"""Проекты с шагами по отделам; пункты шагов связываются с tasks.Task."""
from __future__ import annotations

from django.conf import settings
from django.db import models
from django.db.models import Count, Q
from django.utils.translation import gettext_lazy as _

from core.models.base import BaseModel


class ProjectTemplate(BaseModel):
    name = models.CharField(_('Название'), max_length=200)
    description = models.TextField(_('Описание'), blank=True)
    default_duration_days = models.PositiveIntegerField(
        _('Длительность по умолчанию (дни)'), default=90,
    )
    is_active = models.BooleanField(_('Активен'), default=True)

    class Meta:
        verbose_name = _('Шаблон проекта')
        verbose_name_plural = _('Шаблоны проектов')
        ordering = ['name']

    def __str__(self):
        return self.name


class ProjectTemplateStep(BaseModel):
    template = models.ForeignKey(
        ProjectTemplate, on_delete=models.CASCADE,
        related_name='steps', verbose_name=_('Шаблон'),
    )
    title = models.CharField(_('Название шага'), max_length=250)
    order = models.PositiveSmallIntegerField(_('Порядок'), default=0)
    department = models.ForeignKey(
        'core.Directory', on_delete=models.SET_NULL,
        null=True, blank=True,
        limit_choices_to={'directory_type__code': 'department'},
        related_name='project_template_steps', verbose_name=_('Отдел'),
    )
    offset_days = models.PositiveIntegerField(
        _('Смещение от старта (дни)'), default=0,
        help_text=_('Плановый старт шага = старт проекта + offset.'),
    )
    duration_days = models.PositiveIntegerField(
        _('Длительность шага (дни)'), default=14,
    )

    class Meta:
        verbose_name = _('Шаг шаблона')
        verbose_name_plural = _('Шаги шаблона')
        ordering = ['order', 'id']

    def __str__(self):
        return f'{self.order}. {self.title}'


class ProjectTemplateStepItem(BaseModel):
    step = models.ForeignKey(
        ProjectTemplateStep, on_delete=models.CASCADE,
        related_name='items', verbose_name=_('Шаг'),
    )
    title = models.CharField(_('Название задачи'), max_length=250)
    description = models.TextField(_('Описание'), blank=True)
    priority = models.CharField(
        _('Приоритет'), max_length=10, default='medium',
        choices=[
            ('low', _('Низкий')),
            ('medium', _('Средний')),
            ('high', _('Высокий')),
        ],
    )
    order = models.PositiveSmallIntegerField(_('Порядок'), default=0)

    class Meta:
        verbose_name = _('Пункт шага шаблона')
        verbose_name_plural = _('Пункты шага шаблона')
        ordering = ['order', 'id']

    def __str__(self):
        return self.title


class ProjectQuerySet(models.QuerySet):
    def for_user(self, user):
        """Владелец, участник связанных Task, сотрудник отдела шага, или staff."""
        if not user or not getattr(user, 'is_authenticated', False):
            return self.none()
        if getattr(user, 'is_staff', False) or getattr(user, 'is_superuser', False):
            return self.all()
        dept_id = getattr(user, 'department_id', None)
        q = Q(owner=user) | Q(created_by=user)
        q |= Q(steps__items__task__creator=user)
        q |= Q(steps__items__task__responsible=user)
        q |= Q(steps__items__task__co_executors=user)
        q |= Q(steps__items__task__observers=user)
        if dept_id:
            q |= Q(steps__department_id=dept_id)
        return self.filter(q).distinct()


class Project(BaseModel):
    STATUS_DRAFT = 'draft'
    STATUS_ACTIVE = 'active'
    STATUS_DONE = 'done'
    STATUS_CANCELLED = 'cancelled'
    STATUS_CHOICES = [
        (STATUS_DRAFT, _('Черновик')),
        (STATUS_ACTIVE, _('Активен')),
        (STATUS_DONE, _('Завершён')),
        (STATUS_CANCELLED, _('Отменён')),
    ]

    title = models.CharField(_('Название'), max_length=250)
    description = models.TextField(_('Описание'), blank=True)
    status = models.CharField(
        _('Статус'), max_length=20, choices=STATUS_CHOICES,
        default=STATUS_DRAFT, db_index=True,
    )
    start_date = models.DateField(_('Дата старта'), null=True, blank=True)
    due_date = models.DateField(_('Срок'), null=True, blank=True)
    pharmacy = models.ForeignKey(
        'locations.Pharmacy', on_delete=models.SET_NULL,
        null=True, blank=True, related_name='projects',
        verbose_name=_('Аптека'),
    )
    template = models.ForeignKey(
        ProjectTemplate, on_delete=models.SET_NULL,
        null=True, blank=True, related_name='projects',
        verbose_name=_('Шаблон'),
    )
    owner = models.ForeignKey(
        settings.AUTH_USER_MODEL, on_delete=models.SET_NULL,
        null=True, related_name='owned_projects', verbose_name=_('Владелец'),
    )
    created_by = models.ForeignKey(
        settings.AUTH_USER_MODEL, on_delete=models.SET_NULL,
        null=True, related_name='created_projects', verbose_name=_('Создал'),
    )

    objects = ProjectQuerySet.as_manager()

    class Meta:
        verbose_name = _('Проект')
        verbose_name_plural = _('Проекты')
        ordering = ['-created_at']
        indexes = [
            models.Index(fields=['status', '-created_at']),
        ]

    def __str__(self):
        return self.title

    def progress_counts(self) -> tuple[int, int]:
        """(done_tasks, total_tasks)."""
        agg = (
            self.steps.filter(items__task__isnull=False)
            .aggregate(
                total=Count('items__task', distinct=True),
                done=Count(
                    'items__task',
                    filter=Q(items__task__status='done'),
                    distinct=True,
                ),
            )
        )
        return int(agg['done'] or 0), int(agg['total'] or 0)

    @property
    def progress_percent(self) -> int:
        done, total = self.progress_counts()
        if total <= 0:
            return 0
        return int(round(100 * done / total))


class ProjectStep(BaseModel):
    STATUS_PENDING = 'pending'
    STATUS_IN_PROGRESS = 'in_progress'
    STATUS_DONE = 'done'
    STATUS_CHOICES = [
        (STATUS_PENDING, _('Ожидает')),
        (STATUS_IN_PROGRESS, _('В работе')),
        (STATUS_DONE, _('Выполнен')),
    ]

    project = models.ForeignKey(
        Project, on_delete=models.CASCADE,
        related_name='steps', verbose_name=_('Проект'),
    )
    title = models.CharField(_('Название'), max_length=250)
    order = models.PositiveSmallIntegerField(_('Порядок'), default=0)
    department = models.ForeignKey(
        'core.Directory', on_delete=models.SET_NULL,
        null=True, blank=True,
        limit_choices_to={'directory_type__code': 'department'},
        related_name='project_steps', verbose_name=_('Отдел'),
    )
    status = models.CharField(
        _('Статус'), max_length=20, choices=STATUS_CHOICES,
        default=STATUS_PENDING, db_index=True,
    )
    planned_start = models.DateField(_('План. старт'), null=True, blank=True)
    planned_due = models.DateField(_('План. срок'), null=True, blank=True)

    class Meta:
        verbose_name = _('Шаг проекта')
        verbose_name_plural = _('Шаги проекта')
        ordering = ['order', 'id']

    def __str__(self):
        return f'{self.order}. {self.title}'

    def refresh_status(self, *, save: bool = True) -> str:
        items = list(self.items.select_related('task'))
        if not items:
            new = self.STATUS_PENDING
        else:
            tasks = [i.task for i in items if i.task_id]
            if not tasks:
                new = self.STATUS_PENDING
            elif all(t.status == 'done' for t in tasks):
                new = self.STATUS_DONE
            elif any(t.status in ('in_progress', 'done') for t in tasks):
                new = self.STATUS_IN_PROGRESS
            else:
                new = self.STATUS_PENDING
        if new != self.status:
            self.status = new
            if save:
                self.save(update_fields=['status', 'updated_at'])
        return self.status


class ProjectStepItem(BaseModel):
    step = models.ForeignKey(
        ProjectStep, on_delete=models.CASCADE,
        related_name='items', verbose_name=_('Шаг'),
    )
    task = models.OneToOneField(
        'tasks.Task', on_delete=models.SET_NULL,
        null=True, blank=True, related_name='project_step_item',
        verbose_name=_('Задача'),
    )
    title = models.CharField(_('Название'), max_length=250)
    description = models.TextField(_('Описание'), blank=True)
    priority = models.CharField(_('Приоритет'), max_length=10, default='medium')
    order = models.PositiveSmallIntegerField(_('Порядок'), default=0)

    class Meta:
        verbose_name = _('Пункт шага')
        verbose_name_plural = _('Пункты шага')
        ordering = ['order', 'id']

    def __str__(self):
        return self.title