<?php
/**
 * Session domain logic for Salyut Agents
 *
 * Public API:
 *   salyut_agents_render_transcript( array $messages ) : string
 *   salyut_agents_finalize_session( int $post_id )     : void
 *   salyut_agents_is_finalized( int $post_id )         : bool
 *
 * @package SalyutAgents
 */

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

/**
 * Render a plain-text transcript from an array of message rows.
 *
 * @param array $messages  Array of [ 'role' => string, 'content' => string, ... ]
 *
 * @return string
 */
function salyut_agents_render_transcript( array $messages ): string {
    if ( empty( $messages ) ) {
        return '';
    }

    $lines = [];

    foreach ( $messages as $msg ) {
        if ( empty( $msg['role'] ) || empty( $msg['content'] ) ) {
            continue;
        }

        $label   = $msg['role'] === 'assistant' ? 'Assistant' : 'User';
        $lines[] = "{$label}:\n{$msg['content']}\n";
    }

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

/**
 * Check whether a session has been finalized.
 *
 * @param int $post_id
 *
 * @return bool
 */
function salyut_agents_is_finalized( int $post_id ): bool {
    $value = get_post_meta( $post_id, 'salyut_agents_finalized', true );
    return $value === '1';
}

/**
 * Finalize a chat session.
 *
 * Marks the session as ended, builds the transcript from the custom
 * messages table, and writes it to post_content for admin viewing.
 * Safe to call multiple times — idempotent via meta lock.
 *
 * @param int $post_id  The salyut_lead post ID.
 *
 * @return void
 */
function salyut_agents_finalize_session( int $post_id ): void {
    // Guard: wrong post type.
    if ( get_post_type( $post_id ) !== 'salyut_lead' ) {
        return;
    }

    // Guard: already finalized (string '1' stored consistently).
    if ( salyut_agents_is_finalized( $post_id ) ) {
        return;
    }

    // Optimistic lock: write a sentinel value so concurrent calls
    // (Action Scheduler + lazy finalization) don't both proceed.
    // Note: update_post_meta returns false if value is unchanged, so
    // we check against the current value explicitly before writing.
    $current = get_post_meta( $post_id, 'salyut_agents_finalized', true );
    if ( $current === 'locking' ) {
        // Another process is already finalizing.
        return;
    }

    update_post_meta( $post_id, 'salyut_agents_finalized', 'locking' );

    // Read messages from the custom table.
    $messages   = salyut_agents_get_session_messages( $post_id );
    $transcript = salyut_agents_render_transcript( $messages );
    $transcript = wp_kses_post( $transcript );

    // Preserve the session header that was written at session creation,
    // then append the full transcript below a divider.
    $post            = get_post( $post_id );
    $original_content = $post ? $post->post_content : '';

    preg_match( '/^(.*?)(User:|Assistant:|$)/s', $original_content, $matches );
    $header = isset( $matches[1] ) ? trim( $matches[1] ) : '';

    $final_content = $header
        ? $header . "\n\n---\n\n" . $transcript
        : $transcript;

    wp_update_post( [
        'ID'           => $post_id,
        'post_content' => $final_content,
    ] );

    // Release the lock with the final value (string '1' for consistent meta queries).
    update_post_meta( $post_id, 'salyut_agents_finalized', '1' );

    // Store the finalization time so the digest query can find leads by date.
    // The digest uses post_date from wp_posts rather than this meta, but this
    // acts as an audit trail for when the session actually completed.
    update_post_meta( $post_id, 'salyut_agents_finalized_at', time() );
}