<?php

namespace App\Domains\FiestaFutbolInfantil\Services;

use App\Domains\Catalog\Enums\EventProductType;
use App\Domains\Catalog\Enums\InventoryPolicy;
use App\Domains\Catalog\Models\Attribute;
use App\Domains\Catalog\Models\AttributeOption;
use App\Domains\Catalog\Models\CatalogItem;
use App\Domains\Catalog\Models\Category;
use App\Domains\Catalog\Models\Inventory;
use App\Domains\Catalog\Models\ItemAttribute;
use App\Domains\Catalog\Models\Variant;
use App\Domains\Tenant\Models\Tenant;
use Illuminate\Support\Collection;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Str;
use Illuminate\Validation\ValidationException;

class MerchandiseService
{
    private const ATTRIBUTE_CODES = ['color', 'talle'];

    /** @return Collection<int, CatalogItem> */
    public function all(Tenant $tenant): Collection
    {
        return CatalogItem::query()
            ->where('tenant_code', $tenant->codigo)
            ->where('event_product_type', EventProductType::Product->value)
            ->whereHas('category', fn ($query) => $query->where('nombre', 'Merchandising'))
            ->with([
                'itemAttributes.attribute.options',
                'variants.catalogItem',
                'variants.inventory',
                'variants.definitions',
            ])
            ->orderBy('id')
            ->get();
    }

    /**
     * @param  array<int, array<string, mixed>>  $items
     * @return Collection<int, CatalogItem>
     */
    public function upsertMany(Tenant $tenant, array $items): Collection
    {
        return DB::transaction(function () use ($tenant, $items): Collection {
            $attributes = $this->attributes($tenant);
            $category = Category::query()->firstOrCreate([
                'tenant_code' => $tenant->codigo,
                'nombre' => 'Merchandising',
            ]);
            $reservedSlugs = [];

            return collect($items)->map(function (array $data, int $index) use (
                $tenant,
                $attributes,
                $category,
                &$reservedSlugs,
            ): CatalogItem {
                $item = isset($data['id'])
                    ? $this->existingItem($tenant, $category, (int) $data['id'], $index)
                    : $this->createItem($tenant, $category, $data, $reservedSlugs);

                if (! isset($data['id'])) {
                    $reservedSlugs[] = $item->slug;
                }

                $item->update([
                    'nombre' => trim($data['title']),
                    'descripcion' => $data['description'] ?? null,
                    'category_id' => $category->id,
                    'max_units_per_user' => (int) $data['max_units_per_user'],
                    'event_product_type' => EventProductType::Product->value,
                    'inventory_policy' => InventoryPolicy::Tracked->value,
                    'has_tickets' => false,
                ]);

                $itemAttributes = $this->itemAttributes($item, $attributes);
                $existingVariants = $item->variants()
                    ->with(['inventory', 'definitions'])
                    ->lockForUpdate()
                    ->get();
                $variants = $this->resolveVariants($data['variants'], $attributes, $index);

                $this->validateCombinations($variants, $existingVariants, $itemAttributes, $index);

                foreach ($variants as $variantIndex => $variantData) {
                    $variant = isset($variantData['id'])
                        ? $existingVariants->firstWhere('id', (int) $variantData['id'])
                        : null;

                    if (isset($variantData['id']) && $variant === null) {
                        throw ValidationException::withMessages([
                            "items.{$index}.variants.{$variantIndex}.id" => [
                                'La variante no pertenece al artículo de merchandising.',
                            ],
                        ]);
                    }

                    if ($variant === null) {
                        $this->createVariant($item, $itemAttributes, $variantData);
                    } else {
                        $this->updateVariant($variant, $itemAttributes, $variantData, $index, $variantIndex);
                    }
                }

                $minimumPrice = $item->variants()->min('precio');
                if ($minimumPrice !== null) {
                    $item->update(['precio' => $minimumPrice]);
                }

                return $item->fresh()->load([
                    'itemAttributes.attribute.options',
                    'variants.catalogItem',
                    'variants.inventory',
                    'variants.definitions',
                ]);
            })->values();
        });
    }

    /** @return Collection<string, Attribute> */
    private function attributes(Tenant $tenant): Collection
    {
        $attributes = Attribute::query()
            ->where('tenant_codigo', $tenant->codigo)
            ->whereIn('codigo', self::ATTRIBUTE_CODES)
            ->with('options')
            ->lockForUpdate()
            ->get()
            ->keyBy('codigo');

        $missingCodes = collect(self::ATTRIBUTE_CODES)->diff($attributes->keys());
        if ($missingCodes->isNotEmpty()) {
            throw ValidationException::withMessages([
                'items' => [
                    'Faltan atributos requeridos para merchandising: '.$missingCodes->implode(', ').'.',
                ],
            ]);
        }

        return $attributes;
    }

    private function existingItem(
        Tenant $tenant,
        Category $category,
        int $itemId,
        int $index,
    ): CatalogItem {
        $item = CatalogItem::query()
            ->whereKey($itemId)
            ->where('tenant_code', $tenant->codigo)
            ->where('category_id', $category->id)
            ->where('event_product_type', EventProductType::Product->value)
            ->lockForUpdate()
            ->first();

        if ($item === null) {
            throw ValidationException::withMessages([
                "items.{$index}.id" => ['El artículo no pertenece al merchandising del tenant.'],
            ]);
        }

        return $item;
    }

    /**
     * @param  array<string, mixed>  $data
     * @param  array<int, string>  $reservedSlugs
     */
    private function createItem(
        Tenant $tenant,
        Category $category,
        array $data,
        array $reservedSlugs,
    ): CatalogItem {
        return CatalogItem::query()->create([
            'tenant_code' => $tenant->codigo,
            'slug' => $this->uniqueSlug($tenant, $data['title'], $reservedSlugs),
            'nombre' => trim($data['title']),
            'descripcion' => $data['description'] ?? null,
            'category_id' => $category->id,
            'precio' => collect($data['variants'])->min('price') ?? 0,
            'max_units_per_user' => (int) $data['max_units_per_user'],
            'event_product_type' => EventProductType::Product->value,
            'inventory_policy' => InventoryPolicy::Tracked->value,
            'has_tickets' => false,
            'inventory_id' => null,
        ]);
    }

    /**
     * @param  Collection<string, Attribute>  $attributes
     * @return Collection<string, ItemAttribute>
     */
    private function itemAttributes(CatalogItem $item, Collection $attributes): Collection
    {
        return $attributes->mapWithKeys(function (Attribute $attribute, string $code) use ($item): array {
            $itemAttribute = $item->itemAttributes()->firstOrCreate(
                ['attribute_id' => $attribute->id],
                ['allow_multi_select' => false],
            );

            if ($itemAttribute->allow_multi_select) {
                $itemAttribute->update(['allow_multi_select' => false]);
            }

            return [$code => $itemAttribute];
        });
    }

    /**
     * @param  array<int, array<string, mixed>>  $variants
     * @param  Collection<string, Attribute>  $attributes
     * @return array<int, array<string, mixed>>
     */
    private function resolveVariants(array $variants, Collection $attributes, int $itemIndex): array
    {
        return collect($variants)->map(function (array $variant, int $variantIndex) use (
            $attributes,
            $itemIndex,
        ): array {
            $color = $this->resolveColor($attributes['color'], $variant['color']);
            $size = $this->existingOption(
                $attributes['talle'],
                $variant['size'],
                "items.{$itemIndex}.variants.{$variantIndex}.size",
            );

            return [
                ...$variant,
                'color' => $color->value,
                'size' => $size->value,
                'stock' => (int) $variant['stock'],
            ];
        })->all();
    }

    private function resolveColor(Attribute $attribute, string $color): AttributeOption
    {
        $option = $this->findOption($attribute, $color);
        if ($option !== null) {
            return $option;
        }

        $label = trim($color);
        $option = $attribute->options()->create([
            'value' => $this->valueCode($label),
            'label' => $label,
            'sort_order' => ((int) $attribute->options->max('sort_order')) + 1,
        ]);
        $attribute->options->push($option);

        return $option;
    }

    private function existingOption(
        Attribute $attribute,
        string $value,
        string $validationKey,
    ): AttributeOption {
        $option = $this->findOption($attribute, $value);

        if ($option === null) {
            throw ValidationException::withMessages([
                $validationKey => ["El valor seleccionado no es válido para {$attribute->nombre}."],
            ]);
        }

        return $option;
    }

    private function findOption(Attribute $attribute, string $value): ?AttributeOption
    {
        $key = $this->optionKey($value);

        return $attribute->options->first(
            fn (AttributeOption $option): bool => $this->optionKey($option->value) === $key
                || $this->optionKey($option->label) === $key
        );
    }

    /**
     * @param  array<int, array<string, mixed>>  $incoming
     * @param  Collection<int, Variant>  $existing
     * @param  Collection<string, ItemAttribute>  $itemAttributes
     */
    private function validateCombinations(
        array $incoming,
        Collection $existing,
        Collection $itemAttributes,
        int $itemIndex,
    ): void {
        $incomingIds = collect($incoming)->pluck('id')->filter()->map(fn ($id): int => (int) $id);
        $seen = [];

        foreach ($existing->whereNotIn('id', $incomingIds) as $variant) {
            $values = $variant->definitions->keyBy('item_attribute_id');
            $color = $values->get($itemAttributes['color']->id)?->value;
            $size = $values->get($itemAttributes['talle']->id)?->value;

            if ($color !== null && $size !== null) {
                $seen[$this->combinationKey($color, $size)] = true;
            }
        }

        foreach ($incoming as $variantIndex => $variant) {
            $key = $this->combinationKey($variant['color'], $variant['size']);

            if (isset($seen[$key])) {
                throw ValidationException::withMessages([
                    "items.{$itemIndex}.variants.{$variantIndex}" => [
                        'La combinación de color y talle ya existe para el artículo.',
                    ],
                ]);
            }

            $seen[$key] = true;
        }
    }

    /**
     * @param  Collection<string, ItemAttribute>  $itemAttributes
     * @param  array<string, mixed>  $data
     */
    private function createVariant(
        CatalogItem $item,
        Collection $itemAttributes,
        array $data,
    ): void {
        $inventory = Inventory::query()->create(['real_stock' => $data['stock']]);
        $variant = $item->variants()->create([
            'inventory_id' => $inventory->id,
            'precio' => $data['price'],
        ]);
        $this->syncDefinitions($variant, $itemAttributes, $data);
    }

    /**
     * @param  Collection<string, ItemAttribute>  $itemAttributes
     * @param  array<string, mixed>  $data
     */
    private function updateVariant(
        Variant $variant,
        Collection $itemAttributes,
        array $data,
        int $itemIndex,
        int $variantIndex,
    ): void {
        $inventory = Inventory::query()
            ->whereKey($variant->inventory_id)
            ->lockForUpdate()
            ->firstOrFail();

        if ($data['stock'] < $inventory->reserved_stock) {
            throw ValidationException::withMessages([
                "items.{$itemIndex}.variants.{$variantIndex}.stock" => [
                    'El stock no puede ser menor que la cantidad actualmente reservada.',
                ],
            ]);
        }

        $variant->update(['precio' => $data['price']]);
        $inventory->update(['real_stock' => $data['stock']]);
        $this->syncDefinitions($variant, $itemAttributes, $data);
    }

    /**
     * @param  Collection<string, ItemAttribute>  $itemAttributes
     * @param  array<string, mixed>  $data
     */
    private function syncDefinitions(
        Variant $variant,
        Collection $itemAttributes,
        array $data,
    ): void {
        $variant->definitions()
            ->whereIn('item_attribute_id', $itemAttributes->pluck('id'))
            ->delete();
        $variant->definitions()->createMany([
            [
                'item_attribute_id' => $itemAttributes['color']->id,
                'value' => $data['color'],
            ],
            [
                'item_attribute_id' => $itemAttributes['talle']->id,
                'value' => $data['size'],
            ],
        ]);
    }

    /** @param array<int, string> $reservedSlugs */
    private function uniqueSlug(Tenant $tenant, string $title, array $reservedSlugs): string
    {
        $baseSlug = Str::slug($title) ?: 'merchandising';
        $slug = $baseSlug;
        $suffix = 2;

        while (
            in_array($slug, $reservedSlugs, true)
            || CatalogItem::query()
                ->where('tenant_code', $tenant->codigo)
                ->where('slug', $slug)
                ->exists()
        ) {
            $slug = "{$baseSlug}-{$suffix}";
            $suffix++;
        }

        return $slug;
    }

    private function combinationKey(string $color, string $size): string
    {
        return $this->optionKey($color).'|'.$this->optionKey($size);
    }

    private function optionKey(string $value): string
    {
        return Str::ascii(mb_strtolower((string) preg_replace('/[_\s]+/u', ' ', trim($value))));
    }

    private function valueCode(string $value): string
    {
        return mb_strtolower((string) preg_replace('/\s+/u', '_', trim($value)));
    }
}