<?php

namespace App\Services\Moderation\Rules;

use App\Contracts\Moderation\ModerationRuleInterface;

class RepeatedPhraseRule implements ModerationRuleInterface
{
    public function analyze(string $content, string $normalized, array $context = []): array
    {
        $config = app('config')->get('content_moderation.repeated_phrase', []);
        $minPhraseLength = $config['min_phrase_length'] ?? 4;
        $minRepetitions = $config['min_repetitions'] ?? 3;
        $weights = app('config')->get('content_moderation.weights', []);

        $words = preg_split('/\s+/', $normalized);
        if (count($words) < $minPhraseLength * $minRepetitions) {
            return [];
        }

        $findings = [];
        $repeatedPhrases = [];

        // Check for repeated n-grams of various lengths
        for ($phraseLen = $minPhraseLength; $phraseLen <= min(8, intdiv(count($words), 2)); $phraseLen++) {
            $ngrams = [];
            for ($i = 0; $i <= count($words) - $phraseLen; $i++) {
                $ngram = implode(' ', array_slice($words, $i, $phraseLen));
                $ngrams[$ngram] = ($ngrams[$ngram] ?? 0) + 1;
            }

            foreach ($ngrams as $phrase => $count) {
                if ($count >= $minRepetitions) {
                    $repeatedPhrases[$phrase] = $count;
                }
            }
        }

        if (!empty($repeatedPhrases)) {
            $findings[] = [
                'rule'     => 'repeated_phrase',
                'score'    => $weights['repeated_phrase'] ?? 25,
                'reason'   => 'Contains repeated phrases: ' . implode(', ', array_map(
                    fn ($phrase, $count) => "\"{$phrase}\" ({$count}x)",
                    array_keys($repeatedPhrases),
                    array_values($repeatedPhrases)
                )),
                'links'    => [],
                'domains'  => [],
                'keywords' => array_keys($repeatedPhrases),
            ];
        }

        return $findings;
    }
}