From d2c8ca4fc7f65956140bcf7d1a1e945d805fcfc8 Mon Sep 17 00:00:00 2001
From: Fulvio <fbf@libero.it>
Date: Wed, 1 Feb 2023 17:02:53 +0100
Subject: [PATCH] Allow to import dates with up to 31 days, even for the wrong
 months. This is consistent with game_save which allows such dates for new
 games.

---
 gtest/test_pgnparser.cpp | 22 +++++++++++++-------
 src/date.h               | 45 +++++++++++++++++-----------------------
 2 files changed, 34 insertions(+), 33 deletions(-)

diff --git a/gtest/test_pgnparser.cpp b/gtest/test_pgnparser.cpp
index 05221a71..1a9572be 100644
--- a/gtest/test_pgnparser.cpp
+++ b/gtest/test_pgnparser.cpp
@@ -250,10 +250,6 @@ TEST(Test_PgnParser, date_parsePGNTag) {
 	test("2018.08.31", "2018.08.31");
 	test("2018.08.32", "2018.08.??");
 	test("2018.01.00", "2018.01.??");
-	test("2018.01.32", "2018.01.??");
-	test("2018.02.30", "2018.02.??");
-	test("2018.04.31", "2018.04.??");
-	test("2018.11.31", "2018.11.??");
 	test("2018.01aaa", "2018.01.??");
 	test("2018.01", "2018.01.??");
 
@@ -283,16 +279,28 @@ TEST(Test_PgnParser, date_parsePGNTag) {
 	test("2000.02.28", "2000.02.28");
 	test("1000.02.28", "1000.02.28");
 	test("2020.02.29", "2020.02.29");
-	test("2018.02.29", "2018.02.??");
 	test("2012.02.29", "2012.02.29");
 	test("2000.02.29", "2000.02.29");
-	test("1900.02.29", "1900.02.??");
-	test("1000.02.29", "1000.02.??");
+
+	// Accept incorrect days up to 31
+	test("2018.01.32", "2018.01.??");
+	test("2018.02.32", "2018.02.??");
+	test("2018.04.31", "2018.04.31");
+	test("2018.11.31", "2018.11.31");
+	test("2018.02.31", "2018.02.31");
+	test("2018.02.30", "2018.02.30");
+	test("2018.02.29", "2018.02.29");
+	test("1900.02.29", "1900.02.29");
+	test("1000.02.29", "1000.02.29");
 
 	test("????.??.??", "????.??.??");
 	test("2023.??.??", "2023.??.??");
 	test("2023.01.??", "2023.01.??");
 	test("2023.??.30", "2023.??.30");
+
+	test("2023.10.2", "2023.10.02");
+	test("2023.3.14", "2023.03.14");
+	test("2023.1.2", "2023.01.02");
 }
 
 TEST(Test_PgnParser, TagPairs) {
diff --git a/src/date.h b/src/date.h
index f6ff6fba..cf3a608c 100644
--- a/src/date.h
+++ b/src/date.h
@@ -167,45 +167,38 @@ date_EncodeFromString (const char * str)
  * @returns the dateT object corresponding to @e str.
  */
 inline dateT date_parsePGNTag(const char* str, size_t len) {
-	auto to_int = [](unsigned char ch) {
-		return ch - static_cast<unsigned char>('0');
-	};
 	auto is_digit = [](auto v) { return v >= 0 && v <= 9; };
 
-	if (len < 4)
+	if (len < 4 || len > 10)
 		return {};
 
-	int tmp[4];
-	std::transform(str, str + 4, tmp, to_int);
+	int tmp[10];
+	std::transform(str, str + len, tmp, [](unsigned char ch) {
+		return ch - static_cast<unsigned char>('0');
+	});
+	std::fill(tmp + len, tmp + 10, -1);
+
 	uint32_t year = tmp[0] * 1000 + tmp[1] * 100 + tmp[2] * 10 + tmp[3];
 	if (!std::all_of(tmp, tmp + 4, is_digit) || year > YEAR_MAX)
 		return {};
 
 	uint32_t month = 0;
-	if (len > 6) {
-		auto d1 = to_int(str[5]);
-		auto d2 = to_int(str[6]);
-		if (is_digit(d1) && is_digit(d2)) {
-			month = d1 * 10 + d2;
-			if (month > 12)
-				month = 0;
+	if (!is_digit(tmp[4]) && is_digit(tmp[5])) {
+		if (!is_digit(tmp[6])) {
+			// Accept the format YYYY.M.DD or YYYY.M.D
+			std::rotate(tmp + 5, tmp + 9, tmp + 10);
+			tmp[5] = 0;
 		}
+		month = tmp[5] * 10 + tmp[6];
+		if (month > 12)
+			month = 0;
 	}
 
 	uint32_t day = 0;
-	if (len > 9) {
-		auto d1 = to_int(str[8]);
-		auto d2 = to_int(str[9]);
-		if (is_digit(d1) && is_digit(d2)) {
-			day = d1 * 10 + d2;
-			constexpr unsigned char days[] = {31, 31, 28, 31, 30, 31, 30,
-			                                  31, 31, 30, 31, 30, 31};
-			if (day > days[month]) {
-				if (day != 29 || year % 4 || (year % 100 == 0 && year % 400)) {
-					day = 0;
-				}
-			}
-		}
+	if (!is_digit(tmp[7]) && is_digit(tmp[8])) {
+		day = is_digit(tmp[9]) ? tmp[8] * 10 + tmp[9] : tmp[8];
+		if (day > 31)
+			day = 0;
 	}
 
 	return (year << YEAR_SHIFT) | (month << MONTH_SHIFT) | (day << DAY_SHIFT);