//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2024 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

public import Csourcekitd
import Foundation
import SKLogging
import SourceKitD
import SwiftExtensions
import SwiftSourceKitPluginCommon

private func useNewAPI(for dict: SKDRequestDictionaryReader) -> Bool {
  guard let opts: SKDRequestDictionaryReader = dict[dict.sourcekitd.keys.codeCompleteOptions],
    opts[dict.sourcekitd.keys.useNewAPI] == 1
  else {
    return false
  }
  return true
}

final class RequestHandler: Sendable {
  enum HandleRequestResult {
    /// `handleRequest` will call `receiver`.
    case requestHandled

    /// `handleRequest` will not call `receiver` and a request response should be produced by sourcekitd (not the plugin).
    case handleInSourceKitD
  }

  let requestHandlingQueue = AsyncQueue<Serial>()
  let sourcekitd: SourceKitD
  let completionProvider: CompletionProvider

  init(params: sourcekitd_api_plugin_initialize_params_t, completionResultsBufferKind: UInt64, sourcekitd: SourceKitD) {
    let ideInspectionInstance = sourcekitd.servicePluginApi.plugin_initialize_get_swift_ide_inspection_instance(params)

    self.sourcekitd = sourcekitd
    self.completionProvider = CompletionProvider(
      completionResultsBufferKind: completionResultsBufferKind,
      opaqueIDEInspectionInstance: OpaqueIDEInspectionInstance(ideInspectionInstance),
      sourcekitd: sourcekitd
    )
  }

  func handleRequest(
    _ dict: SKDRequestDictionaryReader,
    handle: RequestHandle?,
    receiver: @Sendable @escaping (SKDResponse) -> Void
  ) -> HandleRequestResult {
    func produceResult(
      body: @escaping @Sendable () async throws -> SKDResponseDictionaryBuilder
    ) -> HandleRequestResult {
      withLoggingScope("request-\(handle?.numericValue ?? 0 % 100)") {
        let start = Date()
        logger.debug(
          """
          Plugin received sourcekitd request (handle: \(handle?.numericValue ?? -1))
          \(dict.description)
          """
        )
        requestHandlingQueue.async {
          let response: SKDResponse
          do {
            response = try await body().response
          } catch {
            response = SKDResponse.from(error: error, sourcekitd: self.sourcekitd)
          }
          logger.debug(
            """
            Finished (took \(Date().timeIntervalSince(start))s)
            \(response.description)
            """
          )
          receiver(response)
        }
        return .requestHandled
      }
    }

    func sourcekitdProducesResult(body: @escaping @Sendable () async -> ()) -> HandleRequestResult {
      requestHandlingQueue.async {
        await body()
      }
      return .handleInSourceKitD
    }

    switch dict[sourcekitd.keys.request] as sourcekitd_api_uid_t? {
    case sourcekitd.requests.editorOpen:
      return sourcekitdProducesResult {
        await self.completionProvider.handleDocumentOpen(dict)
      }
    case sourcekitd.requests.editorReplaceText:
      return sourcekitdProducesResult {
        await self.completionProvider.handleDocumentEdit(dict)
      }
    case sourcekitd.requests.editorClose:
      return sourcekitdProducesResult {
        await self.completionProvider.handleDocumentClose(dict)
      }

    case sourcekitd.requests.codeCompleteOpen:
      guard useNewAPI(for: dict) else {
        return .handleInSourceKitD
      }
      return produceResult {
        try await self.completionProvider.handleCompleteOpen(dict, handle: handle)
      }
    case sourcekitd.requests.codeCompleteUpdate:
      guard useNewAPI(for: dict) else {
        return .handleInSourceKitD
      }
      return produceResult {
        try await self.completionProvider.handleCompleteUpdate(dict)
      }
    case sourcekitd.requests.codeCompleteClose:
      guard useNewAPI(for: dict) else {
        return .handleInSourceKitD
      }
      return produceResult {
        try await self.completionProvider.handleCompleteClose(dict)
      }
    case sourcekitd.requests.codeCompleteDocumentation:
      return produceResult {
        try await self.completionProvider.handleCompletionDocumentation(dict)
      }
    case sourcekitd.requests.codeCompleteDiagnostic:
      return produceResult {
        try await self.completionProvider.handleCompletionDiagnostic(dict)
      }
    case sourcekitd.requests.codeCompleteSetPopularAPI:
      guard useNewAPI(for: dict) else {
        return .handleInSourceKitD
      }
      return produceResult {
        await self.completionProvider.handleSetPopularAPI(dict)
      }
    case sourcekitd.requests.dependencyUpdated:
      return sourcekitdProducesResult {
        await self.completionProvider.handleDependencyUpdated()
      }
    default:
      return .handleInSourceKitD
    }
  }

  func cancel(_ handle: RequestHandle) {
    logger.debug("Cancelling request with handle \(handle.numericValue)")
    self.completionProvider.cancel(handle: handle)
  }
}

#if compiler(>=6.3)
#warning("Remove sourcekitd_plugin_initialize when we no longer support toolchains that call it")
#endif

/// Legacy plugin initialization logic in which sourcekitd does not inform the plugin about the sourcekitd path it was
/// loaded from.
@_cdecl("sourcekitd_plugin_initialize")
public func sourcekitd_plugin_initialize(_ params: sourcekitd_api_plugin_initialize_params_t) {
  #if canImport(Darwin)
  var dlInfo = Dl_info()
  dladdr(#dsohandle, &dlInfo)
  let path = String(cString: dlInfo.dli_fname)
  var url = URL(fileURLWithPath: path, isDirectory: false)
  while url.pathExtension != "framework" && url.lastPathComponent != "/" {
    url.deleteLastPathComponent()
  }
  url =
    url
    .deletingLastPathComponent()
    .appendingPathComponent("sourcekitd.framework")
    .appendingPathComponent("sourcekitd")
  if FileManager.default.fileExists(at: url) {
    try! url.filePath.withCString { sourcekitdPath in
      sourcekitd_plugin_initialize_2(params, sourcekitdPath)
    }
  } else {
    // When using a SourceKit plugin from the build directory, we can't find sourcekitd relative to the plugin.
    // Since sourcekitd_plugin_initialize is only called on Darwin from Xcode toolchains, we know that we are getting
    // called from an XPC sourcekitd. Thus, all sourcekitd symbols that we need should be loaded in the current process
    // already and we can use `RTLD_DEFAULT` for the sourcekitd library.
    sourcekitd_plugin_initialize_2(params, "SOURCEKIT_LSP_PLUGIN_PARENT_LIBRARY_RTLD_DEFAULT")
  }
  #else
  fatalError("sourcekitd_plugin_initialize is not supported on non-Darwin platforms")
  #endif
}

#if canImport(Darwin)
private extension SourceKitD {
  /// When a plugin is initialized, it gets passed the library it was loaded from to `sourcekitd_plugin_initialize_2`.
  ///
  /// Since the plugin wants to interact with sourcekitd in-process, it needs to load `sourcekitdInProc`. This function
  /// loads `sourcekitdInProc` relative to the parent library path, if it exists, or `sourcekitd` if `sourcekitdInProc`
  /// doesn't exist (eg. on Linux where `sourcekitd` is already in-process).
  static func inProcLibrary(relativeTo parentLibraryPath: URL) throws -> SourceKitD {
    var frameworkUrl = parentLibraryPath

    // Remove path components until we reach the `sourcekitd.framework` directory. The plugin might have been loaded
    // from an XPC service, in which case `parentLibraryPath` is
    // `sourcekitd.framework/XPCServices/SourceKitService.xpc/Contents/MacOS/SourceKitService`.
    while frameworkUrl.pathExtension != "framework" {
      guard frameworkUrl.pathComponents.count > 1 else {
        struct NoFrameworkPathError: Error, CustomStringConvertible {
          var parentLibraryPath: URL
          var description: String { "Could not find .framework directory relative to '\(parentLibraryPath)'" }
        }
        throw NoFrameworkPathError(parentLibraryPath: parentLibraryPath)
      }
      frameworkUrl.deleteLastPathComponent()
    }
    frameworkUrl.deleteLastPathComponent()

    let inProcUrl =
      frameworkUrl
      .appendingPathComponent("sourcekitdInProc.framework")
      .appendingPathComponent("sourcekitdInProc")
    if FileManager.default.fileExists(at: inProcUrl) {
      return try SourceKitD(dylib: inProcUrl, pluginPaths: nil, initialize: false)
    }

    let sourcekitdUrl =
      frameworkUrl
      .appendingPathComponent("sourcekitd.framework")
      .appendingPathComponent("sourcekitd")
    return try SourceKitD(dylib: sourcekitdUrl, pluginPaths: nil, initialize: false)
  }
}
#endif

@_cdecl("sourcekitd_plugin_initialize_2")
public func sourcekitd_plugin_initialize_2(
  _ params: sourcekitd_api_plugin_initialize_params_t,
  _ parentLibraryPath: UnsafePointer<CChar>
) {
  let parentLibraryPath = String(cString: parentLibraryPath)
  #if canImport(Darwin)
  if parentLibraryPath == "SOURCEKIT_LSP_PLUGIN_PARENT_LIBRARY_RTLD_DEFAULT" {
    SourceKitD.forPlugin = try! SourceKitD(
      dlhandle: .rtldDefault,
      path: URL(string: "rtld-default://")!,
      pluginPaths: nil,
      initialize: false
    )
  } else {
    SourceKitD.forPlugin = try! SourceKitD.inProcLibrary(relativeTo: URL(fileURLWithPath: parentLibraryPath))
  }
  #else
  // On other platforms, sourcekitd is always in process, so we can load it straight away.
  SourceKitD.forPlugin = try! SourceKitD(
    dylib: URL(fileURLWithPath: parentLibraryPath),
    pluginPaths: nil,
    initialize: false
  )
  #endif
  let sourcekitd = SourceKitD.forPlugin

  let completionResultsBufferKind = sourcekitd.pluginApi.plugin_initialize_custom_buffer_start(params)
  let isClientOnly = sourcekitd.pluginApi.plugin_initialize_is_client_only(params)

  let uidFromCString = sourcekitd.pluginApi.plugin_initialize_uid_get_from_cstr(params)
  let uidGetCString = sourcekitd.pluginApi.plugin_initialize_uid_get_string_ptr(params)

  // Depending on linking and loading configuration, we may need to chain the global UID handlers back to the UID
  // handlers in the caller. The extra hop should not matter, since we cache the results.
  if unsafeBitCast(uidFromCString, to: UnsafeRawPointer.self)
    != unsafeBitCast(sourcekitd.api.uid_get_from_cstr, to: UnsafeRawPointer.self)
  {
    sourcekitd.api.set_uid_handlers(uidFromCString, uidGetCString)
  }

  sourcekitd.pluginApi.plugin_initialize_register_custom_buffer(
    params,
    completionResultsBufferKind,
    CompletionResultsArray.arrayFuncs.rawValue
  )

  if isClientOnly {
    return
  }

  let requestHandler = RequestHandler(
    params: params,
    completionResultsBufferKind: completionResultsBufferKind,
    sourcekitd: sourcekitd
  )

  sourcekitd.servicePluginApi.plugin_initialize_register_cancellation_handler(params) { handle in
    if let handle = RequestHandle(handle) {
      requestHandler.cancel(handle)
    }
  }

  sourcekitd.servicePluginApi.plugin_initialize_register_cancellable_request_handler(params) {
    (request, handle, receiver) -> Bool in
    guard let receiver, let request, let dict = SKDRequestDictionaryReader(request, sourcekitd: sourcekitd) else {
      return false
    }
    let handle = RequestHandle(handle)

    let handledRequest = requestHandler.handleRequest(dict, handle: handle) { receiver($0.underlyingValueRetained()) }

    switch handledRequest {
    case .requestHandled: return true
    case .handleInSourceKitD: return false
    }
  }
}