#!/usr/bin/env python3
"""PyBluez advanced example write-inquiry-scan.py"""

import struct
import sys

import bluetooth._bluetooth as bluez  # low level bluetooth wrappers

def read_inquiry_scan_activity(sock):
    """returns the current inquiry scan interval and window, 
    or -1 on failure"""
    # save current filter
    old_filter = sock.getsockopt(bluez.SOL_HCI, bluez.HCI_FILTER, 14)

    # Setup socket filter to receive only events related to the
    # read_inquiry_mode command
    flt = bluez.hci_filter_new()
    opcode = bluez.cmd_opcode_pack(bluez.OGF_HOST_CTL,
                                   bluez.OCF_READ_INQ_ACTIVITY)
    bluez.hci_filter_set_ptype(flt, bluez.HCI_EVENT_PKT)
    bluez.hci_filter_set_event(flt, bluez.EVT_CMD_COMPLETE)
    bluez.hci_filter_set_opcode(flt, opcode)
    sock.setsockopt(bluez.SOL_HCI, bluez.HCI_FILTER, flt)

    # first read the current inquiry mode.
    bluez.hci_send_cmd(sock, bluez.OGF_HOST_CTL, bluez.OCF_READ_INQ_ACTIVITY)

    pkt = sock.recv(255)

    status, interval, window = struct.unpack("!xxxxxxBHH", pkt)
    interval = bluez.btohs(interval)
    interval = (interval >> 8) | ((interval & 0xFF) << 8)
    window = (window >> 8) | ((window & 0xFF) << 8)

    # restore old filter
    sock.setsockopt(bluez.SOL_HCI, bluez.HCI_FILTER, old_filter)

    return interval, window

def write_inquiry_scan_activity(sock, interval, window):
    """returns 0 on success, -1 on failure"""
    # save current filter
    old_filter = sock.getsockopt(bluez.SOL_HCI, bluez.HCI_FILTER, 14)

    # Setup socket filter to receive only events related to the
    # write_inquiry_mode command
    flt = bluez.hci_filter_new()
    opcode = bluez.cmd_opcode_pack(bluez.OGF_HOST_CTL,
                                   bluez.OCF_WRITE_INQ_ACTIVITY)
    bluez.hci_filter_set_ptype(flt, bluez.HCI_EVENT_PKT)
    bluez.hci_filter_set_event(flt, bluez.EVT_CMD_COMPLETE)
    bluez.hci_filter_set_opcode(flt, opcode)
    sock.setsockopt(bluez.SOL_HCI, bluez.HCI_FILTER, flt)

    # send the command
    bluez.hci_send_cmd(sock, bluez.OGF_HOST_CTL, bluez.OCF_WRITE_INQ_ACTIVITY,
                       struct.pack("HH", interval, window))

    pkt = sock.recv(255)
    status = struct.unpack("xxxxxxB", pkt)[0]

    # restore old filter
    sock.setsockopt(bluez.SOL_HCI, bluez.HCI_FILTER, old_filter)
    if status:
        return -1
    return 0

dev_id = 0
try:
    sock = bluez.hci_open_dev(dev_id)
except:
    print("Error accessing bluetooth device.")
    sys.exit(1)

try:
    interval, window = read_inquiry_scan_activity(sock)
except Exception as e:
    print("Error reading inquiry scan activity.")
    print(e)
    sys.exit(1)
print("Current inquiry scan interval: {} (0x{:02x}) window: {} (0x{:02x})"
      .format(interval, interval, window, window))

if len(sys.argv) == 3:
    interval = int(sys.argv[1])
    window = int(sys.argv[2])
    print("Target interval: {} window {}".format(interval, window))
    write_inquiry_scan_activity(sock, interval, window)
    interval, window = read_inquiry_scan_activity(sock)
    print("Current inquiry scan interval: {} (0x{:02x}) window: {} (0x{:02x})"
          .format(interval, interval, window, window))
