<?php

namespace App\Services;

use App\Models\Product;
use App\Models\UserAbo;
use App\Models\UserAboOneTimeItem;

class AboOneTimeService
{
    /**
     * Verarbeitet eine Einmal-Artikel-Aktion (add/update/remove) für ein Abo.
     *
     * Erwartet einen bereits initialisierten Yard (für die Snapshot-Berechnung beim
     * Hinzufügen). Gibt eine Fehlermeldung zurück oder null bei Erfolg.
     *
     * @param  array<string, mixed>  $data
     */
    public function handleAction(UserAbo $userAbo, array $data): ?string
    {
        $action = $data['action'] ?? null;

        return match ($action) {
            'add' => $this->add($userAbo, (int) ($data['product_id'] ?? 0)),
            'update' => $this->update($userAbo, (int) ($data['one_time_item_id'] ?? 0), (int) ($data['qty'] ?? 1)),
            'remove' => $this->remove($userAbo, (int) ($data['one_time_item_id'] ?? 0)),
            'confirm' => $this->confirm($userAbo),
            'discard' => $this->discard($userAbo),
            default => __('abo.onetime_action_invalid'),
        };
    }

    private function add(UserAbo $userAbo, int $productId): ?string
    {
        $product = Product::find($productId);
        $allowedIds = ProductOrderContext::allowedShowOnIds(false, $userAbo->is_for === 'me' ? 'me' : 'ot-customer');

        if (! $product || ! $product->active || ! ProductOrderContext::productMatchesShowOn($product, $allowedIds)) {
            return __('abo.onetime_product_not_allowed');
        }

        if (AboOrderCart::exceedsMaxWeight($userAbo, (int) $product->weight)) {
            return __('msg.cart_max_weight_reached');
        }

        $existing = UserAboOneTimeItem::withTrashed()
            ->where('user_abo_id', $userAbo->id)
            ->where('product_id', $product->id)
            ->first();

        if ($existing) {
            if ($existing->trashed()) {
                $existing->restore();
                $existing->qty = $existing->confirmed_at ? max(1, (int) $existing->confirmed_qty) + 1 : 1;
            } else {
                $existing->qty = min(100, $existing->qty + 1);
            }
            $existing->qty = min(100, $existing->qty);
            $existing->status = 0;
            $existing->save();

            return null;
        }

        $snapshot = AboOrderCart::buildOneTimeSnapshot($product, $userAbo);
        UserAboOneTimeItem::create(array_merge($snapshot, [
            'user_abo_id' => $userAbo->id,
            'product_id' => $product->id,
            'comp' => 0,
            'qty' => 1,
            'status' => 0,
        ]));

        return null;
    }

    private function update(UserAbo $userAbo, int $itemId, int $qty): ?string
    {
        $item = UserAboOneTimeItem::where('user_abo_id', $userAbo->id)->find($itemId);
        if (! $item) {
            return __('abo.abo_item_not_found');
        }

        $targetQty = max(1, min(100, $qty));
        $product = Product::find($item->product_id);
        if ($product) {
            $additionalWeight = (int) $product->weight * ($targetQty - (int) $item->qty);
            if ($additionalWeight > 0 && AboOrderCart::exceedsMaxWeight($userAbo, $additionalWeight)) {
                return __('msg.cart_max_weight_reached');
            }
        }

        $item->qty = $targetQty;
        $item->status = $item->isConfirmed() ? 1 : 0;
        $item->save();

        return null;
    }

    private function remove(UserAbo $userAbo, int $itemId): ?string
    {
        $item = UserAboOneTimeItem::where('user_abo_id', $userAbo->id)->find($itemId);
        if (! $item) {
            return __('abo.abo_item_not_found');
        }

        if ($item->confirmed_at) {
            $item->delete();
        } else {
            $item->forceDelete();
        }

        return null;
    }

    private function confirm(UserAbo $userAbo): ?string
    {
        UserAboOneTimeItem::withTrashed()
            ->where('user_abo_id', $userAbo->id)
            ->get()
            ->each(function (UserAboOneTimeItem $item): void {
                if ($item->trashed()) {
                    $item->forceDelete();

                    return;
                }

                $item->confirmed_qty = $item->qty;
                $item->confirmed_at = now();
                $item->status = 1;
                $item->save();
            });

        return null;
    }

    private function discard(UserAbo $userAbo): ?string
    {
        UserAboOneTimeItem::withTrashed()
            ->where('user_abo_id', $userAbo->id)
            ->get()
            ->each(function (UserAboOneTimeItem $item): void {
                if (! $item->confirmed_at) {
                    $item->forceDelete();

                    return;
                }

                if ($item->trashed()) {
                    $item->restore();
                }

                $item->qty = max(1, (int) $item->confirmed_qty);
                $item->status = 1;
                $item->save();
            });

        return null;
    }

    public static function hasUnconfirmedChanges(UserAbo $userAbo): bool
    {
        return UserAboOneTimeItem::withTrashed()
            ->where('user_abo_id', $userAbo->id)
            ->get()
            ->contains(function (UserAboOneTimeItem $item): bool {
                if ($item->trashed()) {
                    return $item->confirmed_at !== null;
                }

                return ! $item->isConfirmed();
            });
    }

    public static function hasConfirmedItems(UserAbo $userAbo): bool
    {
        return UserAboOneTimeItem::where('user_abo_id', $userAbo->id)
            ->whereNotNull('confirmed_at')
            ->exists();
    }
}