import Foundation

private let df: DateFormatter = {
    let df = DateFormatter()
    df.dateStyle = .short
    df.timeStyle = .short
    df.locale = Locale(identifier: "de")
    return df
}()

func log(_ message: String, file: String = #file, line: Int = #line) {
    let date = df.string(from: Date())
    let m = "[\(date)][\(file.components(separatedBy: "/").last ?? file):\(line)] \(message)"
    print(m)
    Log.write(m + "\n")
}

enum Log {

    static func set(logFile: String) throws {
        let url = URL(fileURLWithPath: logFile)
        let date = df.string(from: Date())
        if !FileManager.default.fileExists(atPath: logFile) {
            try "[\(date)] New log created.\n".write(to: url, atomically: false, encoding: .utf8)
        }
        guard let f = FileHandle(forWritingAtPath: logFile) else {
            try "[\(date)] Failed to start log.\n".write(to: url, atomically: false, encoding: .utf8)
            return
        }
        f.seekToEndOfFile()
        f.write("[\(date)] Logging started.\n".data(using: .utf8)!)
        file = f
    }

    static func write(_ message: String) {
        guard let f = file else {
            return
        }
        f.write(message.data(using: .utf8)!)
    }

    private static var file: FileHandle?
}