export function logSpace(xMin: number, xMax: number, steps: number): number[] {
  const logMin = Math.log10(xMin);
  const logMax = Math.log10(xMax);
  const out: number[] = [];
  for (let s = 0; s <= steps; s++) {
    out.push(Math.pow(10, logMin + ((logMax - logMin) * s) / steps));
  }
  return out;
}

export type CurvePoint = { x: number; y: number };

export type CurveColors = {
  strokeColor: string;
  fillAbove: string;
  fillAboveFade: string;
  fillBelowFade: string;
  fillBelow: string;
};

export const DEFAULT_CURVE_COLORS: CurveColors = {
  strokeColor: '#e5e7eb',
  fillAbove: 'rgba(74, 222, 128, 0.35)',
  fillAboveFade: 'rgba(74, 222, 128, 0.08)',
  fillBelowFade: 'rgba(248, 113, 113, 0.08)',
  fillBelow: 'rgba(248, 113, 113, 0.35)',
};

export type CurveStyle = {
  strokeColor?: string;
  fillColors?: CurveColors;
  /** Draw the area fill under/around the curve. Defaults to true. */
  fill?: boolean;
  lineWidth?: number;
  dimmed?: boolean;
};

/** A single polyline ready to be handed to `drawCurves`. */
export type Curve = {
  points: CurvePoint[];
  style?: CurveStyle;
};

export function sumCurvePoints(pointArrays: CurvePoint[][]): CurvePoint[] {
  if (pointArrays.length === 0) return [];

  const length = pointArrays[0].length;
  const result: CurvePoint[] = new Array(length);

  for (let i = 0; i < length; i++) {
    let y = 0;
    for (const points of pointArrays) {
      y += points[i]?.y ?? 0;
    }
    result[i] = { x: pointArrays[0][i].x, y };
  }

  return result;
}

export function sumPhaseCurvePoints(pointArrays: CurvePoint[][]): CurvePoint[] {
  if (pointArrays.length === 0) return [];

  const length = pointArrays[0].length;
  const result: CurvePoint[] = new Array(length);

  let previousPhase = 0;

  for (let i = 0; i < length; i++) {
    let phase = 0;

    for (const points of pointArrays) {
      phase += points[i]?.y ?? 0;
    }

    // Keep phase continuous while summing.
    while (phase - previousPhase > 180) {
      phase -= 360;
    }

    while (phase - previousPhase < -180) {
      phase += 360;
    }

    // Wrap to [-180, 180].
    const wrapped = ((((phase + 180) % 360) + 360) % 360) - 180;

    result[i] = {
      x: pointArrays[0][i].x,
      y: wrapped,
    };

    previousPhase = phase;
  }

  return result;
}