Logger.swift

import Foundation

struct Logger {
    
    enum Level: Int {
        case verbose = 0, debug, info, warning, error, none
        var tag: String {
            switch self {
            case .verbose: return "VERVOSE"
            case .debug: return "DEBUG"
            case .info: return "INFO"
            case .warning: return "WARNING"
            case .error: return "ERROR"
            case .none: fatalError("Try to logging `none` level")
            }
        }
    }
    
    var minLevel: Level = .warning
    
    var dateFormatter: DateFormatter = {
        let f = DateFormatter()
        f.dateFormat = "yy/MM/dd|HH:mm:ss.SSS"
        return f
    }()
    
    func log(level: Level, file: String = #file, function: String = #function, line: Int = #line, _ m: [Any]) {
        guard minLevel.rawValue <= level.rawValue else { return }
        
        let datetime = dateFormatter.string(from: Date())
        var place = file.replacingOccurrences(of: "[^/]*/", with: "", options: .regularExpression).split(separator: ".").first!
        place += ":\(line)"
        place += "¶\(function)"
        // Splatting
        switch m.count {
        case 0: print(datetime, "\(level.tag)", place)
        case 1: print(datetime, "\(level.tag)", place, m[0])
        case 2: print(datetime, "\(level.tag)", place, m[0], m[1])
        case 3: print(datetime, "\(level.tag)", place, m[0], m[1], m[2])
        case 4: print(datetime, "\(level.tag)", place, m[0], m[1], m[2], m[3])
        case 5: print(datetime, "\(level.tag)", place, m[0], m[1], m[2], m[3], m[4])
        default: print(datetime, "\(level.tag)", place, m)
        }
    }
    
    static var `default`: Logger = Logger()
    
    static func verbose(file: String = #file, function: String = #function, line: Int = #line, _ messages: Any...) {
        self.default.log(level: .verbose, file: file, function: function, line: line, messages)
    }
    static func debug(file: String = #file, function: String = #function, line: Int = #line, _ messages: Any...) {
        self.default.log(level: .debug, file: file, function: function, line: line, messages)
    }
    static func info(file: String = #file, function: String = #function, line: Int = #line, _ messages: Any...) {
        self.default.log(level: .info, file: file, function: function, line: line, messages)
    }
    static func warning(file: String = #file, function: String = #function, line: Int = #line, _ messages: Any...) {
        self.default.log(level: .warning, file: file, function: function, line: line, messages)
    }
    static func error(file: String = #file, function: String = #function, line: Int = #line, _ messages: Any...) {
        self.default.log(level: .error, file: file, function: function, line: line, messages)
    }
    
}