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"""Reduce position_json size by remove extra space and component id prefix

Revision ID: 7fcdcde0761c
Revises: c18bd4186f15
Create Date: 2018-08-01 11:47:02.233971

"""

# revision identifiers, used by Alembic.
import json
import re

from alembic import op
import sqlalchemy as sa
from sqlalchemy.ext.declarative import declarative_base

from superset import db

revision = '7fcdcde0761c'
down_revision = 'c18bd4186f15'

Base = declarative_base()


class Dashboard(Base):
    """Declarative class to do query in upgrade"""
    __tablename__ = 'dashboards'
    id = sa.Column(sa.Integer, primary_key=True)
    dashboard_title = sa.Column(sa.String(500))
    position_json = sa.Column(sa.Text)


def is_v2_dash(positions):
    return (
        isinstance(positions, dict) and
        positions.get('DASHBOARD_VERSION_KEY') == 'v2'
    )


def upgrade():
    bind = op.get_bind()
    session = db.Session(bind=bind)

    dashboards = session.query(Dashboard).all()
    for i, dashboard in enumerate(dashboards):
        original_text = dashboard.position_json or ''
        position_json = json.loads(original_text or '{}')
        if is_v2_dash(position_json):
            # re-dump the json data and remove leading and trailing white spaces
            text = json.dumps(
                position_json, indent=None, separators=(',', ':'), sort_keys=True)
            # remove DASHBOARD_ and _TYPE prefix/suffix in all the component ids
            text = re.sub(r'DASHBOARD_(?!VERSION)', '', text)
            text = text.replace('_TYPE', '')

            dashboard.position_json = text
            print('dash id:{} position_json size from {} to {}'.format(
                dashboard.id, len(original_text), len(text)))
            session.merge(dashboard)
            session.commit()


def downgrade():
    pass
