<?php

namespace Modules\Maintenance\Services;

use App\BusinessLocation;
use App\HoldingEntity;
use App\PurchaseLine;
use App\Variation;
use App\VariationLocationDetails;
use Illuminate\Support\Collection;
use Modules\Maintenance\Models\MaterialLine;
use Modules\Maintenance\Models\SparePart;
use Modules\Maintenance\Utils\MaintenanceUtil;

class MaterialStockService
{
    public function __construct(
        protected MaintenanceUtil $maintenanceUtil,
        protected SparePartInventoryService $inventoryService
    ) {}

    public function resolveDestinationLocationId(int $businessId, ?int $override = null): ?int
    {
        if ($override) {
            return $override;
        }

        $settings = $this->maintenanceUtil->getMaintenanceSettings($businessId);

        return ! empty($settings['default_stock_location_id'])
            ? (int) $settings['default_stock_location_id']
            : null;
    }

    /**
     * @return array{product_id: ?int, variation_id: ?int}
     */
    public function resolveProductIds(MaterialLine $line): array
    {
        if ($line->product_id && $line->variation_id) {
            return [
                'product_id' => (int) $line->product_id,
                'variation_id' => (int) $line->variation_id,
            ];
        }

        if ($line->spare_part_id) {
            $part = $line->sparePart ?? SparePart::find($line->spare_part_id);
            if ($part && $part->product_id) {
                $variationId = $this->inventoryService->resolveVariationId($part);

                return [
                    'product_id' => (int) $part->product_id,
                    'variation_id' => $variationId,
                ];
            }
        }

        return ['product_id' => null, 'variation_id' => null];
    }

    /**
     * Stock per location for a material line across all business locations (holding warehouses).
     *
     * @return Collection<int, array{location_id: int, location_name: string, entity_name: ?string, qty: float}>
     */
    public function stockByLocation(int $businessId, MaterialLine $line): Collection
    {
        $ids = $this->resolveProductIds($line);
        if (! $ids['product_id'] || ! $ids['variation_id']) {
            return collect();
        }

        $entityMap = $this->locationEntityMap($businessId);

        return VariationLocationDetails::query()
            ->join('business_locations as bl', 'variation_location_details.location_id', '=', 'bl.id')
            ->where('variation_location_details.product_id', $ids['product_id'])
            ->where('variation_location_details.variation_id', $ids['variation_id'])
            ->where('bl.business_id', $businessId)
            ->where('variation_location_details.qty_available', '>', 0)
            ->select(
                'variation_location_details.location_id',
                'bl.name as location_name',
                'variation_location_details.qty_available as qty'
            )
            ->orderByDesc('variation_location_details.qty_available')
            ->get()
            ->map(function ($row) use ($entityMap) {
                $locId = (int) $row->location_id;

                return [
                    'location_id' => $locId,
                    'location_name' => $row->location_name,
                    'entity_name' => $entityMap[$locId] ?? null,
                    'qty' => (float) $row->qty,
                ];
            });
    }

    /**
     * @return array<string, mixed>
     */
    public function analyzeLine(int $businessId, MaterialLine $line, ?int $destinationLocationId = null): array
    {
        $destinationLocationId = $this->resolveDestinationLocationId($businessId, $destinationLocationId);
        $stockRows = $this->stockByLocation($businessId, $line);
        $required = (float) $line->quantity_required;
        $fulfilled = (float) $line->quantity_fulfilled;
        $remaining = max(0, $required - $fulfilled);

        $localQty = 0.0;
        $otherLocations = [];

        foreach ($stockRows as $row) {
            if ($destinationLocationId && $row['location_id'] === $destinationLocationId) {
                $localQty = $row['qty'];
            } else {
                $otherLocations[] = $row;
            }
        }

        $totalAvailable = $stockRows->sum('qty');
        $shortfall = max(0, $remaining - $totalAvailable);

        return [
            'line_id' => $line->id,
            'display_name' => $line->displayName(),
            'part_number' => $line->part_number ?? $line->sparePart?->part_number,
            'quantity_required' => $required,
            'quantity_fulfilled' => $fulfilled,
            'remaining' => $remaining,
            'local_qty' => $localQty,
            'total_available' => $totalAvailable,
            'shortfall' => $shortfall,
            'destination_location_id' => $destinationLocationId,
            'stock_by_location' => $stockRows->values()->all(),
            'other_locations' => $otherLocations,
            'has_product_link' => (bool) $this->resolveProductIds($line)['product_id'],
            'status' => $line->status,
        ];
    }

    /**
     * @return array<int, string>
     */
    protected function locationEntityMap(int $businessId): array
    {
        $map = [];
        $entities = HoldingEntity::where('business_id', $businessId)->where('is_active', true)->get();

        foreach ($entities as $entity) {
            $locId = data_get($entity->meta, 'business_location_id');
            if ($locId) {
                $map[(int) $locId] = $entity->name;
            }
        }

        return $map;
    }

    public function getUnitPrice(int $variationId, ?int $locationId = null, ?int $supplierId = null): float
    {
        $variation = Variation::find($variationId);
        if ($variation && $variation->default_purchase_price) {
            return (float) $variation->default_purchase_price;
        }

        $query = PurchaseLine::join('transactions as t', 'purchase_lines.transaction_id', '=', 't.id')
            ->where('purchase_lines.variation_id', $variationId)
            ->where('t.type', 'purchase')
            ->where('t.status', 'received');

        if ($locationId) {
            $query->where('t.location_id', $locationId);
        }
        if ($supplierId) {
            $query->where('t.contact_id', $supplierId);
        }

        $line = $query->orderByDesc('t.transaction_date')->select('purchase_lines.purchase_price')->first();

        return $line ? (float) $line->purchase_price : 0.0;
    }

    /**
     * @return Collection<int, BusinessLocation>
     */
    public function locationsForBusiness(int $businessId): Collection
    {
        return BusinessLocation::where('business_id', $businessId)->orderBy('name')->get();
    }
}