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
import csv
import os


class Equipment(models.Model):
    EQUIPMENT_CATEGORY_CHOICES = (
        ('Glassware', 'Glassware'),
        ('Miscellaneous', 'Miscellaneous')
    )
    name = models.CharField(max_length=40)
    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}'


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')
    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}'


@receiver(post_migrate)
def create_superuser(sender, **kwargs):
    if sender.name == 'equipments':
        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[2] + ' ' + 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', a, '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)