<?php
/**
 * API - Obtener mensajes de un usuario específico
 * Fecha: 4 de enero de 2026
 */

require_once '../config/config.php';

// Verificar autenticación
requireAuthentication();

header('Content-Type: application/json; charset=utf-8');
header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: GET');
header('Access-Control-Allow-Headers: Content-Type');

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

    // Paginación: limit y before (timestamp) - cargamos N mensajes anteriores a 'before'
    $limit = isset($_GET['limit']) ? intval($_GET['limit']) : 50;
    $limit = max(1, min(200, $limit));
    $before = !empty($_GET['before']) ? $_GET['before'] : null; // expect timestamp string

    $db = Database::getInstance();

    // Construir consulta: obtener mensajes ordenados DESC (más recientes primero) y limitar
    $sql = "SELECT 
            id,
            user_id,
            COALESCE(content, message_text) as content,
            message_id,
            c.media_url,
            u.phone_number as user_phone,
            direction,
            message_type,
            status,
            created_at,
            COALESCE(c.is_read, 0) as is_read
         FROM conversations c 
         LEFT JOIN users u ON c.user_id = u.id
         WHERE user_id = :user_id";

    $params = ['user_id' => $userId];
    if ($before) {
        $sql .= " AND created_at < :before";
        $params['before'] = $before;
    }

    $sql .= " ORDER BY created_at DESC LIMIT " . $limit;

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

    // Si no hay mensajes, devolver array vacío
    if (empty($conversations)) {
        echo json_encode(['success' => true, 'data' => [], 'has_more' => false]);
        exit;
    }

    // Queremos devolver los mensajes en orden cronológico ascendente para la UI
    $conversations = array_reverse($conversations);

    // Indicar si hay más mensajes anteriores (si la consulta original devolvió exactamente $limit, podría haber más)
    $hasMore = count($conversations) >= 1 && count($conversations) == $limit ? true : false;
    
    // Si no hay mensajes en conversations, intentar con conversations
    if (empty($conversations)) {
        $conversations = $db->fetchAll(
            "SELECT 
                id,
                user_id,
                message_text as content,
                direction,
                message_type,
                status,
                created_at
             FROM conversations 
             WHERE user_id = :user_id
             ORDER BY created_at ASC",
            ['user_id' => $userId]
        );
    }
    
    // Formatear fechas y limpiar datos
    $conversations = array_map(function($msg) {
        $external = (isset($msg['media_url']) && $msg['media_url']) ? (preg_match('#^https?://#i', $msg['media_url']) ? $msg['media_url'] : ("api/get_media.php?id=" . urlencode($msg['media_url']))) : null;
        $contentStr = $msg['content'] ?? '';
        if (!$external && $contentStr) {
            $j = json_decode($contentStr, true);
            if (is_array($j)) {
                foreach (['image','document','audio','video'] as $k) {
                    if (isset($j[$k]) && is_array($j[$k])) {
                        if (!empty($j[$k]['link'])) { $external = $j[$k]['link']; break; }
                        if (!empty($j[$k]['url'])) { $external = $j[$k]['url']; break; }
                        if (!empty($j[$k]['id'])) { $external = "api/get_media.php?id=" . urlencode($j[$k]['id']); break; }
                    }
                }
                if (!$external && !empty($j['link'])) $external = $j['link'];
            }
        }

        return [
            'id' => intval($msg['id']),
            'user_id' => intval($msg['user_id']),
            'content' => $msg['content'] ?? '',
            'message_id' => $msg['message_id'] ?? null,
            'media_url' => null,
            'local_file' => $msg['local_file'] ?? null,
            'local_thumb' => $msg['local_thumb'] ?? null,
            'media_url_external' => $external,
            'filename' => $msg['filename'] ?? null,
            'mime_type' => $msg['mime_type'] ?? null,
            'user_phone' => $msg['user_phone'] ?? null,
            'direction' => $msg['direction'] ?? 'incoming',
            'message_type' => $msg['message_type'] ?? 'text',
            'status' => $msg['status'] ?? 'sent',
            'created_at' => $msg['created_at']
        ];
    }, $conversations);

    // earliest message timestamp (para paginación hacia atrás)
    $earliest = $conversations[0]['created_at'] ?? null;

    echo json_encode(['success' => true, 'data' => $conversations, 'has_more' => $hasMore, 'earliest' => $earliest]);
    
} catch (Exception $e) {
    error_log("Error in get_user_conversations.php: " . $e->getMessage());
    http_response_code(500);
    echo json_encode(['error' => 'Error interno del servidor']);
}
?>