<?php

namespace App\Services;

use App\Models\ProductBundle;
use App\Models\ShoppingOrder;
use App\Models\UserInvoice;
use Illuminate\Database\Eloquent\Builder;
use Illuminate\Support\Carbon;

/**
 * Ermittelt die Absatzmengen eines Monats auf zwei klar getrennten Grundlagen:
 *
 * - {@see self::BASIS_SHIPPING}: was im Monat tatsaechlich rausgegangen ist
 *   (`shopping_orders.shipped_at`). Externe/API-Bestellungen zaehlen hier direkt,
 *   die spaetere Sammelrechnung wird uebersprungen, damit nichts doppelt laeuft.
 * - {@see self::BASIS_INVOICE}: was im Monat fakturiert wurde
 *   (`user_invoices.month/year`). Externe Bestellungen erscheinen hier erst ueber
 *   die bezahlte Sammelrechnung des Partners.
 *
 * Stornorechnungen werden auf beiden Grundlagen abgezogen statt addiert.
 *
 * @phpstan-type VolumeRow array{ref: string, date: string, email: string, payment_type: string, product_id: int|null, number: string, name: string, qty: int, note: string}
 */
class SalesVolumeService
{
    public const BASIS_SHIPPING = 'shipping';

    public const BASIS_INVOICE = 'invoice';

    /** Sammelrechnung des Partners – auf Versandbasis kein eigener Warenausgang. */
    private const PAYMENT_FOR_COLLECTIVE_INVOICE = 8;

    private const PAYMENT_FOR_HOMEPARTY = 5;

    /** @var array<int, VolumeRow>|null */
    private ?array $rows = null;

    private Carbon $from;

    private Carbon $to;

    public function __construct(
        private int $month,
        private int $year,
        private string $basis = self::BASIS_SHIPPING,
    ) {
        if (! array_key_exists($this->basis, self::basisOptions())) {
            $this->basis = self::BASIS_SHIPPING;
        }

        $this->from = Carbon::create($this->year, $this->month, 1)->startOfMonth();
        $this->to = $this->from->copy()->endOfMonth();
    }

    /**
     * @return array<string, string>
     */
    public static function basisOptions(): array
    {
        return [
            self::BASIS_SHIPPING => 'Absatz nach Versand (Warenausgang)',
            self::BASIS_INVOICE => 'Absatz nach Rechnungseingang (Zahlung)',
        ];
    }

    public function getBasis(): string
    {
        return $this->basis;
    }

    public function getBasisLabel(): string
    {
        return self::basisOptions()[$this->basis];
    }

    /**
     * Absatz je verkauftem Artikel – Sets bleiben eine eigene Zeile.
     *
     * @return array<int|string, array{product_id: int|null, name: string, number: string, value: int}>
     */
    public function getProductVolumes(): array
    {
        $objects = [];

        foreach ($this->getRows() as $row) {
            $key = $row['product_id'] ?: 'x-'.$row['number'];

            if (isset($objects[$key])) {
                $objects[$key]['value'] += $row['qty'];

                continue;
            }

            $objects[$key] = [
                'product_id' => $row['product_id'],
                'name' => $row['name'],
                'number' => $row['number'],
                'value' => $row['qty'],
            ];
        }

        return $objects;
    }

    /**
     * Absatz je Einzelartikel – Sets/Kits sind in ihre hinterlegten Anlagen aufgeloest.
     *
     * @return array<int|string, array{product_id: int|null, name: string, number: string, value: int}>
     */
    public function getArticleVolumes(): array
    {
        $rows = $this->getRows();
        $bundles = $this->getBundleMap(array_filter(array_column($rows, 'product_id')));
        $objects = [];

        foreach ($rows as $row) {
            $parts = $bundles[$row['product_id']] ?? null;

            if (! $parts) {
                $parts = [[
                    'product_id' => $row['product_id'],
                    'number' => $row['number'],
                    'name' => $row['name'],
                    'quantity' => 1,
                ]];
            }

            foreach ($parts as $part) {
                $key = $part['product_id'] ?: 'x-'.$part['number'];
                $qty = $row['qty'] * $part['quantity'];

                if (isset($objects[$key])) {
                    $objects[$key]['value'] += $qty;

                    continue;
                }

                $objects[$key] = [
                    'product_id' => $part['product_id'],
                    'name' => $part['name'],
                    'number' => $part['number'],
                    'value' => $qty,
                ];
            }
        }

        return $objects;
    }

    /**
     * Einzelpositionen fuer die vollstaendige Liste (Export).
     *
     * @return array<int, VolumeRow>
     */
    public function getRows(): array
    {
        if ($this->rows === null) {
            $this->rows = $this->basis === self::BASIS_INVOICE
                ? $this->collectInvoiceRows()
                : $this->collectShippingRows();
        }

        return $this->rows;
    }

    /**
     * Datengrundlage des Monats: Anzahl Bestellungen und Anteil geschaetzter Versanddaten.
     *
     * @return array{orders: int, estimated: int, estimated_percent: float, without_date: int}
     */
    public function getQualityStats(): array
    {
        if ($this->basis !== self::BASIS_SHIPPING) {
            return ['orders' => 0, 'estimated' => 0, 'estimated_percent' => 0.0, 'without_date' => 0];
        }

        $orders = $this->shippedOrdersQuery()->count();
        $estimated = $this->shippedOrdersQuery()
            ->where('shipped_at_source', ShoppingOrder::SHIPPED_AT_SOURCE_ESTIMATED)
            ->count();

        $withoutDate = ShoppingOrder::query()
            ->where('mode', 'live')
            ->whereIn('shipped', ShoppingOrder::SHIPPED_STATES)
            ->whereNull('shipped_at')
            ->count();

        return [
            'orders' => $orders,
            'estimated' => $estimated,
            'estimated_percent' => $orders > 0 ? round($estimated / $orders * 100, 1) : 0.0,
            'without_date' => $withoutDate,
        ];
    }

    /**
     * @return array<int, VolumeRow>
     */
    private function collectInvoiceRows(): array
    {
        $invoices = UserInvoice::query()
            ->with($this->orderRelations('shopping_order.'))
            ->with('shopping_order')
            ->where('month', $this->month)
            ->where('year', $this->year)
            ->get();

        $rows = [];

        foreach ($invoices as $invoice) {
            $order = $invoice->shopping_order;

            if (! $order) {
                continue;
            }

            $isCancellation = $this->isCancellationInvoice($invoice);

            $rows = array_merge($rows, $this->orderRows(
                $order,
                $isCancellation ? -1 : 1,
                (string) $invoice->full_number,
                $invoice->date ? Carbon::parse($invoice->date)->format('d.m.Y') : '',
                $isCancellation ? 'Storno' : ''
            ));
        }

        return $rows;
    }

    /**
     * @return array<int, VolumeRow>
     */
    private function collectShippingRows(): array
    {
        $rows = [];

        foreach ($this->shippedOrdersQuery()->with($this->orderRelations())->get() as $order) {
            $rows = array_merge($rows, $this->orderRows(
                $order,
                1,
                (string) $order->id,
                $order->shipped_at ? $order->shipped_at->format('d.m.Y') : '',
                $order->shipped_at_source === ShoppingOrder::SHIPPED_AT_SOURCE_ESTIMATED ? 'Versanddatum geschaetzt' : ''
            ));
        }

        return array_merge($rows, $this->collectReturnRows());
    }

    /**
     * Stornos/Retouren im Monat – aber nur fuer Bestellungen, die vorher auch
     * wirklich rausgegangen sind. Vor dem Versand stornierte Bestellungen wurden
     * auf Versandbasis nie gezaehlt und duerfen deshalb auch nicht abgezogen werden.
     *
     * @return array<int, VolumeRow>
     */
    private function collectReturnRows(): array
    {
        $cancellations = UserInvoice::query()
            ->with($this->orderRelations('shopping_order.'))
            ->with('shopping_order')
            ->where('cancellation', true)
            ->whereNull('cancellation_id')
            ->whereBetween('date', [$this->from->toDateString(), $this->to->toDateString()])
            ->get();

        $rows = [];

        foreach ($cancellations as $invoice) {
            $order = $invoice->shopping_order;

            if (! $order || $order->shipped_at === null) {
                continue;
            }

            $rows = array_merge($rows, $this->orderRows(
                $order,
                -1,
                (string) $invoice->full_number,
                $invoice->date ? Carbon::parse($invoice->date)->format('d.m.Y') : '',
                'Storno / Retoure'
            ));
        }

        return $rows;
    }

    /**
     * @return Builder<ShoppingOrder>
     */
    private function shippedOrdersQuery()
    {
        return ShoppingOrder::query()
            ->where('mode', 'live')
            ->where(function ($query) {
                $query->whereNull('payment_for')
                    ->orWhere('payment_for', '!=', self::PAYMENT_FOR_COLLECTIVE_INVOICE);
            })
            ->shippedBetween($this->from, $this->to);
    }

    /**
     * Positionen einer Bestellung – je nach Bestellart aus drei verschiedenen Quellen.
     *
     * @return array<int, VolumeRow>
     */
    private function orderRows(ShoppingOrder $order, int $sign, string $ref, string $date, string $note): array
    {
        $base = [
            'ref' => $ref,
            'date' => $date,
            'email' => $order->shopping_user ? (string) $order->shopping_user->billing_email : 'n/a',
            'payment_type' => $order->getPaymentForType(),
            'note' => $note,
        ];

        $rows = [];

        if ((int) $order->payment_for === self::PAYMENT_FOR_HOMEPARTY) {
            if (! $order->homeparty) {
                return [];
            }

            foreach ($order->homeparty->homeparty_order_items as $item) {
                $rows[] = $base + [
                    'product_id' => $item->product_id ? (int) $item->product_id : null,
                    'number' => $item->product ? (string) $item->product->number : 'n/a '.$item->product_id,
                    'name' => $item->product ? (string) $item->product->name : 'n/a '.$item->product_id,
                    'qty' => $sign * (int) $item->qty,
                ];
            }

            return $rows;
        }

        if ((int) $order->payment_for === self::PAYMENT_FOR_COLLECTIVE_INVOICE) {
            if (! $order->shopping_collect_order) {
                return [];
            }

            foreach ($order->shopping_collect_order->shop_items as $item) {
                $rows[] = $base + [
                    'product_id' => isset($item['pid']) ? (int) $item['pid'] : null,
                    'number' => (string) ($item['number'] ?? ''),
                    'name' => (string) ($item['name'] ?? ''),
                    'qty' => $sign * (int) ($item['qty'] ?? 0),
                ];
            }

            return $rows;
        }

        foreach ($order->shopping_order_items as $item) {
            $rows[] = array_merge($base, [
                'product_id' => $item->product_id ? (int) $item->product_id : null,
                'number' => $item->product ? (string) $item->product->number : 'n/a '.$item->product_id,
                'name' => $item->product ? (string) $item->product->name : 'n/a '.$item->product_id,
                'qty' => $sign * (int) $item->qty,
                'note' => trim($note.($item->comp ? ' Kompensation '.$item->comp : '')),
            ]);
        }

        return $rows;
    }

    /**
     * Die eigentliche Stornorechnung hat cancellation=true und cancellation_id=null;
     * die stornierte Originalrechnung traegt cancellation=true MIT cancellation_id.
     */
    private function isCancellationInvoice(UserInvoice $invoice): bool
    {
        return (bool) $invoice->cancellation && $invoice->cancellation_id === null;
    }

    /**
     * @return array<int, string>
     */
    private function orderRelations(string $prefix = ''): array
    {
        return array_map(fn (string $relation): string => $prefix.$relation, [
            'shopping_user',
            'shopping_order_items.product',
            'homeparty.homeparty_order_items.product',
            'shopping_collect_order',
        ]);
    }

    /**
     * Set/Kit-Anlagen der uebergebenen Produkte.
     *
     * @param  array<int, int>  $productIds
     * @return array<int, array<int, array{product_id: int, number: string, name: string, quantity: int}>>
     */
    private function getBundleMap(array $productIds): array
    {
        if (! $productIds) {
            return [];
        }

        $map = [];

        $bundles = ProductBundle::query()
            ->with('bundleProduct')
            ->whereIn('product_id', array_unique($productIds))
            ->orderBy('pos')
            ->get();

        foreach ($bundles as $bundle) {
            if (! $bundle->bundleProduct) {
                continue;
            }

            $map[$bundle->product_id][] = [
                'product_id' => (int) $bundle->bundle_product_id,
                'number' => (string) $bundle->bundleProduct->number,
                'name' => (string) $bundle->bundleProduct->name,
                'quantity' => max(1, (int) $bundle->quantity),
            ];
        }

        return $map;
    }
}