import hashlib
from datetime import UTC, datetime

import pytest

from tht.evidence.contracts import AcquiredDocument, SourceObject
from tht.evidence.corpus.normalize import MAX_DOCUMENT_BYTES, PermanentNormalizationError, normalize


def acquired(content: bytes, *, media_type: str = "text/markdown") -> AcquiredDocument:
    return AcquiredDocument(
        source=SourceObject(
            source_id="source:guide",
            uri="https://host/guide.md?signature=transport#part",
            fingerprint="etag:abc",
            modified_at=datetime(2026, 7, 12, 12, 0, tzinfo=UTC),
            metadata={"owner": "docs"},
        ),
        content=content,
        media_type=media_type,
        metadata={"transport": "http"},
    )


def test_normalize_utf8_bom_newlines_unicode_and_frontmatter():
    raw = (
        "\ufeff---\r\ntitle: Café\r\ntags: [uno, due]\r\n---\r\n"
        "Cafe\u0301\rBody\r\n"
    ).encode()

    document = normalize(acquired(raw, media_type="text/markdown; charset=UTF-8"), "pipe:v1")

    assert document.content == "Café\nBody\n"
    assert document.title == "Café"
    assert document.metadata["frontmatter"] == {"tags": ["uno", "due"], "title": "Café"}
    assert document.metadata["source"] == {"owner": "docs"}
    assert document.metadata["acquisition"] == {"transport": "http"}
    assert document.source_uri == "https://host/guide.md"
    assert document.modified_at == datetime(2026, 7, 12, 12, 0, tzinfo=UTC)
    assert document.content_hash == "sha256:" + hashlib.sha256(document.content.encode()).hexdigest()


def test_plain_text_that_only_resembles_frontmatter_is_not_dropped():
    document = normalize(acquired(b"---\nnot: closed\nbody"), "pipe:v1")
    assert document.content == "---\nnot: closed\nbody"
    assert "frontmatter" not in document.metadata


def test_frontmatter_can_end_at_eof_without_inventing_content():
    document = normalize(acquired(b"---\ntitle: Empty\n---"), "pipe:v1")
    assert document.title == "Empty"
    assert document.content == ""


def test_normalize_preserves_validated_curated_evidence_for_semantic_projection():
    source = SourceObject(
        source_id="filesystem:fascia-pediatrica",
        uri="file:///safe/evidence/curated/formula/fascia-pediatrica.md",
        fingerprint="sha256:" + "a" * 64,
        metadata={"relative_path": "curated/formula/fascia-pediatrica.md"},
    )
    raw = (
        "---\n"
        "schema_version: 1\n"
        "id: evidence:fascia-pediatrica\n"
        "title: Fascia pediatrica\n"
        "kind: formula\n"
        "purposes: [sql_generation]\n"
        "applies_to:\n"
        "  columns: [clinical.patient.birth_date]\n"
        "language: it\n"
        "provenance:\n"
        "  source_file: source/paziente.md\n"
        "  source_sha256: sha256:" + "b" * 64 + "\n"
        "  supporting_excerpts: [Pazienti con età inferiore a 18 anni.]\n"
        "review_items: []\n"
        "formula:\n"
        "  concept: fascia pediatrica\n"
        "  columns: [clinical.patient.birth_date]\n"
        "  sql: CASE WHEN age < 18 THEN 'pediatric' END\n"
        "---\n"
    ).encode()

    document = normalize(AcquiredDocument(source=source, content=raw, media_type="text/markdown"), "pipe:v1")

    assert document.content == raw.decode()
    assert document.title == "Fascia pediatrica"
    assert document.metadata["curated_evidence"]["id"] == "evidence:fascia-pediatrica"
    assert document.metadata["curated_evidence"]["payload"]["concept"] == "fascia pediatrica"


def test_only_curated_markdown_is_treated_as_canonical_evidence_without_relative_metadata():
    source = SourceObject(
        source_id="filesystem:notes",
        uri="file:///safe/evidence/curated/formula/notes.txt",
        fingerprint="sha256:" + "a" * 64,
    )

    document = normalize(
        AcquiredDocument(source=source, content=b"ordinary note", media_type="text/plain"),
        "pipe:v1",
    )

    assert document.content == "ordinary note"
    assert "curated_evidence" not in document.metadata


@pytest.mark.parametrize(
    "frontmatter",
    [
        "title: first\ntitle: second",
        "title: &shared value\ncopy: *shared",
        "nested: " + "[" * 25 + "x" + "]" * 25,
        "items: [" + ",".join("x" for _ in range(1100)) + "]",
        "api_key: secret",
    ],
)
def test_rejects_unsafe_frontmatter_as_typed_permanent_error(frontmatter):
    raw = f"---\n{frontmatter}\n---\nbody".encode()
    with pytest.raises(PermanentNormalizationError) as caught:
        normalize(acquired(raw), "pipe:v1")
    assert caught.value.reason == "invalid_frontmatter"


def test_pipeline_policy_errors_are_not_misclassified_as_bad_frontmatter():
    with pytest.raises(ValueError, match="pipeline_version") as caught:
        normalize(acquired(b"---\ntitle: valid\n---\nbody"), "")
    assert not isinstance(caught.value, PermanentNormalizationError)


@pytest.mark.parametrize(
    ("content", "media_type", "reason"),
    [
        (b"bad: \xff", "text/plain", "undecodable"),
        (b"hello", "text/plain; charset=iso-8859-1", "unsupported_charset"),
        (b"x" * (MAX_DOCUMENT_BYTES + 1), "text/plain", "oversized"),
    ],
)
def test_rejects_invalid_input_as_typed_permanent_error(content, media_type, reason):
    with pytest.raises(PermanentNormalizationError) as caught:
        normalize(acquired(content, media_type=media_type), "pipe:v1")
    assert caught.value.permanent is True
    assert caught.value.reason == reason