#    Copyright (C)   2011   Nicolo' Barbon
#
#    This file is part of Calise.
#
#    Calise is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    any later version.
#
#    Calise is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with Calise.  If not, see <http://www.gnu.org/licenses/>.

import time
import datetime
import ephem
import re
import urllib


def getDst(curTime=None):
    zg = time.localtime(curTime)
    wg = time.gmtime(curTime)
    dst_shift = (
        (wg.tm_hour * 60 + wg.tm_min) * 60 -\
        (zg.tm_hour * 60 + zg.tm_min) * 60 -\
        time.timezone )
    if dst_shift > 12*3600:
        dst_shift -= 24*3600
    elif dst_shift < -12*3600:
        dst_shift += 24*3600
    return dst_shift


""" Sun-related informations
Given lat/long this function returns rise_time and setting_time in epoch and
for how long (in sec) will the sunlight be "unstable" since dawn/sunset
"""
def getSun(latitude,longitude,curTime=None):
    if curTime is None:
        curTime = time.time()
    obs = ephem.Observer()
    obs.lat = str(latitude)
    obs.long = str(longitude)
    sun = ephem.Sun()
    dst = getDst(curTime)
    # pyEphem works on utc time. This requires a forth conversion since every
    # epoch obtained will be shifted by %timezone%
    obs.date = datetime.date.fromtimestamp(curTime)
    try:
        rise_time = obs.next_rising(sun).datetime()
        rise_epoch = int(rise_time.strftime("%s")) - time.timezone - dst
        set_time = obs.next_setting(sun).datetime()
        set_epoch = int(set_time.strftime("%s")) - time.timezone - dst
        # increase horizon to calculate for how long the sunlight will rapidly
        # change intensity
        # error exception ephem.NeverUpError means that the sun never reaches
        # 15 degrees above the horizon (15 is arbitrary and tested only for
        # 46.04N latitude)
        obs.horizon = "15"
        try:
            set_dur = obs.next_setting(sun).datetime()
            set_dur = (
                set_epoch - int(set_dur.strftime("%s")) +\
                time.timezone + dst )
            rise_dur = obs.next_rising(sun).datetime()
            rise_dur = (
                int(rise_dur.strftime("%s")) - rise_epoch -\
                time.timezone - dst )
        except ephem.NeverUpError:
            set_dur = set_epoch - rise_epoch
            rise_dur = set_epoch - rise_epoch
    except ephem.NeverUpError:
        rise_epoch = False
        set_epoch = True
        rise_dur = 0
        set_dur = 0
    except ephem.AlwaysUpError:
        obs.horizon = "15"
        try:
            set_epoch = int(datetime.date.today().strftime("%s"))+24*60*60
            set_dur = (
                set_epoch -\
                int(obs.next_setting(sun).datetime().strftime("%s")) +\
                time.timezone + dst )
            rise_epoch = int(datetime.date.today().strftime("%s"))
            rise_dur = (
                int(obs.next_rising(sun).datetime().strftime("%s")) -\
                rise_epoch -\
                time.timezone - dst )
        except ephem.AlwaysUpError:
            rise_epoch = True
            set_epoch = False
            rise_dur = 0
            set_dur = 0
    return rise_epoch, set_epoch, rise_dur, set_dur

""" Weather apis parser
Takes api name and, if present, through that api retrives current weather
informations.
If api is not listed or there's no internet connection, returns None.
"""
def url_parse(lat,lon,parser="wunderground"):
    if parser == "wunderground":
        api = "api.wunderground.com/auto/wui/geo/WXCurrentObXML/index.xml"
        params = urllib.urlencode({
            'query': "%.4f,%.4f" % (lat,lon) })
        prog = re.compile((
            ".*?<current_observation>"
            ".*?<weather>([A-Z a-z]*?)</weather>"
            ".*?</current_observation>" ), re.DOTALL )
    elif parser == "google":
        api = "www.google.com/ig/api"
        params = urllib.urlencode({
            "hl": "en", 'weather': ",,,%d,%d" % (lat*1000000,lon*1000000) })
        prog = re.compile((
            ".*?<\?xml.*?\?>.*?<current_conditions>"
            ".*?<condition data=\"([A-Z a-z]*?)\"/>"
            ".*?</xml_api_reply>" ), re.DOTALL )
    try:
        wur = urllib.urlopen( "http://%s?%s" % (api,params) )
    # IOError is raised if there's no internet connection
    except IOError:
        return None
    cm = prog.match(wur.read())
    # Some apis return a blank string instead of None with the second "if"
    # condition the parser is aware of that
    if cm is not None and len(cm.group(1).split()) > 0:
        return cm.group(1)
    else:
        return None

""" Weather informations
Asks the apis defined with url_parse function for weather informations and
transforms them into a multiplier (from defined min to defined max).
If a "weather state" is not indexed, then returns (min+max)/2.
"""
def get_daytime_mul(lat,lon):
    for api in ("wunderground","google"):
        ws = url_parse(lat, lon, api)
        if ws is not None:
            break
    # multiplier minimum and maximum
    minimum = 0.2
    maximum = 1.0
    step = ( maximum - minimum ) / 7.0
    fmul = (minimum + maximum) / 2.0
    if ws is None:
        return fmul
    # daytime multiplier based on weather conditions (from 1.0 to 0.2)
    weather_mul = {
        # Commons
        "clear": minimum + step * 7,
        "mostly sunny": minimum + step * 6,
        "partly sunny": minimum + step * 5,
        "partly cloudy": minimum + step * 4,
        "mostly cloudy": minimum + step * 3,
        "cloudy": minimum + step * 2,
        "overcast": minimum + step * 1,
        # Others
        "chance of rain": minimum + step * 3,
        "light rain": minimum + step * 2,
        "rain": minimum + step * 1,
        "chance of storm": minimum + step * 3,
        "light storm": minimum + step * 2,
        "storm": minimum + step * 1,
        "chance of snow": minimum + step * 3,
        "light snow": minimum + step * 2.5,
        "snow": minimum + step * 2,
        "Mist": minimum + step * 5,
        "Fog": minimum + step * 3,
        }
    try:
        fmul = weather_mul[str(ws).lower()]
    except KeyError:
        pass
    return fmul