"""Add github_id to identity_persons.

Revision ID: 369
Revises: 368
Create Date: 2026-06-30

GitHub username/handle, sourced from SuccessFactors ``cust_Other.cust_id``
(a custom MDF entity keyed by ``externalCode`` = employee_no). Verified
live 2026-06-30: the field IS populated for the employees who filled the
onboarding 「其他声明」form (handles like ``KennethLeeJE8`` — the prior
2026-06-26 ADR that called it "empty, no source" is now stale).

Stored RAW (junk values "无"/"none"/empty skipped at the sync layer);
exposed as the ``github_id`` mapping source field and projected to the
Feishu ``GitHub ID`` custom attribute (``custom_attrs.github_id``).
Nullable, no FK (TiDB-safe), sparse by design — write-when-present,
never NULL-out. ``String(128)`` is ample for the ≤39-char GitHub handle
(and tolerates the occasional pasted URL).
"""
from __future__ import annotations

import sqlalchemy as sa

from alembic import op

revision = "369"
down_revision = "368"
branch_labels = None
depends_on = None

_TABLE = "identity_persons"
_COL = "github_id"


def _has_column(bind, table: str, column: str) -> bool:
    return bind.execute(
        sa.text(
            "SELECT 1 FROM information_schema.COLUMNS "
            "WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = :t "
            "AND COLUMN_NAME = :c"
        ),
        {"t": table, "c": column},
    ).scalar() is not None


def upgrade() -> None:
    bind = op.get_bind()
    if not _has_column(bind, _TABLE, _COL):
        op.add_column(_TABLE, sa.Column(_COL, sa.String(128), nullable=True))


def downgrade() -> None:
    bind = op.get_bind()
    if _has_column(bind, _TABLE, _COL):
        op.drop_column(_TABLE, _COL)