Craig
601c0d461e
- POST auto-closes previous target in one transaction - GET /targets (ordered), GET /targets/current (404 when none) - PUT with invariant enforcement (409 on double-active attempt) - Service-layer historical target lookup for TICKET-004 - Full suite green (62 passed)
172 lines
6.7 KiB
Python
172 lines
6.7 KiB
Python
"""Targets service layer — business logic + DB access (spec §8.1 rules 2–3, 6).
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Auto-close semantics:
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- When a new target is created, the previous active target's end_date is set
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to the new target's start_date (same day).
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- Historical lookup uses an EXCLUSIVE end_date: a target covers dates where
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start_date <= date AND (end_date IS NULL OR end_date > date).
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This forms half-open intervals [start_date, end_date), so there is never
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overlap or ambiguity about which target applies on a boundary date.
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ORM objects never leave this module; functions return Pydantic schemas.
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"""
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from datetime import date
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from sqlalchemy import select
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from sqlalchemy.orm import Session
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from models import Target
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from schemas import TargetCreate, TargetRead, TargetUpdate
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# ── CRUD ─────────────────────────────────────────────────────────────────────
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def list_targets(db: Session) -> list[TargetRead]:
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"""List all targets ordered by start_date."""
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targets = db.scalars(select(Target).order_by(Target.start_date)).all()
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return [TargetRead.model_validate(t) for t in targets]
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def get_current_target(db: Session) -> TargetRead | None:
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"""Return the active target (end_date IS NULL), or None."""
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target = db.scalar(select(Target).where(Target.end_date.is_(None)))
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if target is None:
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return None
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return TargetRead.model_validate(target)
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def create_target(db: Session, data: TargetCreate) -> TargetRead:
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"""Create a new target. Auto-closes the previous active target by setting
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its end_date to the new target's start_date. Runs in a single transaction
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so there is never a window with zero or two active targets (§2.4, §8.1 rule 6).
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Raises ValueError if the auto-close would cause the previous target's
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end_date to be <= its start_date (e.g. backdating a target before the
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current one started).
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"""
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new_start = data.start_date
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# Find the currently active target and auto-close it
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current_active = db.scalar(
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select(Target).where(Target.end_date.is_(None))
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)
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if current_active is not None:
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if new_start <= current_active.start_date:
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raise ValueError(
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f"New target start_date ({new_start}) is not after the current "
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f"active target's start_date ({current_active.start_date}). "
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f"Cannot auto-close without creating an invalid date range."
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)
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current_active.end_date = new_start
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target = Target(
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start_date=data.start_date,
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end_date=None,
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calories=data.calories,
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protein_g=data.protein_g,
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carbs_g=data.carbs_g,
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fat_g=data.fat_g,
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)
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db.add(target)
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db.commit()
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db.refresh(target)
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return TargetRead.model_validate(target)
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def update_target(db: Session, target_id: int, data: TargetUpdate) -> TargetRead | None:
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"""Update a target's values and/or date range. The single-active-target
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invariant is preserved: setting end_date to null when another active
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target already exists is rejected.
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Returns None if the target is not found.
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Raises ValueError for date-range validation failures.
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Raises ActiveTargetConflictError if the update would create two active targets.
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"""
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target = db.get(Target, target_id)
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if target is None:
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return None
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update_data = data.model_dump(exclude_unset=True)
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# Validate the resulting date range if either date field is being changed
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new_start = update_data.get("start_date", target.start_date)
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new_end = update_data.get("end_date", target.end_date) # None means "not being updated"
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# If end_date key is present in update_data, use that value (could be None explicitly)
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if "end_date" in update_data:
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new_end = update_data["end_date"]
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else:
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new_end = target.end_date
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# Validate end_date > start_date when both are set
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if new_end is not None and new_end <= new_start:
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raise ValueError("end_date must be after start_date")
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# Check single-active-target invariant: if setting end_date to NULL,
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# there must not already be another active target
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if "end_date" in update_data and update_data["end_date"] is None:
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if target.end_date is not None: # target is currently NOT active
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other_active = db.scalar(
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select(Target).where(
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Target.end_date.is_(None),
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Target.id != target_id,
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)
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)
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if other_active is not None:
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raise ActiveTargetConflictError(other_active.id)
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# If changing start_date on the active target, ensure it doesn't break
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# the invariant with respect to the previously-closed target.
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# (The previously-closed target's end_date references the OLD start_date;
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# changing start_date on the active one doesn't retroactively fix that.
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# This is fine — historical targets may have end_date values that don't
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# align perfectly after edits. The half-open interval lookup still works.)
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for field, value in update_data.items():
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setattr(target, field, value)
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db.commit()
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db.refresh(target)
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return TargetRead.model_validate(target)
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# ── Historical lookup ────────────────────────────────────────────────────────
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def get_target_for_date(db: Session, lookup_date: date) -> TargetRead | None:
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"""Return the target whose date range contains the given date.
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Uses half-open intervals [start_date, end_date): a target covers dates
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where start_date <= date AND (end_date IS NULL OR end_date > date).
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Returns None if no target covers the given date.
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Exposed for TICKET-004 (day summary endpoint).
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"""
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target = db.scalar(
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select(Target)
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.where(
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Target.start_date <= lookup_date,
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(Target.end_date.is_(None)) | (Target.end_date > lookup_date),
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)
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.order_by(Target.start_date.desc())
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.limit(1)
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)
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if target is None:
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return None
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return TargetRead.model_validate(target)
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# ── Errors ───────────────────────────────────────────────────────────────────
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class ActiveTargetConflictError(Exception):
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"""Raised when an operation would create two active targets."""
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def __init__(self, existing_active_id: int):
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super().__init__(
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f"There is already an active target (id={existing_active_id}). "
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f"Close it first before activating another."
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)
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self.existing_active_id = existing_active_id
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