import NIO
import XCTest
@testable import NIOPosix
@testable import tart

// Avoid NSObject.bind and Tart's Darwin type shadowing the system function.
private let bindTestSocket = bind

@available(macOS 14, *)
final class ControlSocketTests: XCTestCase {
  func testInitializerCreatesControlSocketBeforeReturning() async throws {
    let temporaryDirectory = try makeTemporaryDirectory()
    let originalDirectory = FileManager.default.currentDirectoryPath
    defer {
      FileManager.default.changeCurrentDirectoryPath(originalDirectory)
      try? FileManager.default.removeItem(at: temporaryDirectory)
    }

    let socketURL = URL(fileURLWithPath: "control.sock", relativeTo: temporaryDirectory)
    var controlSocket: ControlSocket? = try await ControlSocket(socketURL)
    let eventLoopGroup = try XCTUnwrap(controlSocket?.eventLoopGroup)

    do {
      let serverChannel = try XCTUnwrap(controlSocket?.serverChannel)
      XCTAssertTrue(FileManager.default.fileExists(atPath: socketURL.path))

      try await serverChannel.executeThenClose { _ in }
    }

    controlSocket = nil
    try await eventLoopGroup.shutdownGracefully()
  }

  func testAcceptErrorsRetryReadingAndForwardOtherErrors() async throws {
    let temporaryDirectory = try makeTemporaryDirectory()
    let originalDirectory = FileManager.default.currentDirectoryPath
    defer {
      FileManager.default.changeCurrentDirectoryPath(originalDirectory)
      try? FileManager.default.removeItem(at: temporaryDirectory)
    }

    let socketURL = URL(fileURLWithPath: "control.sock", relativeTo: temporaryDirectory)
    let controlSocket = try await ControlSocket(socketURL)
    let channel = controlSocket.serverChannel.channel
    let observations = try await channel.eventLoop.submit {
      let observer = AcceptErrorObserver()
      // Placing this after the recovery handler also detects context.read(), which
      // bypasses downstream backpressure handlers instead of starting at the tail.
      try channel.pipeline.syncOperations.addHandler(observer)
      for _ in 0..<3 {
        channel.pipeline.fireErrorCaught(NIOFcntlFailedError())
      }
      let retries = observer.readCount
      let transientErrors = observer.errors.count
      channel.pipeline.fireErrorCaught(ChannelError.inputClosed)
      return (retries, transientErrors, observer.readCount,
              observer.errors.count, observer.errors.first as? ChannelError)
    }.get()

    try await controlSocket.serverChannel.executeThenClose { _ in }
    try await controlSocket.eventLoopGroup.shutdownGracefully()

    XCTAssertEqual(observations.0, 3)
    XCTAssertEqual(observations.1, 0)
    XCTAssertEqual(observations.2, 3)
    XCTAssertEqual(observations.3, 1)
    XCTAssertEqual(observations.4, .inputClosed)
  }

  func testAcceptErrorsDoNotEndInboundConnections() async throws {
    let temporaryDirectory = try makeTemporaryDirectory()
    let originalDirectory = FileManager.default.currentDirectoryPath
    defer {
      FileManager.default.changeCurrentDirectoryPath(originalDirectory)
      try? FileManager.default.removeItem(at: temporaryDirectory)
    }

    let socketURL = URL(fileURLWithPath: "control.sock", relativeTo: temporaryDirectory)
    let controlSocket = try await ControlSocket(socketURL)
    let serverChannel = controlSocket.serverChannel

    do {
      try await serverChannel.executeThenClose { inbound in
        // Bound the wait if the listener stays open but stops accepting connections.
        let timeout = serverChannel.channel.eventLoop.scheduleTask(in: .seconds(10)) {
          serverChannel.channel.close(promise: nil)
        }
        defer { timeout.cancel() }

        var iterator = inbound.makeAsyncIterator()
        for _ in 0..<3 {
          try await serverChannel.channel.eventLoop.submit {
            serverChannel.channel.pipeline.fireErrorCaught(NIOFcntlFailedError())
          }.get()

          let clientChannel = try await ClientBootstrap(group: controlSocket.eventLoopGroup)
            .connectTimeout(.seconds(5))
            .connect(unixDomainSocketPath: socketURL.path)
            .get()
          defer { clientChannel.close(promise: nil) }

          // ControlSocket.run() consumes this stream. A recoverable accept error
          // must not prevent it from receiving the next connection.
          let nextChannel = try await iterator.next()
          let acceptedChannel = try XCTUnwrap(nextChannel, "The listener stopped delivering connections after an accept error")
          try await acceptedChannel.executeThenClose { _, _ in }
        }
      }
    } catch {
      try? await controlSocket.eventLoopGroup.shutdownGracefully()
      throw error
    }
    try await controlSocket.eventLoopGroup.shutdownGracefully()
  }

  func testInitializerPropagatesControlSocketCreationFailure() async throws {
    let temporaryDirectory = try makeTemporaryDirectory()
    let originalDirectory = FileManager.default.currentDirectoryPath
    defer {
      FileManager.default.changeCurrentDirectoryPath(originalDirectory)
      try? FileManager.default.removeItem(at: temporaryDirectory)
    }

    let socketURL = URL(fileURLWithPath: "missing/control.sock", relativeTo: temporaryDirectory)

    do {
      _ = try await ControlSocket(socketURL)
      XCTFail("Binding should fail when the socket's parent directory does not exist")
    } catch {
      XCTAssertFalse(FileManager.default.fileExists(atPath: socketURL.path))
    }
  }

  func testInitializerReplacesStaleSocketInLongEncodedPath() async throws {
    let temporaryDirectory = try makeTemporaryDirectory()
    let originalDirectory = FileManager.default.currentDirectoryPath
    defer {
      FileManager.default.changeCurrentDirectoryPath(originalDirectory)
      try? FileManager.default.removeItem(at: temporaryDirectory)
    }

    let vmDirectory = temporaryDirectory.appendingPathComponent(
      "Tart Home %# 虚拟机 " + String(repeating: "v", count: 104), isDirectory: true
    )
    try FileManager.default.createDirectory(at: vmDirectory, withIntermediateDirectories: false)
    let socketURL = URL(fileURLWithPath: "control.sock", relativeTo: vmDirectory)
    XCTAssertGreaterThan(socketURL.path.utf8.count, 104)

    // Closing a POSIX socket leaves its path behind, as exiting "tart run" does.
    XCTAssertTrue(FileManager.default.changeCurrentDirectoryPath(vmDirectory.path))
    let expectedDirectory = FileManager.default.currentDirectoryPath
    let address = try SocketAddress(unixDomainSocketPath: "control.sock")
    let descriptor = socket(AF_UNIX, SOCK_STREAM, 0)
    XCTAssertGreaterThanOrEqual(descriptor, 0)
    XCTAssertEqual(address.withSockAddr { bindTestSocket(descriptor, $0, socklen_t($1)) }, 0)
    XCTAssertEqual(close(descriptor), 0)
    XCTAssertTrue(FileManager.default.changeCurrentDirectoryPath(originalDirectory))

    var controlSocket: ControlSocket? = try await ControlSocket(socketURL)
    let eventLoopGroup = try XCTUnwrap(controlSocket?.eventLoopGroup)
    do {
      let serverChannel = try XCTUnwrap(controlSocket?.serverChannel)
      XCTAssertEqual(FileManager.default.currentDirectoryPath, expectedDirectory)
      XCTAssertTrue(FileManager.default.fileExists(atPath: socketURL.path))
      try await serverChannel.executeThenClose { _ in }
    }
    controlSocket = nil
    try await eventLoopGroup.shutdownGracefully()
  }

  private func makeTemporaryDirectory() throws -> URL {
    let directory = FileManager.default.temporaryDirectory.appendingPathComponent(
      UUID().uuidString,
      isDirectory: true
    )
    try FileManager.default.createDirectory(at: directory, withIntermediateDirectories: false)
    return directory
  }
}

private final class AcceptErrorObserver: ChannelDuplexHandler {
  typealias InboundIn = Channel
  typealias OutboundIn = ByteBuffer

  var readCount = 0
  var errors: [Error] = []

  func read(context: ChannelHandlerContext) {
    readCount += 1
    context.read()
  }

  func errorCaught(context: ChannelHandlerContext, error: Error) {
    errors.append(error)
  }
}