Repository: PyThaiNLP/pythainlp (python)

Issue:
Add Thai Solar Date convert to Thai Lunar Date
## Detailed description

Add Thai Solar Date convert to Thai Lunar Date

## Context

Th function will help user for converting Thai Solar Date to Thai Lunar Date.

## Possible implementation

Today, I found [gist from github](https://gist.github.com/touchiep/99f4f5bb349d6b983ef78697630ab78e) that write in VBA for MS Excel. https://pantip.com/topic/41786522.

Pull request:
Add Thai Solar Date convert to Thai Lunar Date
Thank @cstorm125 for the function name.

### What does this changes

Add Thai Solar Date convert to Thai Lunar Date

Fixed #993

### Your checklist for this pull request

<!--- Please review the guidelines for contributing to this repository at: -->
<!--- https://github.com/PyThaiNLP/pythainlp/blob/dev/CONTRIBUTING.md -->

- [x] Passed code styles and structures
- [x] Passed code linting checks and unit test


Patch:
diff --git a/docs/api/util.rst b/docs/api/util.rst
index 8f3e3110..76452e12 100644
--- a/docs/api/util.rst
+++ b/docs/api/util.rst
@@ -268,6 +268,16 @@ Modules
 
     The `pythainlp.util.spell_words.spell_word` function is designed for spelling individual words in Thai text, facilitating phonetic analysis and pronunciation guides.
 
+.. autofunction:: to_lunar_date
+    :noindex:
+
+    The `to_lunar_date` function focuses on converts the solar date to Thai Lunar Date.
+
+.. autofunction:: th_zodiac
+    :noindex:
+
+    The `th_zodiac` function is converts a Gregorian year to its corresponding Thai Zodiac name.
+
 .. autoclass:: Trie
     :members:
 
diff --git a/pythainlp/util/__init__.py b/pythainlp/util/__init__.py
index 41857d83..7138ffcd 100644
--- a/pythainlp/util/__init__.py
+++ b/pythainlp/util/__init__.py
@@ -48,6 +48,7 @@ __all__ = [
     "text_to_arabic_digit",
     "text_to_num",
     "text_to_thai_digit",
+    "th_zodiac",
     "thai_digit_to_arabic_digit",
     "thai_keyboard_dist",
     "thai_strptime",
@@ -60,6 +61,7 @@ __all__ = [
     "time_to_thaiword",
     "tis620_to_utf8",
     "to_idna",
+    "to_lunar_date",
     "tone_detector",
     "words_to_num",
 ]
@@ -114,12 +116,15 @@ from pythainlp.util.thai import (
     isthaichar,
     thai_word_tone_detector,
 )
+from pythainlp.util.thai_lunar_date import th_zodiac, to_lunar_date
 from pythainlp.util.thaiwordcheck import is_native_thai
 from pythainlp.util.time import thaiword_to_time, time_to_thaiword
 from pythainlp.util.trie import Trie, dict_trie
 from pythainlp.util.wordtonum import text_to_num, thaiword_to_num, words_to_num
 
-# sound_syllable and pronounce have to be imported last
+# sound_syllable and pronounce have to be imported last,
+# to prevent circular import issues.
+# Other imports should be above this line, sorted.
 from pythainlp.util.syllable import (
     sound_syllable,
     syllable_length,
diff --git a/pythainlp/util/thai_lunar_date.py b/pythainlp/util/thai_lunar_date.py
new file mode 100644
index 00000000..e28be944
--- /dev/null
+++ b/pythainlp/util/thai_lunar_date.py
@@ -0,0 +1,963 @@
+# -*- coding: utf-8 -*-
+# SPDX-FileCopyrightText: 2016-2024 PyThaiNLP Project
+# SPDX-License-Identifier: Apache-2.0
+"""
+This file is port from
+> https://gist.github.com/touchiep/99f4f5bb349d6b983ef78697630ab78e
+"""
+
+from datetime import date, timedelta
+from typing import Tuple, Union
+
+start_y = [[0 for _ in range(2)] for _ in range(113)]
+
+years = [
+    0,
+    1901,
+    1906,
+    1911,
+    1916,
+    1921,
+    1926,
+    1931,
+    1936,
+    1941,
+    1946,
+    1951,
+    1956,
+    1961,
+    1966,
+    1971,
+    1976,
+    1981,
+    1986,
+    1991,
+    1996,
+    2001,
+    2006,
+    2011,
+    2016,
+    2021,
+    2026,
+    2031,
+    2036,
+    2041,
+    2046,
+    2051,
+    2056,
+    2061,
+    2066,
+    2071,
+    2076,
+    2081,
+    2086,
+    2091,
+    2096,
+    2101,
+    2106,
+    2111,
+    2116,
+    2121,
+    2126,
+    2131,
+    2136,
+    2141,
+    2146,
+    2151,
+    2156,
+    2161,
+    2166,
+    2171,
+    2176,
+    2181,
+    2186,
+    2191,
+    2196,
+    2201,
+    2206,
+    2211,
+    2216,
+    2221,
+    2226,
+    2231,
+    2236,
+    2241,
+    2246,
+    2251,
+    2256,
+    2261,
+    2266,
+    2271,
+    2276,
+    2281,
+    2286,
+    2291,
+    2296,
+    2301,
+    2306,
+    2311,
+    2316,
+    2321,
+    2326,
+    2331,
+    2336,
+    2341,
+    2346,
+    2351,
+    2356,
+    2361,
+    2366,
+    2371,
+    2376,
+    2381,
+    2386,
+    2391,
+    2396,
+    2401,
+    2406,
+    2411,
+    2416,
+    2421,
+    2426,
+    2431,
+    2436,
+    2441,
+    2446,
+    2451,
+    2456,
+]
+for i, year in enumerate(years):
+    start_y[i][0] = year
+
+value_years = [
+    0,
+    0.122733000004352,
+    1.91890000045229e-02,
+    -8.43549999953059e-02,
+    -0.187898999995135,
+    -0.291442999994964,
+    7.44250000052413e-02,
+    -2.91189999945876e-02,
+    -0.132662999994416,
+    -0.236206999994245,
+    -0.339750999994074,
+    -0.443294999993903,
+    -7.74269999936981e-02,
+    -0.180970999993527,
+    -0.284514999993356,
+    -0.388058999993185,
+    -0.491602999993014,
+    -0.595146999992842,
+    -0.698690999992671,
+    -0.332822999992466,
+    -0.436366999992295,
+    -0.539910999992124,
+    -0.643454999991953,
+    0.253001000008218,
+    0.149457000008389,
+    -0.484674999991406,
+    -0.588218999991235,
+    0.308237000008937,
+    0.204693000009108,
+    0.101149000009279,
+    -2.39499999055015e-03,
+    -0.105938999990379,
+    0.259929000009826,
+    0.156385000009997,
+    5.28410000101682e-02,
+    -5.07029999896607e-02,
+    -0.15424699998949,
+    -0.257790999989318,
+    0.108077000010887,
+    4.53300001105772e-03,
+    -9.90109999887712e-02,
+    -0.2025549999886,
+    -0.306098999988429,
+    -0.409642999988258,
+    -4.37749999880528e-02,
+    -0.147318999987882,
+    -0.250862999987711,
+    -0.354406999987539,
+    -0.457950999987368,
+    -0.561494999987197,
+    -0.665038999987026,
+    -0.299170999986821,
+    -0.40271499998665,
+    -0.506258999986479,
+    -0.609802999986308,
+    -0.713346999986137,
+    0.183109000014035,
+    -0.45102299998576,
+    -0.554566999985589,
+    0.341889000014582,
+    0.238345000014753,
+    0.134801000014924,
+    3.12570000150951e-02,
+    -7.22869999847338e-02,
+    0.293581000015471,
+    0.190037000015642,
+    8.64930000158135e-02,
+    -1.70509999840154e-02,
+    -0.120594999983844,
+    -0.224138999983673,
+    0.141729000016532,
+    0.038185000016703,
+    -6.53589999831259e-02,
+    -0.168902999982955,
+    -0.272446999982784,
+    -0.375990999982613,
+    -1.01229999824075e-02,
+    -0.113666999982236,
+    -0.217210999982065,
+    -0.320754999981894,
+    -0.424298999981723,
+    -0.527842999981552,
+    -0.631386999981381,
+    -0.265518999981176,
+    -0.369062999981005,
+    -0.472606999980834,
+    -0.576150999980662,
+    -0.679694999980491,
+    0.21676100001968,
+    -0.417370999980115,
+    -0.520914999979944,
+    -0.624458999979773,
+    0.271997000020398,
+    0.168453000020569,
+    6.49090000207404e-02,
+    -3.86349999790885e-02,
+    0.327233000021117,
+    0.223689000021288,
+    0.120145000021459,
+    1.66010000216299e-02,
+    -0.086942999978199,
+    -0.190486999978028,
+    0.175381000022177,
+    7.18370000223483e-02,
+    -3.17069999774806e-02,
+    -0.135250999977309,
+    -0.238794999977138,
+    -0.342338999976967,
+    2.35290000232378e-02,
+    -8.00149999765911e-02,
+    -0.18355899997642,
+    -0.287102999976249,
+    -0.390646999976078,
+]
+for i, value in enumerate(value_years):
+    start_y[i][1] = value
+
+
+def calculate_f_year_f_dev(year: int) -> Tuple[int, float]:
+    if year >= 2456:
+        f_year, f_dev = start_y[112]
+    elif year >= 2451:
+        f_year, f_dev = start_y[111]
+    elif year >= 2446:
+        f_year, f_dev = start_y[110]
+    elif year >= 2441:
+        f_year, f_dev = start_y[109]
+    elif year >= 2436:
+        f_year, f_dev = start_y[108]
+    elif year >= 2431:
+        f_year, f_dev = start_y[107][0], start_y[107][1]
+    elif year >= 2426:
+        f_year, f_dev = start_y[106][0], start_y[106][1]
+    elif year >= 2421:
+        f_year, f_dev = start_y[105][0], start_y[105][1]
+    elif year >= 2416:
+        f_year, f_dev = start_y[104][0], start_y[104][1]
+    elif year >= 2411:
+        f_year, f_dev = start_y[103][0], start_y[103][1]
+    elif year >= 2406:
+        f_year, f_dev = start_y[102][0], start_y[102][1]
+    elif year >= 2401:
+        f_year, f_dev = start_y[101][0], start_y[101][1]
+    elif year >= 2396:
+        f_year, f_dev = start_y[100][0], start_y[100][1]
+    elif year >= 2391:
+        f_year, f_dev = start_y[99][0], start_y[99][1]
+    elif year >= 2386:
+        f_year, f_dev = start_y[98][0], start_y[98][1]
+    elif year >= 2381:
+        f_year, f_dev = start_y[97][0], start_y[97][1]
+    elif year >= 2376:
+        f_year, f_dev = start_y[96][0], start_y[96][1]
+    elif year >= 2371:
+        f_year, f_dev = start_y[95][0], start_y[95][1]
+    elif year >= 2366:
+        f_year, f_dev = start_y[94][0], start_y[94][1]
+    elif year >= 2361:
+        f_year, f_dev = start_y[93][0], start_y[93][1]
+    elif year >= 2356:
+        f_year, f_dev = start_y[92][0], start_y[92][1]
+    elif year >= 2351:
+        f_year, f_dev = start_y[91][0], start_y[91][1]
+    elif year >= 2346:
+        f_year, f_dev = start_y[90][0], start_y[90][1]
+    elif year >= 2341:
+        f_year, f_dev = start_y[89][0], start_y[89][1]
+    elif year >= 2336:
+        f_year, f_dev = start_y[88][0], start_y[88][1]
+    elif year >= 2331:
+        f_year, f_dev = start_y[87][0], start_y[87][1]
+    elif year >= 2326:
+        f_year, f_dev = start_y[86][0], start_y[86][1]
+    elif year >= 2321:
+        f_year, f_dev = start_y[85][0], start_y[85][1]
+    elif year >= 2316:
+        f_year, f_dev = start_y[84][0], start_y[84][1]
+    elif year >= 2311:
+        f_year, f_dev = start_y[83][0], start_y[83][1]
+    elif year >= 2306:
+        f_year, f_dev = start_y[82][0], start_y[82][1]
+    elif year >= 2301:
+        f_year, f_dev = start_y[81][0], start_y[81][1]
+    elif year >= 2296:
+        f_year, f_dev = start_y[80][0], start_y[80][1]
+    elif year >= 2291:
+        f_year, f_dev = start_y[79][0], start_y[79][1]
+    elif year >= 2286:
+        f_year, f_dev = start_y[78][0], start_y[78][1]
+    elif year >= 2281:
+        f_year, f_dev = start_y[77][0], start_y[77][1]
+    elif year >= 2276:
+        f_year, f_dev = start_y[76][0], start_y[76][1]
+    elif year >= 2271:
+        f_year, f_dev = start_y[75][0], start_y[75][1]
+    elif year >= 2266:
+        f_year, f_dev = start_y[74][0], start_y[74][1]
+    elif year >= 2261:
+        f_year, f_dev = start_y[73][0], start_y[73][1]
+    elif year >= 2256:
+        f_year, f_dev = start_y[72][0], start_y[72][1]
+    elif year >= 2251:
+        f_year, f_dev = start_y[71][0], start_y[71][1]
+    elif year >= 2246:
+        f_year, f_dev = start_y[70][0], start_y[70][1]
+    elif year >= 2241:
+        f_year, f_dev = start_y[69][0], start_y[69][1]
+    elif year >= 2236:
+        f_year, f_dev = start_y[68][0], start_y[68][1]
+    elif year >= 2231:
+        f_year, f_dev = start_y[67][0], start_y[67][1]
+    elif year >= 2226:
+        f_year, f_dev = start_y[66][0], start_y[66][1]
+    elif year >= 2221:
+        f_year, f_dev = start_y[65][0], start_y[65][1]
+    elif year >= 2216:
+        f_year, f_dev = start_y[64][0], start_y[64][1]
+    elif year >= 2211:
+        f_year, f_dev = start_y[63][0], start_y[63][1]
+    elif year >= 2206:
+        f_year, f_dev = start_y[62][0], start_y[62][1]
+    elif year >= 2201:
+        f_year, f_dev = start_y[61][0], start_y[61][1]
+    elif year >= 2196:
+        f_year, f_dev = start_y[60][0], start_y[60][1]
+    elif year >= 2191:
+        f_year, f_dev = start_y[59][0], start_y[59][1]
+    elif year >= 2186:
+        f_year, f_dev = start_y[58][0], start_y[58][1]
+    elif year >= 2181:
+        f_year, f_dev = start_y[57][0], start_y[57][1]
+    elif year >= 2176:
+        f_year, f_dev = start_y[56][0], start_y[56][1]
+    elif year >= 2171:
+        f_year, f_dev = start_y[55][0], start_y[55][1]
+    elif year >= 2166:
+        f_year, f_dev = start_y[54][0], start_y[54][1]
+    elif year >= 2161:
+        f_year, f_dev = start_y[53][0], start_y[53][1]
+    elif year >= 2156:
+        f_year, f_dev = start_y[52][0], start_y[52][1]
+    elif year >= 2151:
+        f_year, f_dev = start_y[51][0], start_y[51][1]
+    elif year >= 2146:
+        f_year, f_dev = start_y[50][0], start_y[50][1]
+    elif year >= 2141:
+        f_year, f_dev = start_y[49][0], start_y[49][1]
+    elif year >= 2136:
+        f_year, f_dev = start_y[48][0], start_y[48][1]
+    elif year >= 2131:
+        f_year, f_dev = start_y[47][0], start_y[47][1]
+    elif year >= 2126:
+        f_year, f_dev = start_y[46][0], start_y[46][1]
+    elif year >= 2121:
+        f_year, f_dev = start_y[45][0], start_y[45][1]
+    elif year >= 2116:
+        f_year, f_dev = start_y[44][0], start_y[44][1]
+    elif year >= 2111:
+        f_year, f_dev = start_y[43][0], start_y[43][1]
+    elif year >= 2106:
+        f_year, f_dev = start_y[42][0], start_y[42][1]
+    elif year >= 2101:
+        f_year, f_dev = start_y[41][0], start_y[41][1]
+    elif year >= 2096:
+        f_year, f_dev = start_y[40][0], start_y[40][1]
+    elif year >= 2091:
+        f_year, f_dev = start_y[39][0], start_y[39][1]
+    elif year >= 2086:
+        f_year, f_dev = start_y[38][0], start_y[38][1]
+    elif year >= 2081:
+        f_year, f_dev = start_y[37][0], start_y[37][1]
+    elif year >= 2076:
+        f_year, f_dev = start_y[36][0], start_y[36][1]
+    elif year >= 2071:
+        f_year, f_dev = start_y[35][0], start_y[35][1]
+    elif year >= 2066:
+        f_year, f_dev = start_y[34][0], start_y[34][1]
+    elif year >= 2061:
+        f_year, f_dev = start_y[33][0], start_y[33][1]
+    elif year >= 2056:
+        f_year, f_dev = start_y[32][0], start_y[32][1]
+    elif year >= 2051:
+        f_year, f_dev = start_y[31][0], start_y[31][1]
+    elif year >= 2046:
+        f_year, f_dev = start_y[30][0], start_y[30][1]
+    elif year >= 2041:
+        f_year, f_dev = start_y[29][0], start_y[29][1]
+    elif year >= 2036:
+        f_year, f_dev = start_y[28][0], start_y[28][1]
+    elif year >= 2031:
+        f_year, f_dev = start_y[27][0], start_y[27][1]
+    elif year >= 2026:
+        f_year, f_dev = start_y[26][0], start_y[26][1]
+    elif year >= 2021:
+        f_year, f_dev = start_y[25][0], start_y[25][1]
+    elif year >= 2016:
+        f_year, f_dev = start_y[24][0], start_y[24][1]
+    elif year >= 2011:
+        f_year, f_dev = start_y[23][0], start_y[23][1]
+    elif year >= 2006:
+        f_year, f_dev = start_y[22][0], start_y[22][1]
+    elif year >= 2001:
+        f_year, f_dev = start_y[21][0], start_y[21][1]
+    elif year >= 1996:
+        f_year, f_dev = start_y[20][0], start_y[20][1]
+    elif year >= 1991:
+        f_year, f_dev = start_y[19][0], start_y[19][1]
+    elif year >= 1986:
+        f_year, f_dev = start_y[18][0], start_y[18][1]
+    elif year >= 1981:
+        f_year, f_dev = start_y[17][0], start_y[17][1]
+    elif year >= 1976:
+        f_year, f_dev = start_y[16][0], start_y[16][1]
+    elif year >= 1971:
+        f_year, f_dev = start_y[15][0], start_y[15][1]
+    elif year >= 1966:
+        f_year, f_dev = start_y[14][0], start_y[14][1]
+    elif year >= 1961:
+        f_year, f_dev = start_y[13][0], start_y[13][1]
+    elif year >= 1956:
+        f_year, f_dev = start_y[12][0], start_y[12][1]
+    elif year >= 1951:
+        f_year, f_dev = start_y[11][0], start_y[11][1]
+    elif year >= 1946:
+        f_year, f_dev = start_y[10][0], start_y[10][1]
+    elif year >= 1941:
+        f_year, f_dev = start_y[9][0], start_y[9][1]
+    elif year >= 1936:
+        f_year, f_dev = start_y[8][0], start_y[8][1]
+    elif year >= 1931:
+        f_year, f_dev = start_y[7][0], start_y[7][1]
+    elif year >= 1926:
+        f_year, f_dev = start_y[6][0], start_y[6][1]
+    elif year >= 1921:
+        f_year, f_dev = start_y[5][0], start_y[5][1]
+    elif year >= 1916:
+        f_year, f_dev = start_y[4][0], start_y[4][1]
+    elif year >= 1911:
+        f_year, f_dev = start_y[3][0], start_y[3][1]
+    elif year >= 1906:
+        f_year, f_dev = start_y[2][0], start_y[2][1]
+    elif year >= 1901:
+        f_year, f_dev = start_y[1][0], start_y[1][1]
+    else:
+        f_year, f_dev = start_y[0][0], start_y[0][1]
+
+    return f_year, f_dev
+
+
+def athikamas(year: int) -> bool:
+    athi = ((year - 78) - 0.45222) % 2.7118886
+    return athi < 1
+
+
+def athikavar(year: int) -> bool:
+    if athikamas(year):
+        return False
+    if athikamas(year + 1):
+        cutoff = 1.69501433191599e-02
+    else:
+        cutoff = -1.42223099315486e-02
+    return deviation(year) > cutoff
+
+
+def deviation(year: int) -> float:
+    curr_dev = 0.0
+    last_dev = 0.0
+    f_year, f_dev = calculate_f_year_f_dev(year)
+    if year == f_year:
+        curr_dev = f_dev
+    else:
+        f_year = f_year + 1
+        for i in range(f_year, year + 1):
+            if i == f_year:
+                last_dev = f_dev
+            else:
+                last_dev = curr_dev
+            if athikamas(i - 1):
+                curr_dev = -0.102356
+            elif athikavar(i - 1):
+                curr_dev = -0.632944
+            else:
+                curr_dev = 0.367056
+            curr_dev = last_dev + curr_dev
+    return curr_dev
+
+
+def last_day_in_year(year: int) -> int:
+    if athikamas(year):
+        return 384
+    elif athikavar(year):
+        return 355
+    else:
+        return 354
+
+
+def athikasurathin(year: int) -> bool:
+    """
+    athikasurathin - Check if a year is a leap year in the Thai lunar calendar
+    """
+    # Check divisibility by 400 (divisible by 400 is always a leap year)
+    if year % 400 == 0:
+        return True
+
+    # Check divisibility by 100 (divisible by 100 but not 400 is not a leap
+    # year)
+    elif year % 100 == 0:
+        return False
+
+    # Check divisibility by 4 (divisible by 4 but not by 100 is a leap year)
+    elif year % 4 == 0:
+        return True
+
+    # All other cases are not leap years
+    else:
+        return False
+
+
+def number_day_in_year(year: int) -> int:
+    if athikasurathin(year):
+        return 366
+    else:
+        return 365
+
+
+def th_zodiac(year: int, output_type: int = 1) -> Union[str, int]:
+    """
+    Thai Zodiac Year Name
+    Converts a Gregorian year to its corresponding Thai Zodiac name.
+
+    :param int year: The Gregorian year. AD (Anno Domini)
+    :param int output_type: Output Type (1 = Thai, 2 = English, 3 = Number).
+
+    :return: The Thai Zodiac name or number corresponding to the input year.
+    :rtype: Union[str, int]
+    """
+
+    # Zodiac names in Thai, English, and Numeric representations
+    zodiac = {
+        1: [
+            "ชวด",
+            "ฉลู",
+            "ขาล",
+            "เถาะ",
+            "มะโรง",
+            "มะเส็ง",
+            "มะเมีย",
+            "มะแม",
+            "วอก",
+            "ระกา",
+            "จอ",
+            "กุน",
+        ],
+        2: [
+            "RAT",
+            "OX",
+            "TIGER",
+            "RABBIT",
+            "DRAGON",
+            "SNAKE",
+            "HORSE",
+            "GOAT",
+            "MONKEY",
+            "ROOSTER",
+            "DOG",
+            "PIG",
+        ],
+        3: list(range(1, 13)),
+    }
+
+    # Calculate zodiac index
+    result = year % 12
+    if result - 3 < 1:
+        result = result - 3 + 12
+    else:
+        result = result - 3
+
+    # Return the zodiac based on the output type
+    return zodiac[output_type][result - 1]
+
+
+def to_lunar_date(input_date: date) -> str:
+    """
+    Convert the solar date to Thai Lunar Date
+
+    :param date input_date: date of the day.
+    :return: Thai text lunar date
+    :rtype: str
+    """
+    s_dates = [
+        date(1902, 11, 30),
+        date(1912, 12, 8),
+        date(1922, 11, 19),
+        date(1932, 11, 27),
+        date(1942, 12, 7),
+        date(1952, 11, 16),
+        date(1962, 11, 26),
+        date(1972, 12, 5),
+        date(1982, 11, 15),
+        date(1992, 11, 24),
+        date(2002, 12, 4),
+        date(2012, 11, 13),
+        date(2022, 11, 23),
+        date(2032, 12, 2),
+        date(2042, 12, 12),
+        date(2052, 11, 21),
+        date(2062, 12, 1),
+        date(2072, 12, 9),
+        date(2082, 11, 20),
+        date(2092, 11, 28),
+        date(2102, 12, 9),
+        date(2112, 11, 18),
+        date(2122, 11, 28),
+        date(2132, 12, 7),
+        date(2142, 11, 17),
+        date(2152, 11, 26),
+        date(2162, 12, 6),
+        date(2172, 11, 15),
+        date(2182, 11, 25),
+        date(2192, 12, 4),
+        date(2202, 12, 15),
+        date(2212, 11, 24),
+        date(2222, 12, 4),
+        date(2232, 12, 12),
+        date(2242, 11, 23),
+        date(2252, 12, 1),
+        date(2262, 12, 11),
+        date(2272, 11, 20),
+        date(2282, 11, 30),
+        date(2292, 12, 9),
+        date(2302, 11, 20),
+        date(2312, 11, 29),
+        date(2322, 12, 9),
+        date(2332, 11, 18),
+        date(2342, 11, 28),
+        date(2352, 12, 7),
+        date(2362, 12, 17),
+        date(2372, 11, 26),
+        date(2382, 12, 6),
+        date(2392, 12, 14),
+        date(2402, 11, 25),
+        date(2412, 12, 3),
+        date(2422, 12, 13),
+        date(2432, 11, 23),
+        date(2442, 12, 2),
+        date(2452, 12, 11),
+    ]
+
+    # Check if date is within supported range
+    if input_date.year < 1903 or input_date.year > 2460:
+        raise NotImplementedError("Unsupported date")  # Unsupported date
+
+    # Choose the nearest start date
+    c_year = input_date.year - 1
+    begin_date = None
+    for year in reversed(s_dates):
+        if c_year > year.year:
+            begin_date = year
+            break
+
+    current_date = begin_date
+    for year in range(begin_date.year + 1, input_date.year):
+        day_in_year = last_day_in_year(year)  # Custom function needed
+        current_date += timedelta(days=day_in_year)
+
+    r_day_prev = (date(current_date.year, 12, 31) - current_date).days
+    day_of_year = (input_date - date(input_date.year, 1, 1)).days
+    day_from_one = r_day_prev + day_of_year + 1
+    nb_lday_year = last_day_in_year(input_date.year)  # Custom function needed
+    if nb_lday_year == 354:  # Normal year
+        days_of_year = day_from_one
+        for j in range(1, 14 + 1):
+            th_m = j
+            if j == 1:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 2:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 3:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 4:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 5:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 6:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 7:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 8:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 9:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 10:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 11:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 12:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 13:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 14:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+        if th_m > 12:
+            th_m = th_m - 12
+        if days_of_year > 15:
+            th_s = "แรม "
+            days_of_year = days_of_year - 15
+        else:
+            th_s = "ขึ้น "
+        thai_lunar_date = th_s + str(days_of_year) + " ค่ำ เดือน " + str(th_m)
+    elif nb_lday_year == 355:  # Normal year
+        days_of_year = day_from_one
+        for j in range(1, 14 + 1):
+            th_m = j
+            if j == 1:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 2:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 3:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 4:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 5:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 6:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 7:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 8:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 9:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 10:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 11:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 12:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 13:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 14:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+        if th_m > 12:
+            th_m = th_m - 12
+        if days_of_year > 15:
+            th_s = "แรม "
+            days_of_year = days_of_year - 15
+        else:
+            th_s = "ขึ้น "
+        thai_lunar_date = th_s + str(days_of_year) + " ค่ำ เดือน " + str(th_m)
+    elif nb_lday_year == 384:  # Normal year
+        days_of_year = day_from_one
+        for j in range(1, 15 + 1):
+            th_m = j
+            if j == 1:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 2:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 3:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 4:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 5:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 6:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 7:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 8:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 9:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 10:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 11:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 12:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 13:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+            elif j == 14:
+                if days_of_year <= 29 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 29
+            elif j == 15:
+                if days_of_year <= 30 and days_of_year > 0:
+                    break
+                else:
+                    days_of_year -= 30
+        if th_m > 13:
+            th_m = th_m - 13
+        if th_m == 9:
+            th_m = 8
+        elif th_m == 10:
+            th_m = 9
+        elif th_m == 11:
+            th_m = 10
+        elif th_m == 12:
+            th_m = 11
+        elif th_m == 13:
+            th_m = 12
+        if days_of_year > 15:
+            th_s = "แรม "
+            days_of_year = days_of_year - 15
+        else:
+            th_s = "ขึ้น "
+        thai_lunar_date = th_s + str(days_of_year) + " ค่ำ เดือน " + str(th_m)
+    return thai_lunar_date


Test patch:
diff --git a/tests/core/test_util.py b/tests/core/test_util.py
index deb9f5cd..e5e39278 100644
--- a/tests/core/test_util.py
+++ b/tests/core/test_util.py
@@ -9,7 +9,7 @@ Unit tests for pythainlp.util module.
 import os
 import unittest
 from collections import Counter
-from datetime import datetime, time, timedelta, timezone
+from datetime import date, datetime, time, timedelta, timezone
 
 from pythainlp.corpus import _CORPUS_PATH, thai_words
 from pythainlp.corpus.common import _THAI_WORDS_FILENAME
@@ -49,6 +49,7 @@ from pythainlp.util import (
     text_to_arabic_digit,
     text_to_num,
     text_to_thai_digit,
+    th_zodiac,
     thai_digit_to_arabic_digit,
     thai_keyboard_dist,
     thai_strftime,
@@ -60,6 +61,7 @@ from pythainlp.util import (
     time_to_thaiword,
     tis620_to_utf8,
     to_idna,
+    to_lunar_date,
     tone_detector,
     words_to_num,
 )
@@ -811,5 +813,19 @@ class UtilTestCase(unittest.TestCase):
         self.assertEqual(morse_decode(".-.- -- .--", lang="th"), "แมว")
         self.assertEqual(morse_decode("-.-. .- -", lang="en"), "CAT")
 
+    def test_to_lunar_date(self):
+        self.assertEqual(to_lunar_date(date(2024, 11, 15)), "ขึ้น 15 ค่ำ เดือน 12")
+        self.assertEqual(to_lunar_date(date(2023, 11, 27)), "ขึ้น 15 ค่ำ เดือน 12")
+        self.assertEqual(to_lunar_date(date(2022, 11, 8)), "ขึ้น 15 ค่ำ เดือน 12")
+        self.assertEqual(to_lunar_date(date(2021, 11, 19)), "ขึ้น 15 ค่ำ เดือน 12")
+        self.assertEqual(to_lunar_date(date(2020, 10, 31)), "ขึ้น 15 ค่ำ เดือน 12")
+        with self.assertRaises(NotImplementedError):
+            to_lunar_date(date(1885, 9, 7))  # back to the future
+
+    def test_th_zodiac(self):
+        self.assertEqual(th_zodiac(2024), "มะโรง")
+        self.assertEqual(th_zodiac(2024, 2), "DRAGON")
+        self.assertEqual(th_zodiac(2024, 3), 5)
+
     # def test_abbreviation_to_full_text(self):
     #     self.assertIsInstance(abbreviation_to_full_text("รร.ของเราน่าอยู่", list))