<?php

declare(strict_types=1);

namespace App\Intent;

use App\Config\CommerceIntentConfig;

final class CommerceIntentLite
{
    public const NONE = 'none';
    public const PRODUCT_SEARCH = 'product_search';
    public const ADVISORY_PRODUCT_SEARCH = 'advisory_product_search';

    public function __construct(
        private readonly CommerceIntentConfig $config
    )
    {

    }

    /**
     * @return array{intent:string, score:int, signals:string[]}
     */
    public function detect(string $originalPrompt): array
    {
        $p = mb_strtolower(trim($originalPrompt));

        if ($p === '') {
            return [
                'intent' => self::NONE,
                'score' => 0,
                'signals' => [],
            ];
        }

        $score = 0;
        $signals = [];

        $strongSignals = $this->config->getStrongSignalsList();

        foreach ($strongSignals as $signal) {
            if (str_contains($p, strtolower($signal))) {
                $score += 3;
                $signals[] = $signal;
            }
        }

        if (preg_match('#\d{3,10}#', $p)) {
            $score += 2;
            $signals[] = 'sku';
        }

        $pricePattern = $this->config->getPricePattern();
        if (preg_match('/\b\d+(?:[.,]\d+)?\s*(' . $pricePattern . ')\b/u', $p) === 1) {
            $score += 2;
            $signals[] = 'price';
        }

        $sizePattern = $this->config->getSizePattern();
        if (preg_match('/\b(' . $sizePattern . ')\s*[a-z0-9.-]+\b/u', $p) === 1) {
            $score += 2;
            $signals[] = 'size';
        }

        $sizeTokenPattern = $this->config->getSizeTokenPattern();
        if (preg_match('/\b(' . $sizeTokenPattern . ')\b/u', $p) === 1) {
            $score += 1;
            $signals[] = 'size_token';
        }

        $colorPattern = $this->config->getColorPattern();
        if (preg_match('/\b(' . $colorPattern . ')\b/u', $p) === 1) {
            $score += 1;
            $signals[] = 'color';
        }

        $advisorySignals = $this->config->getAdvisorySignals();

        foreach ($advisorySignals as $signal) {
            if (str_contains($p, $signal)) {
                $score += 1;
                $signals[] = 'advisory:' . $signal;
            }
        }

        $signals = array_values(array_unique($signals));

        if ($score >= 3) {
            return [
                'intent' => self::PRODUCT_SEARCH,
                'score' => $score,
                'signals' => $signals,
            ];
        }

        if ($score >= 2) {
            return [
                'intent' => self::ADVISORY_PRODUCT_SEARCH,
                'score' => $score,
                'signals' => $signals,
            ];
        }

        return [
            'intent' => self::NONE,
            'score' => $score,
            'signals' => $signals,
        ];
    }

}