<?php
/**
 * API - Mensajes de un contacto en el canal turnero
 * Soporta paginación hacia atrás (before / before_id) y polling (since).
 */

require_once __DIR__ . '/../../../config/config.php';
requireAuthentication();

header('Content-Type: application/json; charset=utf-8');
header('Cache-Control: no-cache, no-store, must-revalidate');

try {
    $userId = intval($_GET['user_id'] ?? 0);
    if (!$userId) {
        http_response_code(400);
        echo json_encode(['success' => false, 'error' => 'user_id requerido']);
        exit;
    }

    $limit    = max(1, min(200, intval($_GET['limit'] ?? 50)));
    $before   = !empty($_GET['before'])    ? $_GET['before']    : null;
    $beforeId = !empty($_GET['before_id']) ? intval($_GET['before_id']) : null;
    $since    = !empty($_GET['since'])     ? $_GET['since']     : null;

    $tsRegex = '/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/';
    if ($before && !preg_match($tsRegex, $before)) {
        http_response_code(400); echo json_encode(['success' => false, 'error' => 'before inválido']); exit;
    }
    if ($since && !preg_match($tsRegex, $since)) {
        http_response_code(400); echo json_encode(['success' => false, 'error' => 'since inválido']); exit;
    }

    $db     = Database::getInstance();
    $params = ['user_id' => $userId];

    $sql = "SELECT
                c.id, c.user_id, c.content, c.message_id,
                c.media_url, c.local_file, c.local_thumb,
                c.filename, c.mime_type,
                c.direction, c.message_type, c.status,
                c.created_at, COALESCE(c.is_read, 0) AS is_read,
                c.reply_to_message_id, c.reaction_emoji, c.reaction_to_message_id,
                u.phone_number AS user_phone
            FROM conversations c
            LEFT JOIN users u ON u.id = c.user_id
            WHERE c.user_id = :user_id AND c.canal = 'turnero'";

    if ($since) {
        $sql .= " AND c.created_at > :since";
        $params['since'] = $since;
        $sql .= " ORDER BY c.created_at ASC, c.id ASC LIMIT {$limit}";
    } else {
        if ($before) {
            $sql .= " AND (c.created_at < :before_lt";
            $params['before_lt'] = $before;
            if ($beforeId) {
                $sql .= " OR (c.created_at = :before_eq AND c.id < :before_id)";
                $params['before_eq'] = $before;
                $params['before_id'] = $beforeId;
            }
            $sql .= ")";
        }
        $sql .= " ORDER BY c.created_at DESC, c.id DESC LIMIT {$limit}";
    }

    $rows = $db->fetchAll($sql, $params);

    if (!$since) {
        $rows = array_reverse($rows ?: []);
    }

    $hasMore   = count($rows) === $limit;
    $earliest  = $rows[0]['created_at'] ?? null;
    $earliestId = $rows[0]['id'] ?? null;

    $data = array_map(function($m) {
        $mediaUrl  = $m['media_url'] ?? null;
        $localFile = $m['local_file'] ?? null;
        $external  = null;
        if ($mediaUrl && !$localFile) {
            // WhatsApp CDN URLs require Bearer token — always proxy through media-url.php
            if (preg_match('#^https?://#i', $mediaUrl)) {
                $external = '/api/version/media-url.php?url=' . urlencode($mediaUrl);
            } else {
                $external = '/api/version/media-url.php?id=' . urlencode($mediaUrl);
            }
        }
        return [
            'id'                     => intval($m['id']),
            'user_id'                => intval($m['user_id']),
            'content'                => $m['content'] ?? '',
            'message_id'             => $m['message_id'] ?? null,
            'local_file'             => $m['local_file'] ?? null,
            'local_thumb'            => $m['local_thumb'] ?? null,
            'media_url_external'     => $external,
            'filename'               => $m['filename'] ?? null,
            'mime_type'              => $m['mime_type'] ?? null,
            'user_phone'             => $m['user_phone'] ?? null,
            'direction'              => $m['direction'] ?? 'incoming',
            'message_type'           => $m['message_type'] ?? 'text',
            'status'                 => $m['status'] ?? 'received',
            'created_at'             => $m['created_at'],
            'is_read'                => intval($m['is_read']),
            'reply_to_message_id'    => $m['reply_to_message_id'] ?? null,
            'reaction_emoji'         => $m['reaction_emoji'] ?? null,
            'reaction_to_message_id' => $m['reaction_to_message_id'] ?? null,
        ];
    }, $rows);

    echo json_encode([
        'success'     => true,
        'data'        => $data,
        'has_more'    => $hasMore,
        'earliest'    => $earliest,
        'earliest_id' => $earliestId,
    ], JSON_UNESCAPED_UNICODE);

} catch (Exception $e) {
    error_log('chat_get_messages.php: ' . $e->getMessage());
    http_response_code(500);
    echo json_encode(['success' => false, 'error' => 'Error interno']);
}