// 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)
    internal let kCFRunLoopEntry = CFRunLoopActivity.entry.rawValue
    internal let kCFRunLoopBeforeTimers = CFRunLoopActivity.beforeTimers.rawValue
    internal let kCFRunLoopBeforeSources = CFRunLoopActivity.beforeSources.rawValue
    internal let kCFRunLoopBeforeWaiting = CFRunLoopActivity.beforeWaiting.rawValue
    internal let kCFRunLoopAfterWaiting = CFRunLoopActivity.afterWaiting.rawValue
    internal let kCFRunLoopExit = CFRunLoopActivity.exit.rawValue
    internal let kCFRunLoopAllActivities = CFRunLoopActivity.allActivities.rawValue
#endif

public struct RunLoopMode : RawRepresentable, Equatable, Hashable {
    public private(set) var rawValue: String
    
    public init(_ rawValue: String) {
        self.rawValue = rawValue
    }
    
    public init(rawValue: String) {
        self.rawValue = rawValue
    }
    
    public var hashValue: Int {
        return rawValue.hashValue
    }

    public static func ==(_ lhs: RunLoopMode, _ rhs: RunLoopMode) -> Bool {
        return lhs.rawValue == rhs.rawValue
    }
}


extension RunLoopMode {
    public static let defaultRunLoopMode = RunLoopMode("kCFRunLoopDefaultMode")
    public static let commonModes = RunLoopMode("kCFRunLoopCommonModes")
    
    // Use this instead of .rawValue._cfObject; this will allow CFRunLoop to use pointer equality internally.
    fileprivate var _cfStringUniquingKnown: CFString {
        if self == .defaultRunLoopMode {
            return kCFRunLoopDefaultMode
        } else if self == .commonModes {
            return kCFRunLoopCommonModes
        } else {
            return rawValue._cfObject
        }
    }
}

internal func _NSRunLoopNew(_ cf: CFRunLoop) -> Unmanaged<AnyObject> {
    let rl = Unmanaged<RunLoop>.passRetained(RunLoop(cfObject: cf))
    return unsafeBitCast(rl, to: Unmanaged<AnyObject>.self) // this retain is balanced on the other side of the CF fence
}

open class RunLoop: NSObject {
    internal var _cfRunLoop : CFRunLoop!
    internal static var _mainRunLoop : RunLoop = {
        return RunLoop(cfObject: CFRunLoopGetMain())
    }()

    internal init(cfObject : CFRunLoop) {
        _cfRunLoop = cfObject
    }

    open class var current: RunLoop {
        return _CFRunLoopGet2(CFRunLoopGetCurrent()) as! RunLoop
    }

    open class var main: RunLoop {
        return _CFRunLoopGet2(CFRunLoopGetMain()) as! RunLoop
    }

    open var currentMode: RunLoopMode? {
        if let mode = CFRunLoopCopyCurrentMode(_cfRunLoop) {
            return RunLoopMode(mode._swiftObject)
        } else {
            return nil
        }
    }
    
    open func getCFRunLoop() -> CFRunLoop {
        return _cfRunLoop
    }

    open func add(_ timer: Timer, forMode mode: RunLoopMode) {
        CFRunLoopAddTimer(CFRunLoopGetCurrent(), timer._cfObject, mode._cfStringUniquingKnown)
    }

    open func add(_ aPort: Port, forMode mode: RunLoopMode) {
        NSUnimplemented()
    }

    open func remove(_ aPort: Port, forMode mode: RunLoopMode) {
        NSUnimplemented()
    }

    open func limitDate(forMode mode: RunLoopMode) -> Date? {
        if _cfRunLoop !== CFRunLoopGetCurrent() {
            return nil
        }
        let modeArg = mode.rawValue._cfObject
        
        CFRunLoopRunInMode(modeArg, -10.0, true) /* poll run loop to fire ready timers and performers, as used to be done here */
        if _CFRunLoopFinished(_cfRunLoop, modeArg) {
            return nil
        }
        
        let nextTimerFireAbsoluteTime = CFRunLoopGetNextTimerFireDate(CFRunLoopGetCurrent(), modeArg)

        if (nextTimerFireAbsoluteTime == 0) {
            return Date.distantFuture
        }

        return Date(timeIntervalSinceReferenceDate: nextTimerFireAbsoluteTime)
    }

    open func acceptInput(forMode mode: String, before limitDate: Date) {
        if _cfRunLoop !== CFRunLoopGetCurrent() {
            return
        }
        CFRunLoopRunInMode(mode._cfObject, limitDate.timeIntervalSinceReferenceDate - CFAbsoluteTimeGetCurrent(), true)
    }

}

extension RunLoop {

    public func run() {
        while run(mode: .defaultRunLoopMode, before: Date.distantFuture) { }
    }

    public func run(until limitDate: Date) {
        while run(mode: .defaultRunLoopMode, before: limitDate) && limitDate.timeIntervalSinceReferenceDate > CFAbsoluteTimeGetCurrent() { }
    }

    public func run(mode: RunLoopMode, before limitDate: Date) -> Bool {
        if _cfRunLoop !== CFRunLoopGetCurrent() {
            return false
        }
        let modeArg = mode._cfStringUniquingKnown
        if _CFRunLoopFinished(_cfRunLoop, modeArg) {
            return false
        }
        
        let limitTime = limitDate.timeIntervalSinceReferenceDate
        let ti = limitTime - CFAbsoluteTimeGetCurrent()
        CFRunLoopRunInMode(modeArg, ti, true)
        return true
    }

    public func perform(inModes modes: [RunLoopMode], block: @escaping () -> Void) {
        CFRunLoopPerformBlock(getCFRunLoop(), (modes.map { $0._cfStringUniquingKnown })._cfObject, block)
    }
    
    public func perform(_ block: @escaping () -> Void) {
        perform(inModes: [.defaultRunLoopMode], block: block)
    }
}