import subprocess

from landscape.diff import diff
from landscape.lib.process import ProcessInformation
from landscape.lib.jiffies import detect_jiffies
from landscape.monitor.plugin import DataWatcher


class ActiveProcessInfo(DataWatcher):

message_type = "active-process-info"
scope = "process"

def __init__(self, proc_dir="/proc", boot_time=None, jiffies=None,
uptime=None, popen=subprocess.Popen):
super(ActiveProcessInfo, self).__init__()
self._proc_dir = proc_dir
self._persist_processes = {}
self._previous_processes = {}
self._jiffies_per_sec = jiffies or detect_jiffies()
self._popen = popen
self._first_run = True
self._process_info = ProcessInformation(proc_dir=proc_dir,
jiffies=jiffies,
boot_time=boot_time,
uptime=uptime)

def register(self, manager):
super(ActiveProcessInfo, self).register(manager)
self.call_on_accepted(self.message_type, self.exchange, True)

def _reset(self):
"""Reset active process data."""
self._first_run = True
self._persist_processes = {}
self._previous_processes = {}

def get_message(self):
message = {}
if self._first_run:
message["kill-all-processes"] = True
message.update(self._detect_process_changes())

if message:
message["type"] = "active-process-info"
return message
return None

def persist_data(self):
self._first_run = False
self._persist_processes = self._previous_processes
self._previous_processes = {}
# This forces the registry to write the persistent store to disk
# This means that the persistent data reflects the state of the
# messages sent.
self.registry.flush()

def _get_processes(self):
processes = {}
for process_info in self._process_info.get_all_process_info():
if process_info["state"] != "X":
processes[process_info["pid"]] = process_info
return processes

def _detect_process_changes(self):
changes = {}
processes = self._get_processes()
creates, updates, deletes = diff(self._persist_processes, processes)
if creates:
changes["add-processes"] = list(creates.itervalues())
if updates:
changes["update-processes"] = list(updates.itervalues())
if deletes:
changes["kill-processes"] = list(deletes.iterkeys())

# Update cached values for use on the next run.
self._previous_processes = processes
return changes