"""HTTP routes for the planning engine.

Routers stay thin: validate via Pydantic, call the service, map domain errors
to HTTP. All allocation logic lives in `app.services.allocation_service`, and
all bulk-apply logic (idempotency, collisions, `replace`, validation) lives in
`app.services.planning_service.PlanningService.apply_proposed_days`. See
PLANNING_ENGINE_SPEC.md §4.
"""

from fastapi import APIRouter, HTTPException, status

from app.dependencies import PlanningEngineServiceDep, PlanningServiceDep, WorkspaceScopeDep
from app.models.plan import (
    PlanApplyRequest,
    PlanApplyResponse,
    PlanProposalResponse,
    PlanProposeRequest,
    PlanSyncRequest,
    PlanSyncResponse,
)
from app.utils.errors import NotFoundError, ValidationError

router = APIRouter(prefix="/api/plan", tags=["plan"])


@router.post("/propose", response_model=PlanProposalResponse)
async def propose_plan(
    payload: PlanProposeRequest, service: PlanningEngineServiceDep, scope: WorkspaceScopeDep
) -> PlanProposalResponse:
    """Compute a plan proposal. Read-only — persists nothing, safe to spam."""
    scope.check_workspace(payload.workspace_id)
    try:
        proposal = await service.propose(payload.workspace_id)
    except NotFoundError as exc:
        raise HTTPException(status.HTTP_404_NOT_FOUND, str(exc)) from exc
    except ValidationError as exc:
        raise HTTPException(status.HTTP_422_UNPROCESSABLE_ENTITY, str(exc)) from exc
    return PlanProposalResponse.from_domain(proposal)


@router.post("/apply", response_model=PlanApplyResponse)
async def apply_plan(
    payload: PlanApplyRequest, service: PlanningServiceDep, scope: WorkspaceScopeDep
) -> PlanApplyResponse:
    """Accept a (possibly user-edited) set of proposed days as real plan.

    Always returns 200 with `accepted: false` and a `rejections`/`collisions`
    breakdown when the batch is refused — refusal (a collision without
    `replace`, an invalid day type, a balance/eligibility violation) is an
    expected, structured outcome for the UI to render, not an HTTP error.
    A genuinely missing workspace/child (404) is the one case still raised
    as an HTTP error, since that's not something the batch report can explain.
    """
    scope.check_workspace(payload.workspace_id)
    # Every child/parent named in the batch must belong to the caller's own
    # workspace too — otherwise a forged child_id/parent_personal_data_uuid
    # could write a planned_leave_day row attributed to another tenant's
    # child or parent even though workspace_id itself checks out.
    for child_id in {item.child_id for item in payload.days}:
        await scope.check_child(child_id)
    for parent_id in {item.parent_personal_data_uuid for item in payload.days}:
        await scope.check_member(parent_id)
    try:
        result = await service.apply_proposed_days(
            workspace_id=payload.workspace_id,
            days=[item.to_domain() for item in payload.days],
            replace=payload.replace,
        )
    except NotFoundError as exc:
        raise HTTPException(status.HTTP_404_NOT_FOUND, str(exc)) from exc
    return PlanApplyResponse.from_domain(result)


@router.post("/sync", response_model=PlanSyncResponse)
async def sync_plan(
    payload: PlanSyncRequest, service: PlanningServiceDep, scope: WorkspaceScopeDep
) -> PlanSyncResponse:
    """Recompute and persist a workspace's plan in one step.

    The direct-manipulation calendar UX's one call: no separate preview
    step. Runs propose then apply internally (see
    `PlanningService.sync_plan`), never retyping or overwriting a day the
    user has pinned, and reports exactly what changed (`changes`) so the UI
    can show e.g. "Sommar 2028 flyttades 2 dagar — Ångra" instead of
    silently rewriting the calendar.

    Doubles as its own eviction preview: when the re-derived plan would
    silently delete another wish's days (a shared FP/vacation pool ran out
    for that wish's parent), this call writes NOTHING and returns
    `eviction_preview` describing what ran out and which days would go —
    unless `eviction_choice` names one of the two caller-authorized
    eviction strategies, in which case exactly that category is freed and
    the edit is applied. No separate round trip for the common (fits-
    within-budget) case; see `PlanningService.sync_plan`'s docstring.
    """
    scope.check_workspace(payload.workspace_id)
    try:
        result = await service.sync_plan(
            payload.workspace_id, eviction_choice=payload.eviction_choice
        )
    except NotFoundError as exc:
        raise HTTPException(status.HTTP_404_NOT_FOUND, str(exc)) from exc
    except ValidationError as exc:
        raise HTTPException(status.HTTP_422_UNPROCESSABLE_ENTITY, str(exc)) from exc
    return PlanSyncResponse.from_domain(result)