// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See http://swift.org/LICENSE.txt for license information
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//

import CoreFoundation

#if os(OSX) || os(iOS)
    import Darwin
#elseif os(Linux) || CYGWIN
    import Glibc
#endif

public typealias TimeInterval = Double

public var NSTimeIntervalSince1970: Double {
    return 978307200.0
}

open class NSDate : NSObject, NSCopying, NSSecureCoding, NSCoding {
    typealias CFType = CFDate
    
    open override var hash: Int {
        return Int(bitPattern: CFHash(_cfObject))
    }
    
    open override func isEqual(_ value: Any?) -> Bool {
        if let date = value as? Date {
            return isEqual(to: date)
        } else if let date = value as? NSDate {
            return isEqual(to: Date(timeIntervalSinceReferenceDate: date.timeIntervalSinceReferenceDate))
        }
        return false
    }
    
    deinit {
        _CFDeinit(self)
    }
    
    internal var _cfObject: CFType {
        return unsafeBitCast(self, to: CFType.self)
    }
    
    internal let _base = _CFInfo(typeID: CFDateGetTypeID())
    internal let _timeIntervalSinceReferenceDate: TimeInterval
    
    open var timeIntervalSinceReferenceDate: TimeInterval {
        return _timeIntervalSinceReferenceDate
    }
    
    open class var timeIntervalSinceReferenceDate: TimeInterval {
        return Date().timeIntervalSinceReferenceDate
    }

    public convenience override init() {
        var tv = timeval()
        let _ = withUnsafeMutablePointer(to: &tv) { t in
            gettimeofday(t, nil)
        }
        var timestamp = TimeInterval(tv.tv_sec) - NSTimeIntervalSince1970
        timestamp += TimeInterval(tv.tv_usec) / 1000000.0
        self.init(timeIntervalSinceReferenceDate: timestamp)
    }

    public required init(timeIntervalSinceReferenceDate ti: TimeInterval) {
        _timeIntervalSinceReferenceDate = ti
    }
    
    public convenience required init?(coder aDecoder: NSCoder) {
        guard aDecoder.allowsKeyedCoding else {
            preconditionFailure("Unkeyed coding is unsupported.")
        }
        let ti = aDecoder.decodeDouble(forKey: "NS.time")
        self.init(timeIntervalSinceReferenceDate: ti)
    }

    open override func copy() -> Any {
        return copy(with: nil)
    }

    open func copy(with zone: NSZone? = nil) -> Any {
        return self
    }
    
    public static var supportsSecureCoding: Bool {
        return true
    }
    
    open func encode(with aCoder: NSCoder) {
        guard aCoder.allowsKeyedCoding else {
            preconditionFailure("Unkeyed coding is unsupported.")
        }
        aCoder.encode(_timeIntervalSinceReferenceDate, forKey: "NS.time")
    }

    /**
     A string representation of the date object (read-only).

     The representation is useful for debugging only.

     There are a number of options to acquire a formatted string for a date
     including: date formatters (see
     [NSDateFormatter](//apple_ref/occ/cl/NSDateFormatter) and
     [Data Formatting Guide](//apple_ref/doc/uid/10000029i)),
     and the `NSDate` methods `descriptionWithLocale:`,
     `dateWithCalendarFormat:timeZone:`, and
     `descriptionWithCalendarFormat:timeZone:locale:`.
     */
    open override var description: String {
        let dateFormatterRef = CFDateFormatterCreate(kCFAllocatorSystemDefault, nil, kCFDateFormatterFullStyle, kCFDateFormatterFullStyle)
        let timeZone = CFTimeZoneCreateWithTimeIntervalFromGMT(kCFAllocatorSystemDefault, 0.0)
        CFDateFormatterSetProperty(dateFormatterRef, kCFDateFormatterTimeZoneKey, timeZone)
        CFDateFormatterSetFormat(dateFormatterRef, "uuuu-MM-dd HH:mm:ss '+0000'"._cfObject)

        return CFDateFormatterCreateStringWithDate(kCFAllocatorSystemDefault, dateFormatterRef, _cfObject)._swiftObject
    }

    /**
     Returns a string representation of the receiver using the given locale.

     - Parameter locale: An `NSLocale` object.

       If you pass `nil`, `NSDate` formats the date in the same way as the
       `description` property.

     - Returns: A string representation of the receiver, using the given locale,
       or if the locale argument is `nil`, in the international format
       `YYYY-MM-DD HH:MM:SS ±HHMM`, where `±HHMM` represents the time zone
       offset in hours and minutes from UTC (for example,
       "2001-03-24 10:45:32 +0600")
     */
    open func description(with locale: Locale?) -> String {
        guard let aLocale = locale else { return description }
        let dateFormatterRef = CFDateFormatterCreate(kCFAllocatorSystemDefault, aLocale._cfObject, kCFDateFormatterFullStyle, kCFDateFormatterFullStyle)
        CFDateFormatterSetProperty(dateFormatterRef, kCFDateFormatterTimeZoneKey, CFTimeZoneCopySystem())

        return CFDateFormatterCreateStringWithDate(kCFAllocatorSystemDefault, dateFormatterRef, _cfObject)._swiftObject
    }
    
    override open var _cfTypeID: CFTypeID {
        return CFDateGetTypeID()
    }
}

extension NSDate {
    
    open func timeIntervalSince(_ anotherDate: Date) -> TimeInterval {
        return self.timeIntervalSinceReferenceDate - anotherDate.timeIntervalSinceReferenceDate
    }
    
    open var timeIntervalSinceNow: TimeInterval {
        return timeIntervalSince(Date())
    }
    
    open var timeIntervalSince1970: TimeInterval {
        return timeIntervalSinceReferenceDate + NSTimeIntervalSince1970
    }
    
    open func addingTimeInterval(_ ti: TimeInterval) -> Date {
        return Date(timeIntervalSinceReferenceDate:_timeIntervalSinceReferenceDate + ti)
    }
    
    open func earlierDate(_ anotherDate: Date) -> Date {
        if self.timeIntervalSinceReferenceDate < anotherDate.timeIntervalSinceReferenceDate {
            return Date(timeIntervalSinceReferenceDate: timeIntervalSinceReferenceDate)
        } else {
            return anotherDate
        }
    }
    
    open func laterDate(_ anotherDate: Date) -> Date {
        if self.timeIntervalSinceReferenceDate < anotherDate.timeIntervalSinceReferenceDate {
            return anotherDate
        } else {
            return Date(timeIntervalSinceReferenceDate: timeIntervalSinceReferenceDate)
        }
    }
    
    open func compare(_ other: Date) -> ComparisonResult {
        let t1 = self.timeIntervalSinceReferenceDate
        let t2 = other.timeIntervalSinceReferenceDate
        if t1 < t2 {
            return .orderedAscending
        } else if t1 > t2 {
            return .orderedDescending
        } else {
            return .orderedSame
        }
    }
    
    open func isEqual(to otherDate: Date) -> Bool {
        return timeIntervalSinceReferenceDate == otherDate.timeIntervalSinceReferenceDate
    }
}

extension NSDate {
    internal static let _distantFuture = Date(timeIntervalSinceReferenceDate: 63113904000.0)
    open class var distantFuture: Date {
        return _distantFuture
    }
    
    internal static let _distantPast = Date(timeIntervalSinceReferenceDate: -63113904000.0)
    open class var distantPast: Date {
        return _distantPast
    }
    
    public convenience init(timeIntervalSinceNow secs: TimeInterval) {
        self.init(timeIntervalSinceReferenceDate: secs + Date().timeIntervalSinceReferenceDate)
    }
    
    public convenience init(timeIntervalSince1970 secs: TimeInterval) {
        self.init(timeIntervalSinceReferenceDate: secs - NSTimeIntervalSince1970)
    }
    
    public convenience init(timeInterval secsToBeAdded: TimeInterval, since date: Date) {
        self.init(timeIntervalSinceReferenceDate: date.timeIntervalSinceReferenceDate + secsToBeAdded)
    }
}

extension NSDate: _CFBridgeable, _SwiftBridgeable {
    typealias SwiftType = Date
    var _swiftObject: Date {
        return Date(timeIntervalSinceReferenceDate: timeIntervalSinceReferenceDate)
    }
}

extension CFDate : _NSBridgeable, _SwiftBridgeable {
    typealias NSType = NSDate
    typealias SwiftType = Date
    
    internal var _nsObject: NSType { return unsafeBitCast(self, to: NSType.self) }
    internal var _swiftObject: Date { return _nsObject._swiftObject }
}

extension Date : _NSBridgeable, _CFBridgeable {
    typealias NSType = NSDate
    typealias CFType = CFDate
    
    internal var _nsObject: NSType { return NSDate(timeIntervalSinceReferenceDate: timeIntervalSinceReferenceDate) }
    internal var _cfObject: CFType { return _nsObject._cfObject }
}


open class NSDateInterval : NSObject, NSCopying, NSSecureCoding {
    
    
    /*
     NSDateInterval represents a closed date interval in the form of [startDate, endDate].  It is possible for the start and end dates to be the same with a duration of 0.  NSDateInterval does not support reverse intervals i.e. intervals where the duration is less than 0 and the end date occurs earlier in time than the start date.
     */
    
    open private(set) var startDate: Date
    
    open var endDate: Date {
        get {
            if duration == 0 {
                return startDate
            } else {
                return startDate + duration
            }
        }
    }
    
    open private(set) var duration: TimeInterval
    
    
    // This method initializes an NSDateInterval object with start and end dates set to the current date and the duration set to 0.
    public convenience override init() {
        self.init(start: Date(), duration: 0)
    }
    
    
    public required convenience init?(coder: NSCoder) {
        guard coder.allowsKeyedCoding else {
            preconditionFailure("Unkeyed coding is unsupported.")
        }
        guard let start = coder.decodeObject(of: NSDate.self, forKey: "NS.startDate") else {
            coder.failWithError(NSError(domain: NSCocoaErrorDomain, code: CocoaError.coderValueNotFound.rawValue, userInfo: nil))
            return nil
        }
        guard let end = coder.decodeObject(of: NSDate.self, forKey: "NS.startDate") else {
            coder.failWithError(NSError(domain: NSCocoaErrorDomain, code: CocoaError.coderValueNotFound.rawValue, userInfo: nil))
            return nil
        }
        self.init(start: start._swiftObject, end: end._swiftObject)
    }
    
    
    // This method will throw an exception if the duration is less than 0.
    public init(start startDate: Date, duration: TimeInterval) {
        self.startDate = startDate
        self.duration = duration
    }
    
    
    // This method will throw an exception if the end date comes before the start date.
    public convenience init(start startDate: Date, end endDate: Date) {
        self.init(start: startDate, duration: endDate.timeIntervalSince(startDate))
    }
    
    open func copy(with zone: NSZone?) -> Any {
        return NSDateInterval(start: startDate, duration: duration)
    }
    
    open func encode(with aCoder: NSCoder) {
        guard aCoder.allowsKeyedCoding else {
            preconditionFailure("Unkeyed coding is unsupported.")
        }
        aCoder.encode(startDate._nsObject, forKey: "NS.startDate")
        aCoder.encode(endDate._nsObject, forKey: "NS.endDate")
    }
    
    public static var supportsSecureCoding: Bool {
        return true
    }
    
    /*
     (ComparisonResult)compare:(NSDateInterval *) prioritizes ordering by start date. If the start dates are equal, then it will order by duration.
     e.g.
     Given intervals a and b
     a.   |-----|
     b.      |-----|
     [a compare:b] would return NSOrderAscending because a's startDate is earlier in time than b's start date.
     
     In the event that the start dates are equal, the compare method will attempt to order by duration.
     e.g.
     Given intervals c and d
     c.  |-----|
     d.  |---|
     [c compare:d] would result in NSOrderDescending because c is longer than d.
     
     If both the start dates and the durations are equal, then the intervals are considered equal and NSOrderedSame is returned as the result.
     */
    open func compare(_ dateInterval: DateInterval) -> ComparisonResult {
        let result = startDate.compare(dateInterval.start)
        if result == .orderedSame {
            if self.duration < dateInterval.duration { return .orderedAscending }
            if self.duration > dateInterval.duration { return .orderedDescending }
            return .orderedSame
        }
        return result
    }
    
    
    open func isEqual(to dateInterval: DateInterval) -> Bool {
        return startDate == dateInterval.start && duration == dateInterval.duration
    }
    
    open func intersects(_ dateInterval: DateInterval) -> Bool {
        return contains(dateInterval.start) || contains(dateInterval.end) || dateInterval.contains(startDate) || dateInterval.contains(endDate)
    }
    
    
    /*
     This method returns an NSDateInterval object that represents the interval where the given date interval and the current instance intersect. In the event that there is no intersection, the method returns nil.
     */
    open func intersection(with dateInterval: DateInterval) -> DateInterval? {
        if !intersects(dateInterval) {
            return nil
        }
        
        if isEqual(to: dateInterval) {
            return DateInterval(start: startDate, duration: duration)
        }
        
        let timeIntervalForSelfStart = startDate.timeIntervalSinceReferenceDate
        let timeIntervalForSelfEnd = startDate.timeIntervalSinceReferenceDate
        let timeIntervalForGivenStart = dateInterval.start.timeIntervalSinceReferenceDate
        let timeIntervalForGivenEnd = dateInterval.end.timeIntervalSinceReferenceDate
        
        let resultStartDate : Date
        if timeIntervalForGivenStart >= timeIntervalForSelfStart {
            resultStartDate = dateInterval.start
        } else {
            // self starts after given
            resultStartDate = startDate
        }
        
        let resultEndDate : Date
        if timeIntervalForGivenEnd >= timeIntervalForSelfEnd {
            resultEndDate = endDate
        } else {
            // given ends before self
            resultEndDate = dateInterval.end
        }
        
        return DateInterval(start: resultStartDate, end: resultEndDate)
    }
    
    
    open func contains(_ date: Date) -> Bool {
        let timeIntervalForGivenDate = date.timeIntervalSinceReferenceDate
        let timeIntervalForSelfStart = startDate.timeIntervalSinceReferenceDate
        let timeIntervalforSelfEnd = endDate.timeIntervalSinceReferenceDate
        if (timeIntervalForGivenDate >= timeIntervalForSelfStart) && (timeIntervalForGivenDate <= timeIntervalforSelfEnd) {
            return true
        }
        return false
    }
}

extension NSDate : _StructTypeBridgeable {
    public typealias _StructType = Date
    
    public func _bridgeToSwift() -> Date {
        return Date._unconditionallyBridgeFromObjectiveC(self)
    }
}

extension NSDateInterval : _StructTypeBridgeable {
    public typealias _StructType = DateInterval
    
    public func _bridgeToSwift() -> DateInterval {
        return DateInterval._unconditionallyBridgeFromObjectiveC(self)
    }
}