<?php

declare(strict_types=1);

namespace App\ContentFeed;

/**
 * Builds the searchable Markdown body and the title of a feed record.
 *
 * Every record follows the same pattern: the name as heading, the short introductory
 * fields as paragraphs, then each `text` field as a section under a German heading, in a
 * fixed order. Structured facts that people ask about (WLAN, Sauna, Pistenkilometer) are
 * rendered as a list as well, so the full-text search finds them.
 */
class DocumentBodyBuilder
{
    /**
     * Introductory fields, rendered without a heading. Plain text in the feed.
     */
    private const LEAD_FIELDS = ['subline', 'headline'];

    /**
     * `text` fields per type, in output order, with their section heading. A null heading
     * renders the field as an introduction straight under the title.
     */
    private const TEXT_SECTIONS = [
        'product' => [
            'teaser' => null,
            'teaserLong' => 'Beschreibung',
            'feature' => 'Highlights',
            'conceptDescription' => 'Reisekonzept',
            'boardDescription' => 'Verpflegung',
            'includedServices' => 'Leistungen',
            'additionalServices' => 'Zusatzleistungen',
            'programmeDescription' => 'Programm',
            'skiPassDescription' => 'Skipass',
            'nonBookableInfo' => 'Hinweise zur Buchbarkeit',
        ],
        'hotel' => [
            'teaser' => null,
            'description' => 'Beschreibung',
            'features' => 'Ausstattung',
            'roomTypes' => 'Zimmer',
            'additionalInformation' => 'Weitere Informationen',
        ],
        'region' => [
            'teaser' => null,
            'description' => 'Beschreibung',
            'feature' => 'Highlights',
            'skiArea' => 'Skigebiet',
            'skiAreaExtended' => 'Skigebiet im Detail',
            'skiPass' => 'Skipass',
            'news' => 'Neuigkeiten',
        ],
        'country' => [
            'teaser' => null,
            'description' => 'Beschreibung',
            'descriptionExtended' => 'Mehr erfahren',
        ],
        'city' => [
            'teaser' => null,
            'description' => 'Beschreibung',
            'descriptionExtended' => 'Mehr erfahren',
            'party' => 'Party',
            'leisure' => 'Freizeit',
        ],
        'concept' => [
            'teaser' => null,
            'description' => 'Beschreibung',
            'descriptionExtended' => 'Mehr erfahren',
            'popupText' => 'Kurz erklärt',
        ],
    ];

    /**
     * Facts per type, with their German label.
     */
    private const FACTS = [
        'hotel' => [
            'bedsCount' => 'Betten',
            'parkingCount' => 'Parkplätze',
            'altitude' => 'Höhenlage',
            'distanceBus' => 'Entfernung zur Bushaltestelle',
            'distanceLift' => 'Entfernung zum Lift',
            'shower' => 'Dusche/WC',
            'partyroom' => 'Partyraum',
            'gamesroom' => 'Spieleraum',
            'sauna' => 'Sauna',
            'wifi' => 'WLAN',
        ],
        'region' => [
            'length' => 'Pistenkilometer',
            'height' => 'Höhe',
            'lifts' => 'Lifte',
        ],
    ];

    public function __construct(private readonly HtmlToMarkdownConverter $converter)
    {
    }

    /**
     * @param array<string, mixed> $record
     */
    public function title(string $type, array $record): string
    {
        $title = 'news' === $type ? ($record['title'] ?? null) : ($record['name'] ?? null);

        return is_string($title) ? trim($title) : '';
    }

    /**
     * @param array<string, mixed> $record
     */
    public function build(string $type, array $record): string
    {
        $baseUrl = is_string($record['url'] ?? null) ? $record['url'] : null;
        $blocks = [];

        $title = $this->title($type, $record);
        if ('' !== $title) {
            $blocks[] = '# '.$title;
        }

        if ('news' === $type) {
            return $this->join(array_merge($blocks, $this->newsBlocks($record, $baseUrl)));
        }

        foreach (self::LEAD_FIELDS as $field) {
            $value = $this->plain($record[$field] ?? null);
            if ('' !== $value && $value !== $title) {
                $blocks[] = $value;
            }
        }

        if ('hotel' === $type) {
            $address = $this->plain($record['address'] ?? null);
            if ('' !== $address) {
                $blocks[] = 'Adresse: '.$address;
            }
        }

        $text = is_array($record['text'] ?? null) ? $record['text'] : [];
        foreach (self::TEXT_SECTIONS[$type] ?? [] as $field => $heading) {
            $markdown = $this->converter->convert(is_string($text[$field] ?? null) ? $text[$field] : null, $baseUrl);
            if ('' === $markdown) {
                continue;
            }
            $blocks[] = null === $heading ? $markdown : "## {$heading}\n\n{$markdown}";
        }

        $facts = $this->facts($type, is_array($record['facts'] ?? null) ? $record['facts'] : []);
        if ('' !== $facts) {
            $blocks[] = "## Fakten\n\n".$facts;
        }

        if ('region' === $type && is_string($record['webcam'] ?? null) && '' !== trim($record['webcam'])) {
            $blocks[] = 'Webcam: '.trim($record['webcam']);
        }

        if ('product' === $type) {
            $faqs = $this->faqs(is_array($record['faqs'] ?? null) ? $record['faqs'] : [], $baseUrl);
            if ('' !== $faqs) {
                $blocks[] = "## Häufige Fragen\n\n".$faqs;
            }
        }

        return $this->join($blocks);
    }

    /**
     * @param array<string, mixed> $record
     *
     * @return list<string>
     */
    private function newsBlocks(array $record, ?string $baseUrl): array
    {
        $blocks = [];

        if (is_string($record['datetime'] ?? null) && false !== ($date = date_create_immutable($record['datetime']))) {
            $blocks[] = 'Veröffentlicht am '.$date->format('d.m.Y');
        }

        foreach (['teaser', 'bodytext'] as $field) {
            $markdown = $this->converter->convert(is_string($record[$field] ?? null) ? $record[$field] : null, $baseUrl);
            if ('' !== $markdown) {
                $blocks[] = $markdown;
            }
        }

        $tags = $this->labels($record['tags'] ?? null);
        if ([] !== $tags) {
            $blocks[] = 'Themen: '.implode(', ', $tags);
        }

        return $blocks;
    }

    /**
     * @param array<string, mixed> $facts
     */
    private function facts(string $type, array $facts): string
    {
        $lines = [];

        foreach (self::FACTS[$type] ?? [] as $field => $label) {
            $value = $facts[$field] ?? null;

            $rendered = match (true) {
                is_bool($value) => $value ? 'ja' : 'nein',
                is_int($value), is_float($value) => (string) $value,
                is_string($value) => $this->plain($value),
                default => '',
            };

            if ('' !== $rendered) {
                $lines[] = "- {$label}: {$rendered}";
            }
        }

        return implode("\n", $lines);
    }

    /**
     * @param array<mixed> $faqs
     */
    private function faqs(array $faqs, ?string $baseUrl): string
    {
        $blocks = [];

        foreach ($faqs as $faq) {
            if (!is_array($faq)) {
                continue;
            }

            $question = $this->plain($faq['question'] ?? null);
            $answer = $this->converter->convert(is_string($faq['answer'] ?? null) ? $faq['answer'] : null, $baseUrl);

            if ('' !== $question && '' !== $answer) {
                $blocks[] = "### {$question}\n\n{$answer}";
            }
        }

        return $this->join($blocks);
    }

    /**
     * Tags and categories may arrive as strings or as objects with a title or name.
     *
     * @return list<string>
     */
    private function labels(mixed $values): array
    {
        if (!is_array($values)) {
            return [];
        }

        $labels = [];
        foreach ($values as $value) {
            $label = is_array($value) ? ($value['title'] ?? $value['name'] ?? null) : $value;
            if (is_string($label) && '' !== trim($label)) {
                $labels[] = trim($label);
            }
        }

        return $labels;
    }

    /**
     * A field that is plain text in the feed, defensively stripped of any markup.
     */
    private function plain(mixed $value): string
    {
        if (!is_string($value)) {
            return '';
        }

        return trim((string) preg_replace('/\s+/u', ' ', html_entity_decode(strip_tags($value), \ENT_QUOTES | \ENT_HTML5, 'UTF-8')));
    }

    /**
     * @param list<string> $blocks
     */
    private function join(array $blocks): string
    {
        return implode("\n\n", $blocks);
    }
}