"""jsonb_agg_uniq_by_first_item

Revision ID: 4eb679fb4fd0
Revises: ad2ed41fef92
Create Date: 2019-05-22 07:26:13.962095

"""

# revision identifiers, used by Alembic.
revision = '4eb679fb4fd0'
down_revision = 'ad2ed41fef92'
branch_labels = None
depends_on = None

from alembic import op
import sqlalchemy as sa


def upgrade():
    op.execute('''
create function f_array_append_uniq_first_item(jsonb, jsonb) returns jsonb
    immutable
    language sql
as
$$
SELECT CASE
   WHEN $1 is null then jsonb_build_array($2)
   WHEN (($1->-1)->0) <> ($2->0) THEN $1 || jsonb_build_array($2)
   ELSE $1
END
$$;

create aggregate jsonb_agg_uniq_by_first_item(jsonb) (
    sfunc = f_array_append_uniq_first_item,
    stype = jsonb
    );
    ''')


def downgrade():
    op.execute('''
    drop aggregate jsonb_agg_uniq_by_first_item(jsonb);
    drop function f_array_append_uniq_first_item(jsonb, jsonb);
     ''')