"""Finance saved explorer views.

Adds ``finance_saved_views`` — a finance user's persisted spend-explorer
configuration (group_by + filters + range), optionally shared with all
finance viewers. No FK on ``owner_person_id`` (plain String(36)), same
TiDB CHAR/VARCHAR FK avoidance as the rest of the finance domain.

Idempotent: guarded on table-absence.
"""
from __future__ import annotations

import sqlalchemy as sa

from alembic import op

revision = "295"
down_revision = "294"
branch_labels = None
depends_on = None


def _table_exists(bind, table: str) -> bool:
    row = bind.execute(
        sa.text(
            "SELECT 1 FROM information_schema.TABLES "
            "WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = :t"
        ),
        {"t": table},
    ).fetchone()
    return row is not None


def upgrade() -> None:
    bind = op.get_bind()
    if _table_exists(bind, "finance_saved_views"):
        return
    op.create_table(
        "finance_saved_views",
        sa.Column("id", sa.BigInteger(), autoincrement=True, nullable=False),
        sa.Column("owner_person_id", sa.String(length=36), nullable=False),
        sa.Column("name", sa.String(length=128), nullable=False),
        sa.Column("config", sa.JSON(), nullable=False),
        sa.Column("is_shared", sa.Boolean(), nullable=False, server_default="0"),
        sa.Column(
            "created_at", sa.DateTime(timezone=True),
            server_default=sa.text("CURRENT_TIMESTAMP"), nullable=False,
        ),
        sa.Column(
            "updated_at", sa.DateTime(timezone=True),
            server_default=sa.text("CURRENT_TIMESTAMP"), nullable=False,
        ),
        sa.PrimaryKeyConstraint("id"),
    )
    op.create_index(
        "ix_fin_saved_views_owner", "finance_saved_views", ["owner_person_id"],
    )


def downgrade() -> None:
    bind = op.get_bind()
    if _table_exists(bind, "finance_saved_views"):
        op.drop_table("finance_saved_views")