/**
 * Numerology Timing Cycles
 *
 * Calculates Personal and Universal timing cycles for planning and understanding
 * the energy of different time periods.
 */

const MASTER_NUMBERS = [11, 22, 33];

/**
 * Reduce number to single digit or master number
 */
function reduce(n: number): number {
  if (MASTER_NUMBERS.includes(n)) {
    return n;
  }
  const total = String(n).split('').reduce((sum, digit) => sum + parseInt(digit), 0);
  return total < 10 ? total : reduce(total);
}

/**
 * Parse date string (mm/dd/yyyy)
 */
function parseDate(dateStr: string): { month: number; day: number; year: number } {
  const parts = dateStr.split('/');
  if (parts.length !== 3) {
    throw new Error('Invalid date format. Use mm/dd/yyyy');
  }
  return {
    month: parseInt(parts[0]),
    day: parseInt(parts[1]),
    year: parseInt(parts[2])
  };
}

export interface CycleCalculations {
  targetDate: string;
  birthdate: string;
  universal: {
    year: number;
    month: number;
    day: number;
  };
  personal: {
    year: number;
    month: number;
    day: number;
  };
  calculations: {
    universalYearCalc: string;
    universalMonthCalc: string;
    universalDayCalc: string;
    personalYearCalc: string;
    personalMonthCalc: string;
    personalDayCalc: string;
  };
}

/**
 * Calculate all timing cycles for a specific date
 */
export function calculateCycles(birthdate: string, targetDate?: string): CycleCalculations {
  // Use current date if not specified
  const target = targetDate || new Date().toLocaleDateString('en-US', {
    month: '2-digit',
    day: '2-digit',
    year: 'numeric'
  }).replace(/\//g, '/');

  const birth = parseDate(birthdate);
  const current = parseDate(target);

  // Universal Cycles (based on calendar date only)
  const universalYear = reduce(current.year);
  const universalMonth = reduce(universalYear + current.month);
  const universalDay = reduce(universalMonth + current.day);

  // Personal Cycles (based on birthdate + current date)
  const birthMonth = reduce(birth.month);
  const birthDay = reduce(birth.day);

  // Personal Year = Birth Month + Birth Day + Current Year (all reduced)
  const personalYear = reduce(birthMonth + birthDay + reduce(current.year));

  // Personal Month = Personal Year + Current Month
  const personalMonth = reduce(personalYear + current.month);

  // Personal Day = Personal Month + Current Day
  const personalDay = reduce(personalMonth + current.day);

  return {
    targetDate: target,
    birthdate,
    universal: {
      year: universalYear,
      month: universalMonth,
      day: universalDay
    },
    personal: {
      year: personalYear,
      month: personalMonth,
      day: personalDay
    },
    calculations: {
      universalYearCalc: `${current.year} → ${universalYear}`,
      universalMonthCalc: `UY(${universalYear}) + ${current.month} = ${universalMonth}`,
      universalDayCalc: `UM(${universalMonth}) + ${current.day} = ${universalDay}`,
      personalYearCalc: `BM(${birthMonth}) + BD(${birthDay}) + CY(${reduce(current.year)}) = ${personalYear}`,
      personalMonthCalc: `PY(${personalYear}) + ${current.month} = ${personalMonth}`,
      personalDayCalc: `PM(${personalMonth}) + ${current.day} = ${personalDay}`
    }
  };
}

/**
 * Calculate Personal Year for entire year (Jan-Dec)
 */
export function calculateYearCycles(birthdate: string, year: number): Array<{month: number; personalMonth: number}> {
  const birth = parseDate(birthdate);
  const birthMonth = reduce(birth.month);
  const birthDay = reduce(birth.day);

  const personalYear = reduce(birthMonth + birthDay + reduce(year));

  const months = [];
  for (let month = 1; month <= 12; month++) {
    const personalMonth = reduce(personalYear + month);
    months.push({ month, personalMonth });
  }

  return months;
}

/**
 * Calculate Personal Day for entire month
 */
export function calculateMonthCycles(
  birthdate: string,
  year: number,
  month: number
): Array<{day: number; personalDay: number}> {
  const birth = parseDate(birthdate);
  const birthMonth = reduce(birth.month);
  const birthDay = reduce(birth.day);

  const personalYear = reduce(birthMonth + birthDay + reduce(year));
  const personalMonth = reduce(personalYear + month);

  // Get days in month
  const daysInMonth = new Date(year, month, 0).getDate();

  const days = [];
  for (let day = 1; day <= daysInMonth; day++) {
    const personalDay = reduce(personalMonth + day);
    days.push({ day, personalDay });
  }

  return days;
}

/**
 * Find optimal days in a month based on desired energy
 */
export function findOptimalDays(
  birthdate: string,
  year: number,
  month: number,
  desiredNumber: number
): number[] {
  const days = calculateMonthCycles(birthdate, year, month);
  return days
    .filter(d => d.personalDay === desiredNumber)
    .map(d => d.day);
}

/**
 * Get cycle interpretation context
 */
export function getCycleContext(cycles: CycleCalculations): string {
  let context = `## Timing Cycles for ${cycles.targetDate}\n\n`;

  context += `**Universal Energy (Global):**\n`;
  context += `- Year: ${cycles.universal.year}\n`;
  context += `- Month: ${cycles.universal.month}\n`;
  context += `- Day: ${cycles.universal.day}\n\n`;

  context += `**Personal Energy (Your Rhythm):**\n`;
  context += `- Year: ${cycles.personal.year}\n`;
  context += `- Month: ${cycles.personal.month}\n`;
  context += `- Day: ${cycles.personal.day}\n\n`;

  context += `**Combined Interpretation:**\n`;
  context += `You are in a Personal Year ${cycles.personal.year} within a Universal Year ${cycles.universal.year}.\n`;
  context += `Your Personal Month ${cycles.personal.month} operates within Universal Month ${cycles.universal.month}.\n`;
  context += `Today's Personal Day ${cycles.personal.day} aligns with Universal Day ${cycles.universal.day}.\n`;

  return context;
}