<?php
/**
 * AI Semantic Keyword Hints (Lite)
 */
class AIT_AIPSEO_AI_Keywords {

    public function __construct() {
        add_filter( 'ait_aipseo_semantic_keywords', [ $this, 'get_for_post' ], 10, 2 );
    }

    public function get_for_post( $existing, $post_id ) {
        $post_id = (int) $post_id;
        if ( $post_id <= 0 ) { return []; }

        $limit = (int) AIT_AIPSEO_Settings::get('target_keyword_limit');
        $ttl   = (int) apply_filters( 'ait_aipseo/ai_keywords_cache_ttl', DAY_IN_SECONDS );

        $context = $this->build_context( $post_id );
        $hash    = md5( wp_json_encode( $context ) );

        $cached = get_post_meta( $post_id, '_ait_aipseo_ai_semantic_keywords', true );
        if ( is_array( $cached ) && ! empty( $cached['hash'] ) && $cached['hash'] === $hash && ! empty( $cached['time'] ) && ( time() - (int) $cached['time'] ) < $ttl && ! empty( $cached['data'] ) ) {
            return array_slice( (array) $cached['data'], 0, max( 1, $limit ) );
        }

        $result = $this->query_openai( $context, $limit );
        if ( is_wp_error( $result ) ) {
            if ( class_exists( 'AIT_AIPSEO_Logger' ) ) {
                AIT_AIPSEO_Logger::log_error( 'AI keywords error', [ 'post_id' => $post_id, 'error' => $result->get_error_message() ] );
            }
            return [];
        }

        $data = $this->normalize_list( $result );
        update_post_meta( $post_id, '_ait_aipseo_ai_semantic_keywords', [
            'hash' => $hash,
            'time' => time(),
            'data' => $data,
        ] );

        return array_slice( $data, 0, max( 1, $limit ) );
    }

    private function build_context( int $post_id ): array {
        $post = get_post( $post_id );
        $title = $post ? get_the_title( $post ) : '';
        $content = $post ? (string) $post->post_content : '';

        $headings = [];
        if ( $content ) {
            if ( preg_match_all( '/<h[1-3][^>]*>(.*?)<\/h[1-3]>/', $content, $m ) ) {
                $headings = array_map( 'wp_strip_all_tags', $m[1] );
            }
        }

        $kws = class_exists( 'AIT_AIPSEO_Keyword_Density' )
            ? ( new AIT_AIPSEO_Keyword_Density() )->get_target_keywords( $post_id )
            : [];

        return [
            'post_id'  => $post_id,
            'title'    => trim( (string) $title ),
            'headings' => array_slice( array_values( array_filter( array_map( 'trim', $headings ) ) ), 0, 10 ),
            'keywords' => array_slice( $kws, 0, 5 ),
            'time'     => date('Y-m-d H:i'),
        ];
    }

    private function query_openai( array $context, int $limit ) {
        $api_key = (string) AIT_AIPSEO_Settings::get( 'openai_api_key' );

        if ( '' === trim( $api_key ) ) {
            return new WP_Error( 'aipseo_no_api_key', __( 'OpenAI API key is not set.', 'ai-powered-seo-suggestions' ) );
        }

        $model    = (string) AIT_AIPSEO_Settings::get( 'openai_model' );
        $override = (string) AIT_AIPSEO_Settings::get( 'force_model_override' );

        if ( '' !== trim( $override ) ) { $model = $override; }

        $timeout = (int) ( AIT_AIPSEO_Settings::get( 'request_timeout' ) ?: 20 );

        $sys = (string) apply_filters( 'ait_aipseo/ai_keywords_system_prompt',
            'You are an SEO assistant. Given some data about a post, such as post title, headings, and target keyword(s), suggest short related terms/entities that would improve topical coverage. Output ONLY a compact JSON array of strings (no explanations).'
        );

        $user = [
            'title'    => $context['title'],
            'headings' => $context['headings'],
            'keywords' => $context['keywords'],
            'limit'    => max( 1, $limit ),
        ];

        $body = [
            'model'    => $model,
            'messages' => [
                [ 'role' => 'system', 'content' => $sys ],
                [ 'role' => 'user',   'content' => wp_json_encode( $user ) ],
            ]
        ];

        if ( $model != 'gpt-5' ) {
            $body['temperature'] = 0.2;
        }

        $response = wp_remote_post( 'https://api.openai.com/v1/chat/completions', [
            'timeout' => $timeout,
            'headers' => [
                'Content-Type'  => 'application/json',
                'Authorization' => 'Bearer ' . $api_key,
            ],
            'body'    => wp_json_encode( $body ),
        ] );

        if ( is_wp_error( $response ) ) {
            return $response;
        }

        $code = wp_remote_retrieve_response_code( $response );
        $raw  = wp_remote_retrieve_body( $response );
        if ( $code < 200 || $code > 299 || '' === $raw ) {
            return new WP_Error( 'aipseo_openai_http', __( 'Unexpected response from OpenAI.', 'ai-powered-seo-suggestions' ) );
        }

        $data = json_decode( $raw, true );
        if ( JSON_ERROR_NONE !== json_last_error() ) {
            return new WP_Error( 'aipseo_openai_json', __( 'Invalid JSON from OpenAI.', 'ai-powered-seo-suggestions' ) );
        }

        $content = (string) ( $data['choices'][0]['message']['content'] ?? '' );
        return $content;
    }

    private function normalize_list( $content ): array {
        if ( is_array( $content ) ) {
            return array_values( array_filter( array_map( 'sanitize_text_field', $content ) ) );
        }

        $str = (string) $content;
        if ( preg_match( '/\[.*\]/s', $str, $m ) ) {
            $decoded = json_decode( $m[0], true );
            if ( is_array( $decoded ) ) {
                return array_values( array_filter( array_map( 'sanitize_text_field', $decoded ) ) );
            }
        }

        $parts = preg_split( '/[\n,]+/', $str );
        return array_values( array_filter( array_map( function( $v ) { return sanitize_text_field( trim( (string) $v ) ); }, (array) $parts ) ) );
    }
}