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feat: modern UI with moon phases, celestial theme, solar/lunar toggle #23

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Merged
thaihuynhxyz merged 1 commit into from
Mar 10, 2026
Merged

feat: modern UI with moon phases, celestial theme, solar/lunar toggle #23

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296 changes: 296 additions & 0 deletions lib/lunar_converter.dart
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import 'dart:math' as math;

class LunarConverter {
LunarConverter._();

static const List<String> lunarMonths = [
'Tháng Giêng',
'Tháng Hai',
'Tháng Ba',
'Tháng Tư',
'Tháng Năm',
'Tháng Sáu',
'Tháng Bảy',
'Tháng Tám',
'Tháng Chín',
'Tháng Mười',
'Tháng Một',
'Tháng Chạp',
];

static const List<String> can = [
'Canh', 'Tân', 'Nhâm', 'Quý', 'Giáp', //
'Ất', 'Bính', 'Đinh', 'Mậu', 'Kỷ',
];

static const List<String> chi = [
'Thân', 'Dậu', 'Tuất', 'Hợi', 'Tí', 'Sửu', //
'Dần', 'Mão', 'Thìn', 'Tỵ', 'Ngọ', 'Mùi',
];

static const List<bool> _auspiciousPattern = [
true, true, false, false, true, true, //
false, true, false, false, true, false,
];

static const List<String> hourNames = [
'Tí (23h-1h)',
'Sửu (1h-3h)',
'Dần (3h-5h)',
'Mão (5h-7h)',
'Thìn (7h-9h)',
'Tỵ (9h-11h)',
'Ngọ (11h-13h)',
'Mùi (13h-15h)',
'Thân (15h-17h)',
'Dậu (17h-19h)',
'Tuất (19h-21h)',
'Hợi (21h-23h)',
];

/// Returns [lunarDay, lunarMonth, lunarYear, lunarLeap].
static List<int> solarToLunar(
int dd,
int mm,
int yy, {
double timeZone = 7,
}) {
int lunarDay;
int lunarMonth;
int lunarYear;
int lunarLeap;
final dayNumber = julianDay(dd, mm, yy);

final k = ((dayNumber - 2415021.076998695) / 29.530588853).floor();
var monthStart = _getNewMoonDay(k + 1, timeZone);
if (monthStart > dayNumber) {
monthStart = _getNewMoonDay(k, timeZone);
}
var a11 = _getLunarMonth11(yy, timeZone);
var b11 = a11;
if (a11 >= monthStart) {
lunarYear = yy;
a11 = _getLunarMonth11(yy - 1, timeZone);
} else {
lunarYear = yy + 1;
b11 = _getLunarMonth11(yy + 1, timeZone);
}

lunarDay = dayNumber - monthStart + 1;
final diff = ((monthStart - a11) / 29).floor();
lunarLeap = 0;
lunarMonth = diff + 11;
if (b11 - a11 > 365) {
final leapMonthDiff = _getLeapMonthOffset(a11, timeZone);
if (diff >= leapMonthDiff) {
lunarMonth = diff + 10;
if (diff == leapMonthDiff) {
lunarLeap = 1;
}
}
}
if (lunarMonth > 12) {
lunarMonth = lunarMonth - 12;
}
if (lunarMonth >= 11 && diff < 4) {
lunarYear -= 1;
}
return [lunarDay, lunarMonth, lunarYear, lunarLeap];
}

static DateTime lunarToSolar(
int lunarDay,
int lunarMonth,
int lunarYear,
int lunarLeap, {
double timeZone = 7,
}) {
int a11;
int b11;
if (lunarMonth < 11) {
a11 = _getLunarMonth11(lunarYear - 1, timeZone);
b11 = _getLunarMonth11(lunarYear, timeZone);
} else {
a11 = _getLunarMonth11(lunarYear, timeZone);
b11 = _getLunarMonth11(lunarYear + 1, timeZone);
}
final k = (0.5 + (a11 - 2415021.076998695) / 29.530588853).floor();
var off = lunarMonth - 11;
if (off < 0) {
off += 12;
}
if (b11 - a11 > 365) {
final leapOff = _getLeapMonthOffset(a11, timeZone);
var leapMonth = leapOff - 2;
if (leapMonth < 0) {
leapMonth += 12;
}
if (lunarLeap != 0 && lunarMonth != leapMonth) {
return DateTime(0);
} else if (lunarLeap != 0 || off >= leapOff) {
off += 1;
}
}
final monthStart = _getNewMoonDay(k + off, timeZone);
return _jdToDate(monthStart + lunarDay - 1);
}

static int julianDay(int dd, int mm, int yy) {
final a = (14 - mm) ~/ 12;
final y = yy + 4800 - a;
final m = mm + 12 * a - 3;
var jd = dd +
(153 * m + 2) ~/ 5 +
365 * y +
y ~/ 4 -
y ~/ 100 +
y ~/ 400 -
32045;
if (jd < 2299161) {
jd = dd + (153 * m + 2) ~/ 5 + 365 * y + y ~/ 4 - 32083;
}
return jd;
}

static String getCanChiDay(int jd) {
return '${can[(jd + 3) % can.length]} ${chi[(jd + 5) % chi.length]}';
}

static String getCanChiMonth(int lunarMonth, int year) {
final canYearIndex = year % can.length;
final offset = canYearIndex % 5 + ((canYearIndex % 5 + 7) % can.length) * 2;
return '${can[(offset + lunarMonth - 1) % can.length]} '
'${chi[(lunarMonth + 5) % chi.length]}';
}

static String getCanChiYear(int year) {
return '${can[year % can.length]} ${chi[year % chi.length]}';
}

static List<String> getAuspiciousHours(int jd) {
final chiDayIndex = (jd + 5) % chi.length;
final shift = (chiDayIndex % 6) * 2;
final hours = <String>[];
for (var i = 0; i < 12; i++) {
if (_auspiciousPattern[(i - shift) % 12]) {
hours.add(hourNames[i]);
}
}
return hours;
}

static String getLunarMonthName(int month, {bool isLeap = false}) {
final name = lunarMonths[month - 1];
return isLeap ? '$name Nhuận' : name;
}

// -- Private helpers --

static int _getLeapMonthOffset(int a11, double timeZone) {
final k = (0.5 + (a11 - 2415021.076998695) / 29.530588853).floor();
int last;
var i = 1;
var arc = (_getSunLongitude(_getNewMoonDay(k + i, timeZone), timeZone) / 30)
.floor();
do {
last = arc;
i++;
arc = (_getSunLongitude(_getNewMoonDay(k + i, timeZone), timeZone) / 30)
.floor();
} while (arc != last && i < 14);
return i - 1;
}

static double _sunLongitudeAA98(double jdn) {
final t = (jdn - 2451545.0) / 36525;
final t2 = t * t;
const dr = math.pi / 180;
final m =
357.52910 + 35999.05030 * t - 0.0001559 * t2 - 0.00000048 * t * t2;
final l0 = 280.46645 + 36000.76983 * t + 0.0003032 * t2;
var dl = (1.914600 - 0.004817 * t - 0.000014 * t2) * math.sin(dr * m);
dl = dl +
(0.019993 - 0.000101 * t) * math.sin(dr * 2 * m) +
0.000290 * math.sin(dr * 3 * m);
final l = l0 + dl;
return l - 360 * (l / 360).floor();
}

static double _getSunLongitude(int dayNumber, double timeZone) {
return _sunLongitudeAA98(dayNumber - 0.5 - timeZone / 24);
}

static int _getLunarMonth11(int yy, double timeZone) {
final off = julianDay(31, 12, yy) - 2415021.076998695;
final k = (off / 29.530588853).floor();
var nm = _getNewMoonDay(k, timeZone);
final sunLong = (_getSunLongitude(nm, timeZone) / 30).floor();
if (sunLong >= 9) {
nm = _getNewMoonDay(k - 1, timeZone);
}
return nm;
}

static double _newMoonAA98(int k) {
final t = k / 1236.85;
final t2 = t * t;
final t3 = t2 * t;
const dr = math.pi / 180;
var jd1 =
2415020.75933 + 29.53058868 * k + 0.0001178 * t2 - 0.000000155 * t3;
jd1 = jd1 + 0.00033 * math.sin((166.56 + 132.87 * t - 0.009173 * t2) * dr);
final m = 359.2242 + 29.10535608 * k - 0.0000333 * t2 - 0.00000347 * t3;
final mpr = 306.0253 + 385.81691806 * k + 0.0107306 * t2 + 0.00001236 * t3;
final f = 21.2964 + 390.67050646 * k - 0.0016528 * t2 - 0.00000239 * t3;
var c1 = (0.1734 - 0.000393 * t) * math.sin(m * dr) +
0.0021 * math.sin(2 * dr * m);
c1 = c1 - 0.4068 * math.sin(mpr * dr) + 0.0161 * math.sin(dr * 2 * mpr);
c1 = c1 - 0.0004 * math.sin(dr * 3 * mpr);
c1 = c1 + 0.0104 * math.sin(dr * 2 * f) - 0.0051 * math.sin(dr * (m + mpr));
c1 = c1 -
0.0074 * math.sin(dr * (m - mpr)) +
0.0004 * math.sin(dr * (2 * f + m));
c1 = c1 -
0.0004 * math.sin(dr * (2 * f - m)) -
0.0006 * math.sin(dr * (2 * f + mpr));
c1 = c1 +
0.0010 * math.sin(dr * (2 * f - mpr)) +
0.0005 * math.sin(dr * (2 * mpr + m));
double deltat;
if (t < -11) {
deltat = 0.001 +
0.000839 * t +
0.0002261 * t2 -
0.00000845 * t3 -
0.000000081 * t * t3;
} else {
deltat = -0.000278 + 0.000265 * t + 0.000262 * t2;
}
return jd1 + c1 - deltat;
}

static int _getNewMoonDay(int k, double timeZone) {
final jd = _newMoonAA98(k);
return (jd + 0.5 + timeZone / 24).floor();
}

static DateTime _jdToDate(int jd) {
int b;
int c;
if (jd > 2299160) {
final a = jd + 32044;
b = (4 * a + 3) ~/ 146097;
c = a - (b * 146097) ~/ 4;
} else {
b = 0;
c = jd + 32082;
}
final d = (4 * c + 3) ~/ 1461;
final e = c - (1461 * d) ~/ 4;
final m = (5 * e + 2) ~/ 153;
final day = e - (153 * m + 2) ~/ 5 + 1;
final month = m + 3 - 12 * (m ~/ 10);
final year = b * 100 + d - 4800 + m ~/ 10;
return DateTime(year, month, day);
}
}
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