F-r-ldraledigplannerare/backend/app/services/analytics_service.py

"""Analytics service: days-left-at-age-4 and planned-vs-actual reconciliation.

The headline calculation (§6.5 ARCHITECTURE.md):

  projected_used_by_B4 = days_used + planned_days(date < B4)
  projected_left_at_B4 = total_days - projected_used_by_B4
  savable_after_B4     = min(projected_left_at_B4, 96)   # age-4 ceiling
  expiring_at_B4       = max(projected_left_at_B4 - 96, 0)   # LOST days

All rule constants come from config.LeaveRules — no magic numbers.
dateutil.relativedelta handles leap-year safe 4th-birthday arithmetic.
"""

from __future__ import annotations

from dataclasses import dataclass
from datetime import date
from uuid import UUID

from dateutil.relativedelta import relativedelta

from app.config import settings
from app.repositories.child_repository import ChildRepository
from app.repositories.parental_leave_repository import ParentalLeaveRepository
from app.repositories.personal_data_repository import PersonalDataRepository
from app.repositories.planned_leave_repository import PlannedLeaveRepository
from app.utils.errors import NotFoundError
from app.utils.tip_predicates import days_left_at_age_4_projection


@dataclass
class Age4Projection:
    """Per-parent projection of days remaining at the child's 4th birthday."""

    personal_data_uuid: UUID
    child_id: UUID
    birth_date: date
    fourth_birthday: date
    total_days: int
    days_used: int  # from latest FK snapshot
    planned_days_before_b4: int  # from calendar
    projected_left_at_b4: int
    savable_after_b4: int  # min(projected_left, 96)
    expiring_at_b4: int  # max(projected_left - 96, 0) — LOST if not used


@dataclass
class WorkspaceOverview:
    workspace_id: UUID
    child_id: UUID
    parent_projections: list[Age4Projection]
    combined_days_used: int
    combined_days_left: int
    combined_expiring_at_b4: int


class AnalyticsService:
    def __init__(
        self,
        parental_leave_repo: ParentalLeaveRepository,
        planned_leave_repo: PlannedLeaveRepository,
        child_repo: ChildRepository,
        personal_data_repo: PersonalDataRepository,
    ) -> None:
        self._leave = parental_leave_repo
        self._planned = planned_leave_repo
        self._children = child_repo
        self._parents = personal_data_repo

    async def get_days_left_at_age_4(
        self, personal_data_uuid: UUID, child_id: UUID
    ) -> Age4Projection:
        """Compute the headline projection for a single parent+child pair."""
        rules = settings.rules

        child = await self._children.get_by_id(child_id)
        if child is None:
            raise NotFoundError(f"Child {child_id} not found")

        # Compute the 4th birthday with leap-year-safe arithmetic.
        b4 = child.birth_date + relativedelta(years=4)

        latest = await self._leave.get_latest_by_parent(personal_data_uuid, child_id)
        if latest is None:
            # No FK data yet — assume full entitlement with 0 used.
            days_used = 0
            total_days = rules.days_per_parent
        else:
            days_used = latest.days_used
            total_days = latest.total_days

        # Count föräldrapenning planned days that fall before the 4th birthday.
        # Vacation days do NOT count against the FP pool.
        today = date.today()
        sjukpenning_before_b4 = await self._planned.count_by_parent_type(
            personal_data_uuid,
            child_id,
            "sjukpenning",
            from_date=today,
            to_date=b4,
        )
        lagsta_before_b4 = await self._planned.count_by_parent_type(
            personal_data_uuid,
            child_id,
            "lagsta",
            from_date=today,
            to_date=b4,
        )
        planned_fp_before_b4 = sjukpenning_before_b4 + lagsta_before_b4

        # Shared with the plan-proposal side (`allocation_service._Ledger.
        # build_age4_projections`) so the two surfaces can never re-derive
        # this arithmetic differently — see `days_left_at_age_4_projection`.
        projected_left, expiring = days_left_at_age_4_projection(
            days_used=days_used,
            planned_fp_before_b4=planned_fp_before_b4,
            total_days=total_days,
        )
        savable = min(projected_left, rules.max_savable_days_at_age_4)

        return Age4Projection(
            personal_data_uuid=personal_data_uuid,
            child_id=child_id,
            birth_date=child.birth_date,
            fourth_birthday=b4,
            total_days=total_days,
            days_used=days_used,
            planned_days_before_b4=planned_fp_before_b4,
            projected_left_at_b4=projected_left,
            savable_after_b4=savable,
            expiring_at_b4=expiring,
        )

    async def get_overview(self, workspace_id: UUID, child_id: UUID) -> WorkspaceOverview:
        """Compute projections for all parents in a workspace for one child."""
        members = await self._parents.list_by_workspace(workspace_id)
        if not members:
            raise NotFoundError(f"No parents found in workspace {workspace_id}")

        projections = []
        for pd in members:
            proj = await self.get_days_left_at_age_4(pd.uuid, child_id)
            projections.append(proj)

        combined_used = sum(p.days_used + p.planned_days_before_b4 for p in projections)
        combined_left = sum(p.projected_left_at_b4 for p in projections)
        combined_expiring = sum(p.expiring_at_b4 for p in projections)

        return WorkspaceOverview(
            workspace_id=workspace_id,
            child_id=child_id,
            parent_projections=projections,
            combined_days_used=combined_used,
            combined_days_left=combined_left,
            combined_expiring_at_b4=combined_expiring,
        )

    async def validate_dubbeldagar(self, child_id: UUID, new_date: date) -> None:
        """Raise DubbeldagError if adding a dubbeldagar day would break rules.

        Called from the planning service before persisting a new day.
        """
        from app.utils.errors import DubbeldagError

        child = await self._children.get_by_id(child_id)
        if child is None:
            raise NotFoundError(f"Child {child_id} not found")

        # Window: child's birth_date ... birth_date + 15 months
        window_end = child.birth_date + relativedelta(
            months=settings.rules.dubbeldagar_months_limit
        )
        if new_date > window_end:
            raise DubbeldagError(
                f"Dubbeldagar only allowed within the child's first "
                f"{settings.rules.dubbeldagar_months_limit} months "
                f"(deadline {window_end})",
                message_key="planApply.rejection.dubbeldagWindowExceeded",
                data={
                    "months_limit": settings.rules.dubbeldagar_months_limit,
                    "deadline": window_end.isoformat(),
                },
            )

        # Quota: count already-planned dubbeldagar from child's birth_date onward.
        already_planned = await self._planned.count_dubbeldagar(
            child_id, from_date=child.birth_date
        )
        if already_planned >= settings.rules.max_dubbeldagar:
            raise DubbeldagError(
                f"Dubbeldagar quota ({settings.rules.max_dubbeldagar} days) already reached",
                message_key="planApply.rejection.dubbeldagQuotaReached",
                data={"max_dubbeldagar": settings.rules.max_dubbeldagar},
            )