
+    the same. Produces one list of (new link, old link) tuples.
+
+    Non-link annotations are ignored before pairing to avoid dropping valid
+    links when one page includes additional non-link annotation entries.
+    """
+    new_annotations = new_page.get("/Annots", ArrayObject()).get_object()
+    old_annotations = old_page.get("/Annots", ArrayObject()).get_object()
+    if is_null_or_none(new_annotations):
+        new_annotations = ArrayObject()
+    if is_null_or_none(old_annotations):
+        old_annotations = ArrayObject()
+    if not isinstance(new_annotations, ArrayObject) or not isinstance(old_annotations, ArrayObject):
+        logger_warning(
+            "Expected annotation arrays: %(old_annotations)s %(new_annotations)s. Ignoring annotations.",
+            source=__name__,
+            old_annotations=old_annotations,
+            new_annotations=new_annotations,
+        )
+        return []
+    new_links = [
+        link
+        for annotation in new_annotations
+        if (link := _build_link(annotation, new_page)) is not None
+    ]
+    old_links = [
+        link
+        for annotation in old_annotations
+        if (link := _build_link(annotation, old_page)) is not None
+    ]
+
+    if len(new_links) != len(old_links):
+        logger_warning(
+            "Annotation sizes differ: %(old_count)d vs. %(new_count)d",
+            source=__name__,
+            old_count=len(old_links),
+            new_count=len(new_links),
+        )
+
+    return list(zip(new_links, old_links))
+
+
+def _build_link(indirect_object: IndirectObject, page: "PageObject") -> Optional[ReferenceLink]:
+    src = cast("PdfReader", page.pdf)
+    link = cast(DictionaryObject, indirect_object.get_object())
+    if (not isinstance(link, DictionaryObject)) or link.get("/Subtype") != "/Link":
+        return None
+
+    if "/A" in link:
+        action = cast(DictionaryObject, link["/A"])
+        if action.get("/S") != "/GoTo":
+            return None
+
+        if "/D" not in action:
+            return None
+        return _create_link(action["/D"], src)
+
+    if "/Dest" in link:
+        return _create_link(link["/Dest"], src)
+
+    return None  # Nothing to do here
+
+
+def _create_link(reference: PdfObject, source_pdf: "PdfReader") -> Optional[ReferenceLink]:
+    if isinstance(reference, TextStringObject):
+        return NamedReferenceLink(reference, source_pdf)
+    if isinstance(reference, ArrayObject):
+        return DirectReferenceLink(reference)
+    return None