import Foundation

/// 轻量日志：写到 ~/Library/Logs/TinySTT.log，方便排查（也便于无 UI 时验证）。
enum Log {
    private static let queue = DispatchQueue(label: "tinystt.log")
    private static let url: URL = {
        let dir = FileManager.default.urls(for: .libraryDirectory, in: .userDomainMask)[0]
            .appendingPathComponent("Logs", isDirectory: true)
        try? FileManager.default.createDirectory(at: dir, withIntermediateDirectories: true)
        return dir.appendingPathComponent("TinySTT.log")
    }()

    private static let formatter: DateFormatter = {
        let f = DateFormatter()
        f.dateFormat = "MM-dd HH:mm:ss.SSS"
        return f
    }()

    static func info(_ message: String) {
        write("INFO", message)
    }

    static func error(_ message: String) {
        write("ERR ", message)
    }

    private static func write(_ level: String, _ message: String) {
        queue.async {
            let line = "[\(formatter.string(from: Date()))] \(level) \(message)\n"
            if let attrs = try? FileManager.default.attributesOfItem(atPath: url.path),
               let size = attrs[.size] as? Int, size > 1_000_000 {
                let previous = url.appendingPathExtension("1")
                try? FileManager.default.removeItem(at: previous)
                try? FileManager.default.moveItem(at: url, to: previous)
            }
            guard let data = line.data(using: .utf8) else { return }
            if let handle = try? FileHandle(forWritingTo: url) {
                handle.seekToEndOfFile()
                handle.write(data)
                try? handle.close()
            } else {
                try? data.write(to: url)
            }
            #if DEBUG
            FileHandle.standardError.write(line.data(using: .utf8) ?? Data())
            #endif
        }
    }
}