commit 436ccb7ea99abd63cdab0d442c82e741d0e27bab
Author: 諏訪子 <suwako@076.moe>
Date:   Sun Jul 30 12:06:30 2023 +0900

    最初コミット

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..c26d4af
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+zig-out
+zig-cache
diff --git a/build.zig b/build.zig
new file mode 100644
index 0000000..54a1c2d
--- /dev/null
+++ b/build.zig
@@ -0,0 +1,27 @@
+const std = @import("std");
+
+pub fn build(b: *std.Build) void {
+    const target = b.standardTargetOptions(.{});
+
+    const optimize = b.standardOptimizeOption(.{});
+
+    const lib = b.addStaticLibrary(.{
+        .name = "toki",
+        .root_source_file = .{ .path = "src/main.zig" },
+        .target = target,
+        .optimize = optimize,
+    });
+
+    b.installArtifact(lib);
+
+    const main_tests = b.addTest(.{
+        .root_source_file = .{ .path = "src/main.zig" },
+        .target = target,
+        .optimize = optimize,
+    });
+
+    const run_main_tests = b.addRunArtifact(main_tests);
+
+    const test_step = b.step("test", "Run library tests");
+    test_step.dependOn(&run_main_tests.step);
+}
diff --git a/src/main.zig b/src/main.zig
new file mode 100644
index 0000000..c5839ac
--- /dev/null
+++ b/src/main.zig
@@ -0,0 +1,137 @@
+const std = @import("std");
+const testing = std.testing;
+
+const DateTime = struct {
+    year: u64,
+    month: u64,
+    day: u64,
+    hour: u64,
+    minute: u64,
+    second: u64,
+};
+
+fn getDaysInMonth(year: u64) [12]u64 {
+    var daysInMonth = [_]u64{ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
+
+    if (isLeapYear(year)) {
+        daysInMonth[1] += 1;
+    }
+
+    return daysInMonth;
+}
+
+fn calculateYearAndDayOfYear(days: u64) struct { year: u64, dayOfYear: u64 } {
+    var year: u64 = 1970;
+    var d = days;
+    while (true) {
+        var daysInThisYear: u64 = if (isLeapYear(year)) 366 else 365;
+        if (d < daysInThisYear) break;
+        d -= daysInThisYear;
+        year += 1;
+    }
+
+    return .{ .year = year, .dayOfYear = d };
+}
+
+fn isLeapYear(year: u64) bool {
+    return (year % 4 == 0) and ((year % 100 != 0) or (year % 400 == 0));
+}
+
+fn declareDateVars(seconds: u64) DateTime {
+    var dt = DateTime{
+        .second = @mod(seconds, 60),
+        .minute = (@as(u64, seconds) / 60) % 60,
+        .hour = (seconds / 60 / 60) % 24,
+        .day = 0,
+        .month = 0,
+        .year = 0,
+    };
+
+    var days = seconds / 60 / 60 / 24;
+
+    var yearAndDayOfYear = calculateYearAndDayOfYear(days);
+    var year: u64 = yearAndDayOfYear.year;
+    var dayOfYear: u64 = yearAndDayOfYear.dayOfYear;
+
+    var month: u64 = 0;
+    var daysInMonth = getDaysInMonth(year);
+
+    while (dayOfYear >= daysInMonth[month]) {
+        dayOfYear -= daysInMonth[month];
+        month += 1;
+    }
+
+    dt.month = month + 1;
+    dt.day = dayOfYear + 1;
+    dt.year = year;
+    return dt;
+}
+
+pub fn unixToDateTime(timestamp: u64) DateTime {
+    const seconds: u64 = timestamp;
+    return declareDateVars(seconds);
+}
+
+pub fn dateTimeToUnix(dateTime: DateTime) u64 {
+    var totalSeconds: u64 = 0;
+    totalSeconds += dateTime.second;
+    totalSeconds += dateTime.minute * 60;
+    totalSeconds += dateTime.hour * 60 * 60;
+    totalSeconds += (dateTime.day - 1) * 24 * 60 * 60;
+
+    var daysInMonth = getDaysInMonth(dateTime.year);
+    var i: u64 = 0;
+    while (i < dateTime.month - 1) {
+        totalSeconds += daysInMonth[i] * 24 * 60 * 60;
+        i += 1;
+    }
+
+    var j: u64 = 1970;
+    while (j < dateTime.year) {
+        if (isLeapYear(j)) totalSeconds += 366 * 24 * 60 * 60 else totalSeconds += 365 * 24 * 60 * 60;
+        j += 1;
+    }
+
+    return totalSeconds;
+}
+
+pub fn nanoToSecond(nano: u64) u64 {
+    var sec: u64 = @divTrunc(nano, 1_000_000_000);
+    return sec;
+}
+
+test "test nanoToSecond" {
+    try testing.expect(nanoToSecond(1690514984429000696) == 1690514984);
+}
+
+test "test unixToDateTime" {
+    var timestamp: u64 = 1633639452;
+    var result = unixToDateTime(timestamp);
+
+    if (result.year != 2021) std.debug.panic("エラー：unixToDateTime.year = {}\n", .{result.year});
+    try testing.expect(result.year == 2021);
+    if (result.month != 10) std.debug.panic("エラー：unixToDateTime.month = {}\n", .{result.month});
+    try testing.expect(result.month == 10);
+    if (result.day != 7) std.debug.panic("エラー：unixToDateTime.day = {}\n", .{result.day});
+    try testing.expect(result.day == 7);
+    if (result.hour != 20) std.debug.panic("エラー：unixToDateTime.hour = {}\n", .{result.hour});
+    try testing.expect(result.hour == 20);
+    if (result.minute != 44) std.debug.panic("エラー：unixToDateTime.minute = {}\n", .{result.minute});
+    try testing.expect(result.minute == 44);
+    if (result.second != 12) std.debug.panic("エラー：unixToDateTime.second = {}\n", .{result.second});
+    try testing.expect(result.second == 12);
+}
+
+test "test dateTimeToUnix" {
+    var timestamp: DateTime = .{
+        .year = 2021,
+        .month = 10,
+        .day = 7,
+        .hour = 20,
+        .minute = 44,
+        .second = 12,
+    };
+    var result = dateTimeToUnix(timestamp);
+    if (result != 1633639452) std.debug.panic("エラー：dateTimeToUnix= {}\n", .{result});
+    try testing.expect(result == 1633639452);
+}