<?php

declare(strict_types=1);

namespace SeoScope\Services;

/**
 * Versioned prompts for Quick Win → Topical Gaps SEO AI Assistant.
 */
final class SeoAiTopicalGapsPrompts
{
    public const PROMPT_VERSION = 1;

    public static function systemPrompt(string $localeCode, string $languageLabel): string
    {
        $localeCode = trim($localeCode) !== '' ? trim($localeCode) : 'en';
        $languageLabel = trim($languageLabel) !== '' ? trim($languageLabel) : 'English';

        return <<<TXT
You are an SEO analyst assistant inside a Google Search Console Quick Win report. The user message is JSON whose `gsc_payload` field describes Topical Gaps only: high-impression queries that rank low (beyond the configured position floor) and receive few clicks — content and topical-coverage opportunities. Each row includes query text and aggregate metrics for the selected period.

Rules:
- Focus ONLY on topical/content-gap intent: new pages, cluster expansion, internal linking, and intent coverage—not generic site health, link building, or snippet CTR tweaks alone.
- Use ONLY data in the JSON (top opportunities list + portfolio summary). Do not invent URLs, brands, or countries beyond filter fields.
- Write all human-readable string values in {$languageLabel} (locale: {$localeCode}).
- Reply with a single JSON object only: no markdown, no code fences.
- Required keys (each a non-empty string): "executive_summary", "seo_interpretation", "priority_recommendation".
- executive_summary: at most 2 short sentences on overall topical-gap potential (visibility without clicks, themes in the list).
- seo_interpretation: one or two brief paragraphs on patterns in the listed queries (position depth, impressions vs clicks, themes)—prioritize the highest-score rows.
- priority_recommendation: exactly ONE concrete next step to address the strongest topical gap (content brief, hub page, internal links); no bullet list.
TXT;
    }

    /**
     * @param array<string, mixed> $payload From {@see SeoAiTopicalGapsPayloadService::build()}
     */
    public static function userEnvelope(array $payload): string
    {
        $data = [
            'task' => 'seo_topical_gaps_insight',
            'prompt_version' => self::PROMPT_VERSION,
            'gsc_payload' => $payload,
        ];

        return json_encode(
            $data,
            JSON_THROW_ON_ERROR | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE | JSON_INVALID_UTF8_SUBSTITUTE
        );
    }
}
