<?php

declare(strict_types=1);

namespace Sarcio\WordPress\Assistant;

/**
 * Each person's conversations with the assistant, kept in the plugin's own
 * table on this site so a chat can be picked up again later. Sarcio stores
 * none of it: every turn carries what it needs and nothing more.
 */
final class Conversations
{
    public const LIST_LIMIT = 50;
    public const MAX_MESSAGES = 400;
    public const MAX_TITLE = 120;

    public static function table(): string
    {
        global $wpdb;
        return $wpdb->prefix . 'sarcio_conversations';
    }

    public static function schema(string $collate): string
    {
        $table = self::table();
        return "CREATE TABLE {$table} (
            id bigint(20) unsigned NOT NULL AUTO_INCREMENT,
            user_id bigint(20) unsigned NOT NULL,
            title varchar(200) NOT NULL DEFAULT '',
            summary text NULL,
            messages longtext NULL,
            previews longtext NULL,
            created_at datetime NOT NULL,
            updated_at datetime NOT NULL,
            PRIMARY KEY  (id),
            KEY user_updated (user_id, updated_at)
        ) {$collate};";
    }

    /** @return array<int,array{id:int,title:string,updatedAt:string,createdAt:string,messageCount:int}> */
    public static function listFor(int $userId, int $limit = self::LIST_LIMIT): array
    {
        global $wpdb;
        $table = self::table();
        // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter -- the plugin's own table.
        $rows = $wpdb->get_results($wpdb->prepare("SELECT id, title, created_at, updated_at, messages FROM {$table} WHERE user_id = %d ORDER BY updated_at DESC, id DESC LIMIT %d", $userId, max(1, min(self::LIST_LIMIT, $limit))), ARRAY_A);
        $out = [];
        foreach (is_array($rows) ? $rows : [] as $row) {
            $messages = json_decode((string) ($row['messages'] ?? ''), true);
            $out[] = [
                'createdAt' => (string) $row['created_at'],
                'id' => (int) $row['id'],
                'messageCount' => is_array($messages) ? count($messages) : 0,
                'title' => (string) $row['title'],
                'updatedAt' => (string) $row['updated_at'],
            ];
        }
        return $out;
    }

    /** @return array{id:int,title:string,summary:string,messages:array<int,mixed>,previews:array<string,mixed>,updatedAt:string}|null */
    public static function get(int $id, int $userId): ?array
    {
        global $wpdb;
        $table = self::table();
        // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter -- the plugin's own table.
        $row = $wpdb->get_row($wpdb->prepare("SELECT * FROM {$table} WHERE id = %d AND user_id = %d", $id, $userId), ARRAY_A);
        if (!is_array($row)) {
            return null;
        }
        $messages = json_decode((string) ($row['messages'] ?? ''), true);
        $previews = json_decode((string) ($row['previews'] ?? ''), true);
        return [
            'id' => (int) $row['id'],
            'messages' => is_array($messages) ? array_values($messages) : [],
            'previews' => is_array($previews) ? $previews : [],
            'summary' => (string) ($row['summary'] ?? ''),
            'title' => (string) $row['title'],
            'updatedAt' => (string) $row['updated_at'],
        ];
    }

    /**
     * @param array<int,mixed> $messages
     * @param array<string,mixed> $previews
     * @return array{id:int,title:string}|null null when the id is not this person's
     */
    /**
     * A tool result flagged transient (form entries, other people's details)
     * is read for the turn that asked and never kept in a saved conversation.
     *
     * @param array<int,mixed> $messages
     * @return array<int,mixed>
     */
    public static function withoutTransient(array $messages): array
    {
        foreach ($messages as $i => $message) {
            if (!is_array($message)) {
                continue;
            }
            $results = $message['results'] ?? null;
            if (is_array($results)) {
                foreach ($results as $j => $result) {
                    if (is_array($result) && is_array($result['output'] ?? null) && !empty($result['output']['transient'])) {
                        $messages[$i]['results'][$j]['output'] = ['transient' => true, 'withheld' => __('Not kept: other people’s details.', 'sarcio')];
                    }
                }
            }
        }
        return $messages;
    }

    public static function save(int $id, int $userId, string $title, string $summary, array $messages, array $previews): ?array
    {
        global $wpdb;
        $title = mb_substr(sanitize_text_field($title), 0, self::MAX_TITLE);
        if ($title === '') {
            $title = self::titleFrom($messages);
        }
        $data = [
            'messages' => (string) wp_json_encode(self::withoutTransient(array_slice(array_values($messages), -self::MAX_MESSAGES))),
            'previews' => (string) wp_json_encode($previews === [] ? new \stdClass() : $previews),
            'summary' => mb_substr($summary, 0, 8000),
            'title' => $title,
            'updated_at' => current_time('mysql', true),
        ];
        if ($id > 0) {
            // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- the plugin's own table.
            $updated = $wpdb->update(self::table(), $data, ['id' => $id, 'user_id' => $userId], ['%s', '%s', '%s', '%s', '%s'], ['%d', '%d']);
            if ($updated === false || self::get($id, $userId) === null) {
                return null;
            }
            return ['id' => $id, 'title' => $title];
        }
        // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery -- the plugin's own table.
        $wpdb->insert(self::table(), $data + ['created_at' => current_time('mysql', true), 'user_id' => $userId], ['%s', '%s', '%s', '%s', '%s', '%s', '%d']);
        return ['id' => (int) $wpdb->insert_id, 'title' => $title];
    }

    public static function delete(int $id, int $userId): bool
    {
        global $wpdb;
        // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- the plugin's own table.
        return (int) $wpdb->delete(self::table(), ['id' => $id, 'user_id' => $userId], ['%d', '%d']) > 0;
    }

    public static function drop(): void
    {
        global $wpdb;
        $table = self::table();
        // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.DirectDatabaseQuery.SchemaChange, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter -- uninstall drops the plugin's own table.
        $wpdb->query("DROP TABLE IF EXISTS {$table}");
    }

    /** @param array<int,mixed> $messages */
    public static function titleFrom(array $messages): string
    {
        foreach ($messages as $message) {
            if (is_array($message) && ($message['role'] ?? '') === 'user' && is_string($message['text'] ?? null) && trim($message['text']) !== '') {
                $text = trim((string) preg_replace('/\s+/', ' ', $message['text']));
                return mb_strlen($text) > 80 ? mb_substr($text, 0, 79) . '…' : $text;
            }
        }
        return __('Conversation', 'sarcio');
    }
}