import random
from datetime import date, timedelta
from decimal import Decimal
from typing import Iterator

from dateutil.relativedelta import relativedelta
from django.conf import settings
from django.core.management.base import BaseCommand
from django.db.models import Exists, F, Min, OuterRef, Subquery, Sum
from django.db.models.functions import Coalesce
from django.utils.timezone import make_aware, now
from faker import Faker

from club.models import Club, Membership
from core.models import RealGroup, User
from counter.models import (
    Counter,
    Customer,
    Permanency,
    Product,
    ProductType,
    Refilling,
    Selling,
)
from pedagogy.models import UV
from subscription.models import Subscription


class Command(BaseCommand):
    help = "Add more fixtures for a more complete development environment"

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.faker = Faker("fr_FR")

    def handle(self, *args, **options):
        if not settings.DEBUG:
            raise Exception("Never call this command in prod. Never.")

        self.stdout.write("Creating users...")
        users = [
            User(
                username=self.faker.user_name(),
                first_name=self.faker.first_name(),
                last_name=self.faker.last_name(),
                date_of_birth=self.faker.date_of_birth(minimum_age=15, maximum_age=25),
                email=self.faker.email(),
                phone=self.faker.phone_number(),
                address=self.faker.address(),
            )
            for _ in range(600)
        ]
        # there may a duplicate or two
        # Not a problem, we will just have 599 users instead of 600
        User.objects.bulk_create(users, ignore_conflicts=True)
        users = list(User.objects.order_by("-id")[: len(users)])

        subscribers = random.sample(users, k=int(0.8 * len(users)))
        self.stdout.write("Creating subscriptions...")
        self.create_subscriptions(users)
        self.stdout.write("Creating club memberships...")
        users_qs = User.objects.filter(id__in=[s.id for s in subscribers])
        subscribers_now = list(
            users_qs.annotate(
                filter=Exists(
                    Subscription.objects.filter(
                        member_id=OuterRef("pk"), subscription_end__gte=now()
                    )
                )
            )
        )
        old_subscribers = list(
            users_qs.annotate(
                filter=Exists(
                    Subscription.objects.filter(
                        member_id=OuterRef("pk"), subscription_end__lt=now()
                    )
                )
            )
        )
        self.make_club(
            Club.objects.get(unix_name="ae"),
            random.sample(subscribers_now, k=min(30, len(subscribers_now))),
            random.sample(old_subscribers, k=min(60, len(old_subscribers))),
        )
        self.make_club(
            Club.objects.get(unix_name="troll"),
            random.sample(subscribers_now, k=min(20, len(subscribers_now))),
            random.sample(old_subscribers, k=min(80, len(old_subscribers))),
        )
        self.stdout.write("Creating uvs...")
        self.create_uvs()
        self.stdout.write("Creating products...")
        self.create_products()
        self.stdout.write("Creating sales and refills...")
        sellers = random.sample(list(User.objects.all()), 100)
        self.create_sales(sellers)
        self.stdout.write("Creating permanences...")
        self.create_permanences(sellers)

        self.stdout.write("Done")

    def create_subscriptions(self, users: list[User]):
        def prepare_subscription(user: User, start_date: date) -> Subscription:
            payment_method = random.choice(settings.SITH_SUBSCRIPTION_PAYMENT_METHOD)[0]
            duration = random.randint(1, 4)
            sub = Subscription(member=user, payment_method=payment_method)
            sub.subscription_start = sub.compute_start(d=start_date, duration=duration)
            sub.subscription_end = sub.compute_end(duration)
            return sub

        subscriptions = []
        customers = []
        # first set of subscriptions
        for i, user in enumerate(users):
            sub = prepare_subscription(user, self.faker.past_date("-10y"))
            subscriptions.append(sub)
            customers.append(
                Customer(
                    user=user,
                    account_id=f"{9900 + i}{self.faker.random_lowercase_letter()}",
                )
            )
            while sub.subscription_end < now().date() and random.random() > 0.7:
                # 70% chances to subscribe again
                # (expect if it would make the subscription start after tomorrow)
                sub = prepare_subscription(
                    user, self.faker.past_date(sub.subscription_end)
                )
                subscriptions.append(sub)
        Subscription.objects.bulk_create(subscriptions)
        Customer.objects.bulk_create(customers, ignore_conflicts=True)

    def make_club(self, club: Club, members: list[User], old_members: list[User]):
        def zip_roles(users: list[User]) -> Iterator[tuple[User, int]]:
            roles = iter(sorted(settings.SITH_CLUB_ROLES.keys(), reverse=True))
            user_idx = 0
            while (role := next(roles)) > 2:
                # one member for each major role
                yield users[user_idx], role
                user_idx += 1
            for _ in range(int(0.3 * (len(users) - user_idx))):
                # 30% of the remaining in the board
                yield users[user_idx], 2
                user_idx += 1
            for remaining in users[user_idx + 1 :]:
                # everything else is a simple member
                yield remaining, 1

        memberships = []
        old_members = old_members.copy()
        random.shuffle(old_members)
        for old in old_members:
            start = self.faker.date_between("-3y", "-1y")
            memberships.append(
                Membership(
                    start_date=start,
                    end_date=self.faker.past_date(start),
                    user=old,
                    role=random.choice(list(settings.SITH_CLUB_ROLES.keys())),
                    club=club,
                )
            )
        for member, role in zip_roles(members):
            start = self.faker.past_date("-1y")
            memberships.append(
                Membership(
                    start_date=start,
                    user=member,
                    role=role,
                    club=club,
                )
            )
        Membership.objects.bulk_create(memberships)

    def create_uvs(self):
        root = User.objects.get(username="root")
        categories = ["CS", "TM", "OM", "QC", "EC"]
        branches = ["TC", "GMC", "GI", "EDIM", "E", "IMSI", "HUMA"]
        languages = ["FR", "FR", "EN"]
        semesters = ["AUTUMN", "SPRING", "AUTUMN_AND_SPRING"]
        teachers = [self.faker.name() for _ in range(50)]
        uvs = []
        for _ in range(1000):
            code = (
                self.faker.random_uppercase_letter()
                + self.faker.random_uppercase_letter()
                + str(random.randint(10, 90))
            )
            uvs.append(
                UV(
                    code=code,
                    author=root,
                    manager=random.choice(teachers),
                    title=self.faker.text(max_nb_chars=50),
                    department=random.choice(branches),
                    credit_type=random.choice(categories),
                    credits=6,
                    semester=random.choice(semesters),
                    language=random.choice(languages),
                    program=self.faker.paragraph(random.randint(3, 10)),
                    skills="\n* ".join(self.faker.sentences(random.randint(3, 10))),
                    key_concepts="\n* ".join(
                        self.faker.sentences(random.randint(3, 10))
                    ),
                    hours_CM=random.randint(15, 40),
                    hours_TD=random.randint(15, 40),
                    hours_TP=random.randint(15, 40),
                    hours_THE=random.randint(15, 40),
                    hours_TE=random.randint(15, 40),
                )
            )
        UV.objects.bulk_create(uvs, ignore_conflicts=True)

    def create_products(self):
        categories = []
        for _ in range(10):
            categories.append(ProductType(name=self.faker.text(max_nb_chars=30)))
        ProductType.objects.bulk_create(categories)
        categories = list(
            ProductType.objects.filter(name__in=[c.name for c in categories])
        )
        ae = Club.objects.get(unix_name="ae")
        other_clubs = random.sample(list(Club.objects.all()), k=3)
        groups = list(
            RealGroup.objects.filter(
                name__in=["Subscribers", "Old subscribers", "Public"]
            )
        )
        counters = list(
            Counter.objects.filter(name__in=["Foyer", "MDE", "La Gommette", "Eboutic"])
        )
        # 2/3 of the products are owned by AE
        clubs = [ae, ae, ae, ae, ae, ae, *other_clubs]
        products = []
        buying_groups = []
        selling_places = []
        for _ in range(200):
            price = random.randint(0, 10) + random.choice([0, 0.25, 0.5, 0.75])
            product = Product(
                name=self.faker.text(max_nb_chars=30),
                description=self.faker.text(max_nb_chars=120),
                product_type=random.choice(categories),
                code="".join(self.faker.random_letters(length=random.randint(4, 8))),
                purchase_price=price,
                selling_price=price,
                special_selling_price=price - min(0.5, price),
                club=random.choice(clubs),
                limit_age=0 if random.random() > 0.2 else 18,
                archived=bool(random.random() > 0.7),
            )
            products.append(product)
            for group in random.sample(groups, k=random.randint(0, 3)):
                # there will be products without buying groups
                # but there are also such products in the real database
                buying_groups.append(
                    Product.buying_groups.through(product=product, group=group)
                )
            for counter in random.sample(counters, random.randint(0, 4)):
                selling_places.append(
                    Counter.products.through(counter=counter, product=product)
                )
        Product.objects.bulk_create(products)
        Product.buying_groups.through.objects.bulk_create(buying_groups)
        Counter.products.through.objects.bulk_create(selling_places)

    @staticmethod
    def _update_balances():
        customers = Customer.objects.annotate(
            money_in=Sum(F("refillings__amount"), default=0),
            money_out=Coalesce(
                Subquery(
                    Selling.objects.filter(customer=OuterRef("pk"))
                    .values("customer_id")  # group by customer
                    .annotate(res=Sum(F("unit_price") * F("quantity"), default=0))
                    .values("res")
                ),
                Decimal("0"),
            ),
        ).annotate(real_balance=F("money_in") - F("money_out"))
        for c in customers:
            c.amount = c.real_balance
        Customer.objects.bulk_update(customers, fields=["amount"])

    def create_sales(self, sellers: list[User]):
        customers = list(
            Customer.objects.annotate(
                since=Subquery(
                    Subscription.objects.filter(member__customer=OuterRef("pk"))
                    .annotate(res=Min("subscription_start"))
                    .values("res")[:1]
                )
            )
        )
        products = list(Product.objects.all())
        counters = list(
            Counter.objects.filter(name__in=["Foyer", "MDE", "La Gommette"])
        )
        sales = []
        reloads = []
        for customer in customers:
            # the longer the customer has existed, the higher the mean of nb_products
            mu = 5 + (now().year - customer.since.year) * 2
            nb_sales = max(0, int(random.normalvariate(mu=mu, sigma=mu * 5)))
            favoured_products = random.sample(products, k=(random.randint(1, 5)))
            favoured_counter = random.choice(counters)
            this_customer_sales = []
            for _ in range(nb_sales):
                product = (
                    random.choice(favoured_products)
                    if random.random() > 0.7
                    else random.choice(products)
                )
                counter = (
                    favoured_counter
                    if random.random() > 0.7
                    else random.choice(counters)
                )
                this_customer_sales.append(
                    Selling(
                        product=product,
                        counter=counter,
                        club_id=product.club_id,
                        quantity=random.randint(1, 5),
                        unit_price=product.selling_price,
                        seller=random.choice(sellers),
                        customer=customer,
                        date=make_aware(
                            self.faker.date_time_between(customer.since, now().date())
                        ),
                    )
                )
            total_expanse = sum(s.unit_price * s.quantity for s in this_customer_sales)
            total_reloaded = 0
            while total_reloaded < total_expanse:
                amount = random.choice(list(range(5, 51, 5)))
                total_reloaded += amount
                reloads.append(
                    Refilling(
                        counter=random.choice(counters),
                        amount=amount,
                        operator=random.choice(sellers),
                        customer=customer,
                        date=make_aware(
                            self.faker.date_time_between(customer.since, now().date())
                        ),
                        is_validated=True,
                    )
                )
            sales.extend(this_customer_sales)
        Refilling.objects.bulk_create(reloads)
        Selling.objects.bulk_create(sales)
        self._update_balances()

    def create_permanences(self, sellers: list[User]):
        counters = list(
            Counter.objects.filter(name__in=["Foyer", "MDE", "La Gommette"])
        )
        perms = []
        for seller in sellers:
            favoured_counter = random.choice(counters)
            nb_perms = abs(int(random.normalvariate(mu=275, sigma=100)))
            active_period_start = self.faker.past_date("-10y")
            active_period_end = self.faker.date_between(
                active_period_start,
                min(now().date(), active_period_start + relativedelta(years=5)),
            )
            for _ in range(nb_perms):
                counter = (
                    favoured_counter
                    if random.random() > 0.8
                    else random.choice(counters)
                )
                duration = self.faker.time_delta(timedelta(hours=1))
                start = make_aware(
                    self.faker.date_time_between(active_period_start, active_period_end)
                )
                perms.append(
                    Permanency(
                        counter=counter, user=seller, start=start, end=start + duration
                    )
                )
        Permanency.objects.bulk_create(perms)