<?php

declare(strict_types=1);

namespace App\Libraries;

/**
 * Global tool search with alias support ("yt mp3", "compress mp4",
 * "jpg png"). Deterministic scoring, zero dependencies, instant enough
 * to run on every keystroke server-side.
 */
final class ToolSearch
{
    /** @return list<array> best matches first */
    public function find(string $query, int $limit = 10): array
    {
        $terms = $this->tokenize($query);
        if ($terms === []) {
            return [];
        }

        $scored = [];
        foreach (service('finder')->all() as $tool) {
            $score = $this->scoreTool($tool, $terms);
            if ($score > 0) {
                $tool['_score'] = $score;
                $scored[]       = $tool;
            }
        }

        usort($scored, static fn (array $a, array $b): int => [$b['_score'], (int) $b['popularity']] <=> [$a['_score'], (int) $a['popularity']]);

        return array_slice(array_map(static function (array $t): array {
            unset($t['_score']);

            return $t;
        }, $scored), 0, $limit);
    }

    public function best(string $query): ?array
    {
        return $this->find($query, 1)[0] ?? null;
    }

    private function scoreTool(array $tool, array $terms): float
    {
        $name      = mb_strtolower($tool['name'] . ' ' . str_replace('-', ' ', $tool['slug']));
        $aliases   = implode(' ', array_map('mb_strtolower', (array) ($tool['aliases'] ?? [])));
        $haystacks = [
            'aliases'   => $aliases,
            'name'      => $name,
            'formats'   => mb_strtolower(implode(' ', [...($tool['input_formats'] ?? []), ...($tool['output_formats'] ?? [])])),
            'desc'      => mb_strtolower($tool['short_description'] ?? ''),
        ];

        $weight = ['aliases' => 40, 'name' => 30, 'formats' => 20, 'desc' => 8];
        $score  = 0.0;

        foreach ($terms as $term) {
            $matched = false;
            foreach ($haystacks as $key => $haystack) {
                if ($haystack === '') {
                    continue;
                }
                if (str_starts_with($haystack . ' ', $term . ' ') || $haystack === $term) {
                    $score  += $weight[$key] * 1.5; // exact word start
                    $matched = true;
                } elseif (str_contains(' ' . $haystack, ' ' . $term)) {
                    $score += $weight[$key];
                    $matched = true;
                } elseif ($key !== 'desc' && str_contains($term, ' ') === false && str_contains($haystack, $term)) {
                    $score += $weight[$key] * 0.5; // fuzzy substring
                    $matched = true;
                }
            }
            if (! $matched) {
                return 0; // every term must match somewhere — keeps results relevant
            }
        }

        // popularity tiebreak folded into score for stable ordering
        return $score + min(5, ((int) ($tool['popularity'] ?? 0)) / 2000);
    }

    /** @return list<string> */
    private function tokenize(string $query): array
    {
        $normalized = mb_strtolower(preg_replace('/[^a-z0-9\s]+/iu', ' ', $query) ?? '');
        $tokens     = preg_split('/\s+/', trim($normalized)) ?: [];

        return array_values(array_unique(array_filter($tokens, static fn ($t) => mb_strlen($t) >= 2)));
    }
}