<?php

namespace App\Http\Controllers;

use App\Models\StockMovement;
use App\Models\StockVariant;
use App\Models\UniformItem;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\DB;
use Illuminate\Validation\Rule;
use Illuminate\Validation\ValidationException;

class InventoryController extends Controller
{
    public function index()
    {
        return view('inventory.index', [
            'items' => UniformItem::with('variants')->orderBy('name')->get(),
            'movements' => StockMovement::with('variant.item')->latest()->take(15)->get(),
        ]);
    }

    public function storeItem(Request $request)
    {
        $data = $request->validate([
            'code' => ['required', 'string', 'max:40', 'unique:uniform_items'],
            'name' => ['required', 'string', 'max:120'],
            'description' => ['nullable', 'string', 'max:500'],
            'sizes' => ['required', 'array', 'min:1'],
            'sizes.*' => ['required', 'string', 'distinct', Rule::in($this->allowedSizes())],
            'reorder_level' => ['required', 'integer', 'min:0'],
        ]);

        DB::transaction(function () use ($data) {
            $item = UniformItem::create($data);
            collect($data['sizes'])->map(fn ($size) => strtoupper(trim($size)))->filter()->unique()
                ->each(fn ($size) => $item->variants()->create(['size' => $size, 'reorder_level' => $data['reorder_level']]));
        });

        return back()->with('success', 'Uniform and size options added.');
    }

    public function restock(Request $request)
    {
        $data = $request->validate([
            'uniform_item_id' => ['required', 'exists:uniform_items,id'],
            'stocks' => ['required', 'array', 'min:1'],
            'stocks.*' => ['required', 'integer', 'min:1', 'max:100000'],
            'notes' => ['nullable', 'string', 'max:500'],
        ]);

        $updatedSizes = 0;
        DB::transaction(function () use ($data, &$updatedSizes) {
            $variants = StockVariant::whereIn('id', array_keys($data['stocks']))->lockForUpdate()->get()->keyBy('id');
            if ($variants->count() !== count($data['stocks']) || $variants->contains(fn ($variant) => $variant->uniform_item_id !== (int) $data['uniform_item_id'])) {
                throw ValidationException::withMessages(['stocks' => 'One or more selected sizes do not belong to that uniform.']);
            }

            foreach ($data['stocks'] as $variantId => $quantity) {
                $variant = $variants->get((int) $variantId);
                $variant->increment('quantity', $quantity);
                StockMovement::create([
                    'stock_variant_id' => $variant->id,
                    'type' => 'restock',
                    'quantity_change' => $quantity,
                    'notes' => $data['notes'] ?? null,
                ]);
                $updatedSizes++;
            }
        });

        return back()->with('success', "Stock updated successfully for {$updatedSizes} size(s).");
    }

    private function allowedSizes(): array
    {
        return ['XXS', 'XS', 'S', 'M', 'L', 'XL', '2XL', '3XL', '4XL', '26', '28', '30', '32', '34', '36', '38', '40', '42', '44', '46', '48'];
    }
}