#!/usr/bin/env python3
# converter.py
# 用於西曆與農曆互轉，已封裝成類別

import os
import json
import argparse
from datetime import datetime

class Converter:
    """
    提供西曆與農曆互轉功能：
    - solar_to_lunar(date_str:str) -> dict
    - lunar_to_solar(year:int, month:int, day:int, leap:bool) -> str
    """
    LUNAR_JSON_DIR = 'lunar_json'

    @classmethod
    def load_solar_to_lunar(cls, year: int) -> dict:
        path = os.path.join(cls.LUNAR_JSON_DIR, f"{year}.json")
        if not os.path.exists(path):
            raise FileNotFoundError(f"找不到 {path}")
        with open(path, encoding='utf-8') as f:
            return json.load(f)

    def solar_to_lunar(self, solar_date_str: str) -> dict:
        try:
            dt = datetime.strptime(solar_date_str, '%Y-%m-%d').date()
        except ValueError:
            raise ValueError("西曆日期格式應為 YYYY-MM-DD")
        data = self.load_solar_to_lunar(dt.year)
        if solar_date_str not in data:
            raise KeyError(f"沒有找到對應 {solar_date_str} 的農曆資料")
        return data[solar_date_str]

    def lunar_to_solar(self, lunar_year: int, lunar_month: int, lunar_day: int, leap: bool=False) -> str:
        solar_year = lunar_year + 1 if lunar_month in (11, 12) else lunar_year
        data = self.load_solar_to_lunar(solar_year)
        # 精確匹配
        for solar, info in data.items():
            lstr = info.get('農曆','')
            is_leap = lstr.startswith('閏')
            core = lstr[1:] if is_leap else lstr
            m_str, d_str = core.replace('月','-').replace('日','').split('-')
            if int(m_str)==lunar_month and int(d_str)==lunar_day and is_leap==leap:
                return solar
        # 回退到非閏月匹配
        for solar, info in data.items():
            lstr = info.get('農曆','')
            is_leap = lstr.startswith('閏')
            core = lstr[1:] if is_leap else lstr
            m_str, d_str = core.replace('月','-').replace('日','').split('-')
            if int(m_str)==lunar_month and int(d_str)==lunar_day and not is_leap:
                return solar
        raise KeyError(f"找不到對應農曆 {lunar_year}{'閏' if leap else ''}{lunar_month}月{lunar_day}日 的西曆")


def main():
    parser = argparse.ArgumentParser(description='西曆與農曆互轉工具')
    sub = parser.add_subparsers(dest='command', required=True)

    # 西曆 -> 農曆
    p1 = sub.add_parser('solar2lunar', help='西曆轉農曆')
    p1.add_argument('date', type=str, help='西曆日期 YYYY-MM-DD')

    # 農曆 -> 西曆
    p2 = sub.add_parser('lunar2solar', help='農曆轉西曆')
    p2.add_argument('date', type=str, help='農曆日期 YYYY-MM-DD')
    p2.add_argument('--leap', action='store_true', help='是否閏月')

    args = parser.parse_args()
    conv = Converter()

    if args.command == 'solar2lunar':
        info = conv.solar_to_lunar(args.date)
        print(json.dumps(info, ensure_ascii=False, indent=2))
    elif args.command == 'lunar2solar':
        try:
            y_str, m_str, d_str = args.date.split('-',2)
            y, m, d = int(y_str), int(m_str), int(d_str)
        except Exception:
            raise ValueError("農曆日期格式應為 YYYY-MM-DD，閏月請加 --leap")
        solar = conv.lunar_to_solar(y, m, d, args.leap)
        info = conv.solar_to_lunar(solar)
        print(json.dumps(info, ensure_ascii=False, indent=2))

if __name__ == '__main__':
    main()