<?php
/**
 * POST /api/hub/vcgateway/dm/send.php
 *
 * Send a DM from visitor to host. Rate-limited.
 * Creates the DM channel on first message.
 * Authenticated via X-Visitor-Token header.
 *
 * Body:
 *   Content   string   required  Message text (max 4000 chars)
 *
 * Response:
 *   OK, MessageID, DMChannelID, CreatedAt
 */

require_once __DIR__ . '/../helpers.php';

if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    jsonResponse(['OK' => false, 'ERROR' => 'method_not_allowed'], 405);
}

$visitor = requireVisitorAuth();
$body = readJsonBody();

$content = trim($body['Content'] ?? '');
if (empty($content)) {
    jsonResponse(['OK' => false, 'ERROR' => 'content_required'], 400);
}
if (strlen($content) > 4000) {
    jsonResponse(['OK' => false, 'ERROR' => 'content_too_long', 'MaxLength' => 4000], 400);
}

// Rate limit check
checkVisitorRateLimit((int)$visitor['ID']);

$visitorId = (int)$visitor['ID'];
$hostAddress = $visitor['HostAddress'];
$dmChannelId = $visitor['DMChannelID'] ? (int)$visitor['DMChannelID'] : null;

// Create DM channel if it doesn't exist yet
if (!$dmChannelId) {
    $channelName = 'vc-dm-visitor-' . $visitorId;
    $displayName = 'VC DM: ' . $visitor['DisplayName'];

    queryTimed(
        "INSERT INTO Hub_Channels (Name, DisplayName, Purpose, ChannelType, CreatedBy)
         VALUES (?, ?, ?, 'direct', ?)",
        [
            $channelName,
            $displayName,
            'VC Gateway DM between visitor and host',
            $hostAddress,
        ]
    );

    $dmChannelId = (int)lastInsertId();

    // Add the host as a member
    queryTimed(
        "INSERT INTO Hub_ChannelMembers (ChannelID, AgentAddress, Role)
         VALUES (?, ?, 'owner')",
        [$dmChannelId, $hostAddress]
    );

    // Link the DM channel to the visitor
    queryTimed(
        "UPDATE Hub_Visitors SET DMChannelID = ? WHERE ID = ?",
        [$dmChannelId, $visitorId]
    );
}

// Send the message
// Visitor sender address format: "visitor:{visitorId}:{displayName}"
$senderAddress = 'visitor:' . $visitorId . ':' . $visitor['DisplayName'];

queryTimed(
    "INSERT INTO Hub_Messages (ChannelID, SenderAddress, Content)
     VALUES (?, ?, ?)",
    [$dmChannelId, $senderAddress, $content]
);

$messageId = (int)lastInsertId();

jsonResponse([
    'OK' => true,
    'MessageID' => $messageId,
    'DMChannelID' => $dmChannelId,
    'CreatedAt' => toISO8601(date('Y-m-d H:i:s')),
]);