import collections
import logging
import os
import pipes
import random
import shutil
import time

from autotest_lib.client.common_lib import error
from autotest_lib.client.common_lib import global_config
from autotest_lib.client.cros import constants
from autotest_lib.server import utils

try:
    from chromite.lib import metrics
except ImportError:
    metrics = utils.metrics_mock


# The amortized max filesize to collect.  For example, if _MAX_FILESIZE is 10
# then we would collect a file with size 20 half the time, and a file with size
# 40 a quarter of the time, so that in the long run we are collecting files
# with this max size.
_MAX_FILESIZE = 64 * (2 ** 20)  # 64 MiB


class _RemoteTempDir(object):

    """Context manager for temporary directory on remote host."""

    def __init__(self, host):
        self.host = host
        self.tmpdir = None

    def __repr__(self):
        return '<{cls} host={this.host!r}, tmpdir={this.tmpdir!r}>'.format(
            cls=type(self).__name__, this=self)

    def __enter__(self):
        self.tmpdir = (self.host
                       .run('mktemp -d', stdout_tee=None)
                       .stdout.strip())
        return self.tmpdir

    def __exit__(self, exc_type, exc_value, exc_tb):
        self.host.run('rm -rf %s' % (pipes.quote(self.tmpdir),))


def collect_log_file(host, log_path, dest_path, use_tmp=False, clean=False):
    """Collects a log file from the remote machine.

    Log files are collected from the remote machine and written into the
    destination path. If dest_path is a directory, the log file will be named
    using the basename of the remote log path.

    Very large files will randomly not be collected, to alleviate network
    traffic in the case of widespread crashes dumping large core files. Note
    that this check only applies to the exact file passed as log_path. For
    example, if this is a directory, the size of the contents will not be
    checked.

    @param host: The RemoteHost to collect logs from
    @param log_path: The remote path to collect the log file from
    @param dest_path: A path (file or directory) to write the copies logs into
    @param use_tmp: If True, will first copy the logs to a temporary directory
                    on the host and download logs from there.
    @param clean: If True, remove dest_path after upload attempt even if it
                  failed.

    """
    logging.info('Collecting %s...', log_path)
    try:
        file_stats = _get_file_stats(host, log_path)
        if random.random() > file_stats.collection_probability:
            logging.warning('Collection of %s skipped:'
                            'size=%s, collection_probability=%s',
                            log_path, file_stats.size,
                            file_stats.collection_probability)
        elif use_tmp:
            _collect_log_file_with_tmpdir(host, log_path, dest_path)
        else:
            source_path = log_path
            host.get_file(source_path, dest_path, preserve_perm=False)
    except Exception, e:
        logging.warning('Collection of %s failed: %s', log_path, e)
    finally:
        if clean:
            host.run('rm -rf %s' % (pipes.quote(log_path),))


_FileStats = collections.namedtuple('_FileStats',
                                    'size collection_probability')


def _collect_log_file_with_tmpdir(host, log_path, dest_path):
    """Collect log file from host through a temp directory on the host.

    @param host: The RemoteHost to collect logs from.
    @param log_path: The remote path to collect the log file from.
    @param dest_path: A path (file or directory) to write the copies logs into.

    """
    with _RemoteTempDir(host) as tmpdir:
        host.run('cp -rp %s %s' % (pipes.quote(log_path), pipes.quote(tmpdir)))
        source_path = os.path.join(tmpdir, os.path.basename(log_path))
        host.get_file(source_path, dest_path, preserve_perm=False)


def _get_file_stats(host, path):
    """Get the stats of a file from host.

    @param host: Instance of Host subclass with run().
    @param path: Path of file to check.
    @returns: _FileStats namedtuple with file size and collection probability.
    """
    cmd = 'ls -ld %s | cut -d" " -f5' % (pipes.quote(path),)
    try:
        file_size = int(host.run(cmd).stdout)
    except error.CmdError as e:
        logging.warning('Getting size of file %r on host %r failed: %s',
                        path, host, e)
        file_size = 0
    if file_size == 0:
        return _FileStats(0, 1.0)
    else:
        collection_probability = _MAX_FILESIZE / float(file_size)
        return _FileStats(file_size, collection_probability)


# import any site hooks for the crashdump and crashinfo collection
get_site_crashdumps = utils.import_site_function(
    __file__, "autotest_lib.server.site_crashcollect", "get_site_crashdumps",
    lambda host, test_start_time: None)
get_site_crashinfo = utils.import_site_function(
    __file__, "autotest_lib.server.site_crashcollect", "get_site_crashinfo",
    lambda host, test_start_time: None)
report_crashdumps = utils.import_site_function(
    __file__, "autotest_lib.server.site_crashcollect", "report_crashdumps",
    lambda host: None)
fetch_orphaned_crashdumps = utils.import_site_function(
    __file__, "autotest_lib.server.site_crashcollect", "fetch_orphaned_crashdumps",
    lambda host, host_resultdir: None)
get_host_infodir = utils.import_site_function(
    __file__, "autotest_lib.server.site_crashcollect", "get_host_infodir",
    lambda host: None)


@metrics.SecondsTimerDecorator(
        'chromeos/autotest/autoserv/get_crashdumps_duration')
def get_crashdumps(host, test_start_time):
    get_site_crashdumps(host, test_start_time)


@metrics.SecondsTimerDecorator(
        'chromeos/autotest/autoserv/get_crashinfo_duration')
def get_crashinfo(host, test_start_time):
    logging.info("Collecting crash information...")

    # get_crashdumps collects orphaned crashdumps and symbolicates all
    # collected crashdumps. Symbolicating could happen
    # during a postjob task as well, at which time some crashdumps could have
    # already been pulled back from machine. So it doesn't necessarily need
    # to wait for the machine to come up.
    get_crashdumps(host, test_start_time)

    if wait_for_machine_to_recover(host):
        # run any site-specific collection
        get_site_crashinfo(host, test_start_time)

        crashinfo_dir = get_crashinfo_dir(host, 'crashinfo')
        collect_messages(host)
        collect_command(host, "dmesg", os.path.join(crashinfo_dir, "dmesg"))
        collect_uncollected_logs(host)

        # Collect everything in /var/log.
        log_path = os.path.join(crashinfo_dir, 'var')
        os.makedirs(log_path)
        collect_log_file(host, constants.LOG_DIR, log_path)

        # Collect console-ramoops
        log_path = os.path.join(
                crashinfo_dir, os.path.basename(constants.LOG_CONSOLE_RAMOOPS))
        collect_log_file(host, constants.LOG_CONSOLE_RAMOOPS, log_path,
                         clean=True)
        # Collect i915_error_state, only available on intel systems.
        # i915 contains the Intel graphics state. It might contain useful data
        # when a DUT hangs, times out or crashes.
        log_path = os.path.join(
                crashinfo_dir, os.path.basename(constants.LOG_I915_ERROR_STATE))
        collect_log_file(host, constants.LOG_I915_ERROR_STATE,
                         log_path, use_tmp=True)


# Load default for number of hours to wait before giving up on crash collection.
HOURS_TO_WAIT = global_config.global_config.get_config_value(
    'SERVER', 'crash_collection_hours_to_wait', type=float, default=4.0)


def wait_for_machine_to_recover(host, hours_to_wait=HOURS_TO_WAIT):
    """Wait for a machine (possibly down) to become accessible again.

    @param host: A RemoteHost instance to wait on
    @param hours_to_wait: Number of hours to wait before giving up

    @returns: True if the machine comes back up, False otherwise
    """
    current_time = time.strftime("%b %d %H:%M:%S", time.localtime())
    if host.is_up():
        logging.info("%s already up, collecting crash info", host.hostname)
        return True

    logging.info("Waiting %s hours for %s to come up (%s)",
                 hours_to_wait, host.hostname, current_time)
    if not host.wait_up(timeout=hours_to_wait * 3600):
        (metrics.Counter('chromeos/autotest/errors/collect_crashinfo_timeout')
         .increment())
        logging.warning("%s down, unable to collect crash info",
                        host.hostname)
        return False
    else:
        logging.info("%s is back up, collecting crash info", host.hostname)
        return True


def get_crashinfo_dir(host, dir_prefix):
    """Find and if necessary create a directory to store crashinfo in.

    @param host: The RemoteHost object that crashinfo will be collected from
    @param dir_prefix: Prefix of directory name.

    @returns: The path to an existing directory for writing crashinfo into
    """
    host_resultdir = getattr(getattr(host, "job", None), "resultdir", None)
    if host_resultdir:
        infodir = host_resultdir
    else:
        infodir = os.path.abspath(os.getcwd())
    infodir = os.path.join(infodir, "%s.%s" % (dir_prefix, host.hostname))
    if not os.path.exists(infodir):
        os.mkdir(infodir)
    return infodir


def collect_command(host, command, dest_path):
    """Collects the result of a command on the remote machine.

    The standard output of the command will be collected and written into the
    desitionation path. The destination path is assumed to be filename and
    not a directory.

    @param host: The RemoteHost to collect from
    @param command: A shell command to run on the remote machine and capture
        the output from.
    @param dest_path: A file path to write the results of the log into
    """
    logging.info("Collecting '%s' ...", command)
    try:
        result = host.run(command, stdout_tee=None).stdout
        utils.open_write_close(dest_path, result)
    except Exception, e:
        logging.warning("Collection of '%s' failed:\n%s", command, e)


def collect_uncollected_logs(host):
    """Collects any leftover uncollected logs from the client.

    @param host: The RemoteHost to collect from
    """
    if host.job:
        try:
            logs = host.job.get_client_logs()
            for hostname, remote_path, local_path in logs:
                if hostname == host.hostname:
                    logging.info('Retrieving logs from %s:%s into %s',
                                 hostname, remote_path, local_path)
                    collect_log_file(host, remote_path + '/', local_path + '/')
        except Exception, e:
            logging.warning('Error while trying to collect stranded '
                            'Autotest client logs: %s', e)


def collect_messages(host):
    """Collects the 'new' contents of /var/log/messages.

    If host.VAR_LOG_MESSAGE_COPY_PATH is on the remote machine, collects
    the contents of /var/log/messages excluding whatever initial contents
    are already present in host.VAR_LOG_MESSAGE_COPY_PATH. If it is not
    present, simply collects the entire contents of /var/log/messages.

    @param host: The RemoteHost to collect from
    """
    crashinfo_dir = get_crashinfo_dir(host, 'crashinfo')

    try:
        # paths to the messages files
        messages = os.path.join(crashinfo_dir, "messages")
        messages_raw = os.path.join(crashinfo_dir, "messages.raw")
        messages_at_start = os.path.join(crashinfo_dir, "messages.at_start")

        # grab the files from the remote host
        collect_log_file(host, host.VAR_LOG_MESSAGES_COPY_PATH,
                         messages_at_start)
        collect_log_file(host, "/var/log/messages", messages_raw)

        # figure out how much of messages.raw to skip
        if os.path.exists(messages_at_start):
            # if the first lines of the messages at start should match the
            # first lines of the current messages; if they don't then messages
            # has been erase or rotated and we just grab all of it
            first_line_at_start = utils.read_one_line(messages_at_start)
            first_line_now = utils.read_one_line(messages_raw)
            if first_line_at_start != first_line_now:
                size_at_start = 0
            else:
                size_at_start = os.path.getsize(messages_at_start)
        else:
            size_at_start = 0
        raw_messages_file = open(messages_raw)
        messages_file = open(messages, "w")
        raw_messages_file.seek(size_at_start)
        shutil.copyfileobj(raw_messages_file, messages_file)
        raw_messages_file.close()
        messages_file.close()

        # get rid of the "raw" versions of messages
        os.remove(messages_raw)
        if os.path.exists(messages_at_start):
            os.remove(messages_at_start)
    except Exception, e:
        logging.warning("Error while collecting /var/log/messages: %s", e)