//
//  CoreStoreDefaults.swift
//  CoreStore
//
//  Copyright © 2018 John Rommel Estropia
//
//  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 os


// MARK: - CoreStoreDefaults

/**
Global utilities
*/
public enum CoreStoreDefaults {

    /**
    The `CoreStoreLogger` instance to be used. The default logger is an instance of a `DefaultLogger`.
    */
    public static var logger: CoreStoreLogger {
    
        get {
            
            return self.loggerInstance.withLock {
                
                if let logger = $0 {
                    
                    return logger
                }
                let logger = DefaultLogger()
                $0 = logger
                return logger
            }
        }
        set {
            
            self.loggerInstance.withLock {
                
                $0 = newValue
            }
        }
    }
    
    /**
     The default `DataStack` instance to be used. If `defaultStack` is not set during the first time accessed, a default-configured `DataStack` will be created.
     - SeeAlso: `DataStack`
     - Note: Changing `dataStack` is thread safe, but it is recommended to setup `DataStacks` on a common queue (e.g. the main queue).
     - Important: If `dataStack` is not set during the first time accessed, a default-configured `DataStack` will be created.
     */
    public static var dataStack: DataStack {

        get {
            
            return self.defaultStackInstance.withLock {
                
                if let dataStack = $0 {
                    
                    return dataStack
                }
                let dataStack = DataStack()
                $0 = dataStack
                return dataStack
            }
        }
        set {

            self.defaultStackInstance.withLock {
                
                $0 = newValue
            }
        }
    }


    // MARK: Private

    private static let defaultStackInstance: OSAllocatedUnfairLock<DataStack?> = .init(initialState: nil)
    private static let loggerInstance: OSAllocatedUnfairLock<(any CoreStoreLogger)?> = .init(initialState: nil)
}