"""Add user_id FK to calendars table.

Revision ID: 030
Revises: 029
Create Date: 2026-02-26
"""
from alembic import op
import sqlalchemy as sa

revision = "030"
down_revision = "029"
branch_labels = None
depends_on = None


def upgrade() -> None:
    op.add_column("calendars", sa.Column("user_id", sa.Integer(), nullable=True))
    # Backfill existing calendars to first admin user
    op.execute(
        "UPDATE calendars SET user_id = ("
        "  SELECT id FROM users WHERE role = 'admin' ORDER BY id LIMIT 1"
        ")"
    )
    # On fresh installs no users exist yet, so seeded calendars still have
    # NULL user_id.  Remove them — account setup will recreate defaults.
    op.execute("DELETE FROM calendars WHERE user_id IS NULL")
    op.create_foreign_key(
        "fk_calendars_user_id", "calendars", "users",
        ["user_id"], ["id"], ondelete="CASCADE"
    )
    op.alter_column("calendars", "user_id", nullable=False)
    op.create_index("ix_calendars_user_id", "calendars", ["user_id"])
    op.create_index("ix_calendars_user_default", "calendars", ["user_id", "is_default"])


def downgrade() -> None:
    op.drop_index("ix_calendars_user_default", table_name="calendars")
    op.drop_index("ix_calendars_user_id", table_name="calendars")
    op.drop_constraint("fk_calendars_user_id", "calendars", type_="foreignkey")
    op.drop_column("calendars", "user_id")