/*
 * Copyright (C) 2020 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "pairing_client.h"

#include <netdb.h>
#include <netinet/tcp.h>

#include <atomic>
#include <iomanip>
#include <mutex>
#include <sstream>
#include <thread>
#include <vector>

#include <android-base/logging.h>
#include <android-base/parsenetaddress.h>
#include <android-base/stringprintf.h>
#include <android-base/thread_annotations.h>
#include <android-base/unique_fd.h>
#include <cutils/sockets.h>

namespace adb {
namespace pairing {

using android::base::unique_fd;

static void ConnectionDeleter(PairingConnectionCtx* p) {
    pairing_connection_destroy(p);
}
using ConnectionPtr = std::unique_ptr<PairingConnectionCtx, decltype(&ConnectionDeleter)>;

namespace {

class PairingClientImpl : public PairingClient {
  public:
    explicit PairingClientImpl(const Data& pswd, const PeerInfo& peer_info, const Data& cert,
                               const Data& priv_key);

    // Starts the pairing client. This call is non-blocking. Upon pairing
    // completion, |cb| will be called with the PeerInfo on success,
    // or an empty value on failure.
    //
    // Returns true if PairingClient was successfully started. Otherwise,
    // return false.
    virtual bool Start(std::string_view ip_addr, pairing_client_result_cb cb,
                       void* opaque) override;

  private:
    static ConnectionPtr CreatePairingConnection(const Data& pswd, const PeerInfo& peer_info,
                                                 const Data& cert, const Data& priv_key);

    static void PairingResultCallback(const PeerInfo* peer_info, int fd, void* opaque);
    // Setup and start the PairingConnection
    bool StartConnection();

    enum class State {
        Ready,
        Running,
        Stopped,
    };

    State state_ = State::Ready;
    Data pswd_;
    PeerInfo peer_info_;
    Data cert_;
    Data priv_key_;
    std::string host_;
    int port_;

    ConnectionPtr connection_;
    pairing_client_result_cb cb_;
    void* opaque_ = nullptr;
};  // PairingClientImpl

// static
ConnectionPtr PairingClientImpl::CreatePairingConnection(const Data& pswd,
                                                         const PeerInfo& peer_info,
                                                         const Data& cert, const Data& priv_key) {
    return ConnectionPtr(
            pairing_connection_client_new(pswd.data(), pswd.size(), &peer_info, cert.data(),
                                          cert.size(), priv_key.data(), priv_key.size()),
            ConnectionDeleter);
}

PairingClientImpl::PairingClientImpl(const Data& pswd, const PeerInfo& peer_info, const Data& cert,
                                     const Data& priv_key)
    : pswd_(pswd),
      peer_info_(peer_info),
      cert_(cert),
      priv_key_(priv_key),
      connection_(nullptr, ConnectionDeleter) {
    CHECK(!pswd_.empty() && !cert_.empty() && !priv_key_.empty());

    state_ = State::Ready;
}

bool PairingClientImpl::Start(std::string_view ip_addr, pairing_client_result_cb cb, void* opaque) {
    CHECK(!ip_addr.empty());
    cb_ = cb;
    opaque_ = opaque;

    if (state_ != State::Ready) {
        LOG(ERROR) << "PairingClient already running or finished";
        return false;
    }

    // Try to parse the host address
    std::string err;
    CHECK(android::base::ParseNetAddress(std::string(ip_addr), &host_, &port_, nullptr, &err));
    CHECK(port_ > 0 && port_ <= 65535);

    if (!StartConnection()) {
        LOG(ERROR) << "Unable to start PairingClient connection";
        state_ = State::Stopped;
        return false;
    }

    state_ = State::Running;
    return true;
}

static int network_connect(const std::string& host, int port, int type, int timeout,
                           std::string* error) {
    int getaddrinfo_error = 0;
    int fd = socket_network_client_timeout(host.c_str(), port, type, timeout, &getaddrinfo_error);
    if (fd != -1) {
        return fd;
    }
    if (getaddrinfo_error != 0) {
        *error = android::base::StringPrintf("failed to resolve host: '%s': %s", host.c_str(),
                                             gai_strerror(getaddrinfo_error));
        LOG(WARNING) << *error;
    } else {
        *error = android::base::StringPrintf("failed to connect to '%s:%d': %s", host.c_str(), port,
                                             strerror(errno));
        LOG(WARNING) << *error;
    }
    return -1;
}

// static
void PairingClientImpl::PairingResultCallback(const PeerInfo* peer_info, int /* fd */,
                                              void* opaque) {
    auto* p = reinterpret_cast<PairingClientImpl*>(opaque);
    p->cb_(peer_info, p->opaque_);
}

bool PairingClientImpl::StartConnection() {
    std::string err;
    const int timeout = 10;  // seconds
    unique_fd fd(network_connect(host_, port_, SOCK_STREAM, timeout, &err));
    if (fd.get() == -1) {
        LOG(ERROR) << "Failed to start pairing connection client [" << err << "]";
        return false;
    }
    int off = 1;
    setsockopt(fd.get(), IPPROTO_TCP, TCP_NODELAY, &off, sizeof(off));

    connection_ = CreatePairingConnection(pswd_, peer_info_, cert_, priv_key_);
    if (connection_ == nullptr) {
        LOG(ERROR) << "PairingClient unable to create a PairingConnection";
        return false;
    }

    if (!pairing_connection_start(connection_.get(), fd.release(), PairingResultCallback, this)) {
        LOG(ERROR) << "PairingClient failed to start the PairingConnection";
        state_ = State::Stopped;
        return false;
    }

    return true;
}

}  // namespace

// static
std::unique_ptr<PairingClient> PairingClient::Create(const Data& pswd, const PeerInfo& peer_info,
                                                     const Data& cert, const Data& priv_key) {
    CHECK(!pswd.empty());
    CHECK(!cert.empty());
    CHECK(!priv_key.empty());

    return std::unique_ptr<PairingClient>(new PairingClientImpl(pswd, peer_info, cert, priv_key));
}

}  // namespace pairing
}  // namespace adb