import Foundation

enum Log {
    static let fileURL: URL = {
        let dir = FileManager.default
            .urls(for: .libraryDirectory, in: .userDomainMask)[0]
            .appendingPathComponent("Logs/OpenLess", isDirectory: true)
        try? FileManager.default.createDirectory(at: dir, withIntermediateDirectories: true)
        let url = dir.appendingPathComponent("OpenLess.log")
        if !FileManager.default.fileExists(atPath: url.path) {
            FileManager.default.createFile(atPath: url.path, contents: nil)
        }
        return url
    }()

    private static let formatter: ISO8601DateFormatter = {
        let f = ISO8601DateFormatter()
        f.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
        return f
    }()

    private static let lock = NSLock()

    static func write(_ message: String) {
        let line = "[\(formatter.string(from: Date()))] \(message)\n"
        guard let data = line.data(using: .utf8) else { return }

        lock.lock()
        defer { lock.unlock() }

        if let handle = try? FileHandle(forWritingTo: fileURL) {
            _ = try? handle.seekToEnd()
            try? handle.write(contentsOf: data)
            try? handle.close()
        } else {
            try? data.write(to: fileURL, options: [])
        }
        FileHandle.standardError.write(data)
    }
}