RequestModifier.swift

//
//  RequestModifier.swift
//  Kingfisher
//
//  Created by Wei Wang on 2016/09/05.
//
//  Copyright (c) 2017 Wei Wang <onevcat@gmail.com>
//
//  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

/// Request modifier of image downloader.
public protocol ImageDownloadRequestModifier {
    func modified(for request: URLRequest) -> URLRequest?
}

struct NoModifier: ImageDownloadRequestModifier {
    static let `default` = NoModifier()
    private init() {}
    func modified(for request: URLRequest) -> URLRequest? {
        return request
    }
}

public struct AnyModifier: ImageDownloadRequestModifier {
    
    let block: (URLRequest) -> URLRequest?
    
    public func modified(for request: URLRequest) -> URLRequest? {
        return block(request)
    }
    
    public init(modify: @escaping (URLRequest) -> URLRequest? ) {
        block = modify
    }
}