import os
import logging
from twisted.internet.defer import inlineCallbacks, returnValue

from landscape.lib.fetch import fetch_async
from landscape.lib.fs import read_file
from landscape.lib.lsb_release import LSB_RELEASE_FILENAME, parse_lsb_release
from landscape.lib.cloud import fetch_ec2_meta_data
from landscape.lib.network import get_fqdn
from landscape.monitor.plugin import MonitorPlugin

METADATA_RETRY_MAX = 3 # Number of retries to get EC2 meta-data


class DistributionInfoError(Exception):
pass


class ComputerInfo(MonitorPlugin):
"""Plugin captures and reports basic computer information."""

persist_name = "computer-info"
scope = "computer"

def __init__(self, get_fqdn=get_fqdn,
meminfo_filename="/proc/meminfo",
lsb_release_filename=LSB_RELEASE_FILENAME,
root_path="/", fetch_async=fetch_async):
self._get_fqdn = get_fqdn
self._meminfo_filename = meminfo_filename
self._lsb_release_filename = lsb_release_filename
self._root_path = root_path
self._cloud_instance_metadata = None
self._cloud_retries = 0
self._fetch_async = fetch_async

def register(self, registry):
super(ComputerInfo, self).register(registry)
self._annotations_path = registry.config.annotations_path
self.call_on_accepted("computer-info",
self.send_computer_message, True)
self.call_on_accepted("distribution-info",
self.send_distribution_message, True)
self.call_on_accepted("cloud-instance-metadata",
self.send_cloud_instance_metadata_message, True)

def send_computer_message(self, urgent=False):
message = self._create_computer_info_message()
if message:
message["type"] = "computer-info"
logging.info("Queueing message with updated computer info.")
self.registry.broker.send_message(message, self._session_id,
urgent=urgent)

def send_distribution_message(self, urgent=False):
message = self._create_distribution_info_message()
if message:
message["type"] = "distribution-info"
logging.info("Queueing message with updated distribution info.")
self.registry.broker.send_message(message, self._session_id,
urgent=urgent)

@inlineCallbacks
def send_cloud_instance_metadata_message(self, urgent=False):
message = yield self._create_cloud_instance_metadata_message()
if message:
message["type"] = "cloud-instance-metadata"
logging.info("Queueing message with updated cloud instance "
"metadata.")
self.registry.broker.send_message(message, self._session_id,
urgent=urgent)

def exchange(self, urgent=False):
broker = self.registry.broker
broker.call_if_accepted("computer-info",
self.send_computer_message, urgent)
broker.call_if_accepted("distribution-info",
self.send_distribution_message, urgent)
broker.call_if_accepted("cloud-instance-metadata",
self.send_cloud_instance_metadata_message,
urgent)

def _create_computer_info_message(self):
message = {}
self._add_if_new(message, "hostname", self._get_fqdn())
total_memory, total_swap = self._get_memory_info()
self._add_if_new(message, "total-memory", total_memory)
self._add_if_new(message, "total-swap", total_swap)
annotations = {}
if os.path.exists(self._annotations_path):
for key in os.listdir(self._annotations_path):
annotations[key] = read_file(
os.path.join(self._annotations_path, key))

if annotations:
self._add_if_new(message, "annotations", annotations)
return message

def _add_if_new(self, message, key, value):
if value != self._persist.get(key):
self._persist.set(key, value)
message[key] = value

def _create_distribution_info_message(self):
message = self._get_distribution_info()
if message != self._persist.get("distribution-info"):
self._persist.set("distribution-info", message)
return message
return None

def _get_memory_info(self):
"""Get details in megabytes and return a C{(memory, swap)} tuple."""
message = {}
file = open(self._meminfo_filename)
for line in file:
if line != '\n':
parts = line.split(":")
key = parts[0]
if key in ["MemTotal", "SwapTotal"]:
value = int(parts[1].strip().split(" ")[0])
message[key] = value
file.close()
return (message["MemTotal"] // 1024, message["SwapTotal"] // 1024)

def _get_distribution_info(self):
"""Get details about the distribution."""
message = {}
message.update(parse_lsb_release(self._lsb_release_filename))
return message

@inlineCallbacks
def _create_cloud_instance_metadata_message(self):
"""Fetch cloud metadata and insert it in a message."""
message = None
if (self._cloud_instance_metadata is None and
self._cloud_retries < METADATA_RETRY_MAX):
self._cloud_instance_metadata = yield self._fetch_ec2_meta_data()
message = self._cloud_instance_metadata
returnValue(message)

def _fetch_ec2_meta_data(self):
"""Fetch information about the cloud instance."""
if self._cloud_retries == 0:
logging.info("Querying cloud meta-data.")
deferred = fetch_ec2_meta_data(self._fetch_async)

def log_no_meta_data_found(error):
self._cloud_retries += 1
if self._cloud_retries >= METADATA_RETRY_MAX:
logging.info("No cloud meta-data available. %s" %
error.getErrorMessage())

def log_success(result):
logging.info("Acquired cloud meta-data.")
return result

deferred.addCallback(log_success)
deferred.addErrback(log_no_meta_data_found)
return deferred