import loglevel from 'loglevel';
import { gaussian, randomBetweenMinAndMax } from './random-utils';

interface IPeriodEntry {
  calories: number;
  workout: boolean;
}
interface ISimEntry {
  correctnessFactor: number;
  period: IPeriodEntry[];
}

interface IConfig {
  periodLength: number;
  fastingDays: number;
  targetWorkoutDays: number;
  simulationCount: number;
  dailyTargetCalories: number;
}

const selectPeriodDays = (
  targetDays: number,
  periodLength: number
): number[] => {
  const realizedTarget = Math.floor(gaussian(targetDays, targetDays)());
  if (realizedTarget < 1) {
    return [];
  } else {
    return Array(realizedTarget)
      .fill(false)
      .map(() => randomBetweenMinAndMax(1, periodLength) - 1);
  }
};

const generatePeriodWorkouts = (config: IConfig): number[] =>
  selectPeriodDays(config.targetWorkoutDays, config.periodLength);
const generatePeriodFastingDays = (config: IConfig): number[] =>
  selectPeriodDays(config.fastingDays, config.periodLength);

const generatePeriodCalories = (config: IConfig): number[] => {
  // make a standard gaussian variable.
  const standardDistribution = gaussian(
    config.dailyTargetCalories,
    config.dailyTargetCalories
  );

  return Array(config.periodLength)
    .fill(0)
    .map(() => Math.floor(standardDistribution()));
};

const sumPeriodCalories = (week: IPeriodEntry[]): number =>
  week.reduce((acc, current) => acc + current.calories, 0);

const sumPeriodWorkouts = (week: IPeriodEntry[]): number =>
  week.reduce((acc, current) => {
    if (current.workout) {
      return acc + 1;
    } else {
      return acc;
    }
  }, 0);

const mergeFastingAndWorkouts = (
  calories: number[],
  fastingDays: number[],
  workoutDays: number[]
): IPeriodEntry[] => {
  return calories.map(
    (caloriesInstance: number, index: number): IPeriodEntry => {
      const calIntstanceFastAdjusted = fastingDays.includes(index)
        ? 0
        : caloriesInstance;
      const workout = workoutDays.includes(index);
      return { calories: calIntstanceFastAdjusted, workout };
    }
  );
};

const generatePeriodWithMetadata = (
  config: IConfig,
  periodTarget: number
): ISimEntry => {
  const periodCalories = generatePeriodCalories(config);
  const fastingDays = generatePeriodFastingDays(config);
  const periodWorkouts = generatePeriodWorkouts(config);
  const period = mergeFastingAndWorkouts(
    periodCalories,
    fastingDays,
    periodWorkouts
  );
  const workoutDiff = Math.abs(
    config.targetWorkoutDays - sumPeriodWorkouts(period)
  );
  const calorieDiff = Math.abs(periodTarget - sumPeriodCalories(period));
  return {
    correctnessFactor: workoutDiff + calorieDiff,
    period
  };
};

const generatePeriodSimulations = (config: IConfig): ISimEntry[] => {
  const periodTarget = config.dailyTargetCalories * config.periodLength;
  const periods = [];

  for (let i = 0; i < config.simulationCount; i++) {
    periods.push(generatePeriodWithMetadata(config, periodTarget));
  }
  return periods;
};

const main = (config: IConfig) => {
  const sims = generatePeriodSimulations(config);
  const result = sims.reduce(
    (p: ISimEntry, c: ISimEntry): ISimEntry => {
      if (p.correctnessFactor < c.correctnessFactor) {
        return p;
      } else {
        return c;
      }
    }
  );
  loglevel.error(JSON.stringify(result, null, 2));
};
main({
  dailyTargetCalories: 1800,
  fastingDays: 2,
  periodLength: 7,
  simulationCount: 10000,
  targetWorkoutDays: 5
});