<?php

namespace Modules\Core\Customer\Services;

use Illuminate\Contracts\Auth\Authenticatable;
use Illuminate\Pagination\LengthAwarePaginator;
use Illuminate\Support\Arr;
use Illuminate\Support\Facades\Event;
use Lunar\Models\Address;
use Lunar\Models\Order;
use LogicException;
use Modules\Core\Customer\Events\CustomerAddressCreated;
use Modules\Core\Customer\Events\CustomerAddressDeleted;
use Modules\Core\Customer\Events\CustomerAddressUpdated;
use Modules\Core\Customer\Events\CustomerProfileUpdated;
use Modules\Core\Customer\Exceptions\AddressNotFoundException;
use Modules\Core\Customer\Exceptions\OrderNotFoundException;
use Modules\Core\Customer\Models\Customer;

/**
 * The storefront-facing "My Account" API — mirrors Modules\Core\Cart\
 * Services\CartService's shape, one boboko-owned service a storefront
 * calls, so Lunar's own Customer/Order/Address models stay an
 * implementation detail. Every method is scoped to the given
 * Authenticatable's own Customer::latestCustomer() (see docs/modules.md
 * "Customer/User Pairing") — there is no method here that accepts a bare
 * order/address id without also requiring the owning user, precisely so
 * a controller built on top of this can't accidentally leak one
 * customer's data to another by trusting a client-supplied id alone.
 *
 * $user->latestCustomer() can be null for a User that has no paired
 * Customer yet (shouldn't happen via the normal OTP-login cascade — see
 * Modules\Core\Auth\Events\UserCreated — but is defended against anyway,
 * since nothing stops a User row existing without one, e.g. seeded data)
 * — every method returns an empty/null result rather than throwing in
 * that case, since "no customer paired yet" isn't a not-found error, it's
 * a legitimately empty account.
 *
 * Address/profile writes go through an explicit column allowlist
 * (WRITABLE_ADDRESS_FIELDS/WRITABLE_PROFILE_FIELDS) rather than trusting
 * Lunar\Models\Address/Customer's own $guarded = [] — that flag makes
 * every column mass-assignable at the model layer, including
 * customer_id on addresses, so a caller passing through an unfiltered
 * request array (a real risk for a storefront controller built directly
 * against this service) could otherwise reassign an address to a
 * different customer entirely, or overwrite created_at/id. Arr::only()
 * silently drops anything not on the allowlist rather than erroring —
 * this is a safety boundary, not form validation (a storefront still
 * validates its own request shape before calling this).
 *
 * Authorization here IS the ownership scoping itself, not a separate
 * layer bolted on top — there is deliberately no Laravel Policy/Gate
 * class for Order/Address, since a policy is meaningless without a
 * controller calling authorize() against it, and this branch is scoped
 * to backend services only (no routes/controllers — see the branch's own
 * commit history). Every public method below takes Authenticatable $user
 * as a required first argument and resolves everything else (Order,
 * Address, Customer) strictly through that user's own
 * latestCustomer() — there is no method that looks anything up by a bare
 * id alone. A future storefront controller cannot "forget" the
 * authorization check the way it could with a separate policy class,
 * because the check IS how every lookup happens; skipping it isn't an
 * option the method signatures allow.
 */
class CustomerAccountService
{
    private const WRITABLE_ADDRESS_FIELDS = [
        'title', 'first_name', 'last_name', 'company_name',
        'line_one', 'line_two', 'line_three', 'city', 'state', 'postcode',
        'delivery_instructions', 'contact_email', 'contact_phone',
        'country_id', 'shipping_default', 'billing_default',
    ];

    private const WRITABLE_PROFILE_FIELDS = [
        'title', 'first_name', 'last_name', 'company_name', 'vat_no',
    ];

    public function customer(Authenticatable $user): ?Customer
    {
        /** @var Customer|null */
        return $user->latestCustomer();
    }

    /**
     * Placed orders only (placed_at IS NOT NULL) — a draft/abandoned
     * order with no placed_at is checkout-in-progress state, not
     * something that belongs in order history.
     */
    public function orders(Authenticatable $user, int $perPage = 15): LengthAwarePaginator
    {
        $customer = $this->customer($user);

        if (! $customer) {
            return new LengthAwarePaginator([], 0, $perPage);
        }

        return $customer->orders()
            ->whereNotNull('placed_at')
            ->latest('placed_at')
            ->paginate($perPage);
    }

    /**
     * @throws OrderNotFoundException if $orderId doesn't belong to this
     *   customer, or belongs to a draft (never placed) order
     */
    public function order(Authenticatable $user, int $orderId): Order
    {
        $customer = $this->customer($user);

        $order = $customer
            ?->orders()
            ->whereNotNull('placed_at')
            ->with(['lines', 'shippingAddress', 'billingAddress', 'transactions', 'shipments'])
            ->find($orderId);

        if (! $order) {
            throw new OrderNotFoundException;
        }

        return $order;
    }

    public function addresses(Authenticatable $user): iterable
    {
        $customer = $this->customer($user);

        return $customer?->addresses ?? collect();
    }

    /**
     * @param  array<string, mixed>  $data  Any key not in
     *   WRITABLE_ADDRESS_FIELDS is silently dropped — see this class's
     *   own docblock.
     */
    public function createAddress(Authenticatable $user, array $data): Address
    {
        $customer = $this->customerOrFail($user);

        $address = $customer->addresses()->create(Arr::only($data, self::WRITABLE_ADDRESS_FIELDS));

        $this->enforceSingleDefault($customer, $address);
        $address->refresh();

        Event::dispatch(new CustomerAddressCreated($address, $user));

        return $address;
    }

    /**
     * @throws AddressNotFoundException if $addressId doesn't belong to
     *   this customer
     */
    public function updateAddress(Authenticatable $user, int $addressId, array $data): Address
    {
        $address = $this->ownedAddress($user, $addressId);
        $old = $address->only(array_keys(Arr::only($data, self::WRITABLE_ADDRESS_FIELDS)));

        $address->update(Arr::only($data, self::WRITABLE_ADDRESS_FIELDS));

        $this->enforceSingleDefault($address->customer, $address);
        $address->refresh();

        Event::dispatch(new CustomerAddressUpdated($address, $old, $user));

        return $address;
    }

    /**
     * @throws AddressNotFoundException if $addressId doesn't belong to
     *   this customer
     */
    public function deleteAddress(Authenticatable $user, int $addressId): void
    {
        $address = $this->ownedAddress($user, $addressId);
        $snapshot = $address->getAttributes();

        $address->delete();

        Event::dispatch(new CustomerAddressDeleted($snapshot, $user));
    }

    /**
     * Lunar has no built-in action enforcing "at most one shipping
     * default / one billing default per customer" — a raw update() could
     * otherwise leave two addresses both flagged shipping_default. Runs
     * after every create/update, unconditionally (cheap — at most two
     * single-row UPDATEs, only fired when the just-written address
     * itself is a default), clearing the flag on every OTHER address of
     * the same customer.
     */
    private function enforceSingleDefault(Customer $customer, Address $address): void
    {
        if ($address->shipping_default) {
            $customer->addresses()->where('id', '!=', $address->id)->update(['shipping_default' => false]);
        }

        if ($address->billing_default) {
            $customer->addresses()->where('id', '!=', $address->id)->update(['billing_default' => false]);
        }
    }

    /**
     * @throws AddressNotFoundException if $addressId doesn't belong to
     *   this customer
     */
    private function ownedAddress(Authenticatable $user, int $addressId): Address
    {
        $customer = $this->customer($user);

        $address = $customer?->addresses()->find($addressId);

        if (! $address) {
            throw new AddressNotFoundException;
        }

        return $address;
    }

    /**
     * @param  array<string, mixed>  $data  Any key not in
     *   WRITABLE_PROFILE_FIELDS is silently dropped — see this class's
     *   own docblock.
     */
    public function updateProfile(Authenticatable $user, array $data): Customer
    {
        $customer = $this->customerOrFail($user);
        $old = $customer->only(array_keys(Arr::only($data, self::WRITABLE_PROFILE_FIELDS)));

        $customer->update(Arr::only($data, self::WRITABLE_PROFILE_FIELDS));
        $customer->refresh();

        Event::dispatch(new CustomerProfileUpdated($customer, $old, $user));

        return $customer;
    }

    /**
     * @throws LogicException if $user has no paired Customer at all —
     *   distinct from AddressNotFoundException/OrderNotFoundException
     *   (which mean "this id isn't yours"), this means the account
     *   itself is in an invariant-violating state the normal OTP-login
     *   cascade should never produce.
     */
    private function customerOrFail(Authenticatable $user): Customer
    {
        $customer = $this->customer($user);

        if (! $customer) {
            throw new LogicException('This user has no paired Customer record.');
        }

        return $customer;
    }
}