<?php
/**
 * GET /api/hub/messages/list.php
 *
 * Get messages for a channel, paginated, newest first.
 *
 * Query params:
 *   ChannelID  int     REQUIRED
 *   Limit      int     optional  default 50, max 200
 *   Before     int     optional  message ID — get messages before this ID (cursor pagination)
 *   After      int     optional  message ID — get messages after this ID
 *
 * Response: { OK: true, Messages: [...], HasMore: bool }
 */

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

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

$channelId = (int) ($_GET['ChannelID'] ?? 0);
$limit = min(max((int) ($_GET['Limit'] ?? 50), 1), 200);
$before = isset($_GET['Before']) ? (int) $_GET['Before'] : null;
$after = isset($_GET['After']) ? (int) $_GET['After'] : null;

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

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

// Build query
$sql = "SELECT * FROM Hub_Messages WHERE ChannelID = ? AND IsDeleted = 0 AND ParentID IS NULL";
$params = [$channelId];

if ($before !== null) {
    $sql .= " AND ID < ?";
    $params[] = $before;
}
if ($after !== null) {
    $sql .= " AND ID > ?";
    $params[] = $after;
}

if ($after !== null) {
    $sql .= " ORDER BY ID ASC LIMIT ?";
} else {
    $sql .= " ORDER BY ID DESC LIMIT ?";
}
$params[] = $limit + 1; // fetch one extra to determine HasMore

$rows = queryTimed($sql, $params);
$hasMore = count($rows) > $limit;
if ($hasMore) array_pop($rows);

// If we used ASC (After), reverse for consistent newest-first output
if ($after !== null) {
    $rows = array_reverse($rows);
}

$messages = [];
foreach ($rows as $row) {
    // Get reply count for each root message
    $replyCount = queryOne(
        "SELECT COUNT(*) as cnt FROM Hub_Messages WHERE ParentID = ? AND IsDeleted = 0",
        [(int) $row['ID']]
    );

    $messages[] = [
        'ID'            => (int) $row['ID'],
        'ChannelID'     => (int) $row['ChannelID'],
        'SenderAddress' => $row['SenderAddress'],
        'Content'       => $row['Content'],
        'ParentID'      => null,
        'IsEdited'      => (bool) $row['IsEdited'],
        'ReplyCount'    => (int) ($replyCount['cnt'] ?? 0),
        'CreatedAt'     => toISO8601($row['CreatedAt']),
        'UpdatedAt'     => toISO8601($row['UpdatedAt']),
    ];
}

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