"""Add subscriptions table and link sources

Revision ID: 002
Revises: 001
Create Date: 2025-01-25

"""
from typing import Sequence, Union

from alembic import op
import sqlalchemy as sa
from sqlalchemy.dialects import postgresql

revision: str = '002'
down_revision: Union[str, None] = '001'
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    # Create subscriptions table
    op.create_table(
        'subscriptions',
        sa.Column('id', sa.Integer(), nullable=False),
        sa.Column('name', sa.String(255), nullable=False),
        sa.Column('enabled', sa.Boolean(), default=True),
        sa.Column('priority', sa.Integer(), default=0),
        sa.Column('description', sa.Text(), nullable=True),
        sa.Column('metadata', postgresql.JSONB(), default={}),
        sa.Column('created_at', sa.DateTime(), server_default=sa.func.now()),
        sa.Column('updated_at', sa.DateTime(), server_default=sa.func.now(), onupdate=sa.func.now()),
        sa.PrimaryKeyConstraint('id')
    )
    op.create_index('ix_subscriptions_name', 'subscriptions', ['name'], unique=True)

    # Migrate existing sources to subscriptions
    # Each unique source name becomes a subscription
    conn = op.get_bind()

    # Get existing sources
    existing_sources = conn.execute(
        sa.text("SELECT DISTINCT name FROM sources ORDER BY name")
    ).fetchall()

    # Create subscriptions for each unique source name
    for (name,) in existing_sources:
        conn.execute(
            sa.text("INSERT INTO subscriptions (name, enabled, priority) VALUES (:name, true, 0)"),
            {"name": name}
        )

    # Add subscription_id column to sources
    op.add_column('sources', sa.Column('subscription_id', sa.Integer(), nullable=True))
    op.create_index('ix_sources_subscription_id', 'sources', ['subscription_id'])

    # Update sources with their subscription_id
    conn.execute(sa.text("""
        UPDATE sources s
        SET subscription_id = sub.id
        FROM subscriptions sub
        WHERE s.name = sub.name
    """))

    # Make subscription_id NOT NULL after data migration
    op.alter_column('sources', 'subscription_id', nullable=False)

    # Add foreign key constraint
    op.create_foreign_key(
        'fk_sources_subscription_id',
        'sources', 'subscriptions',
        ['subscription_id'], ['id'],
        ondelete='CASCADE'
    )

    # Remove name and priority columns from sources (now on subscription)
    op.drop_column('sources', 'name')
    op.drop_column('sources', 'priority')


def downgrade() -> None:
    # Add back name and priority columns to sources
    op.add_column('sources', sa.Column('name', sa.String(255), nullable=True))
    op.add_column('sources', sa.Column('priority', sa.Integer(), default=0))

    # Populate name from subscription
    conn = op.get_bind()
    conn.execute(sa.text("""
        UPDATE sources s
        SET name = sub.name, priority = sub.priority
        FROM subscriptions sub
        WHERE s.subscription_id = sub.id
    """))

    op.alter_column('sources', 'name', nullable=False)

    # Remove foreign key and subscription_id column
    op.drop_constraint('fk_sources_subscription_id', 'sources', type_='foreignkey')
    op.drop_index('ix_sources_subscription_id', 'sources')
    op.drop_column('sources', 'subscription_id')

    # Drop subscriptions table
    op.drop_index('ix_subscriptions_name', 'subscriptions')
    op.drop_table('subscriptions')