"""control0002 — Stripe billing columns (MT-8)

Adds billing state columns to the control-plane `tenants` table and
`stripe_price_id` to the `plans` table.

All column additions use INFORMATION_SCHEMA existence checks so the
migration is safe to re-run (CLAUDE.md Rule 14). No ENUM change to the
existing `tenants.status` column — `subscription_status` is a separate
nullable column tracking billing lifecycle independently of operational state.
"""

import sqlalchemy as sa
from alembic import op

revision = 'control0002_billing'
down_revision = 'control0001_init'
branch_labels = None
depends_on = None


def _column_exists(bind, table: str, column: str) -> bool:
    result = bind.execute(sa.text(
        "SELECT COUNT(*) FROM information_schema.columns "
        "WHERE table_schema = DATABASE() AND table_name = :t AND column_name = :c"
    ), {'t': table, 'c': column})
    return result.scalar() > 0


def _index_exists(bind, table: str, index_name: str) -> bool:
    result = bind.execute(sa.text(
        "SELECT COUNT(*) FROM information_schema.statistics "
        "WHERE table_schema = DATABASE() AND table_name = :t AND index_name = :i"
    ), {'t': table, 'i': index_name})
    return result.scalar() > 0


def upgrade():
    bind = op.get_bind()

    # ── plans: stripe_price_id ─────────────────────────────────────────────
    if not _column_exists(bind, 'plans', 'stripe_price_id'):
        op.execute(sa.text(
            "ALTER TABLE plans ADD COLUMN stripe_price_id VARCHAR(100) NULL"
        ))

    # ── tenants: stripe_customer_id ────────────────────────────────────────
    if not _column_exists(bind, 'tenants', 'stripe_customer_id'):
        op.execute(sa.text(
            "ALTER TABLE tenants ADD COLUMN stripe_customer_id VARCHAR(64) NULL"
        ))
    if not _index_exists(bind, 'tenants', 'ix_tenants_stripe_customer'):
        op.execute(sa.text(
            "ALTER TABLE tenants ADD INDEX ix_tenants_stripe_customer (stripe_customer_id)"
        ))

    # ── tenants: stripe_subscription_id ───────────────────────────────────
    if not _column_exists(bind, 'tenants', 'stripe_subscription_id'):
        op.execute(sa.text(
            "ALTER TABLE tenants ADD COLUMN stripe_subscription_id VARCHAR(64) NULL"
        ))
    if not _index_exists(bind, 'tenants', 'ix_tenants_stripe_sub'):
        op.execute(sa.text(
            "ALTER TABLE tenants ADD INDEX ix_tenants_stripe_sub (stripe_subscription_id)"
        ))

    # ── tenants: subscription_status ──────────────────────────────────────
    if not _column_exists(bind, 'tenants', 'subscription_status'):
        op.execute(sa.text(
            "ALTER TABLE tenants ADD COLUMN subscription_status "
            "ENUM('trial','active','past_due','cancelled') NULL"
        ))
    if not _index_exists(bind, 'tenants', 'ix_tenants_sub_status'):
        op.execute(sa.text(
            "ALTER TABLE tenants ADD INDEX ix_tenants_sub_status (subscription_status)"
        ))

    # ── tenants: trial_ends_at ─────────────────────────────────────────────
    if not _column_exists(bind, 'tenants', 'trial_ends_at'):
        op.execute(sa.text(
            "ALTER TABLE tenants ADD COLUMN trial_ends_at DATETIME NULL"
        ))

    # ── tenants: current_period_end ────────────────────────────────────────
    if not _column_exists(bind, 'tenants', 'current_period_end'):
        op.execute(sa.text(
            "ALTER TABLE tenants ADD COLUMN current_period_end DATETIME NULL"
        ))

    # ── tenants: billing_email ─────────────────────────────────────────────
    if not _column_exists(bind, 'tenants', 'billing_email'):
        op.execute(sa.text(
            "ALTER TABLE tenants ADD COLUMN billing_email VARCHAR(255) NULL"
        ))


def downgrade():
    bind = op.get_bind()

    for col in ('billing_email', 'current_period_end', 'trial_ends_at',
                'subscription_status', 'stripe_subscription_id', 'stripe_customer_id'):
        if _column_exists(bind, 'tenants', col):
            op.execute(sa.text(f"ALTER TABLE tenants DROP COLUMN {col}"))

    if _column_exists(bind, 'plans', 'stripe_price_id'):
        op.execute(sa.text("ALTER TABLE plans DROP COLUMN stripe_price_id"))