weather_data.rb

# Encoding: utf-8
# IN GEMFILE : gem 'wombat' #does the scraping magic

class WeatherData < ActiveRecord::Base
  require 'open-uri'
  require 'digest/md5'
  
  attr_accessible :max_wind, :mean_wind, :sea_level_pressure, :station_code, :station_id, :temp, :time_stamp, :wind_direction, :conditions
  belongs_to :station
  
  def self.new_from_metar(station_code)
    begin
      metar_station = Metar::Station.find_by_cccc(station_code)
      parser = metar_station.parser
    
      station = Station.find_or_create_by_title(:title => metar_station.name, :latitude => metar_station.latitude, :longitude => metar_station.longitude, :code => parser.station_code)
    
      data = station.weather_datas.where(:time_stamp => parser.time).first_or_create :sea_level_pressure => parser.sea_level_pressure.to_f * 1000,
                                                                                     :station_id => station.id,
                                                                                     :conditions => parser.present_weather,
                                                                                     :mean_wind => parser.wind.to_s.split('k')[0].to_i,
                                                                                     :wind_direction => WeatherData.convert_to_degrees(parser.wind)
    rescue Exception => msg
     logger.error msg
    end
  end
  
  def self.north_south_pressure_difference(limit = 1)
    lszh = Station.where(:code => "LSZH").first
    lsza = Station.where(:code => "LSZA").first
    
    lszh.weather_datas.order("time_stamp DESC").limit(limit).map { |zrh| {:pressure_gradient => (lsza.weather_datas.where(:time_stamp => zrh.time_stamp).first ? lsza.weather_datas.where(:time_stamp => zrh.time_stamp).first.sea_level_pressure - zrh.sea_level_pressure : nil), :time => zrh.time_stamp} }
  end
  
  
  def self.refresh_data
    WeatherData.new_from_metar("LSZA")
    WeatherData.new_from_metar("LSZH")
    WeatherData.import_new_from_balise_db
    WeatherData.new_from_scraper
  end
  
  def self.new_from_chalais
    results = open "http://chalais.atelier-agile.ch/winds/current.json"
    chalais = JSON.parse(results.read)
    
    station = Station.find_or_create_by_title(:title => 'Chalais')
    
    data = station.weather_datas.where(:time_stamp => chalais[3]).first_or_create :mean_wind => chalais[0],
                                                                          :max_wind => chalais[1],
                                                                          :wind_direction => chalais[2]
  end
  
  def self.conditions_for(title, limit = 1)
    station = Station.where(:title => title).first
    station.weather_datas.order("time_stamp DESC").limit(limit)
  end
  
  def self.import_new_from_balise_db
    station = Station.find_or_create_by_title(:title => 'Chalais')

    # BaliseData.where(["time > ?", (Time.now - 1.month)]).find_each do |data|
    
    BaliseData.where(["time > ?", WeatherData.order("time_stamp DESC").limit(1).first.time_stamp]).find_each do |data|
      case data.sensor_id
      when 2
        new_measure = station.weather_datas.where(:time_stamp => data.time).first_or_create
        new_measure.update_attribute(:mean_wind, data.value)
      when 3
        new_measure = station.weather_datas.where(:time_stamp => data.time).first_or_create
        new_measure.update_attribute(:max_wind, data.value)
      when 1
        new_measure = station.weather_datas.where(:time_stamp => data.time).first_or_create
        new_measure.update_attribute(:wind_direction, data.value)
      when 4
        new_measure = station.weather_datas.where(:time_stamp => data.time).first_or_create
        new_measure.update_attribute(:temp, data.value)
      end
    end
  end
  
  def self.new_from_scraper
    sample = scraped_weather_data
    
    set_data_for("Sion", "sion", sample)
    set_data_for("Visp", "visp", sample)
    set_data_for("Montana", "montana", sample)
    set_data_for("Gütsch", "guetsch", sample)
  end

  # def self.wind_for_visp
  #   url = "http://api.wetter.com/forecast/weather"
  #   search = "CH0CH4146"
  #   cs = Digest::MD5.hexdigest("#{PROJEKT}#{WETTER_API_KEY}#{search}")
  #   
  #   results = open "#{url}/city/#{search}/project/#{PROJEKT}/cs/#{cs}/output/json"
  #   results.read
  # end
  
  def cardinal_points
    case wind_direction.to_i
      when 0..(45-22)
        "Nord"
      when (45-22)..(90-22)
        "Nord-Est"
      when (90-22)..(135-22)
        "Est"
      when (135-22)..(180-22)
        "Sud-Est"
      when (180-22)..(225-22)
        "Sud"
      when (225-22)..(270-22)
        "Sud-Ouest"
      when (270-22)..(315-22)
        "Ouest"
      when (315-22)..(360-22)
        "Nord-Ouest"
      when (360-22)..360
        "Nord"
      else "Variable"
    end
  end
  
  def self.convert_to_degrees(metar_wind)
    direction_string = metar_wind.to_s.split(" ").last
    
    case direction_string
    when "N"
      0
    when "E"
      90
    when "S"
      180
    when "W"
      270
    when "WSW"
      247.50
    when "NNE"
      22.50
    else 
      -1
    end
  end
  
  def self.scraped_weather_data
    Wombat.crawl do
      base_url "http://www.meteoschweiz.admin.ch"
      path "/web/de/wetter/aktuelles_wetter.par0010.html?allStations=1"

      measure_date css: "p.text"
      visp css: "#karte_data_aktueller_wind_numerisch___VIS"
      sion css: "#karte_data_aktueller_wind_numerisch___SIO"
      montana css: "#karte_data_aktueller_wind_numerisch___MVE"
      guetsch css: "#karte_data_aktueller_wind_numerisch___GUE"
    end
  end
  
  def self.set_data_for(title, key, sample)
    date = sample["measure_date"]
    day = date.split(" ")[2]
    time = date.split(" ")[3]
    
    time_stamp = Time.parse("#{day} #{time.gsub(".", ":")}")
    
    station = Station.find_or_create_by_title(:title => title)
    new_measure = station.weather_datas.where(:time_stamp => time_stamp).first_or_create
    new_measure.update_attributes :max_wind => sample[key].split("|")[2].to_i,
                                  :mean_wind => sample[key].split("|")[1].to_i,
                                  :wind_direction => sample[key].split("|")[0].to_i
  end
  
  def time_stamp_corrected
    if self.station_id == 5
      time_stamp - 2.hours
    else
      time_stamp
    end
  end
end