#include <string.h>
#include <stropts.h>
#include <sys/select.h>
#include <unistd.h>
#include <bluetooth/bluetooth.h>
#include <bluetooth/hci.h>
#include <bluetooth/hci_lib.h>
#include <bluetooth/l2cap.h>
#include <map>
#include <sstream>
#include <iomanip>

#include "Bluetooth.h"

// Got to love magic constants. Taken from bluez.git/tools/btgatt-client.c
#define ATT_CID 4

#define MAX_MTU 256

namespace trygvis {
namespace bluetooth {
namespace linux {

class LinuxBluetoothDevice;

class LinuxBluetoothAdapter;

class LinuxBluetoothManager;

class LinuxBluetoothAdapter : public BluetoothAdapter {
public:
    LinuxBluetoothAdapter(int hciDeviceId);

    ~LinuxBluetoothAdapter();

    void runScan(void (*callback)(BluetoothDevice &device));

    BluetoothDevice &getDevice(Mac &mac) override;

private:
    void startScan();

    void stopScan();

    int hciDeviceId;
    int hciSocket;
    struct hci_filter hciFilter;
    bool scanning;

    map<Mac, LinuxBluetoothDevice *> devices;
};

class LinuxBluetoothDevice : public BluetoothDevice {
public:
    LinuxBluetoothDevice(LinuxBluetoothAdapter &adapter, Mac mac);

    Mac const &mac() override;

    LinuxBluetoothAdapter &adapter() override;

    void connect() override;

    void disconnect() override;

    void discoverServices() override;

private:
    LinuxBluetoothAdapter &_adapter;
    Mac _mac;
    int l2cap;
};

// Utilities

string errnoAsString() {
    return string(strerror(errno));
};

// -----------------------------------------------------------------------
// Mac
// -----------------------------------------------------------------------

Mac parseMac(bdaddr_t &a) {
    return Mac(a.b[0], a.b[1], a.b[2], a.b[3], a.b[4], a.b[5]);
}

// -----------------------------------------------------------------------
// Device
// -----------------------------------------------------------------------

LinuxBluetoothDevice::LinuxBluetoothDevice(LinuxBluetoothAdapter &adapter, Mac mac) :
        _adapter(adapter), _mac(mac) {
}

Mac const &LinuxBluetoothDevice::mac() {
    return _mac;
}

LinuxBluetoothAdapter &LinuxBluetoothDevice::adapter() {
    return _adapter;
}

void LinuxBluetoothDevice::connect() {
    struct sockaddr_l2 addr;

    D << "connect: mac=" << _mac.str();

    l2cap = socket(PF_BLUETOOTH, SOCK_SEQPACKET, BTPROTO_L2CAP);
    if (l2cap < 0) {
        throw BluetoothException(this, "LinuxBluetoothDevice::connect(): socket(): " + errnoAsString());
    }

    memset(&addr, 0, sizeof(addr));
    addr.l2_family = AF_BLUETOOTH;
    addr.l2_bdaddr = {{0, 0, 0, 0, 0, 0}};
    addr.l2_cid = htobs(ATT_CID);
    addr.l2_bdaddr_type = BDADDR_LE_PUBLIC;

    if (bind(l2cap, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
        close(l2cap);
        throw BluetoothException(this, "LinuxBluetoothDevice::connect(): bind(): " + errnoAsString());
    }

    struct bt_security btsec;
    memset(&btsec, 0, sizeof(btsec));
    btsec.level = BT_SECURITY_LOW;
    if (setsockopt(l2cap, SOL_BLUETOOTH, BT_SECURITY, &btsec, sizeof(btsec)) != 0) {
        close(l2cap);
        throw BluetoothException(this, "LinuxBluetoothDevice::connect(): setsockopt(): " + errnoAsString());
    }

    memset(&addr, 0, sizeof(addr));
    addr.l2_family = AF_BLUETOOTH;
    addr.l2_cid = htobs(ATT_CID);
    addr.l2_bdaddr_type = BDADDR_LE_RANDOM;
    _mac.copy(addr.l2_bdaddr.b[5],
            addr.l2_bdaddr.b[4],
            addr.l2_bdaddr.b[3],
            addr.l2_bdaddr.b[2],
            addr.l2_bdaddr.b[1],
            addr.l2_bdaddr.b[0]);

    if (::connect(l2cap, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
        close(l2cap);
        throw BluetoothException(this, "LinuxBluetoothDevice::connect(): connect(): " + errnoAsString());
    }
}

void LinuxBluetoothDevice::disconnect() {
    DF << "mac=" << _mac.str();
    close(l2cap);
}

void LinuxBluetoothDevice::discoverServices() {
    DF;

    uint8_t buffer[MAX_MTU];
    ByteBuffer out = ByteBuffer(buffer, MAX_MTU, 0);

    AttPdu::makeReadByGroupType(out, 0x0001, 0xffff, UUID_PRIMARY_SERVICE);

    D << "pdu.size()=" << out.getSize();
    ssize_t written = write(l2cap, buffer, out.getSize());

    D << "written=" << written;

    ssize_t r = read(l2cap, buffer, MAX_MTU);
    ByteBuffer in = ByteBuffer(buffer, MAX_MTU, r);

    D << "read: " << r << " bytes";

    vector<AttributeData> values = AttPdu::parseReadByGroupType(in);

    D << "READ_BY_GROUP_TYPE response has " + to_string(values.size()) + " values";

    for (auto &data: values) {
        D << "handle: " << data.handle << ", groupEndHandle: " << data.groupEndHandle << ", value: " << data.value.toString();
    }
}

// -----------------------------------------------------------------------
// Adapter
// -----------------------------------------------------------------------

LinuxBluetoothAdapter::LinuxBluetoothAdapter(int hciDeviceId) :
        scanning(false) {
    DF << "hciDeviceId=" << hciDeviceId;

    this->hciDeviceId = hciDeviceId;
    hciSocket = ::hci_open_dev(hciDeviceId);

    D << "HCI socket: " << hciSocket;

    if (hciSocket == -1) {
        throw BluetoothException(this, "Could not open HCI device " + hciDeviceId);
    }

    hci_filter_clear(&hciFilter);
    hci_filter_set_ptype(HCI_EVENT_PKT, &hciFilter);
    hci_filter_set_event(EVT_LE_META_EVENT, &hciFilter);
    hci_filter_set_event(EVT_LE_ADVERTISING_REPORT, &hciFilter);
    setsockopt(hciSocket, SOL_HCI, HCI_FILTER, &hciFilter, sizeof(hciFilter));
}

LinuxBluetoothAdapter::~LinuxBluetoothAdapter() {
    DF;

    stopScan();

    close(hciSocket);

    D << "Depeting " << devices.size() << " devices";

    for (auto &pair : devices) {
        delete pair.second;
    }
}

void LinuxBluetoothAdapter::startScan() {
    DF;

    struct hci_dev_info di;

    if (hci_devinfo(hciDeviceId, &di) < 0) {
        throw BluetoothException(this, "hci_devinfo: " + hciDeviceId);
    }

    D << "hciDeviceId.dev_id=" << di.dev_id;
    D << "hciDeviceId.bdaddr=" << parseMac(di.bdaddr).str();
    D << "hciDeviceId.flags=" << hex << setw(8) << setfill('0') << di.flags;
    D << "hciDeviceId.flags RUNNING = " << hci_test_bit(HCI_RUNNING, &di.flags);
    D << "hciDeviceId.flags UP      = " << hci_test_bit(HCI_UP, &di.flags);
    D << "hciDeviceId.flags PSCAN   = " << hci_test_bit(HCI_PSCAN, &di.flags);
    D << "hciDeviceId.flags ISCAN   = " << hci_test_bit(HCI_ISCAN, &di.flags);
    D << "hciDeviceId.name=" << di.name;

    int up = hci_test_bit(HCI_UP, &di.flags);

    if (!up) {
        throw BluetoothException(this, "HCI adapter is not up: " + hciDeviceId);
    }

    if (hci_le_set_scan_parameters(hciSocket, 0x01, htobs(0x0010), htobs(0x0010), 0x00, 0, 1000) < 0) {
        throw BluetoothException(this, "hci_le_set_scan_parameters: " + errnoAsString());
    }

    if (hci_le_set_scan_enable(hciSocket, 1, 0, 1000)) {
        throw BluetoothException(this, "Could not start scanning: other" + errnoAsString());
    }

    scanning = true;
}

void LinuxBluetoothAdapter::stopScan() {
    DF;

    if (!scanning) {
        return;
    }

    scanning = false;

    if (hci_le_set_scan_enable(hciSocket, 0, 0, 1000) < 0) {
        W << "stopScan: hci_le_set_scan_enable: " << errnoAsString();
    }
}

BluetoothDevice &LinuxBluetoothAdapter::getDevice(Mac &mac) {
    map<Mac, LinuxBluetoothDevice *>::iterator it = devices.find(mac);

    if (it == devices.end()) {
        LinuxBluetoothDevice *device = new LinuxBluetoothDevice(*this, mac);
        devices[mac] = device;
        return *device;
    }

    return *it->second;
}

void LinuxBluetoothAdapter::runScan(void (*callback)(BluetoothDevice &device)) {
    fd_set rfds;
    FD_ZERO(&rfds);
    FD_SET(hciSocket, &rfds);

    startScan();

    while (scanning) {
        // Linux can change tv, so it has to be reinitialized
        struct timeval tv;
        tv.tv_sec = 1;
        tv.tv_usec = 0;

        int selected = select(hciSocket + 1, &rfds, NULL, NULL, &tv);

        if (selected == -1) {
            throw BluetoothException(this, "select() failed");
        }

        if (selected == 0) {
            D << "timeout";
            // Timeout, just continue
            continue;
        }

        unsigned char hciEventBuf[HCI_MAX_EVENT_SIZE];

        ssize_t len = read(hciSocket, hciEventBuf, sizeof(hciEventBuf));
        evt_le_meta_event *metaEvent = (evt_le_meta_event *) (hciEventBuf + (1 + HCI_EVENT_HDR_SIZE));
        len -= (1 + HCI_EVENT_HDR_SIZE);

        D << "metaEvent->subevent = " << std::hex << (int) metaEvent->subevent;

        if (metaEvent->subevent == EVT_LE_ADVERTISING_REPORT) {
            le_advertising_info *advertisingInfo = (le_advertising_info *) (metaEvent->data + 1);

            Mac mac = parseMac(advertisingInfo->bdaddr);

            BluetoothDevice &device = getDevice(mac);

            callback(device);
        }
    }
}

}}}

// -----------------------------------------------------------------------
// Implementation of platform-specific method.
// -----------------------------------------------------------------------

namespace trygvis {
namespace bluetooth {
using namespace trygvis::bluetooth::linux;

map<int, LinuxBluetoothAdapter *> adapters;

LinuxBluetoothAdapter &getAdapterImpl(int hciDevice) {
    map<int, LinuxBluetoothAdapter *>::iterator it = adapters.find(hciDevice);

    if (it == adapters.end()) {
        LinuxBluetoothAdapter *adapter = new LinuxBluetoothAdapter(hciDevice);
        adapters[hciDevice] = adapter;
        return *adapter;
    }

    return *it->second;
}

void shutdownImpl() {
    for (auto &pair: adapters) {
        delete pair.second;
    }
}

}}