Alamofire/Source/HTTPHeaders.swift

//
//  HTTPHeaders.swift
//
//  Copyright (c) 2014-2018 Alamofire Software Foundation (http://alamofire.org/)
//
//  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

public typealias HTTPHeaders = [String: String]

// TODO: Make HTTPHeaders a real type.
extension Dictionary where Key == String, Value == String {
    public static func authorization(withUsername username: String, password: String) -> HTTPHeaders {
        let credential = Data("\(username):\(password)".utf8).base64EncodedString()

        return ["Authorization": "Basic \(credential)"]
    }

    /// Creates default values for the "Accept-Encoding", "Accept-Language" and "User-Agent" headers.
    public static let defaultHTTPHeaders: HTTPHeaders = {
        // Accept-Encoding HTTP Header; see https://tools.ietf.org/html/rfc7230#section-4.2.3
        let acceptEncoding: String = {
            let encodings: [String]
            if #available(iOS 11.0, macOS 10.13, tvOS 11.0, watchOS 4.0, *) {
                encodings = ["br", "gzip", "deflate"]
            } else {
                encodings = ["gzip", "deflate"]
            }

            return encodings.enumerated().map { (index, encoding) in
                let quality = 1.0 - (Double(index) * 0.1)
                return "\(encoding);q=\(quality)"
            }.joined(separator: ", ")
        }()

        // Accept-Language HTTP Header; see https://tools.ietf.org/html/rfc7231#section-5.3.5
        let acceptLanguage = Locale.preferredLanguages.prefix(6).enumerated().map { (index, languageCode) in
            let quality = 1.0 - (Double(index) * 0.1)
            return "\(languageCode);q=\(quality)"
        }.joined(separator: ", ")

        // User-Agent Header; see https://tools.ietf.org/html/rfc7231#section-5.5.3
        // Example: `iOS Example/1.0 (org.alamofire.iOS-Example; build:1; iOS 10.0.0) Alamofire/4.0.0`
        let userAgent: String = {
            if let info = Bundle.main.infoDictionary {
                let executable = info[kCFBundleExecutableKey as String] as? String ?? "Unknown"
                let bundle = info[kCFBundleIdentifierKey as String] as? String ?? "Unknown"
                let appVersion = info["CFBundleShortVersionString"] as? String ?? "Unknown"
                let appBuild = info[kCFBundleVersionKey as String] as? String ?? "Unknown"

                let osNameVersion: String = {
                    let version = ProcessInfo.processInfo.operatingSystemVersion
                    let versionString = "\(version.majorVersion).\(version.minorVersion).\(version.patchVersion)"

                    let osName: String = {
                        #if os(iOS)
                        return "iOS"
                        #elseif os(watchOS)
                        return "watchOS"
                        #elseif os(tvOS)
                        return "tvOS"
                        #elseif os(macOS)
                        return "macOS"
                        #elseif os(Linux)
                        return "Linux"
                        #else
                        return "Unknown"
                        #endif
                    }()

                    return "\(osName) \(versionString)"
                }()

                let alamofireVersion: String = {
                    guard
                        let afInfo = Bundle(for: SessionManager.self).infoDictionary,
                        let build = afInfo["CFBundleShortVersionString"]
                        else { return "Unknown" }

                    return "Alamofire/\(build)"
                }()

                return "\(executable)/\(appVersion) (\(bundle); build:\(appBuild); \(osNameVersion)) \(alamofireVersion)"
            }

            return "Alamofire"
        }()

        return ["Accept-Encoding": acceptEncoding,
                "Accept-Language": acceptLanguage,
                "User-Agent": userAgent]
    }()
}