# frozen_string_literal: true

##
# This module is a container for a few classes that wrap a bunch
# of ModBus related stuff
#
module Pzem016
  require 'json'
  require 'awesome_print'

  ##
  # Some abstract behavior for the register parser classes
  #
  class ModbusRegisters
    attr_reader :raw, :slave

    ##
    # This takes two params: name and slave.  Name is a descriptive string
    # for the slave.  Slave is an instance of a ModBus::RTUClient slave
    # that you've previously set up.
    #
    def initialize(name, slave)
      @slave = slave
      @name = name
      @raw = nil
    end

    ##
    # Stub for read logic
    #
    def read
      @raw = []
    end

    ##
    # Simple basic behavior for turning the data read into a hash
    #
    def to_hash
      { raw: @raw }
    end

    ##
    # Returns the sample data as a json string
    #
    def to_json(*_args)
      to_hash.to_json
    end

    ##
    # Outputs a pretty dump of the readings to STDOUT
    #
    def report
      ap to_hash
    end
  end

  ##
  # Parsing logic for the "holding registers", also
  # known as read/write. PZEM-016 is configured via these
  #
  class HoldingRegisters < ModbusRegisters
    ##
    # Specific holding register read logic for PZEM-016
    #
    def read
      @raw = @slave.holding_registers[0..6]
    end

    ##
    # Sets the address of the slave to the new address addr
    #
    def set_address(addr)
      @slave.write_single_register(2, addr)
    end

    ##
    # Sets the alarm threshold to the given number of watts
    def set_alarm(watts)
      @slave.write_single_register(1, watts)
    end

    ##
    # Clears / resets the KWH (energy) counter on the PZEM-016
    #
    def reset_energy
      @slave.query("\x42")
    rescue ModBus::Errors::IllegalFunction
      # the units respond with an error but in fact do reset the counter
      true
    end

    ##
    # Specific logic for generating a hash of the holding registers in a PZEM-016
    #
    def to_hash
      {
        "DeviceName": @name,
        "Address": @raw[2],
        "AlarmWatts": @raw[1]
      }
    end
  end

  ##
  # Parsing logic for the "input registers", also
  # known as readonly.  This is where the sample data
  # shows up
  #
  class InputRegisters < ModbusRegisters
    ##
    # Specific input register read logic for PZEM-016
    #
    def read
      @raw = @slave.input_registers[0..9]
    end

    ##
    # Extracts measured volts from the sample data
    #
    def volts
      (@raw[0] * 0.1).round(3)
    end

    ##
    # Extracts measured amps from the sample data
    #
    def amps
      (((@raw[2] << 16) | @raw[1]) * 0.001).round(3)
    end

    ##
    # Extracts measured watts from the sample data
    #
    def watts
      (((@raw[4] << 16) | @raw[3]) * 0.1).round(3)
    end

    ##
    # Extracts cumulative watt-hours from the sample data
    #
    def wattHours
      (((@raw[6] << 16) | @raw[5]) * 0.1).round(3)
    end

    ##
    # Extracts measured frequency from the sample data
    #
    def hz
      (@raw[7] * 0.1).round(3)
    end

    ##
    # Extracts measured power factor from the sample data
    #
    def powerFactor
      (@raw[8] * 0.01).round(3)
    end

    ##
    # Returns true of power consumption has reached the alarm number of watts
    #
    def alarm?
      @raw[9] == 0xFFFF
    end

    ##
    # Specific logic for generating a hash of the input registers in a PZEM-016
    #
    def to_hash
      {
        "DeviceName": @name,
        "Volts": volts,
        "Amps": amps,
        "Watts": watts,
        "WH": wattHours,
        "HZ": hz,
        "PF": powerFactor,
        "Alarm": alarm?
      }
    end
  end
end