from django.db import models
from django.contrib.auth import get_user_model
from django.utils import timezone
from common.models import BaseModel

User = get_user_model()


class InstallationAssignment(BaseModel):
    """انتخاب نصاب و زمان مراجعه برای یک درخواست"""
    process_instance = models.ForeignKey(
        'processes.ProcessInstance', on_delete=models.CASCADE,
        related_name='installation_assignments', verbose_name='نمونه فرآیند'
    )
    installer = models.ForeignKey(
        User, on_delete=models.SET_NULL, null=True, blank=True,
        related_name='assigned_installations', verbose_name='نصاب'
    )
    scheduled_date = models.DateField(null=True, blank=True, verbose_name='تاریخ مراجعه')
    notes = models.TextField(blank=True, verbose_name='یادداشت')
    assigned_by = models.ForeignKey(
        User, on_delete=models.SET_NULL, null=True, blank=True,
        related_name='assigner_installations', verbose_name='اختصاص‌دهنده'
    )

    class Meta:
        verbose_name = 'اختصاص نصاب'
        verbose_name_plural = 'اختصاص‌های نصاب'
        ordering = ['-created']

    def __str__(self):
        return f"Assignment for {self.process_instance.code} to {getattr(self.installer, 'username', '-') }"


class InstallationReport(BaseModel):
    """گزارش نصب توسط نصاب"""
    assignment = models.ForeignKey(
        InstallationAssignment, on_delete=models.CASCADE,
        related_name='reports', verbose_name='اختصاص'
    )
    visited_date = models.DateField(null=True, blank=True, verbose_name='تاریخ مراجعه')
    new_water_meter_serial = models.CharField(max_length=50, null=True, blank=True, verbose_name='سریال کنتور جدید')
    seal_number = models.CharField(max_length=50, null=True, blank=True, verbose_name='شماره پلمپ')
    is_meter_suspicious = models.BooleanField(default=False, verbose_name='کنتور مشکوک است؟')
    utm_x = models.DecimalField(max_digits=10, decimal_places=6, null=True, blank=True, verbose_name='UTM X')
    utm_y = models.DecimalField(max_digits=10, decimal_places=6, null=True, blank=True, verbose_name='UTM Y')
    description = models.TextField(blank=True, verbose_name='توضیحات')
    created_by = models.ForeignKey(User, on_delete=models.SET_NULL, null=True, blank=True, verbose_name='ایجادکننده')
    approved = models.BooleanField(default=False, verbose_name='تایید شده')
    approved_at = models.DateTimeField(null=True, blank=True, verbose_name='تاریخ تایید')

    class Meta:
        verbose_name = 'گزارش نصب'
        verbose_name_plural = 'گزارش‌های نصب'
        ordering = ['-created']

    def __str__(self):
        return f"Report for {self.assignment.process_instance.code}"

    def save(self, *args, **kwargs):
        # set approved time
        if self.approved and self.approved_at is None:
            self.approved_at = timezone.now()
        super().save(*args, **kwargs)
        # if approved, propagate UTM to well
        try:
            if self.approved and self.assignment and self.assignment.process_instance and self.assignment.process_instance.well:
                well = self.assignment.process_instance.well
                changed = False
                if self.utm_x is not None:
                    well.utm_x = self.utm_x
                    changed = True
                if self.utm_y is not None:
                    well.utm_y = self.utm_y
                    changed = True
                if changed:
                    well.save()
        except Exception:
            pass


class InstallationPhoto(BaseModel):
    report = models.ForeignKey(InstallationReport, on_delete=models.CASCADE, related_name='photos', verbose_name='گزارش')
    image = models.ImageField(upload_to='installations/photos/%Y/%m/%d/', verbose_name='عکس')

    class Meta:
        verbose_name = 'عکس نصب'
        verbose_name_plural = 'عکس‌های نصب'
        ordering = ['created']


class InstallationItemChange(BaseModel):
    """تغییرات اقلام در مرحله نصب (افزودن/حذف نسبت به اقلام مرحله ۱)"""
    CHANGE_CHOICES = [
        ('add', 'افزودن'),
        ('remove', 'حذف'),
    ]
    report = models.ForeignKey(InstallationReport, on_delete=models.CASCADE, related_name='item_changes', verbose_name='گزارش')
    item = models.ForeignKey('invoices.Item', on_delete=models.CASCADE, verbose_name='آیتم')
    change_type = models.CharField(max_length=6, choices=CHANGE_CHOICES, verbose_name='نوع تغییر')
    quantity = models.PositiveIntegerField(verbose_name='تعداد')
    unit_price = models.DecimalField(max_digits=15, decimal_places=2, verbose_name='قیمت واحد', null=True, blank=True)
    total_price = models.DecimalField(max_digits=15, decimal_places=2, verbose_name='قیمت کل', null=True, blank=True)
    notes = models.TextField(blank=True, verbose_name='یادداشت')

    class Meta:
        verbose_name = 'تغییر آیتم نصب'
        verbose_name_plural = 'تغییرات آیتم‌های نصب'
        ordering = ['created']