import AVFoundation
import Foundation
import SwiftUI
import UIKit

/// App log kept in a size-capped file so a tester can send it. Tokens are stripped before anything is written.
final class Log: @unchecked Sendable {
    static let shared = Log()
    enum Level: String { case debug = "D", info = "I", error = "E" }

    static let verboseKey = "verboseLogging"
    static var verbose: Bool {
        get { UserDefaults.standard.bool(forKey: verboseKey) }
        set { UserDefaults.standard.set(newValue, forKey: verboseKey) }
    }

    private let lock = NSLock()
    private let url: URL
    private let maxBytes = 512 * 1024
    private let stamp: DateFormatter = {
        let f = DateFormatter()
        f.dateFormat = "MM-dd HH:mm:ss.SSS"
        return f
    }()

    private init() {
        let dir = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask)[0]
        url = dir.appendingPathComponent("stemify.log")
    }

    private static let secret = try! NSRegularExpression(
        pattern: #"(X-Plex-Token|X-Stem-Token|token|Authorization)([=:"' ]+)[^&\s"',}]+"#, options: [.caseInsensitive])

    static func redact(_ s: String) -> String {
        secret.stringByReplacingMatches(in: s, range: NSRange(s.startIndex..., in: s), withTemplate: "$1$2<redacted>")
    }

    func write(_ level: Level, _ tag: String, _ msg: String) {
        if level == .debug && !Log.verbose { return }
        let line = "\(stamp.string(from: Date())) \(level.rawValue) [\(tag)] \(Log.redact(msg))\n"
        lock.lock(); defer { lock.unlock() }
        guard let data = line.data(using: .utf8) else { return }
        let size = (try? FileManager.default.attributesOfItem(atPath: url.path)[.size] as? Int) ?? 0
        if size > maxBytes { trim() }
        if FileManager.default.fileExists(atPath: url.path) { append(data) } else { try? data.write(to: url) }
    }

    /// Keeps the newest half of the file.
    private func trim() {
        guard let all = try? Data(contentsOf: url) else { return }
        let tail = all.suffix(maxBytes / 2)
        let cut = tail.firstIndex(of: 0x0A).map { tail.index(after: $0) } ?? tail.startIndex
        try? Data(tail[cut...]).write(to: url)
    }

    private func append(_ data: Data) {
        guard let h = try? FileHandle(forWritingTo: url) else { return }
        defer { try? h.close() }
        _ = try? h.seekToEnd()
        try? h.write(contentsOf: data)
    }

    func text() -> String {
        lock.lock(); defer { lock.unlock() }
        return (try? String(contentsOf: url, encoding: .utf8)) ?? ""
    }

    func clear() {
        lock.lock(); defer { lock.unlock() }
        try? FileManager.default.removeItem(at: url)
    }

    /// Device and app details followed by the log, written to a temp file for the share sheet.
    func export() -> URL {
        let b = Bundle.main
        let d = UIDevice.current
        var head = "Stemify \((b.object(forInfoDictionaryKey: "StemifyVersionLabel") ?? b.object(forInfoDictionaryKey: "CFBundleShortVersionString")) as? String ?? "?") "
        head += "(\(b.object(forInfoDictionaryKey: "CFBundleVersion") as? String ?? "?"))\n"
        head += "\(d.model) · \(d.systemName) \(d.systemVersion) · \(UIScreen.main.maximumFramesPerSecond) Hz\n"
        head += "Verbose logging: \(Log.verbose ? "on" : "off")\n"
        head += "Output: \(AirRoute.describe())\n\n"
        let out = FileManager.default.temporaryDirectory.appendingPathComponent("stemify-log.txt")
        try? (head + text()).write(to: out, atomically: true, encoding: .utf8)
        return out
    }

    func debug(_ tag: String, _ msg: @autoclosure () -> String) { if Log.verbose { write(.debug, tag, msg()) } }
    func info(_ tag: String, _ msg: String) { write(.info, tag, msg) }
    func error(_ tag: String, _ msg: String) { write(.error, tag, msg) }
}

/// Where audio is currently going (speaker, AirPlay, Bluetooth…).
enum AirRoute {
    static func describe() -> String {
        let outs = AVAudioSession.sharedInstance().currentRoute.outputs.map { "\($0.portName) (\($0.portType.rawValue))" }
        return outs.isEmpty ? "none" : outs.joined(separator: ", ")
    }
}