<?php
/**
 * GET /api/hub/vcgateway/dm/messages.php
 *
 * List messages in the visitor's DM channel with the host.
 * Authenticated via X-Visitor-Token header.
 *
 * Query params:
 *   Before   int   optional  Cursor: messages before this ID
 *   After    int   optional  Cursor: messages after this ID
 *   Limit    int   optional  Max messages (default: 50, max: 100)
 *
 * Response:
 *   OK, Messages[], DMChannelID, HasMore
 */

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

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

$visitor = requireVisitorAuth();

$dmChannelId = $visitor['DMChannelID'] ? (int)$visitor['DMChannelID'] : null;

// No DM channel yet = no messages
if (!$dmChannelId) {
    jsonResponse([
        'OK' => true,
        'Messages' => [],
        'DMChannelID' => null,
        'HasMore' => false,
    ]);
}

// Pagination
$before = (int)($_GET['Before'] ?? 0);
$after = (int)($_GET['After'] ?? 0);
$limit = min(100, max(1, (int)($_GET['Limit'] ?? 50)));

$where = ['m.ChannelID = ?', 'm.IsDeleted = 0'];
$params = [$dmChannelId];

if ($before > 0) {
    $where[] = 'm.ID < ?';
    $params[] = $before;
}
if ($after > 0) {
    $where[] = 'm.ID > ?';
    $params[] = $after;
}

$whereClause = implode(' AND ', $where);
$fetchLimit = $limit + 1;
$order = ($after > 0) ? 'ASC' : 'DESC';

$rows = queryTimed(
    "SELECT m.ID, m.SenderAddress, m.Content, m.IsEdited, m.CreatedAt
     FROM Hub_Messages m
     WHERE $whereClause
     ORDER BY m.ID $order
     LIMIT $fetchLimit",
    $params
);

$hasMore = count($rows) > $limit;
if ($hasMore) {
    array_pop($rows);
}

if ($after > 0) {
    $rows = array_reverse($rows);
}

$visitorId = (int)$visitor['ID'];
$messages = [];
foreach ($rows as $row) {
    // Determine if sender is visitor or host
    $isVisitor = str_starts_with($row['SenderAddress'], 'visitor:');
    $senderName = $isVisitor ? $visitor['DisplayName'] : $row['SenderAddress'];

    if (!$isVisitor) {
        // Resolve agent name
        $agent = queryOne(
            "SELECT AgentName FROM Sprinter_Agents WHERE FullAddress = ? LIMIT 1",
            [$row['SenderAddress']]
        );
        if ($agent) {
            $senderName = $agent['AgentName'];
        }
    }

    $messages[] = [
        'ID' => (int)$row['ID'],
        'SenderAddress' => $row['SenderAddress'],
        'SenderName' => $senderName,
        'IsVisitor' => $isVisitor,
        'Content' => $row['Content'],
        'IsEdited' => (bool)$row['IsEdited'],
        'CreatedAt' => toISO8601($row['CreatedAt']),
    ];
}

jsonResponse([
    'OK' => true,
    'Messages' => $messages,
    'DMChannelID' => $dmChannelId,
    'HasMore' => $hasMore,
]);