<?php

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

/**
 * The Chats tab: its data, and its AJAX endpoints for opening, searching and
 * deleting chats.
 */
class RSVL_Chats_Admin
{
    /** Chats per page in the Chats tab list. */
    public const PER_PAGE = 20;

    /** @var RSVL_Conversations */
    private $conversations;

    public function __construct()
    {
        $this->conversations = new RSVL_Conversations();
    }

    /** The Chats tab's data. Only the open tab gets its chats. */
    public function get_tab_data(bool $is_active): array
    {
        $settings = RSVL_Settings::all();
        $per_page = self::PER_PAGE;
        $page     = isset($_GET['conv_page']) ? max(1, (int) $_GET['conv_page']) : 1;
        $filter   = isset($_GET['conv_filter']) ? sanitize_key(wp_unslash($_GET['conv_filter'])) : 'all';
        $filter   = array_key_exists($filter, RSVL_Conversations::get_filters()) ? $filter : 'all';
        $view     = isset($_GET['panel']) && 'settings' === $_GET['panel'] ? 'settings' : 'chats';

        // A link to a specific chat can name a page it has since fallen off, as
        // newer conversations push it down the list — or omit the page number
        // entirely. Trust the session over conv_page and show the page it is
        // actually on, so the chat is selected in the list beside it. Everything
        // downstream (pagination targets, the "showing X-Y" range) derives from
        // $page, so correcting it here keeps them all consistent.
        if (! empty($_GET['open_session'])) {
            $page = $this->conversations->get_session_page(
                sanitize_text_field(wp_unslash($_GET['open_session'])),
                $per_page,
                $filter
            );
        }

        $data = [
            'is_active'         => $is_active,
            'is_pro'            => resolver_is_pro(),
            'view'              => $view,
            'filter'            => $filter,
            'filter_options'    => $this->get_conversation_filter_options($filter),
            'sessions'          => [],
            'total'             => 0,
            'range_start'       => 0,
            'range_end'         => 0,
            'count_html'        => '',
            'prev_url'          => '',
            'next_url'          => '',
            'accent_color'      => $settings['accent_color'],
            'retention_days'    => (int) ($settings['chat_retention_days'] ?? 0),
            'retention_options' => $this->get_retention_options(),
        ];

        if (! $data['is_active']) {
            return $data;
        }

        $sessions    = $this->conversations->get_conversation_sessions($per_page, ($page - 1) * $per_page, $filter);
        $total       = $this->conversations->get_conversation_count($filter);
        $total_pages = $total > 0 ? (int) ceil($total / $per_page) : 0;

        $data['sessions'] = array_map([__CLASS__, 'format_conversation_list_item'], $sessions);
        $data['total']    = $total;

        if (! empty($sessions)) {
            $data['range_start'] = ($page - 1) * $per_page + 1;
            $data['range_end']   = $data['range_start'] + count($sessions) - 1;
        }
        $data['count_html'] = self::get_chat_count_html($data['range_start'], $data['range_end'], $total);

        if ($total_pages > 1) {
            $pagination_args = ['page' => RSVL_Admin::PAGE, 'tab' => 'chats', 'conv_filter' => $filter];
            $open_chat_args  = ['open_session', 'open_message'];
            if ($page > 1) {
                $data['prev_url'] = remove_query_arg($open_chat_args, add_query_arg(array_merge($pagination_args, ['conv_page' => $page - 1])));
            }
            if ($page < $total_pages) {
                $data['next_url'] = remove_query_arg($open_chat_args, add_query_arg(array_merge($pagination_args, ['conv_page' => $page + 1])));
            }
        }

        return $data;
    }

    /**
     * AJAX: Get all messages for a conversation session.
     */
    public function ajax_get_conversation()
    {
        $session_id = RSVL_Ajax::text('session_id');

        if (empty($session_id)) {
            wp_send_json_error(['message' => __('Missing session ID.', 'resolver-ai-chatbot')]);
        }

        $messages = $this->conversations->get_conversation_messages($session_id);
        $usage    = $this->conversations->get_conversation_usage($session_id);
        $page_url = $this->conversations->get_page_url($session_id);

        // Derive the date from the first message so the detail header
        // populates correctly when loading a session from a URL param.
        $date = '';
        if (! empty($messages)) {
            $date = wp_date(resolver_date_format(), (int) ($messages[0]['ts'] / 1000));
        }

        $has_error = false;
        foreach ($messages as $message) {
            if ($message['is_error']) {
                $has_error = true;
                break;
            }
        }

        $data = [
            'messages'      => $messages,
            'model'         => $usage['model'],
            'tokens'        => $usage['total_tokens'],
            'date'          => $date,
            'page_path'     => self::get_page_path($page_url),
            'message_count' => count($messages),
            'is_admin'      => $this->conversations->is_admin_session($session_id),
            'has_error'     => $has_error,
        ];

        /**
         * Filter an open chat's data for the Chats screen, to add data of its
         * own for admin scripts (see the rsvl:conversation-* events in admin-chats.js).
         *
         * @param array  $data       As above.
         * @param string $session_id The chat's session ID.
         */
        wp_send_json_success(apply_filters('resolver_conversation_data', $data, $session_id));
    }

    /**
     * AJAX: Search conversations by message content.
     */
    public function ajax_search_conversations()
    {
        $query  = RSVL_Ajax::text('query');
        $filter = RSVL_Ajax::enum('filter', array_keys(RSVL_Conversations::get_filters()), 'all');

        if ('' === $query) {
            wp_send_json_success(['html' => '', 'count' => 0, 'total' => 0, 'page' => 1, 'total_pages' => 0]);
        }

        $per_page = self::PER_PAGE;
        $page     = RSVL_Ajax::page('page');

        $total = $this->conversations->count_search_results($query, $filter);

        // Clamp to the last page so a stale page number from a previous, wider
        // query can't land the user on an empty result set.
        $total_pages = $total > 0 ? (int) ceil($total / $per_page) : 0;
        if ($total_pages > 0 && $page > $total_pages) {
            $page = $total_pages;
        }

        $sessions = $this->conversations->search_conversations($query, $per_page, ($page - 1) * $per_page, $filter);

        // Render the rows server-side through the same template the browse list
        // uses, so search results can't drift away from it again.
        $html = '';

        foreach ($sessions as $session) {
            $html .= resolver_get_template(
                'conversation-list-item',
                ['session' => self::format_conversation_list_item($session)]
            );
        }

        $range_start = $total > 0 ? ($page - 1) * $per_page + 1 : 0;
        $range_end   = $total > 0 ? ($page - 1) * $per_page + count($sessions) : 0;

        wp_send_json_success([
            'html'        => $html,
            'count'       => count($sessions),
            'total'       => $total,
            'page'        => $page,
            'per_page'    => $per_page,
            'total_pages' => $total_pages,
            'range_start' => $range_start,
            'range_end'   => $range_end,
            'count_html'  => self::get_chat_count_html($range_start, $range_end, $total),
        ]);
    }

    /**
     * AJAX: Delete a conversation session and its messages.
     */
    public function ajax_delete_conversation()
    {
        $session_id = RSVL_Ajax::text('session_id');
        if ('' === $session_id) {
            wp_send_json_error(['message' => __('Missing session ID.', 'resolver-ai-chatbot')]);
        }

        $this->conversations->delete_conversation($session_id);

        wp_send_json_success();
    }

    private function get_conversation_filter_options(string $current): array
    {
        $labels = RSVL_Conversations::get_filters();

        // add_query_arg() builds from the current URL, so anything already in it
        // is carried over. Two things must not be: the page number, because the
        // new filter may have fewer pages and land on an empty one; and the open
        // chat, which may not exist in the filtered list at all. The pagination
        // links drop the same pair for the same reason.
        $reset_args = ['conv_page', 'open_session', 'open_message'];

        $options = [];
        foreach ($labels as $value => $label) {
            $options[] = [
                'label' => $label,
                'url'   => remove_query_arg(
                    $reset_args,
                    add_query_arg(['page' => RSVL_Admin::PAGE, 'tab' => 'chats', 'conv_filter' => $value])
                ),
                'active' => $value === $current,
            ];
        }

        return $options;
    }

    private function get_retention_options(): array
    {
        return [
            0   => __('Keep all chats', 'resolver-ai-chatbot'),
            30  => __('Delete after 30 days', 'resolver-ai-chatbot'),
            60  => __('Delete after 60 days', 'resolver-ai-chatbot'),
            90  => __('Delete after 90 days', 'resolver-ai-chatbot'),
            180 => __('Delete after 6 months', 'resolver-ai-chatbot'),
            365 => __('Delete after 1 year', 'resolver-ai-chatbot'),
            730 => __('Delete after 2 years', 'resolver-ai-chatbot'),
        ];
    }

    /** Register the AJAX endpoints. */
    public static function register(): void
    {
        RSVL_Ajax::register(self::ajax_routes(), new self());
    }

    /**
     * Shape one chat row for the conversation list template.
     *
     * Public and static so the search AJAX handler can render its results
     * through the same formatter and template as the browse list.
     */
    public static function format_conversation_list_item(array $session): array
    {
        $item = [
            'session_id'    => $session['session_id'],
            'preview'       => wp_trim_words($session['first_message'], 14, '…'),
            'date'          => wp_date(resolver_date_format(), strtotime($session['updated_at'])),
            'message_count' => (int) $session['message_count'],
            'page_path'     => self::get_page_path($session['page_url'] ?? ''),
            'is_admin'      => ! empty($session['is_admin']),
            'has_error'     => ! empty($session['has_error']),
            'has_like'      => ! empty($session['has_like']),
            'has_dislike'   => ! empty($session['has_dislike']),
        ];

        /**
         * Filter one chat row in the Chats list.
         *
         * @param array $item    The row, as above.
         * @param array $session The session, from RSVL_Conversations.
         */
        return (array) apply_filters('resolver_conversation_list_item', $item, $session);
    }

    /**
     * "Showing 1-20 of 113 chats", with the numbers in <strong>. Shared by the
     * Chats list and its search results, so both read the same in every
     * language.
     */
    public static function get_chat_count_html(int $start, int $end, int $total): string
    {
        return sprintf(
            /* translators: 1: number of the first chat shown, 2: number of the last chat shown, 3: total number of chats. */
            _n(
                'Showing <strong>%1$s-%2$s</strong> of <strong>%3$s</strong> chat',
                'Showing <strong>%1$s-%2$s</strong> of <strong>%3$s</strong> chats',
                $total,
                'resolver-ai-chatbot'
            ),
            number_format_i18n($start),
            number_format_i18n($end),
            number_format_i18n($total)
        );
    }

    /**
     * URL path of a tracked page, or '' when the session has no page URL.
     */
    private static function get_page_path(string $page_url): string
    {
        return '' !== $page_url ? (wp_parse_url($page_url, PHP_URL_PATH) ?: '/') : '';
    }

    /**
     * The Chats tab's AJAX endpoints, with the guards they require.
     *
     * @return array<string, array>
     */
    private static function ajax_routes(): array
    {
        return RSVL_Ajax::admin_routes([
            'resolver_get_conversation'     => 'ajax_get_conversation',
            'resolver_search_conversations' => 'ajax_search_conversations',
            'resolver_delete_conversation'  => 'ajax_delete_conversation',
        ]);
    }
}