//===-- PlatformAndroidRemoteGDBServer.cpp ----------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

// Other libraries and framework includes
#include "lldb/Core/Error.h"
#include "lldb/Core/Log.h"
#include "lldb/Host/common/TCPSocket.h"
#include "lldb/Host/ConnectionFileDescriptor.h"

#include "PlatformAndroidRemoteGDBServer.h"
#include "Utility/UriParser.h"

#include <sstream>

using namespace lldb;
using namespace lldb_private;
using namespace platform_android;

static const lldb::pid_t g_remote_platform_pid = 0; // Alias for the process id of lldb-platform

static Error
ForwardPortWithAdb (const uint16_t local_port,
                    const uint16_t remote_port,
                    const char* remote_socket_name,
                    const llvm::Optional<AdbClient::UnixSocketNamespace>& socket_namespace,
                    std::string& device_id)
{
    Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_PLATFORM));

    AdbClient adb;
    auto error = AdbClient::CreateByDeviceID(device_id, adb);
    if (error.Fail ())
        return error;

    device_id = adb.GetDeviceID();
    if (log)
        log->Printf("Connected to Android device \"%s\"", device_id.c_str ());

    if (remote_port != 0)
    {
        if (log)
            log->Printf("Forwarding remote TCP port %d to local TCP port %d", remote_port, local_port);
        return adb.SetPortForwarding(local_port, remote_port);
    }

    if (log)
        log->Printf("Forwarding remote socket \"%s\" to local TCP port %d", remote_socket_name, local_port);

    if (!socket_namespace)
        return Error("Invalid socket namespace");

    return adb.SetPortForwarding(local_port, remote_socket_name, *socket_namespace);
}

static Error
DeleteForwardPortWithAdb (uint16_t local_port, const std::string& device_id)
{
    AdbClient adb (device_id);
    return adb.DeletePortForwarding (local_port);
}

static Error
FindUnusedPort (uint16_t& port)
{
    Error error;
    std::unique_ptr<TCPSocket> tcp_socket(new TCPSocket(false, error));
    if (error.Fail())
        return error;

    error = tcp_socket->Listen("127.0.0.1:0", 1);
    if (error.Success())
        port = tcp_socket->GetLocalPortNumber();

    return error;
}

PlatformAndroidRemoteGDBServer::PlatformAndroidRemoteGDBServer ()
{
}

PlatformAndroidRemoteGDBServer::~PlatformAndroidRemoteGDBServer ()
{
    for (const auto& it : m_port_forwards)
        DeleteForwardPortWithAdb(it.second, m_device_id);
}

bool
PlatformAndroidRemoteGDBServer::LaunchGDBServer (lldb::pid_t &pid, std::string &connect_url)
{
    uint16_t remote_port = 0;
    std::string socket_name;
    if (!m_gdb_client.LaunchGDBServer ("127.0.0.1", pid, remote_port, socket_name))
        return false;

    Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_PLATFORM));

    auto error = MakeConnectURL (pid,
                                 remote_port,
                                 socket_name.c_str (),
                                 connect_url);
    if (error.Success() && log)
        log->Printf("gdbserver connect URL: %s", connect_url.c_str());

    return error.Success();
}

bool
PlatformAndroidRemoteGDBServer::KillSpawnedProcess (lldb::pid_t pid)
{
    DeleteForwardPort (pid);
    return m_gdb_client.KillSpawnedProcess (pid);
}

Error
PlatformAndroidRemoteGDBServer::ConnectRemote (Args& args)
{
    m_device_id.clear();

    if (args.GetArgumentCount() != 1)
        return Error("\"platform connect\" takes a single argument: <connect-url>");

    int remote_port;
    std::string scheme, host, path;
    const char *url = args.GetArgumentAtIndex (0);
    if (!url)
        return Error("URL is null.");
    if (!UriParser::Parse (url, scheme, host, remote_port, path))
        return Error("Invalid URL: %s", url);
    if (host != "localhost")
        m_device_id = host;

    m_socket_namespace.reset();
    if (scheme == ConnectionFileDescriptor::UNIX_CONNECT_SCHEME)
        m_socket_namespace = AdbClient::UnixSocketNamespaceFileSystem;
    else if (scheme == ConnectionFileDescriptor::UNIX_ABSTRACT_CONNECT_SCHEME)
        m_socket_namespace = AdbClient::UnixSocketNamespaceAbstract;

    std::string connect_url;
    auto error = MakeConnectURL (g_remote_platform_pid,
                                 (remote_port < 0) ? 0 : remote_port,
                                 path.c_str (),
                                 connect_url);

    if (error.Fail ())
        return error;

    args.ReplaceArgumentAtIndex (0, connect_url.c_str ());

    Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_PLATFORM));
    if (log)
        log->Printf("Rewritten platform connect URL: %s", connect_url.c_str());

    error = PlatformRemoteGDBServer::ConnectRemote(args);
    if (error.Fail ())
        DeleteForwardPort (g_remote_platform_pid);

    return error;
}

Error
PlatformAndroidRemoteGDBServer::DisconnectRemote ()
{
    DeleteForwardPort (g_remote_platform_pid);
    return PlatformRemoteGDBServer::DisconnectRemote ();
}

void
PlatformAndroidRemoteGDBServer::DeleteForwardPort (lldb::pid_t pid)
{
    Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_PLATFORM));

    auto it = m_port_forwards.find(pid);
    if (it == m_port_forwards.end())
        return;

    const auto port = it->second;
    const auto error = DeleteForwardPortWithAdb(port, m_device_id);
    if (error.Fail()) {
        if (log)
            log->Printf("Failed to delete port forwarding (pid=%" PRIu64 ", port=%d, device=%s): %s",
                         pid, port, m_device_id.c_str(), error.AsCString());
    }
    m_port_forwards.erase(it);
}

Error
PlatformAndroidRemoteGDBServer::MakeConnectURL(const lldb::pid_t pid,
                                               const uint16_t remote_port,
                                               const char* remote_socket_name,
                                               std::string& connect_url)
{
    static const int kAttempsNum = 5;

    Error error;
    // There is a race possibility that somebody will occupy
    // a port while we're in between FindUnusedPort and ForwardPortWithAdb -
    // adding the loop to mitigate such problem.
    for (auto i = 0; i < kAttempsNum; ++i)
    {
        uint16_t local_port = 0;
        error = FindUnusedPort(local_port);
        if (error.Fail())
            return error;

        error = ForwardPortWithAdb(local_port,
                                   remote_port,
                                   remote_socket_name,
                                   m_socket_namespace,
                                   m_device_id);
        if (error.Success())
        {
            m_port_forwards[pid] = local_port;
            std::ostringstream url_str;
            url_str << "connect://localhost:" << local_port;
            connect_url = url_str.str();
            break;
        }
    }

    return error;
}

lldb::ProcessSP
PlatformAndroidRemoteGDBServer::ConnectProcess(const char* connect_url,
                                               const char* plugin_name,
                                               lldb_private::Debugger &debugger,
                                               lldb_private::Target *target,
                                               lldb_private::Error &error)
{
    // We don't have the pid of the remote gdbserver when it isn't started by us but we still want
    // to store the list of port forwards we set up in our port forward map. Generate a fake pid for
    // these cases what won't collide with any other valid pid on android.
    static lldb::pid_t s_remote_gdbserver_fake_pid = 0xffffffffffffffffULL;

    int remote_port;
    std::string scheme, host, path;
    if (!UriParser::Parse(connect_url, scheme, host, remote_port, path))
    {
        error.SetErrorStringWithFormat("Invalid URL: %s", connect_url);
        return nullptr;
    }

    std::string new_connect_url;
    error = MakeConnectURL(s_remote_gdbserver_fake_pid--,
                           (remote_port < 0) ? 0 : remote_port,
                           path.c_str(),
                           new_connect_url);
    if (error.Fail())
        return nullptr;

    return PlatformRemoteGDBServer::ConnectProcess(new_connect_url.c_str(),
                                                   plugin_name,
                                                   debugger,
                                                   target,
                                                   error);
}