"""

Revision ID: 0366_letter_rates_2022
Revises: 0365_add_nhs_branding
Create Date: 2022-03-01 14:00:00

"""
import itertools
import uuid
from datetime import datetime

from alembic import op
from sqlalchemy.sql import text

from app.models import LetterRate


revision = '0366_letter_rates_2022'
down_revision = '0365_add_nhs_branding'


CHANGEOVER_DATE = datetime(2022, 3, 1, 0, 0)


def get_new_rate(sheet_count, post_class):
    base_prices = {
        'second': 36,
        'first': 58,
        'europe': 88,
        'rest-of-world': 88,
    }
    multiplier = 5 if post_class in ('first', 'second') else 8

    return (base_prices[post_class] + (multiplier * sheet_count)) / 100.0


def upgrade():
    conn = op.get_bind()
    conn.execute(text("UPDATE letter_rates SET end_date = :start WHERE end_date IS NULL"), start=CHANGEOVER_DATE)

    op.bulk_insert(LetterRate.__table__, [
        {
            'id': uuid.uuid4(),
            'start_date': CHANGEOVER_DATE,
            'end_date': None,
            'sheet_count': sheet_count,
            'rate': get_new_rate(sheet_count, post_class),
            'crown': crown,
            'post_class': post_class,
        }
        for sheet_count, crown, post_class in itertools.product(
            range(1, 6),
            [True, False],
            ['first', 'second', 'europe', 'rest-of-world']
        )
    ])


def downgrade():
    # Make sure you've thought about billing implications etc before downgrading!
    conn = op.get_bind()
    conn.execute(text("DELETE FROM letter_rates WHERE start_date = :start"), start=CHANGEOVER_DATE)
    conn.execute(text("UPDATE letter_rates SET end_date = NULL WHERE end_date = :start"), start=CHANGEOVER_DATE)

Add new letter rates for March 1, 2022.
Add new letter rates for March 1, 2022.

- second class postage will go up by 2 pence, plus VAT
- international postage will go up by 7 pence, plus VAT
- first class postage will go down by 6 pence, plus VAT
