/*
  Ogni istanza mantiene lo stato corrente del dispositivo (tensioni, correnti,
  temperature, flag operativi, warnings) aggiornato dai frame CAN broadcast
  (MSG1 status, MSG2 power) e dalle risposte alle richieste di lettura registro.

  I valori esposti sono gia' convertiti in unita' fisiche (V, A, W, °C, Ah).
*/

const {
  conversionsFactors,
  status1Flags,
  errorsFlags,
  registerAddresses,
} = require('./constants');

/*
  Mappa indirizzo registro -> campo di stato e fattore di conversione.
  Usata da updateRegister per convertire il valore raw a 16 bit nel valore fisico.
  I registri di flag (status1, warning) sono gestiti a parte perche' vanno decodificati a bit.
  signed=true indica un intero a 16 bit con segno (complemento a 2), usato per le temperature.
*/
const numericRegisterMap = {
  [registerAddresses.voltageInput]: { field: 'voltageInput', factor: conversionsFactors.voltageInput, signed: false },
  [registerAddresses.currentInput]: { field: 'currentInput', factor: conversionsFactors.currentInput, signed: false },
  [registerAddresses.voltageOutput]: { field: 'voltageOutput', factor: conversionsFactors.voltageOutput, signed: false },
  [registerAddresses.currentOutput]: { field: 'currentOutput', factor: conversionsFactors.currentOutput, signed: false },
  [registerAddresses.powerInput]: { field: 'powerInput', factor: conversionsFactors.powerInput, signed: false },
  [registerAddresses.powerOutput]: { field: 'powerOutput', factor: conversionsFactors.powerOutput, signed: false },
  [registerAddresses.chargeCapacity]: { field: 'chargeCapacity', factor: conversionsFactors.chargeCapacity, signed: false },
  [registerAddresses.temperature1]: { field: 'temperature1', factor: conversionsFactors.temperaturePhase1, signed: true },
  [registerAddresses.temperature2]: { field: 'temperature2', factor: conversionsFactors.temperaturePhase2, signed: true },
};

// Arrotondamenti
const roundedTo1 = (v) => Number(v.toFixed(1));
const roundedTo2 = (v) => Number(v.toFixed(2));
const roundedTo3 = (v) => Number(v.toFixed(3));

// Decodifica un valore numerico in array di stringhe usando una mappa bit -> nome
const decodeFlags = (value, map) => {
  const active = [];
  for (const [bit, name] of Object.entries(map)) {
    if (value & (1 << parseInt(bit, 10))) {
      // Nel caso di status1Flags i valori sono stringhe; nel caso di errorsFlags idem
      active.push(typeof name === 'string' ? name : name.code);
    }
  }
  return active;
};

class MPPT {
  constructor({
    name,
    address,
    log = () => {},
  } = {}) {
    this.name = name;             // identificativo logico (es. 'port', 'starboard')
    this.address = address;       // indirizzo UART/DST del dispositivo (registro Addr)
    this.log = log;

    this.state = {
      voltageInput: null,
      currentInput: null,
      voltageOutput: null,
      currentOutput: null,
      powerInput: null,           // letto via polling registro 20
      powerOutput: null,          // letto via polling registro 21
      temperature1: null,         // [°C]
      temperature2: null,         // [°C]
      chargeCapacity: null,       // [Ah]
      status1Raw: 0,
      warningRaw: 0,
      flags: [],
      warnings: [],
      lastUpdate: 0,
    };
  }

  // Restituisce true se l'MPPT ha trasmesso dati recentemente
  isOnline(thresholdMs = 5000) {
    return this.state.lastUpdate > 0 && (Date.now() - this.state.lastUpdate) < thresholdMs;
  }

  // Calcola l'efficienza istantanea (output/input) come ratio 0..1
  calculateEfficiency() {
    const { voltageInput, currentInput, voltageOutput, currentOutput } = this.state;
    if (voltageInput === null || currentInput === null || voltageOutput === null || currentOutput === null) return null;
    const inputPower = voltageInput * currentInput;
    if (inputPower < 1) return null;
    return roundedTo3((voltageOutput * currentOutput) / inputPower);
  }

  // Deriva la modalita' di carica corrente a partire dai flag attivi
  deriveChargingMode() {
    if (!this.state.flags.includes('PwrOn')) return 'off';
    if (this.state.flags.includes('FloatMod')) return 'float';
    if (this.state.flags.includes('StorMod')) return 'storage';
    return 'bulk';
  }

  /*
    Aggiorna lo stato a partire dalla lettura UART di un singolo registro.
    regAddr  = indirizzo del registro letto
    rawValue = valore raw a 16 bit ricevuto nella risposta (big-endian, gia' decodificato)
  */
  updateRegister(regAddr, rawValue) {
    if (regAddr === registerAddresses.status1) {
      // Registro di stato St1: decodifica i bit in flag operativi
      this.state.status1Raw = rawValue;
      this.state.flags = decodeFlags(rawValue, status1Flags);
    } else if (regAddr === registerAddresses.warning) {
      // Registro Warning: decodifica i bit in codici di errore/warning
      this.state.warningRaw = rawValue;
      this.state.warnings = decodeFlags(rawValue, errorsFlags);
      if (this.state.warnings.length) {
        this.log(`[${this.name}] WARN: ${this.state.warnings.join(',')}`);
      }
    } else {
      // Registri numerici (tensioni, correnti, temperature, capacita')
      const target = numericRegisterMap[regAddr];
      if (!target) return;
      let value = rawValue;
      if (target.signed && value >= 0x8000) value -= 0x10000; // intero con segno
      this.state[target.field] = value / target.factor;
    }
    this.state.lastUpdate = Date.now();
  }

  // Costruisce gli update SignalK (path + value) a partire dallo stato corrente
  // Tutti i valori sono in unita' SI (V, A, W, K, ratio, Ah)
  buildSignalKUpdates() {
    const base = `meb.solar.${this.name}`;
    const s = this.state;
    const updates = [];

    if (s.voltageInput !== null) updates.push({ path: `${base}.panelVoltage`, value: roundedTo1(s.voltageInput) });
    if (s.currentInput !== null) updates.push({ path: `${base}.panelCurrent`, value: roundedTo2(s.currentInput) });
    if (s.voltageInput !== null && s.currentInput !== null) {
      updates.push({ path: `${base}.panelPower`, value: roundedTo2(s.voltageInput * s.currentInput) });
    }
    if (s.voltageOutput !== null) updates.push({ path: `${base}.voltage`, value: roundedTo1(s.voltageOutput) });
    if (s.currentOutput !== null) updates.push({ path: `${base}.current`, value: roundedTo2(s.currentOutput) });
    if (s.voltageOutput !== null && s.currentOutput !== null) {
      updates.push({ path: `${base}.power`, value: roundedTo2(s.voltageOutput * s.currentOutput) });
    }

    const efficiency = this.calculateEfficiency();
    if (efficiency !== null) updates.push({ path: `${base}.efficiency`, value: efficiency });

    if (s.temperature1 !== null) updates.push({ path: `${base}.controllerTemperature.phase1`, value: roundedTo2(s.temperature1 + 273.15) });
    if (s.temperature2 !== null) updates.push({ path: `${base}.controllerTemperature.phase2`, value: roundedTo2(s.temperature2 + 273.15) });

    if (s.chargeCapacity !== null) {
      updates.push({ path: `${base}.chargedCapacity`, value: roundedTo2(s.chargeCapacity) });
      if (s.voltageOutput !== null) {
        // Energia in Joule: Ah * V * 3600
        updates.push({ path: `${base}.chargedEnergy`, value: roundedTo2(s.chargeCapacity * s.voltageOutput * 3600) });
      }
    }

    updates.push({ path: `${base}.chargingMode`, value: this.deriveChargingMode() });
    updates.push({ path: `${base}.flags`, value: s.flags });
    updates.push({ path: `${base}.warnings`, value: s.warnings });

    return updates;
  }

  // Snapshot operativo per logging / debug
  getSnapshot() {
    return {
      online: this.isOnline(),
      voltageInput: this.state.voltageInput,
      currentInput: this.state.currentInput,
      voltageOutput: this.state.voltageOutput,
      currentOutput: this.state.currentOutput,
      temperature1: this.state.temperature1,
      temperature2: this.state.temperature2,
      chargeCapacity: this.state.chargeCapacity,
      flags: this.state.flags,
      warnings: this.state.warnings,
      chargingMode: this.deriveChargingMode(),
      efficiency: this.calculateEfficiency(),
    };
  }
}

module.exports = {
  MPPT,
  decodeFlags,
};