'use strict';

const { BaseDomain, statusBadge, interpolation, gravity, convert, loadCurve } = require('generalFunctions');

// Default curve used when the node's asset model field is not set. Preserves
// the historical behaviour of the hardcoded _loadSpecs() (GVA ELASTOX-R at
// density 2.4 elements/m²) — the existing test suite calibrates against
// these numbers.
const DEFAULT_DIFFUSER_MODEL = 'gva-elastox-r';

class Diffuser extends BaseDomain {
  static name = 'diffuser';

  configure() {
    const d = this.config.diffuser || {};
    this.interpolation = new interpolation({ type: 'linear' });
    this.specs = this._loadSpecs();

    this.idle = true;
    this.warning = { state: false, text: [], flow: { min: { hyst: 2 }, max: { hyst: 2 } } };
    this.alarm = { state: false, text: [], flow: { min: { hyst: 10 }, max: { hyst: 10 } } };

    this.i_pressure = _num(d.headerPressure, 0);
    this.i_local_atm_pressure = _num(d.localAtmPressure, 1013.25);
    this.i_water_density = _num(d.waterDensity, 997);
    this.i_alfa_factor = _num(d.alfaFactor, 0.7);
    this.i_n_elements = _posInt(d.elements, 1);
    this.i_diff_density = _num(d.density, 15);
    this.i_m_water = _num(d.waterHeight, 0);
    this.i_flow = 0;
    this.zoneVolume = _num(d.zoneVolume, 0);

    // Membrane area per element. Curves declare it in _meta — that's the
    // source of truth. Config can override (e.g. for a non-standard build).
    // Final fallback 0.18 m² matches the Jäger TD-65 / GVA placeholder.
    const curveArea = Number(this.specs?._meta?.membraneArea_m2_per_element);
    const cfgArea = Number(d.membraneAreaPerElement);
    this.i_membrane_area = Number.isFinite(cfgArea) && cfgArea > 0
      ? cfgArea
      : (Number.isFinite(curveArea) && curveArea > 0 ? curveArea : 0.18);

    this.n_kg = this._calcAirDensityMbar(1013.25, 0, 20);
    this.n_flow = 0;
    this.o_otr = 0;
    this.o_p_flow = 0;
    this.o_p_water = this._heightToPressureMbar(this.i_water_density, this.i_m_water);
    this.o_p_total = this.o_p_water;
    this.o_kg = 0; this.o_kg_h = 0; this.o_kgo2_h = 0; this.o_kgo2 = 0;
    this.o_kgo2_h_min = 0; this.o_kgo2_h_max = 0;
    this.o_flow_element = 0;
    this.o_flux_per_m2 = 0;
    this.o_otr_min = 0; this.o_otr_max = 0;
    this.o_p_min = 0; this.o_p_max = 0;
    this.o_combined_eff = 0;
    this.o_slope = 0;
  }

  setDensity(v)        { this.i_diff_density = _num(v, this.i_diff_density); this._recalculate(); }
  setFlow(v)           { this.i_flow = Math.max(0, _num(v, 0)); this._recalculate(); }
  setWaterHeight(v)    {
    this.i_m_water = Math.max(0, _num(v, this.i_m_water));
    this.o_p_water = this._heightToPressureMbar(this.i_water_density, this.i_m_water);
    this._recalculate();
  }
  setHeaderPressure(v) { this.i_pressure = _num(v, this.i_pressure); this._recalculate(); }
  setElementCount(v)   { this.i_n_elements = _posInt(v, this.i_n_elements); this._recalculate(); }
  setAlfaFactor(v)     { this.i_alfa_factor = _num(v, this.i_alfa_factor); this._recalculate(); }

  _recalculate() {
    if (this.i_flow <= 0) {
      this.idle = true;
      this.n_flow = 0; this.o_otr = 0; this.o_p_flow = 0;
      this.o_flow_element = 0; this.o_flux_per_m2 = 0;
      this.o_p_total = this.o_p_water;
      this.o_kg = 0; this.o_kg_h = 0; this.o_kgo2_h = 0; this.o_kgo2 = 0;
      this.o_combined_eff = 0; this.o_slope = 0;
      this.warning.text = []; this.warning.state = false;
      this.alarm.text = [];   this.alarm.state = false;
    } else {
      this.idle = false;
      this._calcOtrPressure(this.i_flow);
    }
    this.notifyOutputChanged();
  }

  _getCurveKeys(c) { return Object.keys(c).map(Number).sort((a, b) => a - b); }

  _interpolateSeries(pts, x) {
    this.interpolation.load_spline(pts.x, pts.y, 'linear');
    return this.interpolation.interpolate(x);
  }

  _interpolateCurveByDensity(curve, density, x) {
    const keys = this._getCurveKeys(curve);
    if (keys.length === 1) {
      const only = curve[keys[0]];
      return { value: this._interpolateSeries(only, x),
        minY: Math.min(...only.y), maxY: Math.max(...only.y),
        minX: Math.min(...only.x), maxX: Math.max(...only.x),
        slope: this._getSegmentSlope(only, x) };
    }
    const lowerKey = keys.reduce((a, k) => (k <= density ? k : a), keys[0]);
    const upperKey = keys.find((k) => k >= density) ?? keys[keys.length - 1];
    const lower = curve[lowerKey]; const upper = curve[upperKey];
    if (lowerKey === upperKey) {
      return { value: this._interpolateSeries(lower, x),
        minY: Math.min(...lower.y), maxY: Math.max(...lower.y),
        minX: Math.min(...lower.x), maxX: Math.max(...lower.x),
        slope: this._getSegmentSlope(lower, x) };
    }
    const lv = this._interpolateSeries(lower, x);
    const uv = this._interpolateSeries(upper, x);
    const r = (density - lowerKey) / (upperKey - lowerKey);
    return {
      value: lv + (uv - lv) * r,
      minY: Math.min(...lower.y) + (Math.min(...upper.y) - Math.min(...lower.y)) * r,
      maxY: Math.max(...lower.y) + (Math.max(...upper.y) - Math.max(...lower.y)) * r,
      minX: Math.min(...lower.x), maxX: Math.max(...lower.x),
      slope: this._getSegmentSlope(lower, x),
    };
  }

  _getSegmentSlope(pts, x) {
    const { x: xs, y: ys } = pts;
    for (let i = 0; i < xs.length - 1; i += 1) {
      if (x <= xs[i + 1]) return (ys[i + 1] - ys[i]) / (xs[i + 1] - xs[i]);
    }
    const n = xs.length - 1;
    return (ys[n] - ys[n - 1]) / (xs[n] - xs[n - 1]);
  }

  _combineEff(oOtr, oOtrMin, oOtrMax, oPFlow, oPMin, oPMax) {
    const otrSpan = oOtrMax - oOtrMin;
    const pSpan = oPMax - oPMin;
    const e1 = otrSpan > 0 ? (oOtr - oOtrMin) / otrSpan : 0;
    const e2 = pSpan > 0 ? 1 - ((oPFlow - oPMin) / pSpan) : 0;
    return Math.max(0, e1 * e2 * 100);
  }

  _calcAirDensityMbar(pMbar, RH, tempC) {
    const Rd = 287.05, Rv = 461.495;
    const T = tempC + 273.15;
    const es = Math.pow(10, (8.07131 - (1730.63 / (233.426 + tempC))));
    const e = RH * es / 100;
    const pPa = convert(pMbar).from('mbar').to('Pa');
    const pd = pPa - (e * 100);
    return (pd / (Rd * T)) + ((e * 100) / (Rv * T));
  }

  _heightToPressureMbar(density, height) {
    const pPa = gravity.getStandardGravity() * density * height;
    return convert(pPa).from('Pa').to('mbar');
  }

  _calcOtrPressure(flow) {
    const totalInputPressureMbar = this.i_local_atm_pressure + this.i_pressure;
    this.o_kg = this._calcAirDensityMbar(totalInputPressureMbar, 0, 20);
    this.o_kg_h = this.o_kg * flow;
    this.n_flow = (this.o_kg / this.n_kg) * flow;
    this.o_flow_element = Math.round((this.n_flow / this.i_n_elements) * 100) / 100;
    // Specific flux through the membrane — the canonical x-axis of every
    // curve file under datasets/assetData/curves/. Curves are indexed by
    // bottom coverage % (this.i_diff_density) and queried at this flux.
    const totalMembraneArea = this.i_n_elements * this.i_membrane_area;
    this.o_flux_per_m2 = Math.round((this.n_flow / totalMembraneArea) * 100) / 100;

    const otr = this._interpolateCurveByDensity(this.specs.otr_curve, this.i_diff_density, this.o_flux_per_m2);
    const pressure = this._interpolateCurveByDensity(this.specs.p_curve, 0, this.o_flux_per_m2);

    this.o_otr_min = otr.minY; this.o_otr_max = otr.maxY;
    this.o_p_min = pressure.minY; this.o_p_max = pressure.maxY;
    this.o_otr = Math.round(otr.value * 100) / 100;
    this.o_p_flow = Math.round(pressure.value * 100) / 100;
    this.o_p_total = Math.round((this.o_p_water + this.o_p_flow) * 100) / 100;
    const kgo2 = (n) => Math.round(convert(n * this.n_flow * this.i_m_water * this.i_alfa_factor).from('g').to('kg') * 100) / 100;
    this.o_kgo2_h = kgo2(this.o_otr);
    this.o_kgo2_h_min = kgo2(this.o_otr_min);
    this.o_kgo2_h_max = kgo2(this.o_otr_max);
    this.o_kgo2 = this.o_kgo2_h / 3600;
    this.o_combined_eff = Math.round(this._combineEff(
      this.o_otr, this.o_otr_min, this.o_otr_max,
      this.o_p_flow, this.o_p_min, this.o_p_max,
    ) * 100) / 100;
    this.o_slope = Math.round(otr.slope * 1000) / 1000;

    this._checkLimits(pressure.minX, pressure.maxX);
  }

  _checkLimits(minFlow, maxFlow) {
    this.warning.text = []; this.warning.state = false;
    this.alarm.text   = []; this.alarm.state   = false;
    // Compare against the canonical flux, since pressure.minX / maxX come
    // from the per-m²-membrane curve.
    const f = this.o_flux_per_m2;
    for (const k of ['warning', 'alarm']) {
      const band = this[k];
      const lo = minFlow - minFlow * (band.flow.min.hyst / 100);
      const hi = maxFlow + maxFlow * (band.flow.max.hyst / 100);
      if (f < lo) { band.state = true; band.text.push(`${_cap(k)}: specific flux ${f} Nm³/(h·m²) is below ${Math.round(lo * 100) / 100}`); }
      if (f > hi) { band.state = true; band.text.push(`${_cap(k)}: specific flux ${f} Nm³/(h·m²) exceeds ${Math.round(hi * 100) / 100}`); }
    }
  }

  // Back-compat hooks for the legacy specificClass test suite.
  getStatus() { return this._legacyStatus(); }
  _legacyStatus() {
    if (this.alarm.state)   return { fill: 'red',   shape: 'dot', text: this.alarm.text[0] };
    if (this.warning.state) return { fill: 'yellow', shape: 'dot', text: this.warning.text[0] };
    const fill = this.idle ? 'grey' : 'green';
    return { fill, shape: 'dot', text: `${this.o_kgo2_h} kg o2 / h` };
  }

  getStatusBadge() {
    if (this.alarm.state)   return statusBadge.error(this.alarm.text[0]);
    if (this.warning.state) return statusBadge.compose([`⚠ ${this.warning.text[0]}`], { fill: 'yellow', shape: 'dot' });
    const text = `${this.o_kgo2_h} kg o2 / h`;
    return this.idle ? statusBadge.idle(text) : statusBadge.compose([`🟢 ${text}`]);
  }

  getOutput() {
    return {
      iPressure: this.i_pressure,
      iMWater: this.i_m_water,
      iFlow: this.i_flow,
      nFlow: Math.round(this.n_flow * 100) / 100,
      oOtr: this.o_otr,
      oPLoss: this.o_p_total,
      oKgo2H: this.o_kgo2_h,
      oFlowElement: this.o_flow_element,
      oFluxPerM2:   this.o_flux_per_m2,
      efficiency: this.o_combined_eff,
      slope: this.o_slope,
      oZoneOtr: this.getReactorOtr(this.zoneVolume),
      idle: this.idle,
      warning: [...this.warning.text],
      alarm: [...this.alarm.text],
    };
  }

  getReactorOtr(zoneVolumeM3) {
    const v = Number(zoneVolumeM3);
    if (!Number.isFinite(v) || v <= 0) return 0;
    return this.o_kgo2_h * 1000 * 24 / v;
  }

  _loadSpecs() {
    // Curve lookup id: prefer the asset-menu-saved field, fall back to the
    // legacy GVA ELASTOX-R reference (same numbers as the previous inline
    // _loadSpecs). If a configured id misses the registry, fall back too —
    // a missing curve would otherwise crash the constructor in production.
    const cfgModel =
      this.config?.asset?.model ||
      this.config?.model ||
      DEFAULT_DIFFUSER_MODEL;
    const raw = loadCurve(cfgModel) || loadCurve(DEFAULT_DIFFUSER_MODEL);
    if (!raw || !raw.otr_curve || !raw.p_curve) {
      throw new Error(
        `diffuser: curve '${cfgModel}' is missing otr_curve/p_curve (registry has: ${Object.keys(raw || {}).join(',') || 'nothing'})`,
      );
    }
    return {
      _meta: raw._meta || {},
      supplier: raw._meta?.supplier || null,
      type: raw._meta?.type || null,
      model: raw._meta?.model || cfgModel,
      units: { Nm3: { temp: 20, pressure: 1.01325, RH: 0 } },
      otr_curve: raw.otr_curve,
      p_curve: raw.p_curve,
    };
  }
}

function _num(v, fb = 0) {
  const n = Number(v);
  return Number.isFinite(n) ? n : fb;
}
function _posInt(v, fb = 1) {
  const n = Math.round(Number(v));
  return Number.isFinite(n) && n > 0 ? n : fb;
}
function _cap(s) { return s.charAt(0).toUpperCase() + s.slice(1); }

module.exports = Diffuser;