require 'open-uri'
EASY_ENERGY_TARIFFS = {}

# See https://www.belastingdienst.nl/wps/wcm/connect/bldcontentnl/belastingdienst/zakelijk/overige_belastingen/belastingen_op_milieugrondslag/tarieven_milieubelastingen/tabellen_tarieven_milieubelastingen
# Without VAT
ENERGY_TAX_KWH = { 2020 => 0.09770, 2021 => 0.09428, 2022 => 0.03679}
ODE_KWH = { 2020 => 0.0273, 2021 => 0.0300, 2022 => 0.0305}
# merge by adding values
TAX_KWH = ENERGY_TAX_KWH.merge(ODE_KWH){|key, energy_tax, ode| energy_tax + ode}


class Cost
 
  attr_accessor :max_charge_kwh    
  attr_reader :battery, :entsoe, :zone
  
  def initialize(zone="Amsterdam", battery_capacity=10.0, max_charge=5.0, storage_cost=0.05)
    @zone = zone
    @entsoe = Entsoe.new(zone, storage_cost)
    @max_charge_kwh =  max_charge
    @battery = Battery.new(battery_capacity)
  end
  
  # Government reduced VAT to 9% from 1 July 2022 until 31 Dec 2022
  def vat_at(date)
    jul22 = Date.parse("2022-09-01")
    dec22 = Date.parse("2022-12-31")
    if (date >= jul22 && date <= dec22)
      0.09
    else
      0.21
    end
  end  
  
  def format_cost(cost)
    cost ? "EUR %0.03f" % cost : "EUR ?"
  end
 
  # Assume: usage_kwh_cost, return_kwh_cost already includes vat
  def add_tax(formatted_hour,usage_kwh,usage_kwh_cost,return_kwh, return_kwh_cost)
    return nil if (usage_kwh.nil? || usage_kwh_cost.nil? || return_kwh.nil? || return_kwh_cost.nil?)
    
    vat = 1 + vat_at(Date.parse(formatted_hour))
    year = Date.parse(formatted_hour).year
    # calculate tax per kwh - which the sum of energy_tax and ode
    tax = TAX_KWH[year]*vat
    
    usage_kwh * (usage_kwh_cost + tax) - return_kwh * (return_kwh_cost + tax)  
    
  end
  
  ######################################################
  # Easy Energy API (proprietary) - better to use entsoe
  ######################################################
  
  # returns a hash with keys formatted "yyyy-mm-dd-hr" and values [usage, return]
  # e.g. { 2021-12-16-06"=>[0.36058, 0.298] }
  def easy_energy_tariffs(date)
    p "Fetching EasyEnergy tariffs for %s" % date.strftime("%F-%H")
    
    # calculate offset (date is in UTC, and we want to have tariffs in Amsterdam zone)
    zone = 'Amsterdam'
    offset = DateTime.now.in_time_zone(zone).utc_offset
    date = date.beginning_of_day.advance(seconds: offset)
    
    url = "https://mijn.easyenergy.com/nl/api/tariff/getapxtariffs?startTimestamp=%s&endTimestamp=%s&grouping=" % [date.strftime("%F %T"),date.advance(:hours => 24).strftime("%F %T")]
    #p urlvandaag
    json = JSON.load(URI::open(url))
    # advancing with 1 hrs (to offset for something?)
    json.map{|t| [DateTime.parse(t["Timestamp"]).strftime("%F-%H"), [t["TariffUsage"], t["TariffReturn"]]]}.to_h      
  end
  
  def easy_energy_rate(formatted_hour)
    unless EASY_ENERGY_TARIFFS.key?(formatted_hour)
      EASY_ENERGY_TARIFFS.merge!(easy_energy_tariffs(Date.parse(formatted_hour)))
    end
    EASY_ENERGY_TARIFFS[formatted_hour]
  end
  
  def easy_energy_cost(formatted_hour, usage_kwh, return_kwh)
    return nil if (usage_kwh.nil? || return_kwh.nil?)
    
    usage_kwh_cost, return_kwh_cost = easy_energy_rate(formatted_hour)
    add_tax(formatted_hour, usage_kwh, usage_kwh_cost, return_kwh, return_kwh_cost)
  end
  
  def easy_energy_high_low(date)
    hour_start = date.beginning_of_day
    day_end = hour_start.advance(days: 1)
    max_rate = 0.0
    min_rate = 100.0
    min_hour = nil
    max_hour = nil
    while(hour_start < day_end) do
       easy_usage_rate, easy_return_rate = easy_energy_rate(hour_start.strftime("%F-%H"))
       unless easy_usage_rate.nil?
         # determine max
         if easy_usage_rate > max_rate
           max_rate = easy_usage_rate
           max_hour = hour_start.strftime("%F-%H")
         end
         # determine min
         if easy_usage_rate < min_rate
           min_rate = easy_usage_rate
           min_hour = hour_start.strftime("%F-%H")
         end
       end
       hour_start = hour_start.advance(:hours => 1)
    end  
    return min_hour,max_hour
  end

  ######################################################
  # Oxxio rates and cost
  ######################################################
  
  def oxxio_rate(formatted_hour,  high_tariff)
    year = Date.parse(formatted_hour).year
    case year
      when 2020
        high_tariff ? 0.07865 : 0.06215
      when 2021
        high_tariff ? 0.06782 : 0.05259
      when 2022
        high_tariff ? 0.23665 : 0.19408
    end
  end
    
  def oxxio_energy_cost(formatted_hour, normaal_kwh, dal_kwh, year_shift=0)
    return nil if (normaal_kwh.nil? || dal_kwh.nil?)
    #year = Date.parse(formatted_hour).year+year_shift
    date = Date.parse(formatted_hour).advance(years: year_shift)
    case date.to_time.to_i
      # Date.parse("2019-12-08").to_time.to_i
      # From 8 Dec 2019 until 7 Dec 2020
      when 1575763200..1607385599
         #normaal_kwh * (0.07865 + 0.11822 + 0.03303) + dal_kwh * (0.06215 + 0.11822 + 0.03303) 
         normaal_kwh_cost = 0.07865
         dal_kwh_cost = 0.06215
      # From 8 Dec 2020 until 7 Dec 2021
      when 1607385600..1638921599
         #normaal_kwh * (0.06782 + 0.11408 + 0.03630) + dal_kwh * (0.05259 + 0.11408 + 0.03630) 
         normaal_kwh_cost = 0.06782
         dal_kwh_cost = 0.05259
      #  From 8 Dec 2021 until 7 Sept 2022
      when 1638921600..1662595199
        # normaal_kwh * (0.23665 + 0.04452 + 0.03691) + dal_kwh * (0.19408 + 0.04452 + 0.03691) 
        normaal_kwh_cost = 0.23665
        dal_kwh_cost = 0.19408
      # From 8 Sept 2022 until 7 Dec 2022
      when 1662595200..1670457599
        normaal_kwh_cost = 0.60824
        dal_kwh_cost = 0.43701
    end
    normaal_cost = add_tax(formatted_hour, normaal_kwh,normaal_kwh_cost,0,0) # return_kwh already accounted for
    dal_cost = add_tax(formatted_hour, dal_kwh, dal_kwh_cost,0,0)
    # result
    normaal_cost + dal_cost
  end  
  
  #
  # Entsoe
  #
  
  def entsoe_energy_cost(formatted_hour, usage_kwh, return_kwh)
    return nil if (usage_kwh.nil? || return_kwh.nil?)
    
    usage_kwh_cost = return_kwh_cost = entsoe.price_at(formatted_hour)*(1+vat_at(Date.parse(formatted_hour)))
    add_tax(formatted_hour, usage_kwh, usage_kwh_cost, return_kwh, return_kwh_cost)
  end
  
  ######################################################
  #  Calculate the per_hour usage and costs
  ######################################################
  
  def hours(date, year_shift=0)
    hour_start = date.in_time_zone("Amsterdam").beginning_of_day
    day_end = hour_start.advance(days: 1)
    result = []
    lowest_hour, highest_hour,high_hours = entsoe.high_low_hours(date)
    
    while(hour_start < day_end) do
      hour_end = hour_start.end_of_hour
      formatted_hour = hour_start.strftime("%F %H")
      
      #p "Fetching meter readings between %s and %s" % [hour_start,hour_end]
      hour_readings = Reading.where("created_at > :begin AND created_at < :end", {:begin => hour_start, :end => hour_end})
      hour_diff = hour_readings.last ? hour_readings.last.diff(hour_readings.first) : UNKNOWN_READING
      # calculate cost of this hour
      usage_kwh = hour_diff[:total_kwh_consumed_high] + hour_diff[:total_kwh_consumed_low] rescue nil
      return_kwh = hour_diff[:total_kwh_produced_high] + hour_diff[:total_kwh_produced_low] rescue nil
      entsoe_cost = entsoe_energy_cost(formatted_hour, usage_kwh, return_kwh) # without battery use

      #
      # Make battery work
      #     
      if !usage_kwh.nil?
        # charge battery with return_kwh
        return_kwh -= battery.charge(return_kwh)
        
        if (lowest_hour.eql?(formatted_hour) || entsoe.price_at(formatted_hour) < 0) # lowest_hour = "" if small difference between high/low
          # charge battery during lowest hour, or when prices are negative
          usage_kwh += battery.charge(max_charge_kwh)
        else
          # if during expensive hours || more than <max_charge_kwh> kwh then discharge_battery
          # if (battery.battery_kwh > max_charge_kwh) || high_hours.include?(formatted_hour)
          if high_hours.include?(formatted_hour)
             usage_kwh -= battery.discharge(usage_kwh)
          end   
        end    
      end       
      entsoe_cost_with_battery = entsoe_energy_cost(formatted_hour, usage_kwh, return_kwh) # with battery use
            
      #
      # end of battery work
      #
      
      normal_usage_kwh = hour_diff[:total_kwh_consumed_low] - hour_diff[:total_kwh_produced_low] rescue nil
      low_usage_kwh = hour_diff[:total_kwh_consumed_high] - hour_diff[:total_kwh_produced_high] rescue nil
      oxxio_cost = oxxio_energy_cost(formatted_hour,normal_usage_kwh, low_usage_kwh, year_shift)
      oxxio_rate = oxxio_rate(formatted_hour, (hour_readings.first.high_tarif rescue true))
      
      one_hour = [formatted_hour, 
                  hour_diff[:total_kwh_consumed_high], 
                  hour_diff[:total_kwh_consumed_low], 
                  hour_diff[:total_kwh_produced_high], 
                  hour_diff[:total_kwh_produced_low],
                  usage_kwh,
                  return_kwh,
                  battery.battery_kwh,
                  entsoe.price_at(formatted_hour), # entsoe rate
                  entsoe_cost_with_battery,
                  entsoe_cost,
                  oxxio_rate, 
                  oxxio_cost]
      
      p "%s,%s,%s,%s,%s,%s,%s,%0.1f,%s,%s,%s,%s,%s" % (one_hour[0..7] + one_hour[8..12].map{|c| format_cost(c)})
      result << one_hour

      hour_start = hour_start.advance(:hours => 1)
    end
    result
  end
  
  def summarize_hours(hours)
    usage_kwh = hours.map{|e| (e[1] && e[2]) ? (e[1] + e[2]) : nil}.compact.sum
    return_kwh = hours.map{|e| (e[3] && e[4]) ? (e[3] + e[4]) : nil}.compact.sum
    usage_kwh_with_battery = hours.map{|e| e[5]}.compact.sum
    return_kwh_with_battery = hours.map{|e| e[6]}.compact.sum
    entsoe_cost_with_battery = hours.map{|e| e[9]}.compact.sum
    entsoe_cost = hours.map{|e| e[10]}.compact.sum
    oxxio_cost = hours.map{|e| e[12]}.compact.sum
    
    return usage_kwh, return_kwh, usage_kwh_with_battery, return_kwh_with_battery, format_cost(entsoe_cost_with_battery), format_cost(entsoe_cost), format_cost(oxxio_cost)
  end
  
  def hours_in_month(date, year_shift=0)
    day = date.beginning_of_month
    last_day = date.end_of_month
    all_hours = []
    while (day <= last_day)
      all_hours += hours(day, year_shift)
      day = day.advance(:days => 1)
    end
    all_hours
  end
  
  # heel2021 = hours_in(Date.parse("2021-01-01"), Date.parse("2021-12-31"), 1)
  
  def hours_in(from,to, year_shift=0)
    day = from.to_date
    last_day = to.to_date
    all_hours = []
    while (day <= last_day)
      all_hours += hours(day, year_shift)
      day = day.advance(:days => 1)
    end
    all_hours
  end
  
  def write_csv(filename,hours)
    CSV.open(filename, "wb") do |csv|
      csv << ["hour", "kwh_consumed_low", "kwh_consumed_high", "kwh_produced_low", "kwh_produced_high", "easy_usage_rate", "easy_return_rate", "easy_cost", "oxxio_rate", "oxxio_cost"]
      hours.each do |row| 
        csv << row
      end  
    end
  end
    

end