from django.db import models
from django.utils.timezone import now
from simple_history.models import HistoricalRecords
from django.db.models.signals import post_migrate
from django.dispatch import receiver
from config import settings
from django.core.cache import cache
import csv
import os


class Equipment(models.Model):
    EQUIPMENT_CATEGORY_CHOICES = (
        ('Glassware', 'Glassware'),
        ('Miscellaneous', 'Miscellaneous')
    )
    name = models.CharField(max_length=100)
    category = models.CharField(
        max_length=20, choices=EQUIPMENT_CATEGORY_CHOICES, default='Miscellaneous')
    description = models.TextField(max_length=512, null=True)
    date_added = models.DateTimeField(default=now, editable=False)
    last_updated = models.DateTimeField(auto_now=True, editable=False)
    history = HistoricalRecords()

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

    def save(self, *args, **kwargs):
        cache.delete('equipments')
        return super().save(*args, **kwargs)


class EquipmentInstance(models.Model):
    EQUIPMENT_INSTANCE_STATUS_CHOICES = (
        ('Available', 'Available'),
        ('Pending', 'Pending'),
        ('Broken', 'Broken'),
        ('Borrowed', 'Borrowed'),
    )
    equipment = models.ForeignKey(Equipment, on_delete=models.CASCADE)
    status = models.CharField(
        max_length=20, choices=EQUIPMENT_INSTANCE_STATUS_CHOICES, default='Available', db_index=True)
    remarks = models.TextField(max_length=512, null=True)
    date_added = models.DateTimeField(default=now, editable=False)
    last_updated = models.DateTimeField(auto_now=True, editable=False)
    history = HistoricalRecords()

    def __str__(self):
        return f'{self.equipment.name}'

    def save(self, *args, **kwargs):
        cache.delete('available_equipment_instances')
        cache.delete('equipment_instances')
        return super().save(*args, **kwargs)


seed_database = False


@receiver(post_migrate)
def create_superuser(sender, **kwargs):
    if sender.name == 'equipments':
        if seed_database:
            root_path = os.path.join(settings.MEDIA_ROOT, 'equipment_records')
            csv_files = [f for f in os.listdir(
                root_path) if f.endswith('.csv')]
            print(
                'Warning: Postmigration script will migrate without checking for existing item instances')
            for csv_file in csv_files:
                csv_file_path = os.path.join(root_path, csv_file)
                filename = os.path.splitext(csv_file)[0]
                print('---', 'Adding Equipments from', filename, '---')
                with open(csv_file_path, newline='') as csvfile:

                    reader = csv.reader(csvfile)
                    next(reader)  # Skip the header row
                    for row in reader:
                        if not any(row):
                            continue

                        # Get equipment information
                        category = filename.split('-')[0]
                        name = row[1]
                        # If quantity is missing, set value as 0
                        if (row[3] == ''):
                            available = 0
                        else:
                            available = int(row[3])
                        # If quantity of broken instances is missing, set value as 0
                        if (row[4] == ''):
                            broken = 0
                        else:
                            available = available - int(row[4])
                            broken = int(row[4])

                        def create_instances(a, b, c):
                            print('Adding', a, 'number of working', c.name)
                            # Add working equipments
                            if (a >= 1):
                                for i in range(a):
                                    EquipmentInstance.objects.create(
                                        equipment=c, status='Available')

                            if (b >= 1):
                                print('Adding', b, 'number of broken', c.name)
                                # Add broken equipments
                                for i in range(b):
                                    EquipmentInstance.objects.create(
                                        equipment=c, status='Broken')

                        EQUIPMENT = Equipment.objects.filter(
                            name=name, category=category).first()

                        # Check if equipment exists
                        if (EQUIPMENT):
                            # If so, add equipment instances
                            create_instances(available, broken, EQUIPMENT)

                        # If not, create equipment
                        else:
                            # Create the equipment first
                            EQUIPMENT = Equipment.objects.create(
                                name=name, category=category)
                            # Then create the instances
                            create_instances(available, broken, EQUIPMENT)