//    MIT License
//
//    Copyright (c) 2018 Veldspar Team
//
//    Permission is hereby granted, free of charge, to any person obtaining a copy
//    of this software and associated documentation files (the "Software"), to deal
//    in the Software without restriction, including without limitation the rights
//    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//    copies of the Software, and to permit persons to whom the Software is
//    furnished to do so, subject to the following conditions:
//
//    The above copyright notice and this permission notice shall be included in all
//    copies or substantial portions of the Software.
//
//    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
//    SOFTWARE.

import Foundation
import Dispatch

public class Mutex {
    
    private var thread: Thread? = nil;
    private var lock: DispatchQueue
    
    public init() {
        lock = DispatchQueue(label: UUID().uuidString.lowercased())
    }
    
    public func mutex(_ closure:() -> Void) {
        if thread != Thread.current {
            lock.sync {
                thread = Thread.current
                closure()
                thread = nil
            }
        } else {
            closure()
        }
    }
    
    public func throwingMutex(_ closure:(() throws -> Void)) throws {
        if thread != Thread.current {
            try lock.sync {
                thread = Thread.current
                try closure()
                thread = nil
            }
        } else {
            try closure()
        }
    }
    
    public func mutex<T>(_ closure:() -> T?) -> T? {
        if thread != Thread.current {
            var retValue: T? = nil
            lock.sync {
                thread = Thread.current
                retValue = closure()
                thread = nil
            }
            return retValue
        } else {
            return closure()
        }
    }
    
    public func throwingMutex<T>(_ closure:() throws -> T?) throws -> T? {
        if thread != Thread.current {
            var retValue: T? = nil
            try lock.sync {
                thread = Thread.current
                retValue = try closure()
                thread = nil
            }
            return retValue
        } else {
            return try closure()
        }
    }
    
}

