<?php
/**
 * GET /api/hub/channels/list.php
 *
 * List channels with optional filters.
 *
 * Query params:
 *   ChannelType  string  optional  filter by type (public|private|direct)
 *   Agent        string  optional  only channels this agent is a member of
 *   IncludeArchived  1|0  optional  include archived channels (default: 0)
 *   Limit        int     optional  max results (default: 50, max: 200)
 *   Offset       int     optional  pagination offset (default: 0)
 *
 * Response: { OK: true, Channels: [...], Total: int }
 */

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

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

$channelType = trim($_GET['ChannelType'] ?? '');
$agent = trim($_GET['Agent'] ?? '');
$includeArchived = ($_GET['IncludeArchived'] ?? '0') === '1';
$limit = min(max((int) ($_GET['Limit'] ?? 50), 1), 200);
$offset = max((int) ($_GET['Offset'] ?? 0), 0);

$where = [];
$params = [];

if (!$includeArchived) {
    $where[] = 'c.IsArchived = 0';
}

if ($channelType !== '' && in_array($channelType, ['public', 'private', 'direct'], true)) {
    $where[] = 'c.ChannelType = ?';
    $params[] = $channelType;
}

$join = '';
if ($agent !== '') {
    $join = 'INNER JOIN Hub_ChannelMembers m ON m.ChannelID = c.ID AND m.AgentAddress = ?';
    array_unshift($params, $agent);
}

$whereClause = count($where) > 0 ? 'WHERE ' . implode(' AND ', $where) : '';

// Count total
$countSql = "SELECT COUNT(*) AS cnt FROM Hub_Channels c $join $whereClause";
$countRow = queryOne($countSql, $params);
$total = (int) ($countRow['cnt'] ?? 0);

// Fetch page
$dataSql = "SELECT c.*, (SELECT COUNT(*) FROM Hub_ChannelMembers WHERE ChannelID = c.ID) AS MemberCount
            FROM Hub_Channels c $join $whereClause
            ORDER BY c.CreatedAt DESC LIMIT ? OFFSET ?";
$dataParams = array_merge($params, [$limit, $offset]);
$rows = queryTimed($dataSql, $dataParams);

$channels = [];
foreach ($rows as $r) {
    $channels[] = [
        'ID'          => (int) $r['ID'],
        'Name'        => $r['Name'],
        'DisplayName' => $r['DisplayName'],
        'Purpose'     => $r['Purpose'],
        'ChannelType' => $r['ChannelType'],
        'CreatedBy'   => $r['CreatedBy'],
        'IsArchived'  => (bool) $r['IsArchived'],
        'CreatedAt'   => toISO8601($r['CreatedAt']),
        'UpdatedAt'   => toISO8601($r['UpdatedAt']),
        'MemberCount' => (int) $r['MemberCount'],
    ];
}

jsonResponse(['OK' => true, 'Channels' => $channels, 'Total' => $total]);