//
//  MultiThreadDictionary.swift
//  Tusker
//
//  Created by Shadowfacts on 5/6/20.
//  Copyright © 2020 Shadowfacts. All rights reserved.
//

import Foundation

class MultiThreadDictionary<Key: Hashable, Value> {
    private let name: String
    private var dict = [Key: Value]()
    private let queue: DispatchQueue
    
    init(name: String) {
        self.name = name
        self.queue = DispatchQueue(label: "MultiThreadDictionary (\(name)) Coordinator", attributes: .concurrent)
    }
    
    subscript(key: Key) -> Value? {
        get {
            var result: Value? = nil
            queue.sync {
                result = dict[key]
            }
            return result
        }
        set(value) {
            queue.async(flags: .barrier) {
                self.dict[key] = value
            }
        }
    }
    
    func removeValueWithoutReturning(forKey key: Key) {
        queue.async(flags: .barrier) {
            self.dict.removeValue(forKey: key)
        }
    }
    
    /// If the result of this function is unused, it is preferable to use `removeValueWithoutReturning` as it executes asynchronously and doesn't block the calling thread.
    func removeValue(forKey key: Key) -> Value? {
        var value: Value? = nil
        queue.sync(flags: .barrier) {
            value = dict.removeValue(forKey: key)
        }
        return value
    }
    
    func contains(key: Key) -> Bool {
        var value: Bool!
        queue.sync {
            value = dict.keys.contains(key)
        }
        return value
    }
}