# stdlib
from collections import namedtuple

# project
from resources import (
    agg,
    ResourcePlugin,
    SnapshotDescriptor,
    SnapshotField,
)
from utils.subprocess_output import get_subprocess_output


class Processes(ResourcePlugin):

    RESOURCE_KEY = "processes"
    FLUSH_INTERVAL = 1  # in minutes

    def describe_snapshot(self):
        return SnapshotDescriptor(
            1,
            SnapshotField("user", 'str', aggregator=agg.append, temporal_aggregator=agg.append),
            SnapshotField("pct_cpu", 'float'),
            SnapshotField("pct_mem", 'float'),
            SnapshotField("vsz", 'int'),
            SnapshotField("rss", 'int'),
            SnapshotField("family", 'str', aggregator=None, temporal_aggregator=None,
                          group_on=True, temporal_group_on=True),
            SnapshotField("ps_count", 'int'))

    def _get_proc_list(self):
        # Get output from ps
        try:
            process_exclude_args = self.config.get('exclude_process_args', False)
            if process_exclude_args:
                ps_arg = 'aux'
            else:
                ps_arg = 'auxww'
            output, _, _ = get_subprocess_output(['ps', ps_arg], self.log)
            processLines = output.splitlines()  # Also removes a trailing empty line
        except Exception:
            self.log.exception('Cannot get process list')
            raise

        del processLines[0]  # Removes the headers

        processes = []

        for line in processLines:
            line = line.split(None, 10)
            processes.append(map(lambda s: s.strip(), line))

        return processes

    @staticmethod
    def group_by_family(o):
        return o[5]

    @staticmethod
    def filter_by_usage(o):
        # keep everything over 1% (cpu or ram)
        return o[0] > 1 or o[1] > 1

    def _parse_proc_list(self, processes):

        def _compute_family(command):
            if command.startswith('['):
                return 'kernel'
            else:
                return (command.split()[0]).split('/')[-1]

        PSLine = namedtuple("PSLine", "user,pid,pct_cpu,pct_mem,vsz,rss,tty,stat,started,time,command")

        self.start_snapshot()
        for line in processes:
            try:
                psl = PSLine(*line)
                self.add_to_snapshot([psl.user,
                                      float(psl.pct_cpu),
                                      float(psl.pct_mem),
                                      int(psl.vsz),
                                      int(psl.rss),
                                      _compute_family(psl.command),
                                      1])
            except Exception:
                pass
        self.end_snapshot(group_by=self.group_by_family)

    def flush_snapshots(self, snapshot_group):
        self._flush_snapshots(snapshot_group=snapshot_group,
                              group_by=self.group_by_family,
                              filter_by=self.filter_by_usage)

    def check(self):
        self._parse_proc_list(self._get_proc_list())