"""Создание проектов из шаблона / вручную и активация (Task)."""
from __future__ import annotations

from datetime import timedelta

from django.db import transaction
from django.utils import timezone

from apps.projects.models import (
    Project, ProjectStep, ProjectStepItem,
    ProjectTemplate,
)
from apps.tasks.models import Task


def _department_head(department_id):
    try:
        from apps.reports.it_monthly.builder import department_head
        return department_head(department_id)
    except Exception:  # noqa: BLE001
        return None


def _add_days(base, days: int):
    if base is None:
        return None
    return base + timedelta(days=int(days or 0))


@transaction.atomic
def create_project_from_template(
    *,
    template: ProjectTemplate,
    title: str,
    owner,
    created_by=None,
    start_date=None,
    due_date=None,
    pharmacy=None,
    description: str = '',
) -> Project:
    start = start_date or timezone.localdate()
    if due_date is None and template.default_duration_days:
        due_date = _add_days(start, template.default_duration_days)

    project = Project.objects.create(
        title=(title or template.name).strip() or template.name,
        description=(description or template.description or '').strip(),
        status=Project.STATUS_DRAFT,
        start_date=start,
        due_date=due_date,
        pharmacy=pharmacy,
        template=template,
        owner=owner,
        created_by=created_by or owner,
    )

    for t_step in template.steps.prefetch_related('items').order_by('order', 'id'):
        step = ProjectStep.objects.create(
            project=project,
            title=t_step.title,
            order=t_step.order,
            department=t_step.department,
            status=ProjectStep.STATUS_PENDING,
            planned_start=_add_days(start, t_step.offset_days),
            planned_due=_add_days(start, t_step.offset_days + t_step.duration_days),
        )
        for t_item in t_step.items.order_by('order', 'id'):
            ProjectStepItem.objects.create(
                step=step,
                title=t_item.title,
                description=t_item.description,
                priority=t_item.priority,
                order=t_item.order,
            )
    return project


@transaction.atomic
def create_manual_project(
    *,
    title: str,
    owner,
    created_by=None,
    description: str = '',
    start_date=None,
    due_date=None,
    pharmacy=None,
    steps: list[dict] | None = None,
) -> Project:
    """steps: [{title, department_id, order, items: [{title, description, priority}]}]"""
    start = start_date or timezone.localdate()
    project = Project.objects.create(
        title=title.strip(),
        description=(description or '').strip(),
        status=Project.STATUS_DRAFT,
        start_date=start,
        due_date=due_date,
        pharmacy=pharmacy,
        owner=owner,
        created_by=created_by or owner,
    )
    for idx, raw in enumerate(steps or []):
        step = ProjectStep.objects.create(
            project=project,
            title=(raw.get('title') or f'Шаг {idx + 1}').strip(),
            order=int(raw.get('order', idx)),
            department_id=raw.get('department_id') or None,
            status=ProjectStep.STATUS_PENDING,
            planned_start=raw.get('planned_start') or start,
            planned_due=raw.get('planned_due') or due_date,
        )
        for j, item in enumerate(raw.get('items') or []):
            ProjectStepItem.objects.create(
                step=step,
                title=(item.get('title') or f'Задача {j + 1}').strip(),
                description=(item.get('description') or '').strip(),
                priority=item.get('priority') or 'medium',
                order=int(item.get('order', j)),
            )
    return project


def _ensure_task_for_item(item: ProjectStepItem, *, owner) -> Task | None:
    if item.task_id:
        return item.task
    step = item.step
    head = _department_head(step.department_id)
    task = Task.objects.create(
        title=item.title,
        description=item.description or '',
        status='pending',
        priority=item.priority or 'medium',
        due_date=step.planned_due,
        creator=owner,
    )
    responsible = head or owner
    if responsible is not None:
        task.responsible.add(responsible)
    item.task = task
    item.save(update_fields=['task', 'updated_at'])
    return task


@transaction.atomic
def activate_project(project: Project) -> Project:
    """draft → active: создать Task для всех пунктов без задачи."""
    if project.status == Project.STATUS_CANCELLED:
        raise ValueError('Отменённый проект нельзя активировать.')
    owner = project.owner or project.created_by
    for step in project.steps.prefetch_related('items').order_by('order', 'id'):
        for item in step.items.all():
            _ensure_task_for_item(item, owner=owner)
        step.refresh_status(save=True)
    if project.status == Project.STATUS_DRAFT:
        project.status = Project.STATUS_ACTIVE
        if not project.start_date:
            project.start_date = timezone.localdate()
        project.save(update_fields=['status', 'start_date', 'updated_at'])
    refresh_project_status(project)
    return project


@transaction.atomic
def activate_step(step: ProjectStep) -> ProjectStep:
    project = step.project
    owner = project.owner or project.created_by
    for item in step.items.all():
        _ensure_task_for_item(item, owner=owner)
    step.refresh_status(save=True)
    if project.status == Project.STATUS_DRAFT:
        project.status = Project.STATUS_ACTIVE
        if not project.start_date:
            project.start_date = timezone.localdate()
        project.save(update_fields=['status', 'start_date', 'updated_at'])
    refresh_project_status(project)
    return step


def refresh_project_status(project: Project) -> str:
    """Авто-done, если все шаги done и есть хотя бы один шаг с задачами."""
    steps = list(project.steps.all())
    if not steps:
        return project.status
    for step in steps:
        step.refresh_status(save=True)
    steps = list(project.steps.all())
    if project.status == Project.STATUS_ACTIVE and steps and all(
        s.status == ProjectStep.STATUS_DONE for s in steps
    ):
        project.status = Project.STATUS_DONE
        project.save(update_fields=['status', 'updated_at'])
    return project.status