<?php
namespace Clusterlane\Core;

if ( ! defined( 'ABSPATH' ) ) exit;

/**
 * Settings
 *
 * Single source of truth for all Clusterlane configuration.
 * Stored as a single serialized array under option key 'clusterlane_settings'.
 *
 * Defaults are defined here so the plugin works out of the box
 * without requiring the user to configure anything first.
 */
class Settings {

    const OPTION_KEY = 'clusterlane_settings';

    /** @var self|null */
    private static ?self $instance = null;

    /** @var array<string, mixed> */
    private array $data = [];

    public static function get_instance(): ?self {
        return self::$instance;
    }

    public function __construct() {
        self::$instance = $this;
        $stored         = get_option( self::OPTION_KEY, [] );
        $this->data     = wp_parse_args( $stored, $this->defaults() );
    }

    /* ------------------------------------------------------------------
       Read
    ------------------------------------------------------------------ */

    public function get( string $key, mixed $fallback = null ): mixed {
        return $this->data[ $key ] ?? $fallback;
    }

    public function all(): array {
        return $this->data;
    }

    /* ------------------------------------------------------------------
       Write
    ------------------------------------------------------------------ */

    public function set( string $key, mixed $value ): void {
        $this->data[ $key ] = $value;
        update_option( self::OPTION_KEY, $this->data, false );
    }

    public function save( array $data ): void {
        $this->data = wp_parse_args( $data, $this->defaults() );
        update_option( self::OPTION_KEY, $this->data, false );
    }

    /* ------------------------------------------------------------------
       Convenience getters
    ------------------------------------------------------------------ */

    /* ------------------------------------------------------------------
       AI — effective configuration
       Every AI caller uses these. On multisite they resolve between this
       site's own key and the network key (see NetworkAi); on single site
       they are simply this site's settings.
    ------------------------------------------------------------------ */

    /** Where the AI configuration comes from: 'site', 'network' or 'none'. */
    public function ai_source(): string {
        $site = $this->has_site_ai_api_key();
        if ( class_exists( NetworkAi::class ) && NetworkAi::enabled() ) { // NetworkAi is premium
            return NetworkAi::source_for( $site );
        }
        return $site ? 'site' : 'none';
    }

    public function ai_provider(): string {
        return $this->ai_source() === 'network' ? NetworkAi::provider() : $this->site_ai_provider();
    }

    public function ai_model(): string {
        return $this->ai_source() === 'network' ? NetworkAi::model() : $this->site_ai_model();
    }

    /** Decrypted effective API key, or '' if none. */
    public function ai_api_key(): string {
        return match ( $this->ai_source() ) {
            'site'    => $this->site_ai_api_key(),
            'network' => NetworkAi::api_key(),
            default   => '',
        };
    }

    /** True if an effective key exists (without exposing it). */
    public function has_ai_api_key(): bool {
        return $this->ai_source() !== 'none';
    }

    /* ------------------------------------------------------------------
       AI — this site's own settings (Settings page reads/writes these)
    ------------------------------------------------------------------ */

    public function site_ai_provider(): string { return $this->get( 'ai_provider', 'openai' ); }
    public function site_ai_model(): string    { return $this->get( 'ai_model',    'gpt-4o-mini' ); }

    /** This site's own decrypted key, or '' if none stored. */
    public function site_ai_api_key(): string {
        return self::decrypt_stored( (string) $this->get( 'ai_api_key', '' ) );
    }

    /** True if this site stores its own key. */
    public function has_site_ai_api_key(): bool {
        return $this->get( 'ai_api_key', '' ) !== '';
    }

    /**
     * A site key is stored but can no longer be decrypted — WordPress's AUTH_KEY
     * changed after it was saved (new salts, a clone or move with another
     * wp-config.php). has_site_ai_api_key() is still true then (0.98.174).
     */
    public function site_ai_key_unreadable(): bool {
        return $this->has_site_ai_api_key() && $this->site_ai_api_key() === '';
    }

    /** The key AI calls would use (site or network) is stored but can't be decrypted. */
    public function ai_key_unreadable(): bool {
        return match ( $this->ai_source() ) {
            'site'    => $this->site_ai_key_unreadable(),
            'network' => NetworkAi::has_key() && NetworkAi::api_key() === '',
            default   => false,
        };
    }

    /** Stored value ("cci_enc:…" or legacy plain text) → plain key, or ''. */
    public static function decrypt_stored( string $stored ): string {
        if ( $stored === '' ) return '';
        // Legacy: if not prefixed, it's a plain-text key from before encryption.
        if ( strncmp( $stored, 'cci_enc:', 8 ) !== 0 ) return $stored;
        return self::decrypt_key( substr( $stored, 8 ) ) ?: '';
    }

    /** Plain key → value to store ("cci_enc:…", or plain if OpenSSL is missing). */
    public static function encrypt_for_storage( string $key ): string {
        $encrypted = self::encrypt_key( $key );
        return $encrypted !== false ? 'cci_enc:' . $encrypted : $key;
    }

    /** Encrypt and store the API key. */
    public function save_ai_api_key( string $key ): void {
        if ( $key === '' ) return;
        $data      = $this->all();
        $data['ai_api_key'] = self::encrypt_for_storage( $key );
        $this->data = $data; // keep this request's copy in sync (a later set() would drop the key)
        update_option( 'clusterlane_settings', $data );
    }

    private static function get_encryption_key(): string {
        // Derive a 32-byte key from WP's AUTH_KEY so it never touches the DB.
        $salt = defined( 'AUTH_KEY' ) ? AUTH_KEY : 'clusterlane-fallback-salt-change-me';
        return substr( hash( 'sha256', $salt . 'cci_api_key', true ), 0, 32 );
    }

    private static function encrypt_key( string $plaintext ): string|false {
        if ( ! function_exists( 'openssl_encrypt' ) ) return false;
        $iv  = random_bytes( 16 );
        $enc = openssl_encrypt( $plaintext, 'aes-256-cbc', self::get_encryption_key(), 0, $iv );
        if ( $enc === false ) return false;
        return base64_encode( $iv . base64_decode( $enc ) );
    }

    private static function decrypt_key( string $ciphertext ): string|false {
        if ( ! function_exists( 'openssl_decrypt' ) ) return false;
        $raw = base64_decode( $ciphertext, true );
        if ( $raw === false || strlen( $raw ) < 17 ) return false;
        $iv  = substr( $raw, 0, 16 );
        $enc = base64_encode( substr( $raw, 16 ) );
        return openssl_decrypt( $enc, 'aes-256-cbc', self::get_encryption_key(), 0, $iv ) ?: false;
    }
    /** Custom gallery shortcode names for image counting (one per line). */
    public function gallery_shortcodes(): array {
        $raw = $this->get( 'gallery_shortcodes', '' );
        if ( ! $raw ) return [];
        return array_values( array_filter( array_map(
            'trim',
            preg_split( '/[\n,]+/', $raw )
        ) ) );
    }

    /** How to truncate article titles in Clusterlane's own views (never touches DB). */
    public function title_truncation(): string {
        return $this->get( 'title_truncation', 'none' );
    }

    /** Custom regex pattern for title truncation (used when title_truncation = 'custom'). */
    public function title_truncation_custom(): string {
        return $this->get( 'title_truncation_custom', '' );
    }

    public function language(): string      { return $this->get( 'language',    'en' ); }

    /** Custom stop words for Text Match Scanner, as an array of lowercase strings. */
    public function tms_stop_words(): array {
        $raw = self::heal_entities( (string) $this->get( 'tms_stop_words', '' ) );
        if ( ! $raw ) return [];
        return array_values( array_filter( array_map(
            'trim',
            preg_split( '/[\n,]+/', $raw )
        ) ) );
    }
    public function post_types(): array     { return $this->get( 'post_types',  ['post'] ); }

    /**
     * Scanned post types whose published pages are read as well (0.98.177): links
     * and text the theme adds through its templates — lists, cards, related
     * articles — which are not in the article text. Off by default.
     */
    public function rendered_types(): array {
        return array_values( array_intersect(
            array_map( 'sanitize_key', (array) $this->get( 'rendered_types', [] ) ),
            array_map( 'sanitize_key', (array) $this->post_types() )
        ) );
    }

    /**
     * Terms of any other taxonomy chosen as clusters (0.98.177) — attraction
     * categories, regions, genres … — as taxonomy → term IDs. Categories, tags
     * and product categories keep their own settings.
     * @return array<string, int[]>
     */
    public function enabled_terms(): array {
        $out = [];
        foreach ( (array) $this->get( 'enabled_terms', [] ) as $tax => $ids ) {
            $tax = sanitize_key( (string) $tax );
            if ( $tax === '' || in_array( $tax, [ 'category', 'post_tag', 'product_cat', 'custom' ], true ) ) continue;
            $out[ $tax ] = array_values( array_unique( array_filter( array_map( 'intval', (array) $ids ) ) ) );
        }
        return $out;
    }

    /** User-defined "See also" / link-insertion HTML templates. Each: {id, name, html}. */
    public function link_templates(): array { return $this->get( 'link_templates', [] ); }

    public function taxonomies(): array {
        return $this->get( 'taxonomies', [ 'category' ] );
    }

    public function taxonomy(): string {
        // Legacy single-taxonomy accessor — returns first active taxonomy.
        $taxs = $this->taxonomies();
        return $taxs[0] ?? 'category';
    }

    public function min_term_count(): int {
        return (int) $this->get( 'min_term_count', 1 );
    }

    /** Cluster keys (term slugs) that are disabled by the user. */
    public function disabled_clusters(): array {
        return $this->get( 'disabled_clusters', [] );
    }

    /** Individual category term IDs explicitly chosen as clusters on the Cluster Admin page. */
    public function enabled_categories(): array {
        return array_map( 'intval', (array) $this->get( 'enabled_categories', [] ) );
    }

    /** Product categories (WooCommerce product_cat term IDs) chosen as clusters on the Cluster Admin page (0.98.172). */
    public function enabled_product_cats(): array {
        return array_map( 'intval', (array) $this->get( 'enabled_product_cats', [] ) );
    }

    /** Individual tag term IDs explicitly chosen as clusters on the Cluster Admin page. */
    public function enabled_tags(): array {
        return array_map( 'intval', (array) $this->get( 'enabled_tags', [] ) );
    }

    /**
     * Whether the user has explicitly saved a category/tag selection on
     * the Cluster Admin page at least once. Before that, category/tag
     * clustering falls back to the taxonomy-wide min_term_count behavior
     * so the plugin still works out of the box with zero configuration.
     */
    public function cluster_terms_configured(): bool {
        return (bool) $this->get( 'cluster_terms_configured', false );
    }

    /** CSS selectors whose content the Text Match Scanner should ignore. */
    public function tms_ignore_selectors(): array {
        return $this->get( 'tms_ignore_selectors', ['.info-list', '.visitor-info'] );
    }

    /* ------------------------------------------------------------------
       AI prompts — overrideable per-site
    ------------------------------------------------------------------ */

    public function prompt( string $key ): string {
        $prompts = $this->get( 'prompts', [] );
        return isset( $prompts[ $key ] ) ? self::heal_entities( (string) $prompts[ $key ] ) : ( $this->default_prompts()[ $key ] ?? '' );
    }

    /**
     * Plain text from a settings textarea (prompts, stop words, instructions).
     * Not sanitize_textarea_field(): for text with a lone "<" (a prompt's
     * "<=155 chars", a regex "(?<!…)") it HTML-encodes everything after it,
     * so each save changed the text a little more (fixed in 0.98.128). These
     * values are never output as HTML — they are escaped where shown.
     */
    public static function clean_text( string $v, int $max = 8000 ): string {
        $v = wp_check_invalid_utf8( str_replace( [ "\r\n", "\r" ], "\n", $v ) );
        $v = preg_replace( '/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]/u', '', $v ) ?? '';
        return mb_substr( trim( $v ), 0, $max );
    }

    /** Undo the HTML entities the old sanitizer wrote into saved text (&quot; &lt; …). */
    public static function heal_entities( string $v ): string {
        for ( $i = 0; $i < 3 && preg_match( '/&(?:quot|lt|gt|amp|#0?39|apos);/', $v ); $i++ ) {
            $v = html_entity_decode( $v, ENT_QUOTES | ENT_HTML5, 'UTF-8' );
        }
        return $v;
    }

    /* ------------------------------------------------------------------
       Defaults
    ------------------------------------------------------------------ */

    private function defaults(): array {
        return [
            'ai_provider'          => 'openai',
            'ai_api_key'           => '',
            'ai_model'             => 'gpt-4o-mini',
            'language'             => 'en',
            'post_types'           => ['post'],
            'taxonomies'           => ['category'],
            'min_term_count'       => 1,
            'batch_size'           => 25,
            'title_truncation'     => 'none',
            'title_truncation_custom' => '',
            // SEO title & description (SeoMeta): auto = active SEO plugin, else these fields.
            'seo_source'            => 'auto',
            'seo_title_field'       => 'seo_title',
            'seo_description_field' => 'seo_description',
            'seo_fallback'          => true,
            'show_thumbnails'       => true,     // small featured images in article lists
            // AI suggestions for SEO title/description (Pro).
            'seo_ai_suffix'         => '',
            'seo_ai_suffix_mode'    => 'none',   // none | include | auto
            'seo_ai_language'       => '',       // '' = same as the article
            'seo_ai_instructions'   => '',
            'seo_ai_write'          => true,     // custom fields only (SeoMeta::can_write)
            'gallery_shortcodes'   => '',
            'disabled_clusters'    => [],
            'enabled_categories'      => [],
            'enabled_tags'            => [],
            'enabled_product_cats'    => [],
            'enabled_terms'           => [],     // other taxonomies: taxonomy => term IDs (0.98.177)
            'rendered_types'          => [],     // post types whose published pages are read (0.98.177)
            'rendered_cached'         => false,  // read them as the page cache serves them (0.98.178)
            'enabled_hubs'            => [],     // post types whose pages are clusters (0.98.180)
            'cluster_terms_configured'=> false,
            'tms_ignore_selectors' => ['.info-list', '.visitor-info'],
            'prompts'              => $this->default_prompts(),
            'link_templates'       => $this->default_link_templates(),
        ];
    }

    /** Public static accessor so the Settings page can read defaults without an instance. */
    public static function default_prompts_public(): array {
        return ( new self() )->default_prompts();
    }

    private function default_prompts(): array {
        return [

            'link_style_suggest' =>
                'You are a web designer. Suggest 3 distinct color/style variants for a small ' .
                '"link card" — a short highlighted box inserted into article text, with an optional ' .
                'bold heading line and a sentence containing a link. Base the palette on the ' .
                'description given. Each variant needs a heading (a short label like "Worth exploring", ' .
                'or empty string for no heading), a border_color and background_color that are ' .
                'harmonious and readable together, a text_color with strong contrast against the ' .
                'background, whether to show a left border accent (has_border), and a border_radius ' .
                'in pixels (0-16). All colors as hex strings like "#2271b1". ' .
                'Return ONLY valid JSON: {"variants":[{"heading":"text","has_border":true,' .
                '"border_color":"#hex","background_color":"#hex","text_color":"#hex","border_radius":4}]}',

            'cluster_detect' =>
                'You are a content strategist. The site already groups its articles by category and tag. ' .
                'Find CROSS-CUTTING themes those groups miss — reader situations such as a season or occasion, ' .
                'an audience, a budget, an area or a day itinerary — and group articles from different existing ' .
                'clusters into new clusters a reader would follow. ' .
                'Return ONLY valid JSON in this exact shape: ' .
                '{"clusters":[{"name":"Cluster name","slug":"cluster-slug","post_ids":[1,2,3],"rationale":"Why these belong together"}]}',

            'gap_analysis' =>
                'You are a content strategist. The following articles form a content cluster. ' .
                'Analyse the cluster and identify: ' .
                '1. Topics that are under-covered or missing entirely. ' .
                '2. Three specific new article ideas that would strengthen the cluster. ' .
                'Be concrete and specific to the subject matter. ' .
                'Return ONLY valid JSON: ' .
                '{"analysis":"Your analysis","suggestions":[{"title":"Article title","rationale":"Why it helps"}]}',

            'gap_brief' =>
                'You are a senior content strategist writing a brief for a NEW article that will strengthen an existing content cluster. ' .
                'You are given the cluster name, the proposed article title and rationale, and the existing cluster articles with their IDs, URLs, roles and excerpts. ' .
                'Write a practical brief a human writer (or a writing assistant) can execute. ' .
                'Rules: sections must be specific to the subject, not generic; link_to must ONLY use post IDs from the list; ' .
                'prefer pillar/support articles for link_from; keep the brief concise. ' .
                'Return ONLY valid JSON: ' .
                '{"purpose":"1-2 sentences on what this article adds to the cluster",' .
                '"target_keyword":"primary search phrase",' .
                '"meta_description":"<=155 chars",' .
                '"sections":[{"heading":"H2 heading","notes":"1-2 sentences on what this section should cover"}],' .
                '"link_to":[{"post_id":123,"anchor":"suggested anchor text","why":"short reason"}],' .
                '"link_from":[{"post_id":123,"why":"short reason"}]}',

            'link_suggest' =>
                'You are an SEO specialist. I want to add an internal link from Article A to Article B. ' .
                'Read the excerpt from Article A and suggest 3 different ways to naturally include ' .
                'a link to Article B — varying anchor text, surrounding context, and position in the text. ' .
                'The anchor_text must not repeat words that already appear elsewhere in the context ' .
                'sentence — it should read naturally once substituted for [LINK], with no phrase duplicated. ' .
                'Return ONLY valid JSON: ' .
                '{"suggestions":[{"anchor_text":"text","context":"surrounding sentence with [LINK] placeholder","position":"beginning|middle|end"}]}',
        ];
    }

    /**
     * Starter "See also" card designs, shown out of the box so a fresh
     * install isn't just a blank textarea. Matches the exact style format
     * the Settings page's Quick Style panel produces (same placeholders),
     * so any of these can be reopened there and tweaked normally. Also
     * offered as a one-click "✨ Add starter templates" button on the
     * Settings page itself, for sites that already have link_templates
     * saved — this code default only applies to brand-new installs, since
     * an existing site's saved settings always win over these.
     */
    private function default_link_templates(): array {
        return [
            [
                'id'   => 'tpl_worth_exploring',
                'name' => '💡 Worth exploring',
                'html' => '<blockquote style="margin:1.5em 0;padding:1em 1.25em;background:#f0f6fc;color:#1e1e1e;border-radius:4px;border-left:4px solid #2271b1;"><strong>Worth exploring</strong><br>{sentence}</blockquote>',
            ],
            [
                'id'   => 'tpl_also_worth_reading',
                'name' => '📚 Also worth reading',
                'html' => '<blockquote style="margin:1.5em 0;padding:1em 1.25em;background:#f1f8f2;color:#1e1e1e;border-radius:4px;border-left:4px solid #2e7d32;"><strong>Also worth reading</strong><br>{sentence}</blockquote>',
            ],
            [
                'id'   => 'tpl_nearby',
                'name' => '📍 Nearby',
                'html' => '<blockquote style="margin:1.5em 0;padding:1em 1.25em;background:#fdf3ea;color:#1e1e1e;border-radius:4px;border-left:4px solid #c05c00;"><strong>Nearby</strong><br>{sentence}</blockquote>',
            ],
            [
                'id'   => 'tpl_related',
                'name' => '➜ Related',
                'html' => '<blockquote style="margin:1.5em 0;padding:1em 1.25em;background:#f8fafc;color:#1e1e1e;border-radius:8px;border-left:4px solid #94a3b8;">{sentence}</blockquote>',
            ],
        ];
    }
}