from datetime import timedelta

from django.core.exceptions import ValidationError
from django.core.validators import MaxValueValidator, MinValueValidator
from django.db import models
from django.utils import timezone
from django.utils.translation import gettext_lazy as _

from core.models import BaseModel
from core.models.fields import EncryptedCharField
from core.utils.validators import validate_ukrainian_phone


class InternAccount(BaseModel):
    """Спільний інтерн-обліковий запис з пулу (5 слотів). Призначається заявці
    на час випробування; після approve/reject звільняється."""

    label = models.CharField(_('Метка'), max_length=50, unique=True)
    username = EncryptedCharField(_('Логин'), max_length=512)
    password = EncryptedCharField(_('Пароль'), max_length=512)
    is_active = models.BooleanField(_('Активный'), default=True)
    assigned_to = models.OneToOneField(
        'hiring.HiringRequest', on_delete=models.SET_NULL,
        null=True, blank=True,
        related_name='intern_account', verbose_name=_('Назначено заявке'),
    )

    class Meta:
        verbose_name = _('Интерн-аккаунт')
        verbose_name_plural = _('Пул интерн-аккаунтов')
        ordering = ['label']

    def __str__(self):
        status = _('занят') if self.assigned_to_id else _('свободен')
        return f'{self.label} ({status})'

    @classmethod
    def allocate(cls, hiring_request):
        """Виділяє свободен слот під select_for_update (викликати всередині atomic)."""
        account = (
            cls.objects.select_for_update()
            .filter(is_active=True, assigned_to__isnull=True)
            .order_by('label')
            .first()
        )
        if account is None:
            raise ValidationError({
                '__all__': _(
                    'Нет свободных интерн-аккаунтов. '
                    'Дождитесь завершения стажировки или добавьте слот в админке.'
                ),
            })
        account.assigned_to = hiring_request
        account.save(update_fields=['assigned_to', 'updated_at'])
        return account

    def release(self):
        if self.assigned_to_id is None:
            return
        self.assigned_to = None
        self.save(update_fields=['assigned_to', 'updated_at'])


class HiringRequest(BaseModel):
    """Заявка HR на найм кандидата: інтерн-слот + IT Ticket на випробуванні,
    персональний Employee — лише після затвердження."""

    STATUS_CHOICES = [
        ('trial',    _('На испытании')),
        ('approved', _('Утверждено')),
        ('rejected', _('Отклонено')),
    ]
    TRIAL_DAYS_CHOICES = [(i, _('%(n)d дн.') % {'n': i}) for i in range(1, 6)]

    last_name   = models.CharField(_('Фамилия'), max_length=150)
    first_name  = models.CharField(_('Имя'), max_length=150)
    middle_name = models.CharField(_('Отчество'), max_length=150, blank=True)

    candidate_email = models.EmailField(_('Личный email кандидата'), blank=True)
    candidate_phone = models.CharField(
        _('Телефон кандидата'), max_length=20, blank=True,
        validators=[validate_ukrainian_phone],
    )

    LOCATION_TYPES = [
        ('pharmacy',  _('Аптека')),
        ('warehouse', _('Склад')),
        ('office',    _('Офис')),
    ]
    user_location_type = models.CharField(
        _('Тип локации'), max_length=20, choices=LOCATION_TYPES,
    )
    department = models.ForeignKey(
        'core.Directory', on_delete=models.SET_NULL,
        null=True, blank=True,
        limit_choices_to={'directory_type__code': 'department', 'is_active': True},
        related_name='hiring_requests_department', verbose_name=_('Отдел'),
    )
    user_pharmacy = models.ForeignKey(
        'locations.Pharmacy', on_delete=models.SET_NULL,
        null=True, blank=True,
        related_name='hiring_requests', verbose_name=_('Аптека'),
    )
    user_location = models.ForeignKey(
        'locations.Location', on_delete=models.SET_NULL,
        null=True, blank=True,
        related_name='hiring_requests_location', verbose_name=_('Локация (офис/склад)'),
    )
    post = models.ForeignKey(
        'core.Directory', on_delete=models.SET_NULL,
        null=True, blank=True,
        limit_choices_to={'directory_type__code': 'post', 'is_active': True},
        related_name='hiring_requests_post', verbose_name=_('Должность'),
    )

    hire_date  = models.DateField(_('Дата виходу'), default=timezone.localdate)
    trial_days = models.PositiveSmallIntegerField(
        _('Срок испытания, дней'), choices=TRIAL_DAYS_CHOICES, default=3,
        validators=[MinValueValidator(1), MaxValueValidator(5)],
    )

    requested_access = models.ManyToManyField(
        'core.Directory', blank=True,
        limit_choices_to={'directory_type__code': 'access_system', 'is_active': True},
        related_name='hiring_requests_access', verbose_name=_('Требуемые доступы'),
    )
    access_note = models.TextField(_('Примечание по доступам'), blank=True)

    status = models.CharField(_('Статус'), max_length=10, choices=STATUS_CHOICES, default='trial')

    requested_by = models.ForeignKey(
        'employees.Employee', on_delete=models.PROTECT,
        related_name='hiring_requests_submitted', verbose_name=_('Подал HR'),
    )
    employee = models.OneToOneField(
        'employees.Employee', on_delete=models.SET_NULL,
        null=True, blank=True,
        related_name='hiring_request', verbose_name=_('Учётная запись'),
    )
    decision_by = models.ForeignKey(
        'employees.Employee', on_delete=models.SET_NULL,
        null=True, blank=True,
        related_name='hiring_requests_decided', verbose_name=_('Решение принял'),
    )
    decision_at   = models.DateTimeField(_('Дата решения'), null=True, blank=True)
    decision_note = models.TextField(_('Комментарий к решению'), blank=True)

    granted_ticket = models.ForeignKey(
        'it_manager.Ticket', on_delete=models.SET_NULL,
        null=True, blank=True,
        related_name='hiring_requests', verbose_name=_('Заявка в IT'),
    )
    access_task = models.ForeignKey(
        'tasks.Task', on_delete=models.SET_NULL,
        null=True, blank=True,
        related_name='+', verbose_name=_('Задача на выдачу доступов'),
    )

    # Пароль персонального акаунта після approve — для одноразового PDF.
    issued_password = EncryptedCharField(
        _('Выданный пароль (PDF)'), max_length=512, blank=True,
    )

    class Meta:
        verbose_name        = _('Заявка на найм')
        verbose_name_plural  = _('Заявки на найм')
        ordering = ['-created_at']
        indexes = [
            models.Index(fields=['status']),
        ]

    def __str__(self):
        return f'{self.last_name} {self.first_name} ({self.get_status_display()})'

    @property
    def trial_end_date(self):
        return self.hire_date + timedelta(days=self.trial_days)

    @property
    def is_overdue(self):
        return self.status == 'trial' and self.trial_end_date < timezone.localdate()

    def release_intern(self):
        try:
            account = self.intern_account
        except Exception:
            return
        account.release()


class Vacancy(BaseModel):
    """Открытая вакансия (рекрутинг в HR-портале)."""

    STATUS_CHOICES = [
        ('open', _('Открыта')),
        ('closed', _('Закрыта')),
        ('filled', _('Закрыта наймом')),
    ]
    PRIORITY_CHOICES = [
        ('urgent', _('Срочно')),
        ('medium', _('Средний')),
        ('normal', _('Обычный')),
    ]
    LOCATION_TYPES = [
        ('pharmacy', _('Аптека')),
        ('warehouse', _('Склад')),
        ('office', _('Офис')),
    ]

    title = models.CharField(_('Название'), max_length=200)
    post = models.ForeignKey(
        'core.Directory', on_delete=models.SET_NULL,
        null=True, blank=True,
        limit_choices_to={'directory_type__code': 'post', 'is_active': True},
        related_name='vacancies', verbose_name=_('Должность'),
    )
    user_location_type = models.CharField(
        _('Тип локации'), max_length=20, choices=LOCATION_TYPES, default='pharmacy',
    )
    department = models.ForeignKey(
        'core.Directory', on_delete=models.SET_NULL,
        null=True, blank=True,
        limit_choices_to={'directory_type__code': 'department', 'is_active': True},
        related_name='vacancies_department', verbose_name=_('Отдел'),
    )
    pharmacy = models.ForeignKey(
        'locations.Pharmacy', on_delete=models.SET_NULL,
        null=True, blank=True,
        related_name='pharmacy_vacancies', verbose_name=_('Аптека'),
    )
    location = models.ForeignKey(
        'locations.Location', on_delete=models.SET_NULL,
        null=True, blank=True,
        related_name='location_vacancies', verbose_name=_('Локация'),
    )
    priority = models.CharField(
        _('Приоритет'), max_length=16, choices=PRIORITY_CHOICES, default='normal',
    )
    status = models.CharField(
        _('Статус'), max_length=16, choices=STATUS_CHOICES, default='open',
    )
    opened_at = models.DateField(_('Открыта с'), default=timezone.localdate)
    description = models.TextField(_('Описание'), blank=True)
    candidates_count = models.PositiveIntegerField(_('Кандидатов'), default=0)
    created_by = models.ForeignKey(
        'employees.Employee', on_delete=models.SET_NULL,
        null=True, blank=True,
        related_name='vacancies_created', verbose_name=_('Создал'),
    )

    class Meta:
        verbose_name = _('Вакансия')
        verbose_name_plural = _('Вакансии')
        ordering = ['-opened_at', '-created_at']
        indexes = [
            models.Index(fields=['status', 'priority']),
        ]

    def __str__(self):
        return self.title

    @property
    def place_label(self) -> str:
        if self.user_location_type == 'pharmacy' and self.pharmacy_id:
            return str(self.pharmacy)
        if self.department_id:
            return self.department.name
        if self.location_id:
            return str(self.location)
        return '—'