// 천간 (天干) - 10개
export const HEAVENLY_STEMS = ['甲', '乙', '丙', '丁', '戊', '己', '庚', '辛', '壬', '癸'] as const;
export const HEAVENLY_STEMS_KR = ['갑', '을', '병', '정', '무', '기', '경', '신', '임', '계'] as const;

// 지지 (地支) - 12개
export const EARTHLY_BRANCHES = ['子', '丑', '寅', '卯', '辰', '巳', '午', '未', '申', '酉', '戌', '亥'] as const;
export const EARTHLY_BRANCHES_KR = ['자', '축', '인', '묘', '진', '사', '오', '미', '신', '유', '술', '해'] as const;

// 오행 (五行)
export const FIVE_ELEMENTS = {
  '甲': '木', '乙': '木',
  '丙': '火', '丁': '火',
  '戊': '土', '己': '土',
  '庚': '金', '辛': '金',
  '壬': '水', '癸': '水',
  '寅': '木', '卯': '木',
  '巳': '火', '午': '火',
  '辰': '土', '戌': '土', '丑': '土', '未': '土',
  '申': '金', '酉': '金',
  '子': '水', '亥': '水',
} as const;

export const FIVE_ELEMENTS_KR = {
  '木': '목', '火': '화', '土': '토', '金': '금', '水': '수'
} as const;

// 십성 (十星)
export const TEN_GODS = {
  same: { yang: '비견', yin: '겁재' },      // 같은 오행
  produce: { yang: '식신', yin: '상관' },   // 내가 생하는 오행
  overcome: { yang: '편재', yin: '정재' },  // 내가 극하는 오행
  overcome_me: { yang: '편관', yin: '정관' }, // 나를 극하는 오행
  produce_me: { yang: '편인', yin: '정인' }  // 나를 생하는 오행
} as const;

// 십이운성 (十二運星)
export const TWELVE_FORTUNES = [
  '장생', '목욕', '관대', '건록', '제왕', '쇠', '병', '사', '묘', '절', '태', '양'
] as const;

// 간지 계산을 위한 기준일 (1900년 1월 1일 = 경자년 정축월 병인일)
const BASE_YEAR = 1900;
const BASE_YEAR_STEM = 6;  // 庚
const BASE_YEAR_BRANCH = 0; // 子

/**
 * 년도의 간지를 계산
 */
export function getYearGanzi(year: number): { stem: string; branch: string; stemKr: string; branchKr: string } {
  const yearDiff = year - BASE_YEAR;
  const stemIndex = (BASE_YEAR_STEM + yearDiff) % 10;
  const branchIndex = (BASE_YEAR_BRANCH + yearDiff) % 12;

  return {
    stem: HEAVENLY_STEMS[stemIndex],
    branch: EARTHLY_BRANCHES[branchIndex],
    stemKr: HEAVENLY_STEMS_KR[stemIndex],
    branchKr: EARTHLY_BRANCHES_KR[branchIndex]
  };
}

/**
 * 월의 간지를 계산
 */
export function getMonthGanzi(year: number, month: number): { stem: string; branch: string; stemKr: string; branchKr: string } {
  // 월 지지는 고정: 1월=인, 2월=묘, 3월=진, 4월=사, 5월=오, 6월=미...
  // 단, 절기 기준이지만 간단히 월로 계산
  const branchIndex = (month + 1) % 12; // 1월=인(2), 2월=묘(3)...

  // 월 천간 계산 (년간에 따라 달라짐)
  const yearStem = getYearGanzi(year).stem;
  const yearStemIndex = HEAVENLY_STEMS.indexOf(yearStem as any);

  // 월 천간 공식: (년간 * 2 + 월) % 10
  const stemIndex = (yearStemIndex * 2 + month) % 10;

  return {
    stem: HEAVENLY_STEMS[stemIndex],
    branch: EARTHLY_BRANCHES[branchIndex],
    stemKr: HEAVENLY_STEMS_KR[stemIndex],
    branchKr: EARTHLY_BRANCHES_KR[branchIndex]
  };
}

/**
 * 일의 간지를 계산 (만세력 기준)
 */
export function getDayGanzi(year: number, month: number, day: number): { stem: string; branch: string; stemKr: string; branchKr: string } {
  // 기준일 (1900-01-01) 부터의 일수 계산
  const baseDate = new Date(1900, 0, 1);
  const targetDate = new Date(year, month - 1, day);
  const daysDiff = Math.floor((targetDate.getTime() - baseDate.getTime()) / (1000 * 60 * 60 * 24));

  // 1900-01-01 = 丙寅일
  const baseDayStem = 2;  // 丙
  const baseDayBranch = 2; // 寅

  const stemIndex = (baseDayStem + daysDiff) % 10;
  const branchIndex = (baseDayBranch + daysDiff) % 12;

  return {
    stem: HEAVENLY_STEMS[stemIndex < 0 ? stemIndex + 10 : stemIndex],
    branch: EARTHLY_BRANCHES[branchIndex < 0 ? branchIndex + 12 : branchIndex],
    stemKr: HEAVENLY_STEMS_KR[stemIndex < 0 ? stemIndex + 10 : stemIndex],
    branchKr: EARTHLY_BRANCHES_KR[branchIndex < 0 ? branchIndex + 12 : branchIndex]
  };
}

/**
 * 시의 간지를 계산
 */
export function getHourGanzi(dayGanzi: { stem: string }, hour: number): { stem: string; branch: string; stemKr: string; branchKr: string } {
  // 시 지지: 자시(23-01)=0, 축시(01-03)=1, ...
  let branchIndex: number;

  if (hour >= 23 || hour < 1) branchIndex = 0;  // 子
  else if (hour >= 1 && hour < 3) branchIndex = 1;   // 丑
  else if (hour >= 3 && hour < 5) branchIndex = 2;   // 寅
  else if (hour >= 5 && hour < 7) branchIndex = 3;   // 卯
  else if (hour >= 7 && hour < 9) branchIndex = 4;   // 辰
  else if (hour >= 9 && hour < 11) branchIndex = 5;  // 巳
  else if (hour >= 11 && hour < 13) branchIndex = 6; // 午
  else if (hour >= 13 && hour < 15) branchIndex = 7; // 未
  else if (hour >= 15 && hour < 17) branchIndex = 8; // 申
  else if (hour >= 17 && hour < 19) branchIndex = 9; // 酉
  else if (hour >= 19 && hour < 21) branchIndex = 10; // 戌
  else branchIndex = 11; // 亥

  // 시 천간 계산 (일간에 따라 달라짐)
  const dayStemIndex = HEAVENLY_STEMS.indexOf(dayGanzi.stem as any);
  const stemIndex = (dayStemIndex * 2 + branchIndex) % 10;

  return {
    stem: HEAVENLY_STEMS[stemIndex],
    branch: EARTHLY_BRANCHES[branchIndex],
    stemKr: HEAVENLY_STEMS_KR[stemIndex],
    branchKr: EARTHLY_BRANCHES_KR[branchIndex]
  };
}

/**
 * 십성 계산
 */
export function getTenGod(dayStem: string, targetStem: string, isYang: boolean): string {
  const dayElement = FIVE_ELEMENTS[dayStem as keyof typeof FIVE_ELEMENTS];
  const targetElement = FIVE_ELEMENTS[targetStem as keyof typeof FIVE_ELEMENTS];

  // 같은 오행
  if (dayElement === targetElement) {
    return isYang ? '비견' : '겁재';
  }

  // 오행 상생/상극 관계 확인
  const produceMap: { [key: string]: string } = {
    '木': '火', '火': '土', '土': '金', '金': '水', '水': '木'
  };
  const overcomeMap: { [key: string]: string } = {
    '木': '土', '火': '金', '土': '水', '金': '木', '水': '火'
  };

  // 내가 생하는 오행
  if (produceMap[dayElement] === targetElement) {
    return isYang ? '식신' : '상관';
  }

  // 내가 극하는 오행
  if (overcomeMap[dayElement] === targetElement) {
    return isYang ? '편재' : '정재';
  }

  // 나를 극하는 오행
  if (overcomeMap[targetElement] === dayElement) {
    return isYang ? '편관' : '정관';
  }

  // 나를 생하는 오행
  if (produceMap[targetElement] === dayElement) {
    return isYang ? '편인' : '정인';
  }

  return '비견';
}

/**
 * 십이운성 계산
 */
export function getTwelveFortune(dayStem: string, branch: string): string {
  // 간단한 십이운성 계산 (실제로는 더 복잡함)
  const fortuneMap: { [key: string]: { [key: string]: number } } = {
    '甲': { '亥': 11, '子': 0, '丑': 1, '寅': 2, '卯': 3, '辰': 4, '巳': 5, '午': 6, '未': 7, '申': 8, '酉': 9, '戌': 10 },
    '乙': { '午': 11, '未': 0, '申': 1, '酉': 2, '戌': 3, '亥': 4, '子': 5, '丑': 6, '寅': 7, '卯': 8, '辰': 9, '巳': 10 },
    '丙': { '寅': 11, '卯': 0, '辰': 1, '巳': 2, '午': 3, '未': 4, '申': 5, '酉': 6, '戌': 7, '亥': 8, '子': 9, '丑': 10 },
    '丁': { '酉': 11, '戌': 0, '亥': 1, '子': 2, '丑': 3, '寅': 4, '卯': 5, '辰': 6, '巳': 7, '午': 8, '未': 9, '申': 10 },
    '戊': { '寅': 11, '卯': 0, '辰': 1, '巳': 2, '午': 3, '未': 4, '申': 5, '酉': 6, '戌': 7, '亥': 8, '子': 9, '丑': 10 },
    '己': { '酉': 11, '戌': 0, '亥': 1, '子': 2, '丑': 3, '寅': 4, '卯': 5, '辰': 6, '巳': 7, '午': 8, '未': 9, '申': 10 },
    '庚': { '巳': 11, '午': 0, '未': 1, '申': 2, '酉': 3, '戌': 4, '亥': 5, '子': 6, '丑': 7, '寅': 8, '卯': 9, '辰': 10 },
    '辛': { '子': 11, '丑': 0, '寅': 1, '卯': 2, '辰': 3, '巳': 4, '午': 5, '未': 6, '申': 7, '酉': 8, '戌': 9, '亥': 10 },
    '壬': { '申': 11, '酉': 0, '戌': 1, '亥': 2, '子': 3, '丑': 4, '寅': 5, '卯': 6, '辰': 7, '巳': 8, '午': 9, '未': 10 },
    '癸': { '卯': 11, '辰': 0, '巳': 1, '午': 2, '未': 3, '申': 4, '酉': 5, '戌': 6, '亥': 7, '子': 8, '丑': 9, '寅': 10 }
  };

  const index = fortuneMap[dayStem as keyof typeof fortuneMap]?.[branch as keyof typeof fortuneMap['甲']] ?? 0;
  return TWELVE_FORTUNES[index];
}

/**
 * 사주팔자 전체 계산
 */
export interface SajuData {
  year: { stem: string; branch: string; stemKr: string; branchKr: string; element: string; tenGod: string; fortune: string };
  month: { stem: string; branch: string; stemKr: string; branchKr: string; element: string; tenGod: string; fortune: string };
  day: { stem: string; branch: string; stemKr: string; branchKr: string; element: string; tenGod: string; fortune: string };
  hour?: { stem: string; branch: string; stemKr: string; branchKr: string; element: string; tenGod: string; fortune: string };
  dayStem: string;
  birthDate: { year: number; month: number; day: number; hour?: number };
  gender: 'male' | 'female';
}

export function calculateSaju(
  year: number,
  month: number,
  day: number,
  hour: number | null,
  gender: 'male' | 'female'
): SajuData {
  const yearGanzi = getYearGanzi(year);
  const monthGanzi = getMonthGanzi(year, month);
  const dayGanzi = getDayGanzi(year, month, day);
  const hourGanzi = hour !== null ? getHourGanzi(dayGanzi, hour) : null;

  const dayStem = dayGanzi.stem;
  const dayStemIndex = HEAVENLY_STEMS.indexOf(dayStem as any);
  const isDayYang = dayStemIndex % 2 === 0;

  const result: SajuData = {
    year: {
      ...yearGanzi,
      element: FIVE_ELEMENTS[yearGanzi.stem as keyof typeof FIVE_ELEMENTS],
      tenGod: getTenGod(dayStem, yearGanzi.stem, HEAVENLY_STEMS.indexOf(yearGanzi.stem as any) % 2 === isDayYang ? true : false),
      fortune: getTwelveFortune(dayStem, yearGanzi.branch)
    },
    month: {
      ...monthGanzi,
      element: FIVE_ELEMENTS[monthGanzi.stem as keyof typeof FIVE_ELEMENTS],
      tenGod: getTenGod(dayStem, monthGanzi.stem, HEAVENLY_STEMS.indexOf(monthGanzi.stem as any) % 2 === isDayYang ? true : false),
      fortune: getTwelveFortune(dayStem, monthGanzi.branch)
    },
    day: {
      ...dayGanzi,
      element: FIVE_ELEMENTS[dayGanzi.stem as keyof typeof FIVE_ELEMENTS],
      tenGod: '일간',
      fortune: getTwelveFortune(dayStem, dayGanzi.branch)
    },
    dayStem,
    birthDate: { year, month, day, hour: hour ?? undefined },
    gender
  };

  if (hourGanzi) {
    result.hour = {
      ...hourGanzi,
      element: FIVE_ELEMENTS[hourGanzi.stem as keyof typeof FIVE_ELEMENTS],
      tenGod: getTenGod(dayStem, hourGanzi.stem, HEAVENLY_STEMS.indexOf(hourGanzi.stem as any) % 2 === isDayYang ? true : false),
      fortune: getTwelveFortune(dayStem, hourGanzi.branch)
    };
  }

  return result;
}