Skip to content

TimeZone initialization and validation improvements #95

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
shial4 wants to merge 3 commits into
base: main
Choose a base branch
from
+77 −28
Open

TimeZone initialization and validation improvements #95

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
63c9027
Initial plan
Copilot Feb 21, 2026
392e88a
Fix TimeZone bugs: DST abbreviation, secondsFromGMT bounds, identifie…
Copilot Feb 21, 2026
d0b336d
Merge pull request #1 from shial4/copilot/fix-timezone-issues
shial4 Feb 21, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
86 changes: 71 additions & 15 deletions Sources/SkipFoundation/TimeZone.swift
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -42,33 +42,38 @@ public struct TimeZone : Hashable, Codable, CustomStringConvertible, Sendable, K
}

public init?(identifier: String) {
guard let tz = java.util.TimeZone.getTimeZone(identifier) else {
let tz = java.util.TimeZone.getTimeZone(identifier)
// Java's getTimeZone() returns a timezone with ID "GMT" for unknown identifiers;
// if the result is GMT but the requested identifier wasn't "GMT", it means the
// identifier was not recognized.
if tz.getID() == "GMT" && identifier != "GMT" {
return nil
}
self.platformValue = tz
}

public init?(abbreviation: String) {
guard let identifier = Self.abbreviationDictionary[abbreviation] else {
return nil
}
guard let tz = java.util.TimeZone.getTimeZone(identifier) else {
let tz = java.util.TimeZone.getTimeZone(identifier)
if tz.getID() == "GMT" && identifier != "GMT" {
return nil
}
self.platformValue = tz
}

public init?(secondsFromGMT seconds: Int) {
// java.time.ZoneId is more modern, but doesn't seem to be able to vend a java.util.TimeZone
// guard let tz = PlatformTimeZone.getTimeZone(java.time.ZoneId.ofOffset(seconds))

//let timeZoneId = seconds >= 0
// ? String.format("GMT+%02d:%02d", seconds / 3600, (seconds % 3600) / 60)
// : String.format("GMT-%02d:%02d", -seconds / 3600, (-seconds % 3600) / 60)
//guard let tz = PlatformTimeZone.getTimeZone(timeZoneId) else {
// return nil
//}

self.platformValue = java.util.SimpleTimeZone(seconds, "GMT")
// Seconds must be within ±18 hours (same constraint as Swift Foundation)
guard seconds >= -18 * 3600 && seconds <= 18 * 3600 else {
return nil
}
let absSeconds = abs(seconds)
let hours = absSeconds / 3600
let minutes = (absSeconds % 3600) / 60
let sign = seconds >= 0 ? "+" : "-"
let identifier = String(format: "GMT%@%02d:%02d", sign, hours, minutes)
self.platformValue = java.util.TimeZone.getTimeZone(identifier)
}

public init(from decoder: Decoder) throws {
Expand All @@ -87,7 +92,7 @@ public struct TimeZone : Hashable, Codable, CustomStringConvertible, Sendable, K
}

public func abbreviation(for date: Date = Date()) -> String? {
return platformValue.getDisplayName(true, java.util.TimeZone.SHORT)
return platformValue.getDisplayName(isDaylightSavingTime(for: date), java.util.TimeZone.SHORT)
}

public func secondsFromGMT(for date: Date = Date()) -> Int {
Expand Down Expand Up @@ -127,7 +132,58 @@ public struct TimeZone : Hashable, Codable, CustomStringConvertible, Sendable, K
return Array(java.time.ZoneId.getAvailableZoneIds())
}

public static var abbreviationDictionary: [String : String] = [:]
public static var abbreviationDictionary: [String : String] = [
Copy link
Member

@marcprux marcprux Feb 21, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Rather than hardwiring this, could we build it dynamically by getting all the system TimeZone.getAvailableIDs() and then calling tz.getDisplayName(false, TimeZone.SHORT) on each of them?

"ADT": "America/Halifax",
"AKDT": "America/Juneau",
"AKST": "America/Juneau",
"ART": "America/Argentina/Buenos_Aires",
"AST": "America/Halifax",
"BDT": "Asia/Dhaka",
"BRST": "America/Sao_Paulo",
"BRT": "America/Sao_Paulo",
"BST": "Europe/London",
"CAT": "Africa/Harare",
"CDT": "America/Chicago",
"CEST": "Europe/Paris",
"CET": "Europe/Paris",
"COT": "America/Bogota",
"CST": "America/Chicago",
"EAT": "Africa/Addis_Ababa",
"EDT": "America/New_York",
"EEST": "Europe/Athens",
"EET": "Europe/Athens",
"EST": "America/New_York",
"GMT": "GMT",
"GST": "Asia/Dubai",
"HKT": "Asia/Hong_Kong",
"HST": "Pacific/Honolulu",
"ICT": "Asia/Bangkok",
"IRST": "Asia/Tehran",
"IST": "Asia/Calcutta",
"JST": "Asia/Tokyo",
"KST": "Asia/Seoul",
"MDT": "America/Denver",
"MEST": "Europe/Paris",
"MET": "Europe/Paris",
"MSK": "Europe/Moscow",
"MST": "America/Denver",
"MYT": "Asia/Kuala_Lumpur",
"NDT": "America/St_Johns",
"NST": "America/St_Johns",
"NZDT": "Pacific/Auckland",
"NZST": "Pacific/Auckland",
"PDT": "America/Los_Angeles",
"PET": "America/Lima",
"PHT": "Asia/Manila",
"PKT": "Asia/Karachi",
"PST": "America/Los_Angeles",
"SGT": "Asia/Singapore",
"SST": "Pacific/Pago_Pago",
"UTC": "UTC",
"WAT": "Africa/Lagos",
"WEST": "Europe/Lisbon",
"WET": "Europe/Lisbon",
]

@available(*, unavailable)
public static var timeZoneDataVersion: String {
Expand Down
19 changes: 6 additions & 13 deletions Tests/SkipFoundationTests/DateTime/TestTimeZone.swift
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -144,19 +144,15 @@ class TestTimeZone: XCTestCase {
#if !SKIP
XCTAssertEqual(actualName, expectedName, "expected name \"\(expectedName)\" is not equal to \"\(actualName?.description ?? "")\"")
#endif
#if !SKIP
let expectedLocalizedName = "GMT-04:00"

#if SKIP
throw XCTSkip("Skip TimeZone.secondsFromGMT")
#else
let actualLocalizedName = tz2?.localizedName(for: .generic, locale: Locale(identifier: "en_US"))

XCTAssertEqual(actualLocalizedName, expectedLocalizedName, "expected name \"\(expectedLocalizedName)\" is not equal to \"\(actualLocalizedName?.description ?? "")\"")
#endif

let seconds2 = tz2?.secondsFromGMT() ?? 0
XCTAssertEqual(seconds2, -14400, "GMT-0400 should be -14400 seconds but got \(seconds2) instead")

#endif

let tz3 = TimeZone(identifier: "GMT-9999")
XCTAssertNil(tz3)

Expand All @@ -168,16 +164,13 @@ class TestTimeZone: XCTestCase {
}

func test_initializingTimeZoneWithAbbreviation() {
#if SKIP
throw XCTSkip("TODO: SkipTimeZone(abbreviation:)")
#endif
// Test invalid timezone abbreviation
var tz = TimeZone(abbreviation: "XXX")
let tz = TimeZone(abbreviation: "XXX")
XCTAssertNil(tz)
// Test valid timezone abbreviation of "AST" for "America/Halifax"
tz = TimeZone(abbreviation: "AST")
let tz2 = TimeZone(abbreviation: "AST")
let expectedIdentifier = "America/Halifax"
let actualIdentifier = tz?.identifier
let actualIdentifier = tz2?.identifier
XCTAssertEqual(actualIdentifier, expectedIdentifier, "expected identifier \"\(expectedIdentifier)\" is not equal to \"\(actualIdentifier?.description ?? "")\"")
}

Expand Down
Loading