Repository: Alamofire/Alamofire
File: Source/RedirectHandler.swift (Swift)

Code before:
//  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

/// A type that handles how an HTTP redirect response from a remote server should be redirected to the new request.
public protocol RedirectHandler {
    /// Determines how the HTTP redirect response should be redirected to the new request.
    ///
    /// The `completion` closure should be passed one of three possible options:
    ///
    ///   1. The new request specified by the redirect (this is the most common use case).
    ///   2. A modified version of the new request (you may want to route it somewhere else).
    ///   3. A `nil` value to deny the redirect request and return the body of the redirect response.
    ///
    /// - Parameters:
    ///   - task:       The task whose request resulted in a redirect.
    ///   - request:    The URL request object to the new location specified by the redirect response.
    ///   - response:   The response containing the server's response to the original request.
    ///   - completion: The closure to execute containing the new request, a modified request, or `nil`.
    func task(_ task: URLSessionTask,
              willBeRedirectedTo request: URLRequest,
              for response: HTTPURLResponse,
              completion: @escaping (URLRequest?) -> Void)
}

// MARK: -

public struct Redirector {
    public enum Behavior {
        case follow
        case doNotFollow
        case modify((URLSessionTask, URLRequest, HTTPURLResponse) -> URLRequest?)
    }

    public let behavior: Behavior

    public init(behavior: Behavior) {
        self.behavior = behavior
    }
}

extension Redirector: RedirectHandler {
    public func task(_ task: URLSessionTask,
              willBeRedirectedTo request: URLRequest,
              for response: HTTPURLResponse,

Review comment (suggestion):
Might it be useful to make this function `throws`? It would allow anyone needing error handling to get it while placing no burden on those who don't. It shouldn't make the implementation much more difficult either.

Code after:
//  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

/// A type that handles how an HTTP redirect response from a remote server should be redirected to the new request.
public protocol RedirectHandler {
    /// Determines how the HTTP redirect response should be redirected to the new request.
    ///
    /// The `completion` closure should be passed one of three possible options:
    ///
    ///   1. The new request specified by the redirect (this is the most common use case).
    ///   2. A modified version of the new request (you may want to route it somewhere else).
    ///   3. A `nil` value to deny the redirect request and return the body of the redirect response.
    ///
    /// - Parameters:
    ///   - task:       The task whose request resulted in a redirect.
    ///   - request:    The URL request object to the new location specified by the redirect response.
    ///   - response:   The response containing the server's response to the original request.
    ///   - completion: The closure to execute containing the new request, a modified request, or `nil`.
    func task(_ task: URLSessionTask,
              willBeRedirectedTo request: URLRequest,
              for response: HTTPURLResponse,
              completion: @escaping (URLRequest?) -> Void)
}

// MARK: -

/// `Redirector` is a convenience `RedirectHandler` making it easy to follow, not follow, or modify a redirect.
public struct Redirector {
    /// Defines the behavior of the `Redirector` type.
    ///
    /// - follow:      Follows the redirect as defined in the response.
    /// - doNotFollow: Does not follow the redirect defined in the response.
    /// - modify:      Modifies the redirect request defined in the response.
    public enum Behavior {
        case follow
        case doNotFollow
        case modify((URLSessionTask, URLRequest, HTTPURLResponse) -> URLRequest?)
    }

    /// Returns a `Redirector` with a follow `Behavior`.
    public static let follow = Redirector(behavior: .follow)
    /// Returns a `Redirector` with a do not follow `Behavior`.
    public static let doNotFollow = Redirector(behavior: .doNotFollow)