"""Persian normalization (ADR-0018).

Characters are written as escapes rather than literals: Arabic letterforms are
visually indistinguishable in a monospace editor, and literals would render
right-to-left and visually reorder each assertion.
"""

import pytest

from src.application.ingestion import normalize_persian_text

pytestmark = pytest.mark.unit

ARABIC_KAF = chr(0x0643)
PERSIAN_KEHEH = chr(0x06A9)
ARABIC_YEH = chr(0x064A)
ALEF_MAKSURA = chr(0x0649)
PERSIAN_YEH = chr(0x06CC)
ALEF_HAMZA_ABOVE = chr(0x0623)
ALEF_HAMZA_BELOW = chr(0x0625)
ALEF = chr(0x0627)
ALEF_FINAL_FORM = chr(0xFE8E)

FATHA = chr(0x064E)
SHADDA = chr(0x0651)
TATWEEL = chr(0x0640)
SUPERSCRIPT_ALEF = chr(0x0670)

PERSIAN_DIGITS = "".join(chr(0x06F1 + offset) for offset in range(3))
ARABIC_SEMICOLON = chr(0x061B)
ARABIC_THOUSANDS_SEPARATOR = chr(0x066C)


@pytest.mark.parametrize(
    ("source", "expected"),
    [
        (ARABIC_KAF, PERSIAN_KEHEH),
        (ARABIC_YEH, PERSIAN_YEH),
        (ALEF_MAKSURA, PERSIAN_YEH),
        (ALEF_HAMZA_ABOVE, ALEF),
        (ALEF_HAMZA_BELOW, ALEF),
    ],
)
def test_normalize_arabic_letterform_folds_to_persian(source: str, expected: str) -> None:
    assert normalize_persian_text(source) == expected


def test_normalize_mixed_keyboard_spellings_converge_to_one_form() -> None:
    """The defect this module exists for: one word, two spellings, two embeddings."""
    arabic_spelling = f"{ARABIC_KAF}{ARABIC_YEH}"
    persian_spelling = f"{PERSIAN_KEHEH}{PERSIAN_YEH}"

    assert normalize_persian_text(arabic_spelling) == normalize_persian_text(persian_spelling)


@pytest.mark.parametrize("mark", [FATHA, SHADDA, TATWEEL, SUPERSCRIPT_ALEF])
def test_normalize_diacritic_is_removed(mark: str) -> None:
    assert normalize_persian_text(f"{ALEF}{mark}{ALEF}") == f"{ALEF}{ALEF}"


def test_normalize_not_sign_becomes_space() -> None:
    assert normalize_persian_text(f"{ALEF}¬{ALEF}") == f"{ALEF} {ALEF}"


def test_normalize_applies_nfkc_compatibility_forms() -> None:
    # U+FE8E is the final presentation form of alef; NFKC maps it to the base
    # letter, so a document pasted from a PDF renderer matches a typed one.
    assert normalize_persian_text(ALEF_FINAL_FORM) == ALEF


def test_normalize_collapses_whitespace_runs_and_strips() -> None:
    assert normalize_persian_text("  a \t\n  b  ") == "a b"


@pytest.mark.parametrize(
    "preserved",
    [PERSIAN_DIGITS, ARABIC_SEMICOLON, ARABIC_THOUSANDS_SEPARATOR],
)
def test_normalize_digits_and_punctuation_survive_unchanged(preserved: str) -> None:
    """ADR-0018 deliberately folds letters only.

    Rewriting Persian digits to Western ones would render citations wrong to a
    Persian reader, so this guards against a later 'helpful' addition.
    """
    assert normalize_persian_text(preserved) == preserved


def test_normalize_already_normalized_text_is_unchanged() -> None:
    normalized = normalize_persian_text(f"{ARABIC_KAF}{FATHA} {ALEF_HAMZA_ABOVE}")

    assert normalize_persian_text(normalized) == normalized


def test_normalize_empty_string_returns_empty() -> None:
    assert normalize_persian_text("") == ""