import { MaybeNumber } from 'ontime-types';
import { formatFromMillis, MILLIS_PER_HOUR, MILLIS_PER_MINUTE, MILLIS_PER_SECOND } from 'ontime-utils';

/**
 * @description safe parse string to int
 * @param {string} valueAsString
 * @return {number}
 */
const parse = (valueAsString: string): number => {
  const parsed = parseInt(valueAsString, 10);
  if (isNaN(parsed)) {
    return 0;
  }
  return Math.abs(parsed);
};

/**
 * @description Utility function to check if a string contain am/pm indicators
 * @param {string} value
 */
function checkAmPm(value: string) {
  let isPM = false;
  let isAM = false;
  if (value.toLowerCase().includes('pm')) {
    isPM = true;
    value = value.replace(/pm/i, '');
  } else if (value.toLowerCase().includes('p')) {
    isPM = true;
    value = value.replace(/p/i, '');
  }

  // we need to remove am, but it doesn't actually change anything
  if (value.toLowerCase().includes('am')) {
    isAM = true;
    value = value.replace(/am/i, '');
  } else if (value.toLowerCase().includes('a')) {
    isAM = true;
    value = value.replace(/a/i, '');
  }

  return { isAM, isPM, value };
}

/**
 * @description Utility function to check if a string contain h / m / s indicators
 * @param {string} value
 */
function checkMatchers(value: string) {
  const hoursMatch = /(\d+)h/i.exec(value);
  const hoursMatchValue = hoursMatch ? parse(hoursMatch[1]) : 0;

  const minutesMatch = /(\d+)m/i.exec(value);
  const minutesMatchValue = minutesMatch ? parse(minutesMatch[1]) : 0;

  const secondsMatch = /(\d+)s/i.exec(value);
  const secondsMatchValue = secondsMatch ? parse(secondsMatch[1]) : 0;

  if (hoursMatchValue > 0 || minutesMatchValue > 0 || secondsMatchValue > 0) {
    return (
      hoursMatchValue * MILLIS_PER_HOUR + minutesMatchValue * MILLIS_PER_MINUTE + secondsMatchValue * MILLIS_PER_SECOND
    );
  }
  return { hoursMatchValue };
}

/**
 * @description Utility function to infer separators from a whole string
 * @param {string} value
 * @param {boolean} isAM
 * @param {boolean} isPM
 */
function inferSeparators(value: string, isAM: boolean, isPM: boolean) {
  const length = value.length;
  let inferredMillis = 0;
  let addAM = 0;
  if (length === 1) {
    if (isPM || isAM) {
      inferredMillis = parse(value) * MILLIS_PER_HOUR;
      if (isAM) {
        // this ensures we dont add 12 hours in the end
        addAM = inferredMillis;
      }
    } else {
      inferredMillis = parse(value) * MILLIS_PER_MINUTE;
    }
  } else if (length === 2) {
    if (isPM || isAM) {
      inferredMillis = parse(value) * inferredMillis;
      if (isAM) {
        // this ensures we dont add 12 hours in the end
        addAM = 12;
      }
    } else {
      inferredMillis = parse(value) * MILLIS_PER_MINUTE;
    }
  } else if (length === 3) {
    inferredMillis = parse(value[0]) * MILLIS_PER_HOUR + parse(value.substring(1)) * MILLIS_PER_MINUTE;
  } else if (length === 4) {
    inferredMillis = parse(value.substring(0, 2)) * MILLIS_PER_HOUR + parse(value.substring(2)) * MILLIS_PER_MINUTE;
  } else if (length >= 5) {
    const hours = parse(value.substring(0, 2));
    const minutes = parse(value.substring(2, 4));
    const seconds = parse(value.substring(4));
    inferredMillis = hours * MILLIS_PER_HOUR + minutes * MILLIS_PER_MINUTE + seconds * MILLIS_PER_SECOND;
  }
  return { inferredMillis, addAM };
}

/**
 * @description Parses a time string to millis, auto-filling to the left
 * @param {string} value - time string
 * @returns {number} - time string in millis
 */
export const forgivingStringToMillis = (value: string): number => {
  if (value === '12am') {
    return 0;
  }

  const { isAM, isPM, value: parsingValue } = checkAmPm(value);
  const maybeMillisFromMatchers = checkMatchers(parsingValue);
  if (typeof maybeMillisFromMatchers === 'number') {
    return maybeMillisFromMatchers;
  }

  let { hoursMatchValue } = maybeMillisFromMatchers;

  let millis = 0;

  // split string at known separators    : , .
  const separatorRegex = /[\s,:.]+/;
  const [first, second, third] = parsingValue.split(separatorRegex);

  if (first != null && second != null && third != null) {
    // if string has three sections, treat as [hours] [minutes] [seconds]
    millis = parse(first) * MILLIS_PER_HOUR;
    millis += parse(second) * MILLIS_PER_MINUTE;
    millis += parse(third) * MILLIS_PER_SECOND;
  } else if (first != null && second == null && third == null) {
    // we only have one section, infer separators
    const { inferredMillis, addAM } = inferSeparators(first, isAM, isPM);
    millis = inferredMillis;
    hoursMatchValue = addAM;
  }
  if (first != null && second != null && third == null) {
    // if string has two sections, treat as [hours] [minutes]
    millis = parse(first) * MILLIS_PER_HOUR;
    millis += parse(second) * MILLIS_PER_MINUTE;
  }

  // Add 12 hours if it is PM
  if (isPM && hoursMatchValue < 12) {
    millis += 12 * MILLIS_PER_HOUR;
  }

  return millis;
};

export function millisToDelayString(millis: MaybeNumber, format: 'compact' | 'expanded' = 'compact'): string {
  if (millis == null || millis === 0) {
    return '';
  }

  const isNegative = millis < 0;
  const absMillis = Math.abs(millis);
  const isCompact = format === 'compact';
  const delayed = isCompact ? '+' : 'delayed by ';
  const ahead = isCompact ? '-' : 'ahead by ';

  if (absMillis < MILLIS_PER_MINUTE) {
    return `${isNegative ? ahead : delayed}${formatFromMillis(absMillis, 's')} sec`;
  } else if (absMillis < MILLIS_PER_HOUR && absMillis % MILLIS_PER_MINUTE === 0) {
    return `${isNegative ? ahead : delayed}${formatFromMillis(absMillis, 'm')} min`;
  }

  return `${isNegative ? ahead : delayed}${formatFromMillis(absMillis, 'HH:mm:ss')}`;
}