"""Add calendars table and calendar_id to calendar_events

Revision ID: 006
Revises: 005
Create Date: 2026-02-21 00:00:00.000000

"""
from typing import Sequence, Union

from alembic import op
import sqlalchemy as sa
from sqlalchemy.sql import table, column


# revision identifiers, used by Alembic.
revision: str = '006'
down_revision: Union[str, None] = '005'
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    # 1. Create the calendars table
    op.create_table(
        'calendars',
        sa.Column('id', sa.Integer(), primary_key=True, index=True),
        sa.Column('name', sa.String(100), nullable=False),
        sa.Column('color', sa.String(20), nullable=False),
        sa.Column('is_default', sa.Boolean(), nullable=False, server_default='false'),
        sa.Column('is_system', sa.Boolean(), nullable=False, server_default='false'),
        sa.Column('is_visible', sa.Boolean(), nullable=False, server_default='true'),
        sa.Column('created_at', sa.DateTime(), server_default=sa.func.now()),
        sa.Column('updated_at', sa.DateTime(), server_default=sa.func.now()),
    )

    # 2. Seed the two default calendars
    calendars_table = table(
        'calendars',
        column('name', sa.String),
        column('color', sa.String),
        column('is_default', sa.Boolean),
        column('is_system', sa.Boolean),
        column('is_visible', sa.Boolean),
    )

    op.bulk_insert(calendars_table, [
        {
            'name': 'Personal',
            'color': '#3b82f6',
            'is_default': True,
            'is_system': False,
            'is_visible': True,
        },
        {
            'name': 'Birthdays',
            'color': '#ec4899',
            'is_default': False,
            'is_system': True,
            'is_visible': True,
        },
    ])

    # 3. Add calendar_id as nullable first so existing rows don't violate NOT NULL
    op.add_column('calendar_events', sa.Column('calendar_id', sa.Integer(), nullable=True))

    # 4. Set all existing events to the Personal (default) calendar
    op.execute(
        """
        UPDATE calendar_events
        SET calendar_id = (SELECT id FROM calendars WHERE is_default = true LIMIT 1)
        WHERE calendar_id IS NULL
        """
    )

    # 5. Alter to NOT NULL and add FK constraint
    op.alter_column('calendar_events', 'calendar_id', nullable=False)
    op.create_foreign_key(
        'fk_calendar_events_calendar_id',
        'calendar_events',
        'calendars',
        ['calendar_id'],
        ['id'],
    )


def downgrade() -> None:
    op.drop_constraint('fk_calendar_events_calendar_id', 'calendar_events', type_='foreignkey')
    op.drop_column('calendar_events', 'calendar_id')
    op.drop_table('calendars')