/**
 * Core Numerology Calculator
 * Shared functions for calculating Life Path, Expression, Soul Urge, Birthday
 */

const MASTER_NUMBERS = [11, 22, 33];

export 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);
}

function nameToNumber(name: string): number {
  const cleaned = name.toLowerCase().replace(/[^a-z]/g, '');
  let total = 0;
  for (const char of cleaned) {
    const value = char.charCodeAt(0) - 96;
    total += value < 10 ? value : reduce(value);
  }
  return total;
}

function masterCheck(total: number): number {
  if (MASTER_NUMBERS.includes(total)) return total;
  const reduced = String(total).split('').reduce((sum, digit) => sum + parseInt(digit), 0);
  return reduced < 10 ? reduced : reduce(reduced);
}

function extractVowels(name: string): string {
  return name.toLowerCase().replace(/[^aeiou]/g, '');
}

function extractConsonants(name: string): string {
  return name.toLowerCase().replace(/[^bcdfghjklmnpqrstvwxyz]/g, '');
}

function letterToNumber(letter: string): number {
  const value = letter.toLowerCase().charCodeAt(0) - 96;
  return value;
}

export interface CoreNumbers {
  lifePath: number;
  expression: number;
  soulUrge: number;
  birthday: number;
}

export interface AdditionalNumbers {
  maturity: number;
  personality: number;
  hiddenPassion: number | null;
  hiddenPassionCount: number;
  karmicLessons: number[];
  balance: number;
}

export function calculateCoreNumbers(name: string, birthdate: string): CoreNumbers {
  // Parse birthdate
  const parts = birthdate.split('/');
  const month = parseInt(parts[0]);
  const day = parseInt(parts[1]);
  const year = parseInt(parts[2]);

  // Life Path
  const monthReduced = reduce(month);
  const dayReduced = reduce(day);
  const yearReduced = reduce(year);
  const birthDateSum = monthReduced + dayReduced + yearReduced;
  const lifePath = reduce(birthDateSum);

  // Birthday
  const birthday = reduce(day);

  // Expression (from full name)
  const nameParts = name.trim().split(/\s+/);
  const namesToUse = nameParts.length > 4
    ? [nameParts[0], nameParts[nameParts.length - 1]]
    : nameParts;

  let expressionTotal = 0;
  for (const part of namesToUse) {
    const value = nameToNumber(part);
    const checked = masterCheck(value);
    expressionTotal += checked;
  }
  const expression = masterCheck(reduce(expressionTotal));

  // Soul Urge (from vowels)
  let soulUrgeTotal = 0;
  for (const part of nameParts) {
    const vowels = extractVowels(part);
    if (vowels) {
      const value = nameToNumber(vowels);
      const checked = masterCheck(value);
      soulUrgeTotal += checked;
    }
  }
  const soulUrge = masterCheck(reduce(soulUrgeTotal));

  return { lifePath, expression, soulUrge, birthday };
}

export function calculateAdditionalNumbers(
  name: string,
  coreNumbers: CoreNumbers
): AdditionalNumbers {
  const nameParts = name.trim().split(/\s+/);
  const fullName = name.trim();

  // 1. Maturity Number (Life Path + Expression)
  const maturitySum = coreNumbers.lifePath + coreNumbers.expression;
  const maturity = reduce(maturitySum);

  // 2. Personality Number (consonants in full name)
  let personalityTotal = 0;
  for (const part of nameParts) {
    const consonants = extractConsonants(part);
    if (consonants) {
      const value = nameToNumber(consonants);
      const checked = masterCheck(value);
      personalityTotal += checked;
    }
  }
  const personality = masterCheck(reduce(personalityTotal));

  // 3. Hidden Passion Number (most frequent letter value)
  const letterCounts: Record<number, number> = {};
  const cleanedName = fullName.toLowerCase().replace(/[^a-z]/g, '');

  for (const char of cleanedName) {
    const num = letterToNumber(char);
    const reduced = reduce(num);
    letterCounts[reduced] = (letterCounts[reduced] || 0) + 1;
  }

  let hiddenPassion: number | null = null;
  let hiddenPassionCount = 0;

  for (const [num, count] of Object.entries(letterCounts)) {
    if (count > hiddenPassionCount) {
      hiddenPassionCount = count;
      hiddenPassion = parseInt(num);
    }
  }

  // 4. Karmic Lessons (missing numbers 1-9)
  const karmicLessons: number[] = [];
  for (let i = 1; i <= 9; i++) {
    if (!letterCounts[i]) {
      karmicLessons.push(i);
    }
  }

  // 5. Balance Number (first letter of each name part)
  let balanceTotal = 0;
  for (const part of nameParts) {
    if (part.length > 0) {
      const firstLetter = part[0];
      const num = letterToNumber(firstLetter);
      balanceTotal += num;
    }
  }
  const balance = reduce(balanceTotal);

  return {
    maturity,
    personality,
    hiddenPassion,
    hiddenPassionCount,
    karmicLessons,
    balance
  };
}