# Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import base64
import datetime
import logging
import os
import re
import time

from autotest_lib.client.common_lib import error


def _get_machine_domain(hostname):
    """Parses hostname to extract machine and domain info.

    @param hostname String, machine name in wifi cell.
    @return a tuple of (string, string), domain name (if any) and machine name.

    """
    domain = ''
    machine = hostname
    if hostname.find('.') > 0:
        domain_start = hostname.find('.')
        domain = hostname[domain_start:]
        machine = hostname[0:domain_start]
    return (machine, domain)


def get_server_addr_in_lab(hostname):
    """
    If we are in the lab use the names for the server, AKA rspro, and the
    router as defined in: go/chromeos-lab-hostname-convention

    @param hostname String machine name in wifi cell
            (e.g. chromeos1-shelf1-host1.cros)
    @return String server name in cell
            (e.g. chromeos1-shelf1-host1-server.cros)

    """
    return '%s-server%s' % _get_machine_domain(hostname)


def get_router_addr_in_lab(hostname):
    """
    If we are in the lab use the names for the server, AKA rspro, and the
    router as defined in: go/chromeos-lab-hostname-convention

    @param hostname String machine name in wifi cell
            (e.g. chromeos1-shelf1-host1.cros)
    @return String router name in cell
            (e.g. chromeos1-shelf1-host1-router.cros)

    """
    return '%s-router%s' % _get_machine_domain(hostname)


def get_attenuator_addr_in_lab(hostname):
    """
    For wifi rate vs. range tests, look up attenuator host name.

    @param hostname String, DUT name in wifi cell.
            (e.g. chromeos3-grover-host1.cros)
    @return String, attenuator host name
            (e.g. chromeos3-grover-host1-attenuator.cros)

    """
    return '%s-attenuator%s' % _get_machine_domain(hostname)


def is_installed(host, filename):
    """
    Checks if a file exists on a remote machine.

    @param host Host object representing the remote machine.
    @param filename String path of the file to check for existence.
    @return True if filename is installed on host; False otherwise.

    """
    result = host.run('ls %s' % filename, ignore_status=True)
    m = re.search(filename, result.stdout)
    return m is not None


def get_install_path(host, filename, paths):
    """
    Checks if a file exists on a remote machine in one of several paths.

    @param host Host object representing the remote machine.
    @param filename String name of the file to check for existence.
    @param paths List of paths to check for filename in.
    @return String full path of installed file, or None if not found.

    """
    if not paths:
        return None

    # A single path entry is the same as testing is_installed().
    if len(paths) == 1:
        install_path = os.path.join(paths, filename)
        if is_installed(host, install_path):
            return install_path
        return None

    result = host.run('ls {%s}/%s' % (','.join(paths), filename),
                      ignore_status=True)
    found_path = result.stdout.split('\n')[0]
    return found_path or None


def must_be_installed(host, cmd):
    """
    Asserts that cmd is installed on a remote machine at some path and raises
    an exception if this is not the case.

    @param host Host object representing the remote machine.
    @param cmd String name of the command to check for existence.
    @return String full path of cmd on success.  Error raised on failure.

    """
    if is_installed(host, cmd):
        return cmd

    # Hunt for the equivalent file in a bunch of places.
    cmd_base = os.path.basename(cmd)
    local_paths = ['/bin',
                   '/sbin',
                   '/usr/bin',
                   '/usr/sbin',
                   '/usr/local/bin',
                   '/usr/local/sbin']
    alternate_path = get_install_path(host, cmd_base, local_paths)
    if alternate_path:
        return alternate_path

    raise error.TestFail('Unable to find %s on %s' % (cmd, host.ip))


def get_default_ssid(test_name, ipaddr, host):
    """
    Calculate ssid based on test name.

    This lets us track progress by watching beacon frames.  Generate a unique
    suffix for this SSID based either a unique MAC address on the AP, or
    failing this, the IP address of the AP.

    @param test_name String name of this test (e.g. network_WiFiMatFunc).
    @param ipaddr String IP address of the AP in this test.
    @param host Host object representing the router.
    @return String 32 character SSID.

    """
    if test_name.find('network_') == 0:
        # Many of our tests start with this very uninteresting prefix.
        # Remove it so we can have more unique substring bytes.
        test_name = test_name[len('network_'):]
    address_lines = []
    if host:
        address_lines = host.run('/usr/sbin/ip addr show',
                                 ignore_status=True).stdout.splitlines()

    mac_re = re.compile('link/ether (?P<mac>(([0-9a-f]{2}):?){6}) ',
                        flags=re.IGNORECASE)
    for line in address_lines:
        mac_match = mac_re.search(line)
        if mac_match:
            mac_string = mac_match.group('mac')
            if mac_string not in ['00:00:00:00:00:00', 'ff:ff:ff:ff:ff:ff']:
                mac_bytes = ''
                for octet in mac_string.split(':'):
                    mac_bytes += chr(int(octet, 16))
                unique_name = base64.b64encode(mac_bytes)
                break
    else:
        unique_name = ipaddr
    return re.sub('[^a-zA-Z0-9_]', '_', '%s_%s' %
            (test_name, unique_name))[0:32]


def get_wlan_devs(host, command_iw):
    """Get a list of WiFi devices.

    @param host host object representing a remote machine.
    @param command_iw string path to 'iw' executable on host
    @return list of string wifi device names. (e.g. ['mlan0']).

    """
    ret = []
    result = host.run('%s dev' % command_iw)
    current_if = None
    for line in result.stdout.splitlines():
        ifmatch = re.search('Interface (\S*)', line)
        if ifmatch is not None:
            current_if = ifmatch.group(1)
        elif ('type managed' in line or 'type IBSS' in line) and current_if:
            ret.append(current_if)
    logging.info('Found wireless interfaces %r', ret)
    return ret


def get_interface_mac(host, ifname, command_ip):
    """Get the MAC address of a given interface on host.

    @param host host object representing remote machine.
    @param ifname string interface name.
    @param command_ip string ip command on host.
    @return string MAC address for interface on host.

    """
    result = host.run('%s link show %s' % (command_ip, ifname))
    macmatch = re.search('link/ether (\S*)', result.stdout)
    if macmatch is not None:
        return macmatch.group(1)
    return None


def sync_host_times(host_list):
    """Sync system times on test machines to our local time.

    @param host_list iterable object containing SSHHost objects.

    """
    for host in host_list:
        epoch_seconds = time.time()
        busybox_format = '%Y%m%d%H%M.%S'
        busybox_date = datetime.datetime.utcnow().strftime(busybox_format)
        host.run('date -u --set=@%s 2>/dev/null || date -u %s' % (epoch_seconds,
                                                                  busybox_date))