"""Add system_settings table for application-wide configuration flags.

Revision ID: 002_add_system_settings
Revises: 001_widen_ticket_history_values
Create Date: 2026-03-30

Rationale
---------
Introduces a generic key-value settings store so that runtime configuration
flags (such as registration_enabled) can be toggled by administrators through
the UI without requiring a code deployment or server restart.

Apply
-----
    flask db upgrade

Rollback
--------
    flask db downgrade
"""

from alembic import op
import sqlalchemy as sa

revision = '002_add_system_settings'
down_revision = '001_widen_ticket_history_values'
branch_labels = None
depends_on = None


def upgrade():
    op.create_table(
        'system_settings',
        sa.Column('id',          sa.Integer(),    nullable=False),
        sa.Column('key',         sa.String(100),  nullable=False),
        sa.Column('value',       sa.String(500),  nullable=False),
        sa.Column('description', sa.String(256),  nullable=True),
        sa.Column('updated_at',  sa.DateTime(),   nullable=True),
        sa.PrimaryKeyConstraint('id'),
    )
    op.create_index('ix_system_settings_key', 'system_settings', ['key'], unique=True)

    # Seed the default: registration is open on fresh installs.
    op.execute(
        "INSERT INTO system_settings (key, value, description, updated_at) "
        "VALUES ('registration_enabled', 'true', "
        "'Allow new users to self-register via /auth/register', NOW())"
    )


def downgrade():
    op.drop_index('ix_system_settings_key', table_name='system_settings')
    op.drop_table('system_settings')