M6-T04: add EnergyContract CRUD + versions + profile validation API
- app/services/contracts.py: create_contract, add_version (append-only,
auto-closes prior version), activate_contract (mutex), and
active_contract_version_at (half-open [from, to)) for the billing engine.
- app/schemas/energy_contract.py + routes/api/energy_contracts.py: 6 endpoints
(GET/POST contracts, GET/PATCH contracts/{id}, POST .../versions, GET profiles).
Values validated against pricing profiles (422 on mismatch); no DELETE.
- main.py registers router; OpenAPI re-exported; tests for CRUD/version/activate.
This commit is contained in:
@@ -0,0 +1,338 @@
|
||||
"""Service layer for EnergyContract CRUD, versioning, and activation.
|
||||
|
||||
All functions accept an explicit SQLAlchemy Session; callers are responsible
|
||||
for committing or rolling back the transaction.
|
||||
|
||||
Design decisions
|
||||
----------------
|
||||
- ``create_contract``: validates values against the pricing profile *before*
|
||||
writing any rows; raises ``ProfileValidationError`` on non-compliance.
|
||||
- ``add_version``: append-only; closes the previous open version by
|
||||
setting its ``effective_to`` to the new version's ``effective_from``; raises
|
||||
``ContractVersionError`` if the new date is strictly earlier than the previous
|
||||
version's ``effective_from``.
|
||||
- ``activate_contract``: mutual-exclusion; sets all other contracts' ``active``
|
||||
to False, then sets the given contract's ``active`` to True.
|
||||
- ``active_contract_version_at``: returns the single version of the currently
|
||||
active contract that covers *ts* (``effective_from ≤ ts < effective_to``,
|
||||
or open-ended when ``effective_to`` is None).
|
||||
|
||||
SQLite timezone note
|
||||
--------------------
|
||||
SQLite stores ``DateTime(timezone=True)`` columns as naive UTC strings; on
|
||||
read-back they come out as **timezone-naive** datetimes. Wherever this code
|
||||
compares timestamps from the DB against timezone-aware values (e.g. from
|
||||
Pydantic or ``datetime.now(UTC)``), it calls ``_as_utc()`` to make both sides
|
||||
comparable without tripping on "offset-naive vs offset-aware" TypeErrors.
|
||||
"""
|
||||
|
||||
from __future__ import annotations
|
||||
|
||||
import logging
|
||||
from datetime import UTC, datetime
|
||||
from typing import Any
|
||||
|
||||
from sqlalchemy import select
|
||||
from sqlalchemy.orm import Session
|
||||
|
||||
from app.integrations.pricing.profiles import validate_values
|
||||
from app.models.energy import EnergyContract, EnergyContractVersion
|
||||
|
||||
logger = logging.getLogger(__name__)
|
||||
|
||||
|
||||
# ---------------------------------------------------------------------------
|
||||
# Internal helpers
|
||||
# ---------------------------------------------------------------------------
|
||||
|
||||
|
||||
def _as_utc(dt: datetime) -> datetime:
|
||||
"""Return *dt* as a timezone-aware UTC datetime.
|
||||
|
||||
SQLite's DateTime(timezone=True) column type stores datetimes as naive UTC
|
||||
strings and gives them back as naive datetimes on read. This helper
|
||||
re-attaches the UTC timezone info when it is missing, making cross-origin
|
||||
comparisons safe.
|
||||
"""
|
||||
if dt.tzinfo is None:
|
||||
return dt.replace(tzinfo=UTC)
|
||||
return dt
|
||||
|
||||
|
||||
# ---------------------------------------------------------------------------
|
||||
# Custom exception
|
||||
# ---------------------------------------------------------------------------
|
||||
|
||||
|
||||
class ContractVersionError(ValueError):
|
||||
"""Raised when a new contract version has an invalid effective date.
|
||||
|
||||
Specifically: the new version's ``effective_from`` must be greater than or
|
||||
equal to the previous open version's ``effective_from``. Allowing equal
|
||||
timestamps would cause ambiguous overlap; the service therefore also rejects
|
||||
strictly-equal values (same second) to avoid silent data loss.
|
||||
"""
|
||||
|
||||
|
||||
# ---------------------------------------------------------------------------
|
||||
# Helpers
|
||||
# ---------------------------------------------------------------------------
|
||||
|
||||
|
||||
def get_contract_or_none(session: Session, contract_id: int) -> EnergyContract | None:
|
||||
"""Return the contract with the given id, or None if not found."""
|
||||
return session.execute(
|
||||
select(EnergyContract).where(EnergyContract.id == contract_id)
|
||||
).scalar_one_or_none()
|
||||
|
||||
|
||||
def list_contracts(session: Session) -> list[EnergyContract]:
|
||||
"""Return all contracts ordered by id (ascending)."""
|
||||
return list(
|
||||
session.execute(select(EnergyContract).order_by(EnergyContract.id)).scalars().all()
|
||||
)
|
||||
|
||||
|
||||
def _open_version(session: Session, contract: EnergyContract) -> EnergyContractVersion | None:
|
||||
"""Return the current open version (effective_to IS NULL) for *contract*, or None."""
|
||||
return session.execute(
|
||||
select(EnergyContractVersion)
|
||||
.where(
|
||||
EnergyContractVersion.contract_id == contract.id,
|
||||
EnergyContractVersion.effective_to.is_(None),
|
||||
)
|
||||
.order_by(EnergyContractVersion.effective_from.desc())
|
||||
.limit(1)
|
||||
).scalar_one_or_none()
|
||||
|
||||
|
||||
# ---------------------------------------------------------------------------
|
||||
# Core service functions
|
||||
# ---------------------------------------------------------------------------
|
||||
|
||||
|
||||
def create_contract(
|
||||
session: Session,
|
||||
*,
|
||||
name: str,
|
||||
kind: str,
|
||||
currency: str = "EUR",
|
||||
values: dict[str, Any],
|
||||
effective_from: datetime,
|
||||
) -> EnergyContract:
|
||||
"""Create a new energy contract with its first pricing version.
|
||||
|
||||
Parameters
|
||||
----------
|
||||
session:
|
||||
Active SQLAlchemy session. Caller must commit after this returns.
|
||||
name:
|
||||
Human-readable label for the contract.
|
||||
kind:
|
||||
Pricing strategy identifier (``"manual"`` or ``"tibber"``).
|
||||
currency:
|
||||
ISO 4217 currency code (default ``"EUR"``).
|
||||
values:
|
||||
Pricing values dict conforming to the named profile's structure.
|
||||
Validated via ``validate_values(kind, values)`` before any writes.
|
||||
effective_from:
|
||||
UTC datetime at which the first pricing version takes effect.
|
||||
|
||||
Returns
|
||||
-------
|
||||
EnergyContract
|
||||
The newly created contract (not yet committed).
|
||||
|
||||
Raises
|
||||
------
|
||||
ProfileNotFoundError
|
||||
If no YAML profile exists for *kind*.
|
||||
ProfileValidationError
|
||||
If *values* does not conform to the profile structure.
|
||||
"""
|
||||
# Validate (and fill defaults) before any DB write.
|
||||
filled_values = validate_values(kind, values)
|
||||
|
||||
now = datetime.now(UTC)
|
||||
contract = EnergyContract(
|
||||
name=name,
|
||||
kind=kind,
|
||||
currency=currency,
|
||||
active=False, # New contracts are inactive; caller must explicitly activate.
|
||||
created_at=now,
|
||||
updated_at=now,
|
||||
)
|
||||
session.add(contract)
|
||||
session.flush() # Assign contract.id so we can reference it in the version FK.
|
||||
|
||||
version = EnergyContractVersion(
|
||||
contract_id=contract.id,
|
||||
effective_from=effective_from,
|
||||
effective_to=None,
|
||||
values=filled_values,
|
||||
created_at=now,
|
||||
)
|
||||
session.add(version)
|
||||
|
||||
logger.info("Created energy contract %r (kind=%s, id=%d)", name, kind, contract.id)
|
||||
return contract
|
||||
|
||||
|
||||
def add_version(
|
||||
session: Session,
|
||||
contract: EnergyContract,
|
||||
*,
|
||||
effective_from: datetime,
|
||||
values: dict[str, Any],
|
||||
) -> EnergyContractVersion:
|
||||
"""Add a new pricing version to an existing contract (append-only).
|
||||
|
||||
The previous open version's ``effective_to`` is automatically set to the
|
||||
new version's ``effective_from`` (version closure), ensuring there is never
|
||||
a gap or overlap between consecutive versions.
|
||||
|
||||
The new ``effective_from`` **must be strictly greater than** the previous
|
||||
open version's ``effective_from``. Equal timestamps are rejected because
|
||||
they would produce two versions starting at the same instant, making it
|
||||
impossible to determine which is current. If this constraint is not met,
|
||||
``ContractVersionError`` is raised and **no rows are written**.
|
||||
|
||||
Parameters
|
||||
----------
|
||||
session:
|
||||
Active SQLAlchemy session. Caller must commit after this returns.
|
||||
contract:
|
||||
The parent ``EnergyContract`` to append a version to.
|
||||
effective_from:
|
||||
UTC datetime at which this version's pricing takes effect.
|
||||
values:
|
||||
New pricing values dict conforming to the contract's profile.
|
||||
|
||||
Returns
|
||||
-------
|
||||
EnergyContractVersion
|
||||
The newly created version (not yet committed).
|
||||
|
||||
Raises
|
||||
------
|
||||
ContractVersionError
|
||||
If *effective_from* is not strictly after the previous open version's
|
||||
``effective_from``.
|
||||
ProfileNotFoundError
|
||||
If no YAML profile exists for the contract's kind.
|
||||
ProfileValidationError
|
||||
If *values* does not conform to the profile structure.
|
||||
"""
|
||||
# Validate (and fill defaults) before any DB write.
|
||||
filled_values = validate_values(contract.kind, values)
|
||||
|
||||
prev = _open_version(session, contract)
|
||||
if prev is not None:
|
||||
# Enforce strictly-after constraint to prevent ambiguous overlap.
|
||||
# Use _as_utc() on both sides: the incoming value may be tz-aware
|
||||
# while the DB-read value is tz-naive (SQLite limitation).
|
||||
if _as_utc(effective_from) <= _as_utc(prev.effective_from):
|
||||
raise ContractVersionError(
|
||||
f"New version effective_from ({effective_from.isoformat()}) must be strictly "
|
||||
f"after the previous open version's effective_from "
|
||||
f"({prev.effective_from.isoformat()})."
|
||||
)
|
||||
# Close the previous open version.
|
||||
prev.effective_to = effective_from
|
||||
|
||||
now = datetime.now(UTC)
|
||||
new_version = EnergyContractVersion(
|
||||
contract_id=contract.id,
|
||||
effective_from=effective_from,
|
||||
effective_to=None,
|
||||
values=filled_values,
|
||||
created_at=now,
|
||||
)
|
||||
session.add(new_version)
|
||||
|
||||
logger.info(
|
||||
"Added version to contract id=%d (kind=%s, effective_from=%s)",
|
||||
contract.id,
|
||||
contract.kind,
|
||||
effective_from.isoformat(),
|
||||
)
|
||||
return new_version
|
||||
|
||||
|
||||
def activate_contract(session: Session, contract: EnergyContract) -> None:
|
||||
"""Activate a contract with mutual exclusion.
|
||||
|
||||
Sets every other contract's ``active`` flag to False, then sets the given
|
||||
contract's ``active`` to True. This guarantees at most one active contract
|
||||
at any time.
|
||||
|
||||
Caller must commit after this returns.
|
||||
"""
|
||||
# Deactivate all contracts (including the target; we re-activate below).
|
||||
for other in session.execute(select(EnergyContract)).scalars().all():
|
||||
other.active = False
|
||||
contract.active = True
|
||||
contract.updated_at = datetime.now(UTC)
|
||||
logger.info("Activated contract %r (id=%d)", contract.name, contract.id)
|
||||
|
||||
|
||||
def deactivate_contract(session: Session, contract: EnergyContract) -> None:
|
||||
"""Deactivate a contract without touching other contracts.
|
||||
|
||||
Caller must commit after this returns.
|
||||
"""
|
||||
contract.active = False
|
||||
contract.updated_at = datetime.now(UTC)
|
||||
logger.info("Deactivated contract %r (id=%d)", contract.name, contract.id)
|
||||
|
||||
|
||||
def active_contract_version_at(
|
||||
session: Session, ts: datetime
|
||||
) -> EnergyContractVersion | None:
|
||||
"""Return the active contract's version that covers *ts*.
|
||||
|
||||
A version covers *ts* when:
|
||||
``effective_from ≤ ts`` AND (``effective_to IS NULL`` OR ``ts < effective_to``)
|
||||
|
||||
Returns None when:
|
||||
- There is no active contract.
|
||||
- The active contract has no version covering *ts*.
|
||||
|
||||
Parameters
|
||||
----------
|
||||
session:
|
||||
Active SQLAlchemy session (read-only usage).
|
||||
ts:
|
||||
UTC datetime to look up.
|
||||
|
||||
Returns
|
||||
-------
|
||||
EnergyContractVersion | None
|
||||
"""
|
||||
active = session.execute(
|
||||
select(EnergyContract).where(EnergyContract.active.is_(True)).limit(1)
|
||||
).scalar_one_or_none()
|
||||
|
||||
if active is None:
|
||||
return None
|
||||
|
||||
# Build a query for all versions of the active contract covering ts.
|
||||
stmt = (
|
||||
select(EnergyContractVersion)
|
||||
.where(
|
||||
EnergyContractVersion.contract_id == active.id,
|
||||
EnergyContractVersion.effective_from <= ts,
|
||||
)
|
||||
.order_by(EnergyContractVersion.effective_from.desc())
|
||||
.limit(1)
|
||||
)
|
||||
version = session.execute(stmt).scalar_one_or_none()
|
||||
|
||||
if version is None:
|
||||
return None
|
||||
|
||||
# Exclude versions whose effective window has already closed before ts.
|
||||
if version.effective_to is not None and _as_utc(ts) >= _as_utc(version.effective_to):
|
||||
return None
|
||||
|
||||
return version
|
||||
Reference in New Issue
Block a user