<?php

namespace App\Domains\Catalog\Services;

use App\Domains\Catalog\Enums\InventoryPolicy;
use App\Domains\Catalog\Models\CatalogItem;
use App\Domains\Catalog\Models\Variant;
use Illuminate\Support\Collection;

class VariantSelectionService
{
    /**
     * @param  array<string, mixed>  $selectedValues
     * @param  list<int>  $excludedVariantIds
     * @return array<string, mixed>
     */
    public function options(
        CatalogItem $catalogItem,
        array $selectedValues,
        array $excludedVariantIds = [],
        ?int $includedVariantId = null,
    ): array {
        $catalogItem->load([
            'itemAttributes.attribute',
            'variants' => fn ($query) => $query->orderBy('id'),
            'variants.inventory',
            'variants.eventDate',
            'variants.eventDates',
            'variants.definitions' => fn ($query) => $query->orderBy('id'),
            'variants.definitions.itemAttribute.attribute.options',
        ]);

        $excluded = collect($excludedVariantIds)->map(fn ($id): int => (int) $id);
        $variants = $catalogItem->visibleVariants($includedVariantId)
            ->reject(fn (Variant $variant): bool => $variant->id !== $includedVariantId
                && $excluded->contains($variant->id))
            ->values();
        $normalizedSelections = collect($selectedValues)
            ->mapWithKeys(fn ($value, string $key): array => [$key => $this->normalizeValue($value)])
            ->filter(fn ($value): bool => $value !== null && $value !== '' && $value !== [])
            ->all();
        $matchingVariants = $variants
            ->filter(fn (Variant $variant): bool => $this->matches($variant, $normalizedSelections))
            ->values();
        $attributeKeys = $variants
            ->flatMap(fn (Variant $variant): array => $variant
                ->selectorOptions($catalogItem->itemAttributes)
                ->keys()
                ->all())
            ->unique()
            ->values();
        $isComplete = $attributeKeys->isNotEmpty()
            && $attributeKeys->every(fn (string $key): bool => array_key_exists($key, $normalizedSelections));
        $resolvedVariant = $isComplete && $matchingVariants->count() === 1
            ? $matchingVariants->first()
            : null;

        return [
            'variants' => $variants
                ->map(fn (Variant $variant): array => $this->variantData($catalogItem, $variant))
                ->values(),
            'options' => $this->availableOptions($catalogItem, $matchingVariants),
            'selected_values' => $normalizedSelections,
            'resolved_variant_id' => $resolvedVariant?->id,
            'valid' => $matchingVariants->isNotEmpty(),
        ];
    }

    /** @param array<string, mixed> $selectedValues */
    private function matches(Variant $variant, array $selectedValues): bool
    {
        $variantValues = $variant->selectionValues();

        foreach ($selectedValues as $key => $selectedValue) {
            if (! $variantValues->has($key)
                || $this->valueKey($variantValues->get($key)) !== $this->valueKey($selectedValue)) {
                return false;
            }
        }

        return true;
    }

    /**
     * @param  Collection<int, Variant>  $variants
     * @return array<string, list<mixed>>
     */
    private function availableOptions(CatalogItem $catalogItem, Collection $variants): array
    {
        $options = [];
        $seen = [];

        foreach ($variants as $variant) {
            foreach ($variant->selectorOptions($catalogItem->itemAttributes) as $key => $option) {
                $optionKey = $this->valueKey($option);
                if (isset($seen[$key][$optionKey])) {
                    continue;
                }

                $seen[$key][$optionKey] = true;
                $options[$key][] = $option;
            }
        }

        return $options;
    }

    /** @return array<string, mixed> */
    private function variantData(CatalogItem $catalogItem, Variant $variant): array
    {
        return [
            'id' => $variant->id,
            'descripcion' => $variant->getDescription(),
            'precio' => number_format($variant->getPrice(), 2, '.', ''),
            'stock_tecnico' => $catalogItem->inventory_policy === InventoryPolicy::Unlimited
                ? null
                : $variant->inventory?->availableStock(),
            'values' => $variant->selectorOptions($catalogItem->itemAttributes),
        ];
    }

    private function normalizeValue(mixed $value): mixed
    {
        if (is_array($value) && array_key_exists('value', $value)) {
            return (string) $value['value'];
        }

        if (is_array($value)) {
            return array_map(fn ($item) => $this->normalizeValue($item), $value);
        }

        return is_scalar($value) ? (string) $value : null;
    }

    private function valueKey(mixed $value): string
    {
        $normalized = $this->normalizeValue($value);

        if (is_array($normalized)) {
            sort($normalized);
        }

        return json_encode($normalized, JSON_THROW_ON_ERROR);
    }
}