from __future__ import annotations

import pytest

from app.core.errors import EncryptedPDFError, InvalidPDFError, PDFTextUnavailableError
from app.services.pdf import extract_resume, sanitize_filename
from tests.conftest import make_encrypted_pdf, make_pdf, resume_pdf


class TestSanitizeFilename:
    @pytest.mark.parametrize(
        ("raw", "expected"),
        [
            ("resume.pdf", "resume.pdf"),
            ("../../etc/passwd.pdf", "passwd.pdf"),
            # PurePosixPath alone leaves this untouched on POSIX -- the reason
            # PureWindowsPath runs first.
            (r"..\..\windows\system32\evil.pdf", "evil.pdf"),
            (r"C:\Users\me\Desktop\cv.pdf", "cv.pdf"),
            ("/absolute/path/cv.pdf", "cv.pdf"),
            ("mixed/sep\\cv.pdf", "cv.pdf"),
            ('cv<>:"|?*.pdf', "cv_______.pdf"),
            ("", "resume.pdf"),
            (None, "resume.pdf"),
            ("..", "resume.pdf"),
            ("...", "resume.pdf"),
        ],
    )
    def test_reduces_to_safe_basename(self, raw: str | None, expected: str) -> None:
        assert sanitize_filename(raw) == expected

    def test_strips_null_bytes(self) -> None:
        assert sanitize_filename("cv\x00.pdf") == "cv_.pdf"

    def test_caps_length(self) -> None:
        assert len(sanitize_filename("a" * 400 + ".pdf")) == 255


class TestExtractResume:
    def test_extracts_text_from_a_valid_pdf(self) -> None:
        resume = extract_resume(resume_pdf("Ada"), "ada.pdf", 60_000)

        assert "Candidate Ada" in resume.text
        assert resume.page_count == 1
        assert resume.truncated is False
        assert resume.candidate_id

    def test_joins_pages_in_order_with_separators(self) -> None:
        data = make_pdf([["First page content here."], ["Second page content here."]])

        resume = extract_resume(data, "multi.pdf", 60_000)

        assert resume.page_count == 2
        assert "[Page 1]" in resume.text
        assert "[Page 2]" in resume.text
        assert resume.text.index("[Page 1]") < resume.text.index("[Page 2]")
        assert resume.text.index("First page") < resume.text.index("Second page")

    def test_rejects_a_pdf_with_no_extractable_text(self) -> None:
        """Stands in for a scanned/image-only resume."""
        with pytest.raises(PDFTextUnavailableError):
            extract_resume(make_pdf([[]]), "scanned.pdf", 60_000)

    def test_rejects_text_below_the_usable_threshold(self) -> None:
        with pytest.raises(PDFTextUnavailableError):
            extract_resume(make_pdf([["hi"]]), "tiny.pdf", 60_000)

    def test_rejects_missing_pdf_signature(self) -> None:
        with pytest.raises(InvalidPDFError):
            extract_resume(b"this is plain text, not a pdf at all", "fake.pdf", 60_000)

    def test_rejects_malformed_pdf(self) -> None:
        with pytest.raises(InvalidPDFError):
            extract_resume(b"%PDF-1.4\ngarbage garbage garbage", "broken.pdf", 60_000)

    def test_rejects_encrypted_pdf(self) -> None:
        with pytest.raises(EncryptedPDFError):
            extract_resume(make_encrypted_pdf(), "locked.pdf", 60_000)

    def test_truncates_at_the_configured_limit_and_records_it(self) -> None:
        long_pdf = make_pdf([[f"Line {i} of a very long resume document." for i in range(400)]])

        resume = extract_resume(long_pdf, "long.pdf", 500)

        assert resume.truncated is True
        assert len(resume.text) <= 500

    def test_does_not_flag_truncation_when_under_the_limit(self) -> None:
        resume = extract_resume(resume_pdf("Ada"), "ada.pdf", 60_000)
        assert resume.truncated is False

    def test_normalises_whitespace_without_destroying_line_breaks(self) -> None:
        data = make_pdf([["Header line for the resume", "Body line for the resume"]])

        resume = extract_resume(data, "spaced.pdf", 60_000)

        assert "\n" in resume.text
        assert "   " not in resume.text
        assert "\x00" not in resume.text

    def test_tolerates_junk_bytes_before_the_signature(self) -> None:
        data = b"\n\n" + resume_pdf("Ada")
        resume = extract_resume(data, "ada.pdf", 60_000)
        assert "Candidate Ada" in resume.text