<?php
/**
 * POST /api/hub/channels/update.php
 *
 * Update a channel's metadata.
 *
 * Body:
 *   ID           int     REQUIRED
 *   DisplayName  string  optional
 *   Purpose      string  optional
 *   IsArchived   bool    optional
 *   Agent        string  REQUIRED  requesting agent (must be admin/owner)
 *
 * Response: { OK: true, Channel: { ... } }
 */

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

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

$body = readJsonBody();

$id = (int) ($body['ID'] ?? 0);
$agent = trim($body['Agent'] ?? '');

if ($id <= 0) {
    jsonResponse(['OK' => false, 'ERROR' => 'id_required']);
}
if ($agent === '') {
    jsonResponse(['OK' => false, 'ERROR' => 'agent_required']);
}

// Verify channel exists
$channel = queryOne("SELECT * FROM Hub_Channels WHERE ID = ?", [$id]);
if (!$channel) {
    jsonResponse(['OK' => false, 'ERROR' => 'channel_not_found'], 404);
}

// Check permissions: must be admin or owner
$membership = queryOne(
    "SELECT Role FROM Hub_ChannelMembers WHERE ChannelID = ? AND AgentAddress = ?",
    [$id, $agent]
);
if (!$membership || !in_array($membership['Role'], ['admin', 'owner'], true)) {
    jsonResponse(['OK' => false, 'ERROR' => 'not_authorized'], 403);
}

// Build update fields
$sets = [];
$params = [];

if (isset($body['DisplayName'])) {
    $val = trim($body['DisplayName']);
    if (strlen($val) > 200) $val = substr($val, 0, 200);
    $sets[] = 'DisplayName = ?';
    $params[] = $val;
}

if (isset($body['Purpose'])) {
    $val = trim($body['Purpose']);
    if (strlen($val) > 500) $val = substr($val, 0, 500);
    $sets[] = 'Purpose = ?';
    $params[] = $val;
}

if (isset($body['IsArchived'])) {
    $sets[] = 'IsArchived = ?';
    $params[] = $body['IsArchived'] ? 1 : 0;
}

if (count($sets) === 0) {
    jsonResponse(['OK' => false, 'ERROR' => 'nothing_to_update']);
}

$params[] = $id;
queryTimed("UPDATE Hub_Channels SET " . implode(', ', $sets) . " WHERE ID = ?", $params);

// Fetch updated
$channel = queryOne("SELECT * FROM Hub_Channels WHERE ID = ?", [$id]);
$memberCount = queryOne("SELECT COUNT(*) AS cnt FROM Hub_ChannelMembers WHERE ChannelID = ?", [$id]);

jsonResponse([
    'OK' => true,
    'Channel' => [
        'ID'          => (int) $channel['ID'],
        'Name'        => $channel['Name'],
        'DisplayName' => $channel['DisplayName'],
        'Purpose'     => $channel['Purpose'],
        'ChannelType' => $channel['ChannelType'],
        'CreatedBy'   => $channel['CreatedBy'],
        'IsArchived'  => (bool) $channel['IsArchived'],
        'CreatedAt'   => toISO8601($channel['CreatedAt']),
        'UpdatedAt'   => toISO8601($channel['UpdatedAt']),
        'MemberCount' => (int) ($memberCount['cnt'] ?? 0),
    ],
]);