<?php
/**
 * GET /api/hub/channels/stats.php
 *
 * Get channel statistics: member count, message count, pinned count, unread count.
 *
 * Query params:
 *   ChannelID     int     REQUIRED
 *   AgentAddress  string  optional  if provided, includes unread count for this agent
 *
 * Response: { OK: true, Stats: { ... } }
 */

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

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

$channelId = (int) ($_GET['ChannelID'] ?? 0);
$agentAddress = trim($_GET['AgentAddress'] ?? '');

if ($channelId <= 0) jsonResponse(['OK' => false, 'ERROR' => 'channel_id_required']);

$channel = queryOne("SELECT ID FROM Hub_Channels WHERE ID = ?", [$channelId]);
if (!$channel) jsonResponse(['OK' => false, 'ERROR' => 'channel_not_found']);

$memberCount = (int) (queryOne(
    "SELECT COUNT(*) as cnt FROM Hub_ChannelMembers WHERE ChannelID = ?",
    [$channelId]
)['cnt'] ?? 0);

$messageCount = (int) (queryOne(
    "SELECT COUNT(*) as cnt FROM Hub_Messages WHERE ChannelID = ? AND IsDeleted = 0",
    [$channelId]
)['cnt'] ?? 0);

$pinnedCount = (int) (queryOne(
    "SELECT COUNT(*) as cnt FROM Hub_PinnedPosts WHERE ChannelID = ?",
    [$channelId]
)['cnt'] ?? 0);

$unreadCount = 0;
if ($agentAddress !== '') {
    $membership = queryOne(
        "SELECT LastViewedAt FROM Hub_ChannelMembers WHERE ChannelID = ? AND AgentAddress = ?",
        [$channelId, $agentAddress]
    );
    if ($membership && $membership['LastViewedAt']) {
        $unreadCount = (int) (queryOne(
            "SELECT COUNT(*) as cnt FROM Hub_Messages
             WHERE ChannelID = ? AND IsDeleted = 0 AND CreatedAt > ?",
            [$channelId, $membership['LastViewedAt']]
        )['cnt'] ?? 0);
    } elseif ($membership) {
        // Never viewed — all messages are unread
        $unreadCount = $messageCount;
    }
}

jsonResponse([
    'OK' => true,
    'Stats' => [
        'ChannelID'    => $channelId,
        'MemberCount'  => $memberCount,
        'MessageCount' => $messageCount,
        'PinnedCount'  => $pinnedCount,
        'UnreadCount'  => $unreadCount,
    ],
]);