"""
Tests for documents.pdf_ops.

These use real PDFs from the sample directories. No database, Celery or mocks.
Pages are compared by a hash of their content stream, so page identity and order
are easy to assert.
"""

import hashlib
from collections.abc import Callable
from pathlib import Path

import pikepdf
import pytest

from documents import pdf_ops
from documents.pdf_ops import PageSpec

SRC_ROOT = Path(__file__).parents[2]
SAMPLES = Path(__file__).parent / "samples"
THREE_PAGES = SAMPLES / "documents" / "originals" / "0000002.pdf"
TWELVE_PAGES = SAMPLES / "barcodes" / "split-by-asn-2.pdf"
ENCRYPTED = SAMPLES / "password-is-test.pdf"
SIGNED = SRC_ROOT / "paperless" / "tests" / "samples" / "tesseract" / "signed.pdf"


def _page_fingerprint(page: pikepdf.Page) -> str:
    contents = page.obj.get("/Contents")
    assert contents is not None, "sample page has no /Contents"
    streams = list(contents) if isinstance(contents, pikepdf.Array) else [contents]
    return hashlib.sha256(b"".join(s.read_bytes() for s in streams)).hexdigest()


def fingerprints(path: Path) -> list[str]:
    with pikepdf.open(path) as pdf:
        return [_page_fingerprint(page) for page in pdf.pages]


def rotations(path: Path) -> list[int]:
    with pikepdf.open(path) as pdf:
        return [int(page.obj.get("/Rotate", 0)) for page in pdf.pages]


def docinfo_keys(path: Path) -> set[str]:
    with pikepdf.open(path) as pdf:
        return set(pdf.docinfo.keys())


def constant(path: Path) -> Callable[[], Path]:
    return lambda: path


@pytest.fixture
def source_fingerprints() -> list[str]:
    fps = fingerprints(THREE_PAGES)
    assert len(set(fps)) == 3, "sample must have three distinct pages"
    return fps


class TestRotatePdf:
    def test_rotation_is_relative_and_applies_to_every_page(
        self,
        tmp_path: Path,
    ) -> None:
        """
        GIVEN:
            - A three page PDF
        WHEN:
            - It is rotated by 90 degrees, then the result is rotated by 90 again
        THEN:
            - Every page is rotated relative to its current rotation
            - The page content itself is unchanged
        """
        once = tmp_path / "once.pdf"
        twice = tmp_path / "twice.pdf"

        pdf_ops.rotate_pdf(THREE_PAGES, once, 90)
        pdf_ops.rotate_pdf(once, twice, 90)

        assert rotations(once) == [90, 90, 90]
        assert rotations(twice) == [180, 180, 180]
        assert fingerprints(twice) == fingerprints(THREE_PAGES)

    def test_keeps_document_info(self, tmp_path: Path) -> None:
        """
        GIVEN:
            - A PDF with document info
        WHEN:
            - It is rotated
        THEN:
            - The document info is still present in the output
        """
        dst = tmp_path / "out.pdf"

        pdf_ops.rotate_pdf(THREE_PAGES, dst, 90)

        assert "/Creator" in docinfo_keys(dst)


class TestRemovePages:
    @pytest.mark.parametrize(
        ("pages", "kept"),
        [
            pytest.param([2], [0, 2], id="single"),
            pytest.param([3, 1], [1], id="unordered"),
            pytest.param([2, 2], [0, 2], id="duplicates-remove-once"),
            pytest.param([], [0, 1, 2], id="empty-keeps-everything"),
            pytest.param([1, 2, 3], [], id="every-page"),
        ],
    )
    def test_removes_only_the_requested_pages(
        self,
        tmp_path: Path,
        source_fingerprints: list[str],
        pages: list[int],
        kept: list[int],
    ) -> None:
        """
        GIVEN:
            - A three page PDF
        WHEN:
            - Pages are removed, in any order and possibly repeated
        THEN:
            - Exactly the other pages remain, in their original order
        """
        dst = tmp_path / "out.pdf"

        pdf_ops.remove_pages(THREE_PAGES, dst, pages)

        assert fingerprints(dst) == [source_fingerprints[i] for i in kept]

    def test_keeps_document_info(self, tmp_path: Path) -> None:
        """
        GIVEN:
            - A PDF with document info
        WHEN:
            - A page is removed
        THEN:
            - The document info is still present in the output
        """
        dst = tmp_path / "out.pdf"

        pdf_ops.remove_pages(THREE_PAGES, dst, [1])

        assert "/Creator" in docinfo_keys(dst)

    @pytest.mark.parametrize(
        "bad_page",
        [
            pytest.param(0, id="zero"),
            pytest.param(-1, id="negative"),
        ],
    )
    def test_rejects_pages_below_one(self, tmp_path: Path, bad_page: int) -> None:
        """
        GIVEN:
            - A three page PDF
        WHEN:
            - Pages are removed and one of them is below 1
        THEN:
            - ValueError is raised
            - No output file is written
        """
        dst = tmp_path / "out.pdf"

        with pytest.raises(ValueError, match="start at 1"):
            pdf_ops.remove_pages(THREE_PAGES, dst, [1, bad_page])

        assert not dst.exists()


class TestBuildPdfs:
    def test_selects_and_orders_pages(
        self,
        tmp_path: Path,
        source_fingerprints: list[str],
    ) -> None:
        """
        GIVEN:
            - A three page PDF
        WHEN:
            - One output is built from pages 3 then 1
        THEN:
            - The output has those pages in that order
            - Its path is returned
        """
        dst = tmp_path / "out.pdf"

        written = pdf_ops.build_pdfs(
            THREE_PAGES,
            [([PageSpec(3), PageSpec(1)], constant(dst))],
        )

        assert written == [dst]
        assert fingerprints(dst) == [source_fingerprints[2], source_fingerprints[0]]

    def test_rotates_only_the_requested_pages(self, tmp_path: Path) -> None:
        """
        GIVEN:
            - A three page PDF
        WHEN:
            - One output is built with a different rotation on each page
        THEN:
            - Each output page has exactly the rotation requested for it
        """
        dst = tmp_path / "out.pdf"

        pdf_ops.build_pdfs(
            THREE_PAGES,
            [([PageSpec(1), PageSpec(2, 90), PageSpec(3, 180)], constant(dst))],
        )

        assert rotations(dst) == [0, 90, 180]

    def test_writes_one_file_per_output_in_order(self, tmp_path: Path) -> None:
        """
        GIVEN:
            - A twelve page PDF
        WHEN:
            - Two outputs are built from different page ranges
        THEN:
            - Two files are written and returned in output order
            - Each holds exactly its own pages
        """
        first = tmp_path / "first.pdf"
        second = tmp_path / "second.pdf"
        source = fingerprints(TWELVE_PAGES)

        written = pdf_ops.build_pdfs(
            TWELVE_PAGES,
            [
                ([PageSpec(p) for p in (1, 2, 3)], constant(first)),
                ([PageSpec(p) for p in range(4, 13)], constant(second)),
            ],
        )

        assert written == [first, second]
        assert fingerprints(first) == source[:3]
        assert fingerprints(second) == source[3:]

    def test_empty_page_list_writes_a_zero_page_file(self, tmp_path: Path) -> None:
        """
        GIVEN:
            - A three page PDF
        WHEN:
            - An output with no pages is built
        THEN:
            - A PDF with zero pages is written
        """
        dst = tmp_path / "out.pdf"

        pdf_ops.build_pdfs(THREE_PAGES, [([], constant(dst))])

        assert fingerprints(dst) == []

    def test_destination_is_not_requested_when_a_page_is_out_of_range(
        self,
        tmp_path: Path,
    ) -> None:
        """
        GIVEN:
            - A three page PDF
        WHEN:
            - Several outputs are built
            - A later output refers to a page past the end
        THEN:
            - IndexError is raised
            - No destination was requested for any output, including earlier valid ones
        """
        requested: list[Path] = []

        def make_dst() -> Path:
            requested.append(tmp_path / "out.pdf")
            return requested[-1]

        with pytest.raises(IndexError):
            pdf_ops.build_pdfs(
                THREE_PAGES,
                [([PageSpec(1)], make_dst), ([PageSpec(99)], make_dst)],
            )

        assert requested == []

    @pytest.mark.parametrize(
        "bad_page",
        [
            pytest.param(0, id="zero"),
            pytest.param(-1, id="negative"),
        ],
    )
    def test_rejects_pages_below_one_before_opening_anything(
        self,
        tmp_path: Path,
        bad_page: int,
    ) -> None:
        """
        GIVEN:
            - A three page PDF
        WHEN:
            - Several outputs are built and a later one has a page below 1
        THEN:
            - ValueError is raised
            - No destination was requested for any output
        """
        requested: list[Path] = []

        def make_dst() -> Path:
            requested.append(tmp_path / "out.pdf")
            return requested[-1]

        with pytest.raises(ValueError, match="start at 1"):
            pdf_ops.build_pdfs(
                THREE_PAGES,
                [([PageSpec(1)], make_dst), ([PageSpec(bad_page)], make_dst)],
            )

        assert requested == []


class TestValidatePageOperations:
    def test_returns_the_output_count(self) -> None:
        """
        GIVEN:
            - Operations that all target the default output
        WHEN:
            - They are validated
        THEN:
            - One output document is reported
        """
        operations = [{"page": 1}, {"page": 2}, {"page": 3}]

        assert pdf_ops.validate_page_operations(operations, single_output=True) == 1

    def test_gap_in_output_indices_counts_up_to_the_highest(self) -> None:
        """
        GIVEN:
            - Operations that target outputs 0 and 2 but never 1
        WHEN:
            - They are validated
        THEN:
            - Three output documents are reported
        """
        operations = [
            {"page": 1, "doc": 0},
            {"page": 2, "doc": 2},
            {"page": 3, "doc": 0},
        ]

        count = pdf_ops.validate_page_operations(operations, single_output=False)

        assert count == 3

    def test_empty_operations_are_rejected(self) -> None:
        """
        GIVEN:
            - No operations
        WHEN:
            - They are validated
        THEN:
            - ValueError is raised
        """
        with pytest.raises(ValueError, match="index is out of bounds"):
            pdf_ops.validate_page_operations([], single_output=False)

    def test_multiple_outputs_rejected_when_single_output_required(self) -> None:
        """
        GIVEN:
            - Operations that target two outputs
        WHEN:
            - They are validated with a single output required
        THEN:
            - ValueError is raised
        """
        operations = [{"page": 1, "doc": 0}, {"page": 2, "doc": 1}]

        with pytest.raises(ValueError, match="Multiple output documents"):
            pdf_ops.validate_page_operations(operations, single_output=True)

    @pytest.mark.parametrize(
        "doc",
        [
            pytest.param(-1, id="negative"),
            pytest.param(2, id="equal-to-operation-count"),
            pytest.param(2**32, id="huge"),
        ],
    )
    def test_output_index_out_of_bounds(self, doc: int) -> None:
        """
        GIVEN:
            - Two operations, one with an output index that is out of bounds
        WHEN:
            - They are validated
        THEN:
            - ValueError is raised
        """
        operations = [{"page": 1, "doc": 0}, {"page": 2, "doc": doc}]

        with pytest.raises(ValueError, match="index is out of bounds"):
            pdf_ops.validate_page_operations(operations, single_output=False)


class TestDecrypt:
    @pytest.mark.parametrize(
        ("path", "expected"),
        [
            pytest.param(ENCRYPTED, True, id="password-required"),
            pytest.param(SIGNED, True, id="opens-without-password-but-encrypted"),
            pytest.param(THREE_PAGES, False, id="not-encrypted"),
        ],
    )
    def test_needs_decrypt(self, path: Path, *, expected: bool) -> None:
        """
        GIVEN:
            - A PDF that is encrypted, or encrypted but openable, or plain
        WHEN:
            - needs_decrypt is asked about it
        THEN:
            - Only the unencrypted PDF reports False
        """
        assert pdf_ops.needs_decrypt(path) is expected

    def test_decrypt_writes_an_unencrypted_copy(self, tmp_path: Path) -> None:
        """
        GIVEN:
            - A password protected PDF
        WHEN:
            - It is decrypted with the correct password
        THEN:
            - The path from make_dst is returned
            - The written copy no longer needs decrypting
        """
        dst = tmp_path / "out.pdf"

        result = pdf_ops.decrypt_pdf(ENCRYPTED, constant(dst), "test")

        assert result == dst
        assert pdf_ops.needs_decrypt(dst) is False

    def test_wrong_password_raises_and_never_requests_a_destination(
        self,
        tmp_path: Path,
    ) -> None:
        """
        GIVEN:
            - A password protected PDF
        WHEN:
            - It is decrypted with the wrong password
        THEN:
            - PasswordError is raised
            - No destination was requested
        """
        requested: list[Path] = []

        def make_dst() -> Path:
            requested.append(tmp_path / "out.pdf")
            return requested[-1]

        with pytest.raises(pikepdf.PasswordError):
            pdf_ops.decrypt_pdf(ENCRYPTED, make_dst, "wrong")

        assert requested == []


class TestPdfMerger:
    def test_pages_are_appended_in_the_order_added(
        self,
        tmp_path: Path,
        source_fingerprints: list[str],
    ) -> None:
        """
        GIVEN:
            - A reordered PDF and the original three page PDF
        WHEN:
            - Both are added to a merger in that order and saved
        THEN:
            - The output holds all pages in the order they were added
        """
        reordered = tmp_path / "reordered.pdf"
        merged = tmp_path / "merged.pdf"
        pdf_ops.build_pdfs(
            THREE_PAGES,
            [([PageSpec(3), PageSpec(1)], constant(reordered))],
        )

        with pdf_ops.PdfMerger() as merger:
            merger.add(reordered)
            merger.add(THREE_PAGES)
            merger.save(merged)

        assert fingerprints(merged) == [
            source_fingerprints[2],
            source_fingerprints[0],
            *source_fingerprints,
        ]

    def test_output_version_is_at_least_the_highest_source_version(
        self,
        tmp_path: Path,
    ) -> None:
        """
        GIVEN:
            - Two PDFs with different PDF versions
        WHEN:
            - Both are added to a merger and saved
        THEN:
            - The output version is at least the highest source version
        """
        merged = tmp_path / "merged.pdf"
        with pikepdf.open(TWELVE_PAGES) as pdf:
            source_versions = [pdf.pdf_version]
        with pikepdf.open(THREE_PAGES) as pdf:
            source_versions.append(pdf.pdf_version)

        with pdf_ops.PdfMerger() as merger:
            merger.add(TWELVE_PAGES)
            merger.add(THREE_PAGES)
            merger.save(merged)

        with pikepdf.open(merged) as pdf:
            assert pdf.pdf_version >= max(source_versions)