#!/usr/bin/env python

import sys
import time
import signal
import optparse

try:
  import whisper
except ImportError:
  raise SystemExit('[ERROR] Please make sure whisper is installed properly')

_DROP_FUNCTIONS = {
    'zeroes': lambda x: x != 0,
    'nulls': lambda x: x is not None,
    'empty': lambda x: x != 0 and x is not None
}

# Ignore SIGPIPE
signal.signal(signal.SIGPIPE, signal.SIG_DFL)

now = int(time.time())
yesterday = now - (60 * 60 * 24)

option_parser = optparse.OptionParser(usage='''%prog [options] path''')
option_parser.add_option(
  '--from', default=yesterday, type='int', dest='_from',
  help=("Unix epoch time of the beginning of "
        "your requested interval (default: 24 hours ago)"))
option_parser.add_option(
  '--until', default=now, type='int',
  help="Unix epoch time of the end of your requested interval (default: now)")
option_parser.add_option(
  '--json', default=False, action='store_true',
  help="Output results in JSON form")
option_parser.add_option(
  '--pretty', default=False, action='store_true',
  help="Show human-readable timestamps instead of unix times")
option_parser.add_option(
  '-t', '--time-format', action='store', type='string', dest='time_format',
  help='Time format to use with --pretty; see time.strftime()')
option_parser.add_option(
  '--drop', choices=list(_DROP_FUNCTIONS.keys()), action='store',
  help="Specify 'nulls' to drop all null values. "
       "Specify 'zeroes' to drop all zero values. "
       "Specify 'empty' to drop both null and zero values")

(options, args) = option_parser.parse_args()

if len(args) != 1:
  option_parser.print_help()
  sys.exit(1)

path = args[0]

from_time = int(options._from)
until_time = int(options.until)

try:
  data = whisper.fetch(path, from_time, until_time)
  if not data:
    raise SystemExit('No data in selected timerange')
  (timeInfo, values) = data
except (whisper.WhisperException, IOError) as exc:
  raise SystemExit('[ERROR] %s' % str(exc))

if options.drop:
  fcn = _DROP_FUNCTIONS.get(options.drop)
  values = [x for x in values if fcn(x)]

(start, end, step) = timeInfo

if options.json:
  values_json = str(values).replace('None', 'null')
  print('''{
    "start" : %d,
    "end" : %d,
    "step" : %d,
    "values" : %s
  }''' % (start, end, step, values_json))
  sys.exit(0)

t = start
for value in values:
  if options.pretty:
    if options.time_format:
      timestr = time.strftime(options.time_format, time.localtime(t))
    else:
      timestr = time.ctime(t)
  else:
    timestr = str(t)
  if value is None:
    valuestr = "None"
  else:
    valuestr = "%f" % value
  print("%s\t%s" % (timestr, valuestr))
  t += step