import { Field } from '../core/field';
import { Rng, valueNoise2D } from '../core/rng';

/**
 * THE HEAT SOURCE — the bone between the knob and the browning integrator.
 *
 * Every heat surface in the game used to map its dial STRAIGHT into the cooker:
 * roastStep read s.power, toastStep read power, and the number the knob asked for
 * was the number the food got. No real cook believes that. A HeatSource sits in
 * between: the knob sets a `target`, an `output` chases it on a fuel-specific lag,
 * and every station reads `output` where it read `power`.
 *
 *   gas       — output glued to the knob (fast rise AND fall). No memory.
 *   electric  — slow rise, slower fall: the coil remembers, you cook its future.
 *   induction — instant both ways, flattest heat, DEAD to a non-ferrous pan.
 *   charcoal  — no knob; a heat you bank and it decays over a service (see zone).
 *   radiant   — the element: slow, top-biased — what the toaster & fan oven ARE.
 *
 * You never cook the knob — you cook the lag.
 *
 * Pure: Field + Rng only, so the harness measures the same numbers the judge does.
 * Retrofit is golden-preserving: a station passing no source reads `power` exactly
 * as before (see roasting.ts / the M-H2 golden test).
 */

export type Fuel = 'gas' | 'electric' | 'induction' | 'charcoal' | 'radiant';

export interface HeatSource {
  fuel: Fuel;
  /** 0..10 — what the knob commands (charcoal: the banked bed level). */
  target: number;
  /** 0..10 — what actually reaches the vessel. EVERY station reads this. */
  output: number;
  /** units/sec climbing toward target. */
  riseRate: number;
  /** units/sec falling toward target. LOW = residual heat that won't let go. */
  fallRate: number;
  /** powerMax clamp — cheap hobs top out below 10. */
  maxOut: number;
  /** blotch amplitude blended into the station's heat-map (hot-spots). */
  evenNoise: number;
  /** radial concentration of the heat map — a burner ring, a coal pile, a centre-hot oven. */
  hotspot: number;
  /** has a flame → wind steals from output, fat can flare it. */
  flame: boolean;
  /** induction rejects a non-ferrous vessel → output pinned at ambient. */
  needsFerrous: boolean;
  /** how hard rendered fat spikes output (gas high, induction zero). */
  flareGain: number;
  /** charcoal only: a 2D heat-zone gradient you arrange. */
  zone?: Field;
}

export interface Environment {
  place: 'indoor' | 'outdoor';
  /** the temp cooling pulls toward (a cold night lowers it). */
  ambient: number;
  wind: number; // 0..1 base
  gust: number; // 0..1 live, walks toward wind
  /** lid / windbreak / lee side → gust forced to 0 (the dodgeable floor). */
  sheltered: boolean;
  /** does the mounted pan take induction. */
  vesselFerrous: boolean;
  /** indoor only: burnt food accumulates it → fires the ZAP once. */
  smoke: number;
  rng: Rng;
}

type Profile = Omit<HeatSource, 'fuel' | 'target' | 'output' | 'zone'>;

/**
 * Base fuel profiles. Tuned to the M-H1 exit bars: chase 3→9 is gas <1s,
 * electric 5-9s, induction <0.15s; residual after 9→0 is gas <1 within 1s,
 * electric still >6 at 6s, charcoal still >5 at 30s.
 */
export const FUELS: Record<Fuel, Profile> = {
  gas: { riseRate: 14, fallRate: 14, maxOut: 10, evenNoise: 0.1, hotspot: 0.35, flame: true, needsFerrous: false, flareGain: 3.5 },
  electric: { riseRate: 1.0, fallRate: 0.4, maxOut: 9, evenNoise: 0.28, hotspot: 0.2, flame: false, needsFerrous: false, flareGain: 0 },
  induction: { riseRate: 45, fallRate: 45, maxOut: 10, evenNoise: 0.03, hotspot: 0.1, flame: false, needsFerrous: true, flareGain: 0 },
  charcoal: { riseRate: 6, fallRate: 0.02, maxOut: 10, evenNoise: 0.35, hotspot: 0.6, flame: true, needsFerrous: false, flareGain: 4.0 },
  radiant: { riseRate: 0.9, fallRate: 0.5, maxOut: 10, evenNoise: 0.14, hotspot: 0.05, flame: false, needsFerrous: false, flareGain: 0.5 },
};

/**
 * Appliance SKUs — a base fuel with overrides. This is both the two oven
 * variants (gas hot-at-top vs electric fan even) and the P12 buy mechanism
 * (a cheap hob is noise + a slow chase, never a flat score tax).
 */
export const HEATSOURCE_SKUS: Record<string, Partial<Profile> & { fuel: Fuel }> = {
  // Gas oven: preheats fast-ish, top/centre-hot, blotchy → uneven roast (high stdev).
  oven_gas: { fuel: 'gas', riseRate: 2.2, fallRate: 1.2, evenNoise: 0.24, hotspot: 0.62, maxOut: 10 },
  // Electric fan oven: slow to preheat, laboratory-flat → even roast (low stdev).
  oven_fan: { fuel: 'radiant', riseRate: 0.8, fallRate: 0.5, evenNoise: 0.03, hotspot: 0.0, maxOut: 10 },
  // P12: a cheap thin electric hob — hot-spot noise + a slow chase, tops out low.
  cheap_electric: { fuel: 'electric', maxOut: 8.2, evenNoise: 0.42, hotspot: 0.5, riseRate: 0.9 },
};

export function newHeatSource(fuelOrSku: Fuel | string): HeatSource {
  const sku = HEATSOURCE_SKUS[fuelOrSku];
  const fuel: Fuel = sku ? sku.fuel : (fuelOrSku as Fuel);
  const p: Profile = { ...FUELS[fuel], ...(sku ?? {}) };
  return {
    fuel,
    target: 0,
    output: 0,
    riseRate: p.riseRate,
    fallRate: p.fallRate,
    maxOut: p.maxOut,
    evenNoise: p.evenNoise,
    hotspot: p.hotspot,
    flame: p.flame,
    needsFerrous: p.needsFerrous,
    flareGain: p.flareGain,
  };
}

export function newIndoorEnv(seed = 7): Environment {
  return { place: 'indoor', ambient: 0, wind: 0, gust: 0, sheltered: true, vesselFerrous: true, smoke: 0, rng: new Rng(seed) };
}

const INDOOR = newIndoorEnv();

/** Set the knob. Charcoal ignores this (target is the bed level; use stoke). */
export function setKnob(hs: HeatSource, k: number): void {
  if (hs.fuel === 'charcoal') return;
  hs.target = Math.max(0, Math.min(hs.maxOut, k));
}

/** Charcoal: fan the coals — bump the bed ceiling. */
export function stoke(hs: HeatSource, amt = 1.5): void {
  hs.target = Math.min(hs.maxOut, hs.target + amt);
}

/**
 * Advance the source one tick. output chases target on the fuel's lag; a flame
 * loses ground to wind and gains it from fat; a dead (non-ferrous) induction pan
 * sits at ambient. This is TempClock's linear drift and coolStep's decay, married.
 */
export function heatStep(hs: HeatSource, dt: number, env: Environment = INDOOR, fatLoad = 0): void {
  if (hs.needsFerrous && !env.vesselFerrous) {
    hs.output = env.ambient;
    return;
  }
  const t = hs.flame ? hs.target * (1 - 0.35 * env.gust) : hs.target;
  if (hs.output < t) hs.output = Math.min(t, hs.output + hs.riseRate * dt);
  else hs.output = Math.max(t, hs.output - hs.fallRate * dt);
  if (fatLoad > 0 && hs.flareGain > 0) {
    hs.output = Math.min(hs.maxOut, hs.output + hs.flareGain * fatLoad);
  }
}

/** Walk the live gust toward the base wind (0 indoors or when sheltered). */
export function envStep(env: Environment, dt: number): void {
  const target = env.place === 'outdoor' && !env.sheltered ? env.wind : 0;
  // A lazy first-order walk with a little value-noise jitter so gusts feel alive.
  const jitter = (env.rng.next() - 0.5) * 0.4 * env.wind;
  env.gust += (target + jitter - env.gust) * Math.min(1, dt * 1.5);
  env.gust = Math.max(0, Math.min(1, env.gust));
}

/**
 * Reshape a station's heat map for this fuel — the only spatial hook. A flat fan
 * (hotspot 0, evenNoise ~0) leaves a near-uniform disc; a gas/coal source (high
 * hotspot + blotch) concentrates heat toward the centre and speckles it, so an
 * even cook becomes a real skill. Normalized over `mask` (or the whole grid) so
 * two fuels compared at equal cook time have equal MEAN heat — the difference is
 * pure evenness (the M-H2 bar).
 */
export function applyToHeatMap(heat: Float32Array, n: number, hs: HeatSource, rng: Rng, mask?: Field): void {
  const bias = valueNoise2D(rng, n, n, 3);
  let sum = 0;
  let count = 0;
  for (let y = 0; y < n; y++) {
    for (let x = 0; x < n; x++) {
      const i = y * n + x;
      const u = x / (n - 1);
      const v = y / (n - 1);
      const dc = Math.hypot(u - 0.5, v - 0.5);
      const centre = 1 - hs.hotspot * Math.min(1, dc / 0.6);
      const blot = 1 + hs.evenNoise * (bias[i] * 2 - 1);
      const val = Math.max(0.05, centre * blot);
      heat[i] = val;
      if (!mask || mask.data[i] >= 0.5) {
        sum += val;
        count++;
      }
    }
  }
  // Normalize so the masked average matches the legacy heat map's ~0.9.
  const avg = count > 0 ? sum / count : 1;
  const k = avg > 0 ? 0.9 / avg : 1;
  for (let i = 0; i < heat.length; i++) heat[i] *= k;
}

/** A human tell for the current source state — for a diegetic HUD, never a bar. */
export function fuelWord(hs: HeatSource): string {
  const o = hs.output;
  switch (hs.fuel) {
    case 'gas':
      return o < 0.5 ? 'flame out' : o > 8 ? 'roaring blue' : 'blue flame';
    case 'electric':
      return o < 0.5 ? 'cold coil' : o > hs.target + 0.5 ? 'still glowing (residual)' : o > 6 ? 'glowing orange' : 'warming';
    case 'induction':
      return o < 0.3 ? 'dead — wrong pan?' : 'silent, exact';
    case 'charcoal':
      return o > 6 ? 'coals screaming' : o > 3 ? 'good bed' : 'coals fading';
    default:
      return o > 6 ? 'element hot' : o > 2 ? 'warming' : 'cold';
  }
}