# backend/modules/task_management/models.py

from django.db import models
from django.conf import settings
from django.core.exceptions import ValidationError
from django.utils.translation import gettext_lazy as _
from core.base_models import BaseModel


class Task(BaseModel):
    """
    Modularni Task model nasljeđuje sva polja iz BaseModel.
    """
    STATUS_CHOICES = [
        ('aktivan', 'Aktivan'),
        ('servis', 'U tijeku'),
        ('spreman_za_zavrsetak', 'Spreman za završetak'),
        ('zavrsen', 'Završen'),
        ('neaktivan', 'Otkazano'),
    ]
    title = models.CharField(max_length=255)
    description = models.TextField(blank=True)
    status = models.CharField(
        max_length=20,
        choices=STATUS_CHOICES,
        default='aktivan'
    )
    assigned_to = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.SET_NULL,
        null=True,
        related_name='tasks'
    )
    vehicle = models.ForeignKey(
        'fleet.Vehicle',
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='tasks',
        verbose_name=_("Dizalica"),
    )
    work_order = models.ForeignKey(
        'fleet.WorkOrder',
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='work_order_tasks',
        verbose_name=_("Putni nalog"),
    )
    scheduled_date = models.DateField(
        null=True,
        blank=True,
        db_index=True,
        verbose_name=_("Planirani datum izvršenja"),
        help_text=_("Datum kada je planirano izvršenje radnog zadatka."),
    )
    service_report_note = models.TextField(
        blank=True,
        default='',
        verbose_name=_("Napomena izvještaja servisera"),
        help_text=_("Tekst napomene za PDF izvještaj servisera za ovaj zadatak."),
    )

    class Meta:
        ordering = ['-created_at']

    def __str__(self):
        return f"{self.title} ({self.status})"

    def clean(self):
        super().clean()
        if self.status in {'neaktivan', 'zavrsen'} and not self.work_order_id:
            raise ValidationError({
                'work_order': "Putni nalog je obavezan prije zatvaranja zadatka."
            })


class TaskCalendar(Task):
    class Meta:
        proxy = True
        verbose_name = _("Kalendar zadatka")
        verbose_name_plural = _("Kalendar zadataka")


class TaskWorkHoursTable(BaseModel):
    """Interaktivna tablica radnih sati povezana s radnim zadatkom."""

    task = models.OneToOneField(
        Task,
        on_delete=models.CASCADE,
        related_name='work_hours_table',
        verbose_name=_("Radni zadatak"),
    )
    data = models.JSONField(
        null=True,
        blank=True,
        default=None,
        verbose_name=_("Podaci tablice radnih sati"),
    )

    class Meta:
        ordering = ['-updated_at']
        verbose_name = _("Tablica radnih sati")
        verbose_name_plural = _("Tablice radnih sati")

    def __str__(self):
        return f"Work hours table for task {self.task_id}"


class TaskTemplate(BaseModel):
    """Predložak za brzo kreiranje servisnog radnog zadatka."""

    code = models.SlugField(max_length=64, unique=True)
    title = models.CharField(max_length=255)
    description = models.TextField(blank=True)
    status = models.CharField(max_length=20, choices=Task.STATUS_CHOICES, default='aktivan')

    class Meta:
        ordering = ['title']

    def __str__(self):
        return f"{self.title} ({self.code})"


class TaskTemplateEntry(BaseModel):
    """Predlošci radnih unosa koji se generiraju prilikom kreiranja Taska."""

    task_template = models.ForeignKey(
        TaskTemplate,
        on_delete=models.CASCADE,
        related_name='entries',
    )
    sort_order = models.PositiveSmallIntegerField(default=1)
    title = models.CharField(max_length=255)
    work_description = models.TextField(blank=True)
    active_faults = models.TextField(blank=True, help_text=_("Aktivne greške."))
    explanation_hr = models.TextField(blank=True, help_text=_("Obrazloženje na hrvatskom jeziku."))

    class Meta:
        ordering = ['sort_order', 'created_at']
        constraints = [
            models.UniqueConstraint(
                fields=['task_template', 'sort_order'],
                name='task_template_entry_sort_order_unique',
            )
        ]

    def __str__(self):
        return f"{self.task_template.code} #{self.sort_order} - {self.title}"


class TaskWorkEntry(BaseModel):
    """Radni unos na konkretnom Tasku (generiran iz templatea ili ručno)."""

    task = models.ForeignKey(
        Task,
        on_delete=models.CASCADE,
        related_name='work_entries',
    )
    template_entry = models.ForeignKey(
        TaskTemplateEntry,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='task_work_entries',
    )
    sort_order = models.PositiveSmallIntegerField(default=1)
    title = models.CharField(max_length=255)
    work_description = models.TextField(blank=True)
    active_faults = models.TextField(blank=True)
    explanation_hr = models.TextField(blank=True)

    class Meta:
        ordering = ['sort_order', 'created_at']

    def __str__(self):
        return f"{self.task_id} #{self.sort_order} - {self.title}"