Add date helpers

Author: alex-ross

Sources/EasyMode/Date.swift

@@ -0,0 +1,96 @@
+import Foundation
+
+extension Date {
+    public var startOfWeek: Date {
+       return previous(.monday, considerToday: true)
+    }
+
+    public var endOfWeek: Date {
+        return next(.sunday, considerToday: true)
+    }
+
+    public var isoDate: String {
+        let formatter = DateFormatter()
+        formatter.dateFormat = "yyyy-MM-dd"
+        formatter.timeZone = TimeZone(abbreviation: "CET")!
+
+        return formatter.string(from: self)
+    }
+}
+
+extension Date {
+
+    public static func today() -> Date {
+        return Date()
+    }
+
+    public func next(_ weekday: Weekday, considerToday: Bool = false) -> Date {
+        return get(.next,
+                   weekday,
+                   considerToday: considerToday)
+    }
+
+    public func previous(_ weekday: Weekday, considerToday: Bool = false) -> Date {
+        return get(.previous,
+                   weekday,
+                   considerToday: considerToday)
+    }
+
+    public func get(_ direction: SearchDirection,
+             _ weekDay: Weekday,
+             considerToday consider: Bool = false) -> Date {
+
+        let dayName = weekDay.rawValue
+
+        let weekdaysName = getWeekDaysInEnglish().map { $0.lowercased() }
+
+        assert(weekdaysName.contains(dayName), "weekday symbol should be in form \(weekdaysName)")
+
+        let searchWeekdayIndex = weekdaysName.firstIndex(of: dayName)! + 1
+
+        let calendar = Calendar(identifier: .gregorian)
+
+        if consider && calendar.component(.weekday, from: self) == searchWeekdayIndex {
+            return self
+        }
+
+        var nextDateComponent = DateComponents()
+        nextDateComponent.weekday = searchWeekdayIndex
+
+
+        let date = calendar.nextDate(after: self,
+                                     matching: nextDateComponent,
+                                     matchingPolicy: .nextTime,
+                                     direction: direction.calendarSearchDirection)
+
+        return date!
+    }
+
+}
+
+// MARK: Helper methods
+extension Date {
+    public func getWeekDaysInEnglish() -> [String] {
+        var calendar = Calendar(identifier: .gregorian)
+        calendar.locale = Locale(identifier: "en_US_POSIX")
+        return calendar.weekdaySymbols
+    }
+
+    public enum Weekday: String {
+        case monday, tuesday, wednesday, thursday, friday, saturday, sunday
+    }
+
+    public enum SearchDirection {
+        case next
+        case previous
+
+        var calendarSearchDirection: Calendar.SearchDirection {
+            switch self {
+            case .next:
+                return .forward
+            case .previous:
+                return .backward
+            }
+        }
+    }
+}

Tests/EasyModeTests/DateTests.swift

@@ -0,0 +1,47 @@
+import XCTest
+@testable import EasyMode
+
+class DateTests: XCTestCase {
+    func testStartOfWeek() {
+        let current = DateComponents(calendar: Calendar.current, year: 2019, month: 8, day: 28).date!
+        let expected = DateComponents(calendar: Calendar.current, year: 2019, month: 8, day: 26).date!
+
+        XCTAssertEqual(expected, current.startOfWeek)
+    }
+
+    func testEndOfWeek() {
+        let current = DateComponents(calendar: Calendar.current, year: 2019, month: 8, day: 28).date!
+        let expected = DateComponents(calendar: Calendar.current, year: 2019, month: 9, day: 1).date!
+
+        XCTAssertEqual(expected, current.endOfWeek)
+    }
+
+    func testEndOfLastWeek() {
+        let current = DateComponents(calendar: Calendar.current, year: 2019, month: 8, day: 28).date!
+        let expected = DateComponents(calendar: Calendar.current, year: 2019, month: 8, day: 25).date!
+
+        let oneWeekAgo = Calendar.current.date(byAdding: .day, value: -7, to: current)!
+
+        XCTAssertEqual(expected, oneWeekAgo.endOfWeek)
+    }
+
+    func testIsoDate() {
+        let date = DateComponents(calendar: Calendar.current, year: 2019, month: 8, day: 6).date!
+
+        XCTAssertEqual("2019-08-06", date.isoDate)
+    }
+
+    func testIsoDateWhenSunday() {
+        let date = DateComponents(calendar: Calendar.current, year: 2019, month: 9, day: 8).date!
+
+        XCTAssertEqual("2019-09-08", date.endOfWeek.isoDate)
+    }
+    
+    static var allTests = [
+       ("testStartOfWeek", testStartOfWeek),
+       ("testEndOfWeek", testEndOfWeek),
+       ("testEndOfLastWeek", testEndOfLastWeek),
+       ("testIsoDate", testIsoDate),
+       ("testIsoDateWhenSunday", testIsoDateWhenSunday),
+   ]
+}

Tests/EasyModeTests/XCTestManifests.swift

@@ -4,7 +4,8 @@ import XCTest
 public func allTests() -> [XCTestCaseEntry] {
     return [
         testCase(EasyModeTests.allTests),
-        testCase(StringTests.allTests)
+        testCase(StringTests.allTests),
+        testCase(DateTests.allTests),
     ]
 }
 #endif