"""Fix guest_users email+tenant_id unique index.

Alembic 0059 created ix_guest_users_email_tenant as a normal (non-unique) index.
The SQLAlchemy model defines it as unique=True, and production already has
a UNIQUE INDEX. This migration aligns Alembic with production.

Before creating the unique index, checks for duplicate (email, tenant_id) pairs.
If duplicates exist, the migration aborts with a data cleanup report.

Revision ID: 0095
Revises: 0094
"""

from __future__ import annotations

from alembic import op
import sqlalchemy as sa

revision = "0095"
down_revision = "0094"
branch_labels = None
depends_on = None


def upgrade() -> None:
    # Check for duplicates before creating unique index
    conn = op.get_bind()
    duplicates = conn.execute(
        sa.text(
            "SELECT email, tenant_id, count(*) FROM guest_users "
            "GROUP BY email, tenant_id HAVING count(*) > 1"
        )
    ).fetchall()

    if duplicates:
        raise RuntimeError(
            f"Cannot create unique index: {len(duplicates)} duplicate (email, tenant_id) pairs found. "
            "Data cleanup required before migration."
        )

    # Drop the non-unique index and recreate as unique
    op.execute("DROP INDEX IF EXISTS ix_guest_users_email_tenant")
    op.execute(
        "CREATE UNIQUE INDEX IF NOT EXISTS ix_guest_users_email_tenant "
        "ON guest_users (email, tenant_id)"
    )


def downgrade() -> None:
    op.execute("DROP INDEX IF EXISTS ix_guest_users_email_tenant")
    op.execute(
        "CREATE INDEX IF NOT EXISTS ix_guest_users_email_tenant "
        "ON guest_users (email, tenant_id)"
    )