import { lessThan, multiply, sub, add, divide, greaterThan, lessOrEq, eq } from '../operators';
import invariant from 'fbjs/lib/invariant';
import AnimatedNode from '../core/AnimatedNode';
import { createAnimatedCond as cond } from '../core/AnimatedCond';
import { createAnimatedFunction as proc } from '../core/AnimatedFunction';
const interpolateInternalSingleProc = proc(function (value, inS, inE, outS, outE) {
  const progress = divide(sub(value, inS), sub(inE, inS)); // logic below was made in order to provide a compatibility witn an Animated API

  const resultForNonZeroRange = add(outS, multiply(progress, sub(outE, outS)));
  const result = cond(eq(inS, inE), cond(lessOrEq(value, inS), outS, outE), resultForNonZeroRange);
  return result;
});

function interpolateInternalSingle(value, inputRange, outputRange, offset) {
  const inS = inputRange[offset];
  const inE = inputRange[offset + 1];
  const outS = outputRange[offset];
  const outE = outputRange[offset + 1];
  return interpolateInternalSingleProc(value, inS, inE, outS, outE);
}

function interpolateInternal(value, inputRange, outputRange, offset = 0) {
  if (inputRange.length - offset === 2) {
    return interpolateInternalSingle(value, inputRange, outputRange, offset);
  }

  return cond(lessThan(value, inputRange[offset + 1]), interpolateInternalSingle(value, inputRange, outputRange, offset), interpolateInternal(value, inputRange, outputRange, offset + 1));
}

export const Extrapolate = {
  EXTEND: 'extend',
  CLAMP: 'clamp',
  IDENTITY: 'identity'
};

function checkNonDecreasing(name, arr) {
  for (let i = 1; i < arr.length; ++i) {
    // We can't validate animated nodes in JS.
    if (arr[i] instanceof AnimatedNode || arr[i - 1] instanceof AnimatedNode) continue;
    invariant(arr[i] >= arr[i - 1], '%s must be monotonically non-decreasing. (%s)', name, arr);
  }
}

function checkMinElements(name, arr) {
  invariant(arr.length >= 2, '%s must have at least 2 elements. (%s)', name, arr);
}

function checkValidNumbers(name, arr) {
  for (let i = 0; i < arr.length; i++) {
    // We can't validate animated nodes in JS.
    if (arr[i] instanceof AnimatedNode || typeof arr[i] !== 'number') continue;
    invariant(Number.isFinite(arr[i]), '%s cannot include %s. (%s)', name, arr[i], arr);
  }
}

function convertToRadians(outputRange) {
  for (const [i, value] of outputRange.entries()) {
    if (typeof value === 'string' && value.endsWith('deg')) {
      outputRange[i] = parseFloat(value) * (Math.PI / 180);
    } else if (typeof value === 'string' && value.endsWith('rad')) {
      outputRange[i] = parseFloat(value);
    }
  }
}

export default function interpolate(value, config) {
  const {
    inputRange,
    outputRange,
    extrapolate = Extrapolate.EXTEND,
    extrapolateLeft,
    extrapolateRight
  } = config;
  checkMinElements('inputRange', inputRange);
  checkValidNumbers('inputRange', inputRange);
  checkMinElements('outputRange', outputRange);
  checkValidNumbers('outputRange', outputRange);
  checkNonDecreasing('inputRange', inputRange);
  invariant(inputRange.length === outputRange.length, 'inputRange and outputRange must be the same length.');
  convertToRadians(outputRange);
  const left = extrapolateLeft || extrapolate;
  const right = extrapolateRight || extrapolate;
  let output = interpolateInternal(value, inputRange, outputRange);

  if (left === Extrapolate.EXTEND) {} else if (left === Extrapolate.CLAMP) {
    output = cond(lessThan(value, inputRange[0]), outputRange[0], output);
  } else if (left === Extrapolate.IDENTITY) {
    output = cond(lessThan(value, inputRange[0]), value, output);
  }

  if (right === Extrapolate.EXTEND) {} else if (right === Extrapolate.CLAMP) {
    output = cond(greaterThan(value, inputRange[inputRange.length - 1]), outputRange[outputRange.length - 1], output);
  } else if (right === Extrapolate.IDENTITY) {
    output = cond(greaterThan(value, inputRange[inputRange.length - 1]), value, output);
  }

  return output;
}
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