#!/usr/bin/env python

import ephem
import time
import os
import sys
import urllib
from MmdDb import Db
from MmdLocation import Location

def dms2degdec (lonlat):
  '''
  convert a position argument from Deg:Min:Sec.Frac to
  Deg.Frac and round the result to 5 decimal points
  '''

  parts = lonlat.split (':')
  if len (parts) != 3:
    return 0.0
  degrees = float (parts[0])
  fraction =  (float (parts[1]) * 60.0 + float (parts[2])) / 3600
  if parts[0][0] == '-':
    return round (degrees - fraction, 5)
  return round (degrees + fraction, 5)

class Satellite:

  def __init__ (self, observer = False):
    self.name = 'RADIOSCAF-B'
    self.nickname = 'ARISSAT-1'
    self.tle_filename = '/usr/local/mmd/tles/current'
    self.db = Db ()
    self._initSatellite (observer)
 
  def getCurrentSSP (self):
    ssp = self._loadCurrentSSP ()
    return ssp['timestamp'], ssp['longitude'], ssp['latitude']

  def getTrajectoryAsJavaArray (self, name, minutes = 180):
    astring = 'var {0} = new Array (\n'.format (name)
    astring = '{0}\tnew Array ('.format (astring)
    astring = '{0}\n\t\tnew OpenLayers.LonLat ({1}, {2}).transform (from, to),'.format (
      astring,
      self.longitude,
      self.latitude
    )
    last = 'east'
    if str (self.longitude)[0] == '-':
      last = 'west'
  
    for row in self._loadTrajectory (minutes):
      if str (row['longitude'])[0] == '-':
        if last == 'east':
          astring = astring[:-1]
          astring = '{0}\n\t\t),\n\tnew Array ('.format (astring)
        last = 'west'
      else:
        last = 'east'
      astring = '{0}\n\t\tnew OpenLayers.LonLat ({1}, {2}).transform (from, to),'.format (
        astring, row['longitude'], row['latitude'])
    if astring[-1] == ',':
      astring = astring[:-1]
    astring = '{0}\n\t\t)\n\t);'.format (astring)
    return astring

  def cronJob (self):
    if self._updateTLEFile ():
      self._updateTrajectory ()
    return self._computeTrajectory ()

  def getLatestSSP (self):
    return self.db.satelliteGetLatestSSP ()

  def getNextPass (self):
    '''
    return 6-tuple with info for next pass
    '''
    sat = ephem.readtle (self._tle[0], self._tle[1], self._tle[2])
    observer = ephem.Observer ()
    observer.date = time.strftime ('%Y/%m/%d %H:%M', time.gmtime ())
    observer.long, observer.lat, observer.elevation = str (self.observer.longitude), str (self.observer.latitude), self.observer.altitude
    observer.pressure = 0
    observer.horizon = '-0:34'
    return observer.next_pass (sat)

  def _loadTrajectory (self, minutes):
    return self.db.satelliteLoadTrajectory (time.strftime ('%s'), minutes)

  def _loadCurrentSSP (self):
    return self.db.satelliteLoadCurrentSSP (time.strftime ('%s'))

  def _initSatellite (self, observer = False):
    if not self._loadTLE ():
      return False
    if observer:
      self.observer = observer
    else:
      self.observer = Location ()

    sat = ephem.readtle (self._tle[0], self._tle[1], self._tle[2])
    observer = ephem.Observer ()
    observer.long, observer.lat, observer.elevation = str (self.observer.longitude), str (self.observer.latitude), self.observer.altitude
    sat.compute (observer)
    self.longitude = dms2degdec (sat.sublong.__str__ ())
    self.latitude = dms2degdec (sat.sublat.__str__ ())
    self.altitude = round (float (sat.elevation.__str__ ()), 1)

  def _computeTrajectory (self):
    '''
    computes 5 hours of future trajectory data, starting at the
    latest timestamp found in data base
    '''
    if not self._loadTLE ():
      return False

    sat = ephem.readtle (self._tle[0], self._tle[1], self._tle[2])
    graz = ephem.Observer ()
    graz.long, graz.lat, graz.elevation = '15.44226', '47.06576', 376

    latest = self.db.satelliteGetLatestSSP ()
    if latest:
      timestamp = int (latest['timestamp']) + 60
    else:
      timestamp = int (time.strftime ('%s')) + 60
    while timestamp % 60 != 0:
      timestamp += 1

    for i in range (60 * 5):
      graz.date = time.strftime ('%Y/%m/%d %H:%M:%S', time.gmtime (timestamp))
      sat.compute (graz)
      self.db.satelliteInsertNewSSP (timestamp, dms2degdec (sat.sublong.__str__ ()), dms2degdec (sat.sublat.__str__ ()))
      timestamp += 60
    return  True

  def _loadTLE (self):
    try:
      tle = open (self.tle_filename, 'r')
    except IOError:
      return False
    self._tle = []
    count = 0
    for line in tle.readlines ():
      self._tle.append (line)
      count += 1
    if count != 3:
      return False
    return True

  def _updateTLEFile (self):
    '''
    store new TLE data in file with format
    YYYYMMDDhhmmss (Year Month Day hour minute second)
    and make symlink to self.tle_filename
    '''
    if not self._getTLEFileFromNetwork ():
      return False
    filename = '/usr/local/mmd/tles/{0}'.format (time.strftime ('%Y%m%d%H%M%S'))
    for line in self.tle_data:
      if line.startswith (self.name):
        tle = open (filename, 'w')
        tle.write (line)
        tle.write (self.tle_data.next ())
        tle.write (self.tle_data.next ())
        tle.close ()
        return self._compareAndLinkNewTLEFile (filename)
    return False

  def _createOrbtrackTLEFile (self):
    tle_file = open (self.tle_filename)
    orbtrack_file = open ("/var/www/hofos.at/mmd/static/tle.js", "w")
    orbtrack_file.write ("//Created by MmdSatellite.py\n//{0}\nPLib.tleData = \n[\n".format (time.strftime ("%Y-%m-%d - %H:%M:%S")))
    count = 0
    for line in tle_file.readlines ():
      l = line[:-2]
      if count == 2:
        orbtrack_file.write ('  "{0}"'.format (l))
      else:
        orbtrack_file.write ('  "{0}",\n'.format (l))
      count += 1
    orbtrack_file.write ("\n];\n// EOF\n")
    tle_file.close ()
    orbtrack_file.close ()

  def _compareAndLinkNewTLEFile (self, filename):
    '''
    we should use field 21-32 from first line of TLE to
    compare data;  then use this date to generate a filename
    and update the database;
    '''
    old_data = open (self.tle_filename).read ()
    new_data = open (filename).read ()
    if old_data == new_data:
      os.unlink (filename)
      return False
    os.unlink (self.tle_filename)
    os.symlink (filename, self.tle_filename)
    self._createOrbtrackTLEFile ()
    return True

  def _updateTrajectory (self):
    self.db.satelliteDeleteObsoleteSSPs (time.strftime ('%s'))

  def _getTLEFileFromNetwork (self):
    '''
    retreive TLE update from NORAD/celestrak
    '''
    networkfile = 'http://www.celestrak.com/NORAD/elements/amateur.txt'
    try:
      self.tle_data = urllib.urlopen (networkfile)
    except IOError:
      return False
    return True

if __name__ == "__main__":
  satellite = Satellite ()
  # print satellite.longitude, satellite.latitude
  # print satellite.getTrajectoryAsJavaArray ('test', 100)
  try:
    assert satellite.cronJob (), 'executing cronjob failed'
    # satellite._createOrbtrackTLEFile ()
    # next_pass = satellite.getNextPass ()
    # assert next_pass, 'getting next pass failed'
    # print next_pass
  except AssertionError as e:
    print 'Error: {0}'.format (e)
    sys.exit (1)
  sys.exit (0)

# vim: tw=0 ts=2
# EOF