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//
// RequestModifier.swift
// Kingfisher
//
// Created by Wei Wang on 2016/09/05.
//
// Copyright (c) 2019 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
/// Represents and wraps a method for modifying request before an image download request starts.
public protocol ImageDownloadRequestModifier {
/// A method will be called just before the `request` being sent.
/// This is the last chance you can modify the image download request. You can modify the request for some
/// customizing purpose, such as adding auth token to the header, do basic HTTP auth or something like url mapping.
///
/// Usually, you pass an `ImageDownloadRequestModifier` as the associated value of
/// `KingfisherOptionsInfoItem.requestModifier` and use it as the `options` parameter in related methods.
///
/// If you do nothing with the input `request` and return it as is, a downloading process will start with it.
///
/// - Parameter request: The input request contains necessary information like `url`. This request is generated
/// according to your resource url as a GET request.
/// - Returns: A modified version of request, which you wish to use for downloading an image. If `nil` returned,
/// a `KingfisherError.requestError` with `.emptyRequest` as its reason will occur.
///
func modified(for request: URLRequest) -> URLRequest?
}
/// A wrapper for creating an `ImageDownloadRequestModifier` easier.
/// This type conforms to `ImageDownloadRequestModifier` and wraps an image modify block.
public struct AnyModifier: ImageDownloadRequestModifier {
let block: (URLRequest) -> URLRequest?
/// For `ImageDownloadRequestModifier` conformation.
public func modified(for request: URLRequest) -> URLRequest? {
return block(request)
}
/// Creates a value of `ImageDownloadRequestModifier` which runs `modify` block.
///
/// - Parameter modify: The request modifying block runs when a request modifying task comes.
/// The return `URLRequest?` value of this block will be used as the image download request.
/// If `nil` returned, a `KingfisherError.requestError` with `.emptyRequest` as its
/// reason will occur.
public init(modify: @escaping (URLRequest) -> URLRequest?) {
block = modify
}
}