from pathlib import Path

from api.v1.modules.a76.layouts_csv.common.csv_reader import (
    CsvReadPlan,
    detect_text_encoding,
    inspect_csv,
    iter_csv_rows,
    iter_csv_rows_with_plan,
)
from api.v1.modules.a76.layouts_csv.classes.template_config import (
    detect_headers_or_data as detect_classes_headers,
    row_from_template as row_from_classes_template,
)
from api.v1.modules.a76.layouts_csv.parts.template_config import detect_headers_or_data as detect_parts_headers
from api.v1.modules.a76.layouts_csv.pedmientos.template_config import (
    detect_headers_or_data as detect_pedimentos_headers,
    parse_pedimento_col_a,
)


def _write_bytes(tmp_path: Path, name: str, payload: bytes) -> Path:
    file_path = tmp_path / name
    file_path.write_bytes(payload)
    return file_path


def test_detect_text_encoding_handles_truncated_utf8_sample(tmp_path: Path):
    # Regression: "ó" in "Descripción" empieza en byte 21 (0xC3 0xB3).
    # sample_bytes=22 lee bytes 0-21, terminando en 0xC3 (primer byte de ó, secuencia incompleta).
    # El código viejo: raw.decode("utf-8-sig") fallaba → caía a cp1252 → mojibake.
    # El código nuevo: decoder incremental tolera el corte → retorna utf-8-sig.
    payload = "DESCRIPCION\nDescripción español\n".encode("utf-8")
    file_path = _write_bytes(tmp_path, "truncated_utf8.csv", payload)

    enc = detect_text_encoding(str(file_path), sample_bytes=22)

    assert enc in ("utf-8", "utf-8-sig"), (
        f"Got {enc!r} — el archivo UTF-8 con corte de muestra a mitad de multibyte "
        "fue detectado como cp1252, produciendo mojibake (español / Descripción)"
    )


def test_utf8_enie_at_sample_boundary_not_detected_as_cp1252(tmp_path: Path):
    # Regresión directa del bug mojibake reportado en producción.
    # Construye un payload donde 'ñ' (0xC3 0xB1 en UTF-8) cae exactamente en el byte 19,
    # y sample_bytes=20 lee sólo 0xC3 (primer byte) — secuencia incompleta.
    # Resultado esperado: utf-8 / utf-8-sig (no cp1252).
    header = b"CLASE,DESC\n"  # 11 bytes
    row = "C01,español\n".encode("utf-8")  # ñ en bytes 19-20 del payload total
    payload = header + row
    file_path = _write_bytes(tmp_path, "regression_mojibake.csv", payload)

    enc = detect_text_encoding(str(file_path), sample_bytes=20)

    assert enc in ("utf-8", "utf-8-sig"), (
        f"Got {enc!r} en lugar de utf-8 — leer como cp1252 produciría "
        "'español' en lugar de 'español'"
    )


def test_iter_csv_rows_preserves_utf8_values(tmp_path: Path):
    payload = "CLASE,DESCRIPCION ESPAÑOL\nCLASE01,Clase prueba español\n".encode("utf-8")
    file_path = _write_bytes(tmp_path, "utf8_values.csv", payload)

    rows = list(iter_csv_rows(str(file_path)))

    assert len(rows) == 1
    _, row = rows[0]
    assert row["DESCRIPCION ESPAÑOL"] == "Clase prueba español"


def test_iter_csv_rows_keeps_cp1252_compatibility(tmp_path: Path):
    payload = "CLASE,DESCRIPCION ESPAÑOL\nCLASE01,Descripción\n".encode("cp1252")
    file_path = _write_bytes(tmp_path, "cp1252_values.csv", payload)

    rows = list(iter_csv_rows(str(file_path)))

    assert len(rows) == 1
    _, row = rows[0]
    assert row["DESCRIPCION ESPAÑOL"] == "Descripción"


def test_parts_detect_headers_or_data_handles_cp1252(tmp_path: Path):
    payload = "NUMERO DE PARTE,DESCRIPCION EN ESPAÑOL\nP-01,Descripción\n".encode("cp1252")
    file_path = _write_bytes(tmp_path, "parts_cp1252.csv", payload)

    fieldnames, has_header = detect_parts_headers(str(file_path), lambda s: (s or "").strip().upper())

    assert has_header is True
    assert fieldnames is None


def test_pedimentos_detect_headers_or_data_handles_cp1252_data_first_row(tmp_path: Path):
    payload = "24,1234,1234567,I,A1\n".encode("cp1252")
    file_path = _write_bytes(tmp_path, "pedimentos_cp1252_data.csv", payload)

    fieldnames, has_header = detect_pedimentos_headers(
        str(file_path),
        lambda s: (s or "").strip().upper(),
        parse_pedimento_col_a,
    )

    assert has_header is False
    assert fieldnames is not None


def test_classes_detect_headers_or_data_handles_cp1252(tmp_path: Path):
    payload = "CLAVE CLASE;DESCRIPCION ESPAÑOL\nC01;Descripción\n".encode("cp1252")
    file_path = _write_bytes(tmp_path, "classes_cp1252_semicolon.csv", payload)

    fieldnames, has_header = detect_classes_headers(str(file_path), lambda s: (s or "").strip().upper())

    assert has_header is True
    assert fieldnames is None


def test_classes_row_from_template_recovers_collapsed_header_with_semicolon():
    row = {"CLAVE CLASE,DESCRIPCION ESPAÑOL": "C01;Descripción;Description"}
    mapped = row_from_classes_template(row, lambda s: (s or "").strip().upper())
    assert mapped["CLASE"] == "C01"


def test_iter_csv_rows_with_plan_headerless_and_semicolon(tmp_path: Path):
    payload = "C01;Descripcion 1\nC02;Descripcion 2\n".encode("utf-8")
    file_path = _write_bytes(tmp_path, "headerless_semicolon.csv", payload)
    plan = CsvReadPlan(
        header_mode="headerless",
        fieldnames=["CLASE", "DESCRIPCIONE"],
    )

    rows = list(iter_csv_rows_with_plan(str(file_path), plan))

    assert len(rows) == 2
    assert rows[0][1]["CLASE"] == "C01"
    assert rows[1][1]["DESCRIPCIONE"] == "Descripcion 2"


def test_inspect_csv_auto_mode_switches_to_headerless(tmp_path: Path):
    payload = "C01,Descripcion\n".encode("utf-8")
    file_path = _write_bytes(tmp_path, "auto_mode.csv", payload)
    plan = CsvReadPlan(
        header_mode="auto",
        fieldnames=["CLASE", "DESCRIPCIONE"],
        headerless_first_cell_values={"C01"},
    )

    metadata = inspect_csv(str(file_path), plan)

    assert metadata.has_header is False
    assert metadata.fieldnames == ["CLASE", "DESCRIPCIONE"]