"""add col_snapshot table for cached cost-of-living data

Revision ID: 0005
Revises: 0004
Create Date: 2026-05-21 12:00:00.000000

Phase 2 of the cost-of-living subsystem (`fire_planner.col`). Caches
Numbeo / Expatistan headline data with a 1-year TTL so the simulator
can scale `spending_gbp` to local prices without re-scraping per-call.
Refresh is async (Phase-3 CronJob); user-facing lookups never block on
the network in the steady state.

Unique on (city_slug, source_name) — multiple sources per city are
allowed; service.py reconciles them when computing the headline.
"""
from collections.abc import Sequence

import sqlalchemy as sa

from alembic import op

revision: str = "0005"
down_revision: str | None = "0004"
branch_labels: str | Sequence[str] | None = None
depends_on: str | Sequence[str] | None = None

SCHEMA = "fire_planner"


def upgrade() -> None:
    op.create_table(
        "col_snapshot",
        sa.Column("id", sa.Integer(), nullable=False, autoincrement=True),
        sa.Column("city_slug", sa.String(length=64), nullable=False),
        sa.Column("city_display", sa.String(length=128), nullable=False),
        sa.Column("country", sa.String(length=64), nullable=False),
        sa.Column("source_name", sa.String(length=32), nullable=False),
        sa.Column("source_url", sa.String(), nullable=True),
        sa.Column("snapshot_date", sa.Date(), nullable=False),
        sa.Column("fetched_at", sa.TIMESTAMP(timezone=True), nullable=False,
                  server_default=sa.func.now()),
        sa.Column("expires_at", sa.TIMESTAMP(timezone=True), nullable=False),
        sa.Column("total_no_rent_gbp", sa.Numeric(12, 2), nullable=False),
        sa.Column("total_with_rent_gbp", sa.Numeric(12, 2), nullable=False),
        sa.Column("rent_1bed_center_gbp", sa.Numeric(12, 2), nullable=False),
        sa.Column("rent_1bed_outside_gbp", sa.Numeric(12, 2), nullable=True),
        sa.Column("raw_currency", sa.String(length=3), nullable=False,
                  server_default=sa.text("'GBP'")),
        sa.Column("gbp_per_unit", sa.Numeric(12, 8), nullable=False,
                  server_default=sa.text("1")),
        sa.Column("by_category_json", sa.JSON(), nullable=True),
        sa.PrimaryKeyConstraint("id"),
        sa.UniqueConstraint("city_slug", "source_name", name="uq_col_snapshot_city_source"),
        schema=SCHEMA,
    )
    op.create_index(
        "ix_col_snapshot_city_slug",
        "col_snapshot",
        ["city_slug"],
        schema=SCHEMA,
    )
    op.create_index(
        "ix_col_snapshot_expires_at",
        "col_snapshot",
        ["expires_at"],
        schema=SCHEMA,
    )


def downgrade() -> None:
    op.drop_index("ix_col_snapshot_expires_at", table_name="col_snapshot", schema=SCHEMA)
    op.drop_index("ix_col_snapshot_city_slug", table_name="col_snapshot", schema=SCHEMA)
    op.drop_table("col_snapshot", schema=SCHEMA)