CenterHole

class CenterHole(Feature):
    """
    Represents a center hole specified by a standard (e.g.
    `DIN 332-A 2,5x5,3`, `ISO 6411-A 2/4.25`, `DIN 332-D M16`).
    """

    quantity: int = Field(
        ...,
        ge=1,
        description="The number of center holes or instances. Must be at least 1.",
        examples=[2],
    )
    standard: str = Field(
        ...,
        description="The standard the center hole is specified by, as written on the drawing.",
        examples=["DIN 332"],
    )
    form: Optional[str] = Field(
        None,
        description=(
            "The form defined by the standard (e.g. `A`, `B`, `R`, or `D`, "
            "`DR`, `DS` for the threaded forms of DIN 332-2), if stated."
        ),
        examples=["A"],
    )
    pilot_diameter: Optional[Size] = Field(
        None,
        description=(
            "The diameter of the pilot hole (e.g. `2.5` in `A 2,5x5,3`), if "
            "stated. For the threaded forms of DIN 332-2 the pilot is the "
            "thread's core hole and is normally not written."
        ),
        examples=[
            Size(
                size_type=SizeType.DIAMETER,
                value=Decimal("2.5"),
                tolerance=None,
                unit="millimeter",
            )
        ],
    )
    outer_diameter: Optional[Size] = Field(
        None,
        description=(
            "The outer diameter of the countersink (e.g. `5.3` in `A 2,5x5,3`), "
            "if stated. For the threaded forms of DIN 332-2 this is the "
            "countersink's outer diameter d4. A drawing may state the "
            "countersink's two diameters d3 x d4 instead of the thread (e.g. "
            "`DIN 332-D 8,4x12,2`, the row for M8): `12.2` is d4, and d3 "
            "(`8.4`) is fixed by the thread in the standard's table, so it "
            "is carried by `thread` rather than by a field of its own."
        ),
    )
    requirement: Optional[CenterHoleRequirement] = Field(
        None,
        description="Whether the center hole must, may or must not remain on the finished part, if stated.",
    )
    thread: Optional[ThreadUnion] = Field(
        None,
        description=(
            "The thread in a threaded center hole (e.g. `M16` in "
            "`DIN 332-D M16`, DIN 332-2 forms D, DR and DS), or None for a "
            "center hole without a thread. A pitch that is not written is "
            "the standard coarse pitch."
        ),
    )

class CenterHoleRequirement(str, Enum):
    """Whether a center hole must remain on the finished part (ISO 6411).

    - REQUIRED: the center hole is required on the finished part.
    - PERMITTED: the center hole may remain, but is not required (often
      written as "optional").
    - NOT_PERMITTED: the center hole must not remain on the finished part.
    """

    REQUIRED = "REQUIRED"
    PERMITTED = "PERMITTED"
    NOT_PERMITTED = "NOT_PERMITTED"