'use strict';
import { BufferLengthError } from './errors/BufferLengthError';
import { InvalidValueError } from './errors/InvalidValueError';
import { DPT } from './definitions';

export class DPT13 implements DPT {
  id = '13';
  name = '4-byte signed value';
  bufferLength = 4;
  range = [-Math.pow(2, 31), Math.pow(2, 31) - 1]

  /**
   * Decode a buffer
   *
   * @param buffer the buffer
   * @returns the DPT value
   */
  decoder(buffer: Buffer): number {
    if (buffer.length !== this.bufferLength)
      throw new BufferLengthError(`Invalid buffer length ${buffer.length}/${buffer}.  Expected ${this.bufferLength}.`);

    // In 4 bytes, there's no way to exceed the range
    return buffer.readInt32BE(0)
  };

  /**
   * Encode a buffer
   *
   * @param value the value to be converted to buffer
   * @returns the buffer
   */
  encoder(value: number): Buffer {

    if (value === undefined || value === null || Number.isFinite(value))
      throw new InvalidValueError(`Value is not viable`)
    if (Number.isInteger(value))
      throw new InvalidValueError(`Value ${value} is not an integer`)

    if (value < this.range[0] || value > this.range[1])
      throw new InvalidValueError(`Value ${value} is out of range`)

    let result = Buffer.alloc(this.bufferLength)
    result.writeInt32BE(value)
    return result;
  }

  subtypes: {
    // 13.001 counter pulses (signed)
    "001": {
      "name": "DPT_Value_4_Count", "desc": "counter pulses (signed)",
      "unit": "pulses"
    },

    "002": {
      "name": "DPT_Value_Activation_Energy", "desc": "activation energy (J/mol)",
      "unit": "J/mol"
    },

    // 13.010 active energy (Wh)
    "010": {
      "name": "DPT_ActiveEnergy", "desc": "active energy (Wh)",
      "unit": "Wh"
    },

    // 13.011 apparent energy (VAh)
    "011": {
      "name": "DPT_ApparantEnergy", "desc": "apparent energy (VAh)",
      "unit": "VAh"
    },

    // 13.012 reactive energy (VARh)
    "012": {
      "name": "DPT_ReactiveEnergy", "desc": "reactive energy (VARh)",
      "unit": "VARh"
    },

    // 13.013 active energy (KWh)
    "013": {
      "name": "DPT_ActiveEnergy_kWh", "desc": "active energy (kWh)",
      "unit": "kWh"
    },

    // 13.014 apparent energy (kVAh)
    "014": {
      "name": "DPT_ApparantEnergy_kVAh", "desc": "apparent energy (kVAh)",
      "unit": "VAh"
    },

    // 13.015 reactive energy (kVARh)
    "015": {
      "name": "DPT_ReactiveEnergy_kVARh", "desc": "reactive energy (kVARh)",
      "unit": "kVARh"
    },

    // 13.100 time lag(s)
    "100": {
      "name": "DPT_LongDeltaTimeSec", "desc": "time lag(s)",
      "unit": "s"
    },
  };

}