from datetime import date
from django.db import transaction
from .models import ProjectRequest, ProjectsDeclined, Project, Account

def approve_project_request(request_id: int, decided_by: str, account_code: str) -> Project:
    # Use a DB transaction so either all changes commit, or none (atomic workflow).
    with transaction.atomic():
        # SELECT ... FOR UPDATE: lock the row to avoid concurrent approvals/declines.
        req = ProjectRequest.objects.select_for_update().get(pk=request_id)

        # Mark the request as approved and persist the decision metadata.
        req.decision = 'APPROVED'
        req.decision_date = date.today()   # For DateField a date is fine; prefer timezone.localdate() if TZ-sensitive.
        req.decided_by = decided_by
        req.save()

        # The Account (Kostenstelle) must be assigned by WMDE in the admin workflow.
        # .get() will raise DoesNotExist/MultipleObjectsReturned if data integrity is broken.
        account = Account.objects.get(code=account_code)

        # Create the actual Project from the request data.
        # Project.save() will generate pid/finance_id/end_quartal according to your model logic.
        proj = Project.objects.create(
            realname=req.realname,
            email=req.email,
            end_mail_send=False,
            name=req.name,
            description=req.description,
            start=req.start,
            end=req.end,
            page=req.page,
            group=req.group,
            location=req.location,
            participants_estimated=req.participants_estimated,
            insurance=req.insurance,
            cost=req.cost,
            account=account,
            notes=req.notes,
            granted=True,
            granted_date=date.today(),   # Consider timezone.localdate() if you care about time zones.
            granted_from=decided_by,
        )

        # After successful creation we remove the original request (it has been fulfilled).
        # Because we're inside an atomic block, both operations succeed/fail together.
        req.delete()

        # Return the created project for further processing in the caller if needed.
        return proj


def decline_project_request(request_id: int, reason: str | None = None):
    # Same transactional guarantees for declines.
    with transaction.atomic():
        # Lock the row to prevent concurrent decisions.
        req = ProjectRequest.objects.select_for_update().get(pk=request_id)

        # Mark as declined and persist decision date.
        req.decision = 'DECLINED'
        req.decision_date = date.today()
        req.save()

        # Archive minimal relevant information in a dedicated table.
        # No pid/finance_id should be created for declined items.
        ProjectsDeclined.objects.create(
            original_request_id=req.id,
            name=req.name,
            realname=req.realname,
            email=req.email,
            decision_date=req.decision_date,
            reason=reason or '',
        )

        # Remove the original request after archiving.
        req.delete()