import Convert from "../convert"
import {
  LanguageClientConnection,
  FileChangeType,
  TextDocumentSaveReason,
  TextDocumentSyncKind,
  TextDocumentSyncOptions,
  TextDocumentContentChangeEvent,
  VersionedTextDocumentIdentifier,
  ServerCapabilities,
  DidSaveTextDocumentParams,
} from "../languageclient"
import ApplyEditAdapter from "./apply-edit-adapter"
import { CompositeDisposable, Disposable, TextEditor, BufferStoppedChangingEvent, TextChange } from "atom"
import * as Utils from "../utils"

/**
 * Public: Synchronizes the documents between Atom and the language server by notifying each end of changes, opening,
 * closing and other events as well as sending and applying changes either in whole or in part depending on what the
 * language server supports.
 */
export default class DocumentSyncAdapter {
  private _disposable = new CompositeDisposable()
  public _documentSync: TextDocumentSyncOptions
  private _editors: WeakMap<TextEditor, TextEditorSyncAdapter> = new WeakMap()
  private _versions: Map<string, number> = new Map()

  /**
   * Public: Determine whether this adapter can be used to adapt a language server based on the serverCapabilities
   * matrix textDocumentSync capability either being Full or Incremental.
   *
   * @param serverCapabilities The {ServerCapabilities} of the language server to consider.
   * @returns A {Boolean} indicating adapter can adapt the server based on the given serverCapabilities.
   */
  public static canAdapt(serverCapabilities: ServerCapabilities): boolean {
    return this.canAdaptV2(serverCapabilities) || this.canAdaptV3(serverCapabilities)
  }

  private static canAdaptV2(serverCapabilities: ServerCapabilities): boolean {
    return (
      serverCapabilities.textDocumentSync === TextDocumentSyncKind.Incremental ||
      serverCapabilities.textDocumentSync === TextDocumentSyncKind.Full
    )
  }

  private static canAdaptV3(serverCapabilities: ServerCapabilities): boolean {
    const options = serverCapabilities.textDocumentSync
    return (
      options !== null &&
      typeof options === "object" &&
      (options.change === TextDocumentSyncKind.Incremental || options.change === TextDocumentSyncKind.Full)
    )
  }

  /**
   * Public: Create a new {DocumentSyncAdapter} for the given language server.
   *
   * @param _connection A {LanguageClientConnection} to the language server to be kept in sync.
   * @param documentSync The document syncing options.
   * @param _editorSelector A predicate function that takes a {TextEditor} and returns a {boolean} indicating whether
   *   this adapter should care about the contents of the editor.
   * @param _getLanguageIdFromEditor A function that returns a {string} of `languageId` used for `textDocument/didOpen`
   *   notification.
   */
  constructor(
    private _connection: LanguageClientConnection,
    private _editorSelector: (editor: TextEditor) => boolean,
    documentSync: TextDocumentSyncOptions | TextDocumentSyncKind | undefined,
    private _reportBusyWhile: Utils.ReportBusyWhile,
    private _getLanguageIdFromEditor: (editor: TextEditor) => string
  ) {
    if (typeof documentSync === "object") {
      this._documentSync = documentSync
    } else {
      this._documentSync = {
        change: documentSync || TextDocumentSyncKind.Full,
      }
    }
    this._disposable.add(atom.textEditors.observe(this.observeTextEditor.bind(this)))
  }

  /** Dispose this adapter ensuring any resources are freed and events unhooked. */
  public dispose(): void {
    this._disposable.dispose()
  }

  /**
   * Examine a {TextEditor} and decide if we wish to observe it. If so ensure that we stop observing it when it is
   * closed or otherwise destroyed.
   *
   * @param editor A {TextEditor} to consider for observation.
   */
  public observeTextEditor(editor: TextEditor): void {
    const listener = editor.observeGrammar((_grammar) => this._handleGrammarChange(editor))
    this._disposable.add(
      editor.onDidDestroy(() => {
        this._disposable.remove(listener)
        listener.dispose()
      })
    )
    this._disposable.add(listener)
    if (!this._editors.has(editor) && this._editorSelector(editor)) {
      this._handleNewEditor(editor)
    }
  }

  private _handleGrammarChange(editor: TextEditor): void {
    const sync = this._editors.get(editor)
    if (sync != null && !this._editorSelector(editor)) {
      this._editors.delete(editor)
      this._disposable.remove(sync)
      sync.didClose()
      sync.dispose()
    } else if (sync == null && this._editorSelector(editor)) {
      this._handleNewEditor(editor)
    }
  }

  private _handleNewEditor(editor: TextEditor): void {
    const sync = new TextEditorSyncAdapter(
      editor,
      this._connection,
      this._documentSync,
      this._versions,
      this._reportBusyWhile,
      this._getLanguageIdFromEditor
    )
    this._editors.set(editor, sync)
    this._disposable.add(sync)
    this._disposable.add(
      editor.onDidDestroy(() => {
        const destroyedSync = this._editors.get(editor)
        if (destroyedSync) {
          this._editors.delete(editor)
          this._disposable.remove(destroyedSync)
          destroyedSync.dispose()
        }
      })
    )
  }

  public getEditorSyncAdapter(editor: TextEditor): TextEditorSyncAdapter | undefined {
    return this._editors.get(editor)
  }
}

/** Public: Keep a single {TextEditor} in sync with a given language server. */
export class TextEditorSyncAdapter {
  private _disposable = new CompositeDisposable()
  private _currentUri: string
  private _fakeDidChangeWatchedFiles: boolean

  /**
   * Public: Create a {TextEditorSyncAdapter} in sync with a given language server.
   *
   * @param _editor A {TextEditor} to keep in sync.
   * @param _connection A {LanguageClientConnection} to a language server to keep in sync.
   * @param _documentSync The document syncing options.
   */
  constructor(
    private _editor: TextEditor,
    private _connection: LanguageClientConnection,
    private _documentSync: TextDocumentSyncOptions,
    private _versions: Map<string, number>,
    private _reportBusyWhile: Utils.ReportBusyWhile,
    private _getLanguageIdFromEditor: (editor: TextEditor) => string
  ) {
    this._fakeDidChangeWatchedFiles = atom.project.onDidChangeFiles == null

    const changeTracking = this.setupChangeTracking(_documentSync)
    if (changeTracking != null) {
      this._disposable.add(changeTracking)
    }

    // These handlers are attached only if server supports them
    if (_documentSync.willSave) {
      this._disposable.add(_editor.getBuffer().onWillSave(this.willSave.bind(this)))
    }
    if (_documentSync.willSaveWaitUntil) {
      this._disposable.add(_editor.getBuffer().onWillSave(this.willSaveWaitUntil.bind(this)))
    }
    // Send close notifications unless it's explicitly disabled
    if (_documentSync.openClose !== false) {
      this._disposable.add(_editor.onDidDestroy(this.didClose.bind(this)))
    }
    this._disposable.add(_editor.onDidSave(this.didSave.bind(this)), _editor.onDidChangePath(this.didRename.bind(this)))

    this._currentUri = this.getEditorUri()

    if (_documentSync.openClose !== false) {
      this.didOpen()
    }
  }

  /** The change tracking disposable listener that will ensure that changes are sent to the language server as appropriate. */
  public setupChangeTracking(documentSync: TextDocumentSyncOptions): Disposable | null {
    switch (documentSync.change) {
      case TextDocumentSyncKind.Full:
        return this._editor.onDidChange(this.sendFullChanges.bind(this))
      case TextDocumentSyncKind.Incremental:
        return this._editor.getBuffer().onDidChangeText(this.sendIncrementalChanges.bind(this))
    }
    return null
  }

  /** Dispose this adapter ensuring any resources are freed and events unhooked. */
  public dispose(): void {
    this._disposable.dispose()
  }

  /** Get the languageId field that will be sent to the language server by simply using the `_getLanguageIdFromEditor`. */
  public getLanguageId(): string {
    return this._getLanguageIdFromEditor(this._editor)
  }

  /**
   * Public: Create a {VersionedTextDocumentIdentifier} for the document observed by this adapter including both the Uri
   * and the current Version.
   */
  public getVersionedTextDocumentIdentifier(): VersionedTextDocumentIdentifier {
    return {
      uri: this.getEditorUri(),
      version: this._getVersion(this._editor.getPath() || ""),
    }
  }

  /** Public: Send the entire document to the language server. This is used when operating in Full (1) sync mode. */
  public sendFullChanges(): void {
    if (!this._isPrimaryAdapter()) {
      return
    } // Multiple editors, we are not first

    this._bumpVersion()
    this._connection.didChangeTextDocument({
      textDocument: this.getVersionedTextDocumentIdentifier(),
      contentChanges: [{ text: this._editor.getText() }],
    })
  }

  /**
   * Public: Send the incremental text changes to the language server. This is used when operating in Incremental (2) sync mode.
   *
   * @param event The event fired by Atom to indicate the document has stopped changing including a list of changes
   *   since the last time this event fired for this text editor. NOTE: The order of changes in the event is guaranteed
   *   top to bottom. Language server expects this in reverse.
   */
  public sendIncrementalChanges(event: BufferStoppedChangingEvent): void {
    if (event.changes.length > 0) {
      if (!this._isPrimaryAdapter()) {
        return
      } // Multiple editors, we are not first

      this._bumpVersion()
      this._connection.didChangeTextDocument({
        textDocument: this.getVersionedTextDocumentIdentifier(),
        contentChanges: event.changes.map(TextEditorSyncAdapter.textEditToContentChange).reverse(),
      })
    }
  }

  /**
   * Public: Convert an Atom {TextEditEvent} to a language server {TextDocumentContentChangeEvent} object.
   *
   * @param change The Atom {TextEditEvent} to convert.
   * @returns A {TextDocumentContentChangeEvent} that represents the converted {TextEditEvent}.
   */
  public static textEditToContentChange(change: TextChange): TextDocumentContentChangeEvent {
    return {
      range: Convert.atomRangeToLSRange(change.oldRange),
      rangeLength: change.oldText.length,
      text: change.newText,
    }
  }

  private _isPrimaryAdapter(): boolean {
    const lowestIdForBuffer = Math.min(
      ...atom.workspace
        .getTextEditors()
        .filter((t) => t.getBuffer() === this._editor.getBuffer())
        .map((t) => t.id)
    )
    return lowestIdForBuffer === this._editor.id
  }

  private _bumpVersion(): void {
    const filePath = this._editor.getPath()
    if (filePath == null) {
      return
    }
    this._versions.set(filePath, this._getVersion(filePath) + 1)
  }

  /**
   * Ensure when the document is opened we send notification to the language server so it can load it in and keep track
   * of diagnostics etc.
   */
  private didOpen(): void {
    const filePath = this._editor.getPath()
    if (filePath == null) {
      return
    } // Not yet saved

    if (!this._isPrimaryAdapter()) {
      return
    } // Multiple editors, we are not first

    this._connection.didOpenTextDocument({
      textDocument: {
        uri: this.getEditorUri(),
        languageId: this.getLanguageId().toLowerCase(),
        version: this._getVersion(filePath),
        text: this._editor.getText(),
      },
    })
  }

  private _getVersion(filePath: string): number {
    return this._versions.get(filePath) || 1
  }

  /** Called when the {TextEditor} is closed and sends the 'didCloseTextDocument' notification to the connected language server. */
  public didClose(): void {
    if (this._editor.getPath() == null) {
      return
    } // Not yet saved

    const fileStillOpen = atom.workspace.getTextEditors().find((t) => t.getBuffer() === this._editor.getBuffer())
    if (fileStillOpen) {
      return // Other windows or editors still have this file open
    }

    this._connection.didCloseTextDocument({ textDocument: { uri: this.getEditorUri() } })
  }

  /** Called just before the {TextEditor} saves and sends the 'willSaveTextDocument' notification to the connected language server. */
  public willSave(): void {
    if (!this._isPrimaryAdapter()) {
      return
    }

    const uri = this.getEditorUri()
    this._connection.willSaveTextDocument({
      textDocument: { uri },
      reason: TextDocumentSaveReason.Manual,
    })
  }

  /**
   * Called just before the {TextEditor} saves, sends the 'willSaveWaitUntilTextDocument' request to the connected
   * language server and waits for the response before saving the buffer.
   */
  public async willSaveWaitUntil(): Promise<void> {
    if (!this._isPrimaryAdapter()) {
      return Promise.resolve()
    }

    const buffer = this._editor.getBuffer()
    const uri = this.getEditorUri()
    const title = this._editor.getLongTitle()

    const applyEditsOrTimeout = Utils.promiseWithTimeout(
      2500, // 2.5 seconds timeout
      this._connection.willSaveWaitUntilTextDocument({
        textDocument: { uri },
        reason: TextDocumentSaveReason.Manual,
      })
    )
      .then((edits) => {
        const cursor = this._editor.getCursorBufferPosition()
        ApplyEditAdapter.applyEdits(buffer, Convert.convertLsTextEdits(edits))
        this._editor.setCursorBufferPosition(cursor)
      })
      .catch((err) => {
        atom.notifications.addError("On-save action failed", {
          description: `Failed to apply edits to ${title}`,
          detail: err.message,
        })
        return
      })

    const withBusySignal = this._reportBusyWhile(`Applying on-save edits for ${title}`, () => applyEditsOrTimeout)
    return withBusySignal || applyEditsOrTimeout
  }

  /**
   * Called when the {TextEditor} saves and sends the 'didSaveTextDocument' notification to the connected language
   * server. Note: Right now this also sends the `didChangeWatchedFiles` notification as well but that will be sent from
   * elsewhere soon.
   */
  public didSave(): void {
    if (!this._isPrimaryAdapter()) {
      return
    }

    const uri = this.getEditorUri()
    const didSaveNotification = {
      textDocument: { uri, version: this._getVersion(uri) },
    } as DidSaveTextDocumentParams
    if (typeof this._documentSync.save === "object" && this._documentSync.save.includeText) {
      didSaveNotification.text = this._editor.getText()
    }
    this._connection.didSaveTextDocument(didSaveNotification)
    if (this._fakeDidChangeWatchedFiles) {
      this._connection.didChangeWatchedFiles({
        changes: [{ uri, type: FileChangeType.Changed }],
      })
    }
  }

  public didRename(): void {
    if (!this._isPrimaryAdapter()) {
      return
    }

    const oldUri = this._currentUri
    this._currentUri = this.getEditorUri()
    if (!oldUri) {
      return // Didn't previously have a name
    }

    if (this._documentSync.openClose !== false) {
      this._connection.didCloseTextDocument({ textDocument: { uri: oldUri } })
    }

    if (this._fakeDidChangeWatchedFiles) {
      this._connection.didChangeWatchedFiles({
        changes: [
          { uri: oldUri, type: FileChangeType.Deleted },
          { uri: this._currentUri, type: FileChangeType.Created },
        ],
      })
    }

    // Send an equivalent open event for this editor, which will now use the new
    // file path.
    if (this._documentSync.openClose !== false) {
      this.didOpen()
    }
  }

  /** Public: Obtain the current {TextEditor} path and convert it to a Uri. */
  public getEditorUri(): string {
    return Convert.pathToUri(this._editor.getPath() || "")
  }
}