"""Add account_id to tree_shares and backfill via tree owner's account.

The share belongs to the tree's tenant, not the actor who created it.
A super admin in account A can share a tree owned by account B; that share
must land in account B so account B's RLS filter sees it.

Revision ID: a05e1a1bea7c
Revises: 2a9056eddd90
Create Date: 2026-04-11 00:00:00.000000
"""
from typing import Sequence, Union
from alembic import op
import sqlalchemy as sa

revision: str = 'a05e1a1bea7c'
down_revision: Union[str, None] = '2a9056eddd90'
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    op.add_column('tree_shares', sa.Column('account_id', sa.UUID(), nullable=True))
    op.create_foreign_key(
        'fk_tree_shares_account_id', 'tree_shares', 'accounts',
        ['account_id'], ['id'], ondelete='CASCADE',
    )

    # Backfill: derive from the tree's account, not the creator's account.
    # A share lives in the same tenant as its tree so that the tree owner's
    # RLS context covers their own shares regardless of who created them.
    op.execute("""
        UPDATE tree_shares ts
        SET account_id = t.account_id
        FROM trees t
        WHERE ts.tree_id = t.id
          AND t.account_id IS NOT NULL
          AND ts.account_id IS NULL
    """)

    result = op.get_bind().execute(
        sa.text("SELECT COUNT(*) FROM tree_shares WHERE account_id IS NULL")
    )
    count = result.scalar()
    if count > 0:
        raise RuntimeError(
            f"ROLLBACK: {count} tree_shares rows have NULL account_id after backfill. "
            "All share entries must have a creating user with an account."
        )

    op.alter_column('tree_shares', 'account_id', nullable=False)
    op.create_index('ix_tree_shares_account_id', 'tree_shares', ['account_id'])


def downgrade() -> None:
    op.drop_index('ix_tree_shares_account_id', table_name='tree_shares')
    op.drop_constraint('fk_tree_shares_account_id', 'tree_shares', type_='foreignkey')
    op.drop_column('tree_shares', 'account_id')