// Copyright (c) Jupyter Development Team.
// Distributed under the terms of the Modified BSD License.

import { Cell, CodeCell } from '@jupyterlab/cells';

import { CodeMirrorEditor } from '@jupyterlab/codemirror';

import { ActivityMonitor } from '@jupyterlab/coreutils';

import { IObservableString } from '@jupyterlab/observables';

import { IDisposable } from '@phosphor/disposable';

import { Signal } from '@phosphor/signaling';

import { Editor } from 'codemirror';

import { Breakpoints, SessionTypes } from '../breakpoints';

import { Callstack } from '../callstack';

import { Debugger } from '../debugger';

import { IDebugger } from '../tokens';

const LINE_HIGHLIGHT_CLASS = 'jp-breakpoint-line-highlight';

const CELL_CHANGED_TIMEOUT = 1000;

export class CellManager implements IDisposable {
  constructor(options: CellManager.IOptions) {
    // TODO: should we use the client name or a debug session id?
    this._id = options.debuggerService.session.client.name;
    this._debuggerService = options.debuggerService;
    this.onModelChanged();
    this._debuggerService.modelChanged.connect(() => this.onModelChanged());
    this.activeCell = options.activeCell;
  }

  isDisposed: boolean;

  private onModelChanged() {
    this._debuggerModel = this._debuggerService.model;
    if (!this._debuggerModel) {
      return;
    }
    this.breakpointsModel = this._debuggerModel.breakpointsModel;

    this._debuggerModel.callstackModel.currentFrameChanged.connect(
      (_, frame) => {
        CellManager.clearHighlight(this.activeCell);
        if (!frame) {
          return;
        }
      }
    );

    this.breakpointsModel.changed.connect(async () => {
      if (
        !this.activeCell ||
        !this.activeCell.isVisible ||
        this.activeCell.isDisposed
      ) {
        return;
      }
      this.addBreakpointsToEditor(this.activeCell);
    });

    this.breakpointsModel.restored.connect(async () => {
      if (!this.activeCell || this.activeCell.isDisposed) {
        return;
      }
      this.addBreakpointsToEditor(this.activeCell);
    });

    if (this.activeCell && !this.activeCell.isDisposed) {
      this._debuggerModel.codeValue = this.activeCell.model.value;
    }
  }

  dispose(): void {
    if (this.isDisposed) {
      return;
    }
    if (this._cellMonitor) {
      this._cellMonitor.dispose();
    }
    this.removeGutterClick(this.activeCell);
    CellManager.clearHighlight(this.activeCell);
    CellManager.clearGutter(this.activeCell);
    Signal.clearData(this);
    this.isDisposed = true;
  }

  set previousCell(cell: CodeCell) {
    this._previousCell = cell;
  }

  get previousCell() {
    return this._previousCell;
  }

  set activeCell(cell: CodeCell) {
    if (cell) {
      this._activeCell = cell;
      this._debuggerModel.codeValue = cell.model.value;
      this.onActiveCellChanged();
    }
  }

  get activeCell(): CodeCell {
    return this._activeCell;
  }

  onActiveCellChanged() {
    if (
      this.activeCell &&
      this.activeCell.isAttached &&
      this.activeCell.editor &&
      this._debuggerService &&
      this._debuggerService.session
    ) {
      if (this.previousCell && !this.previousCell.isDisposed) {
        if (this._cellMonitor) {
          this._cellMonitor.dispose();
        }
        this.removeGutterClick(this.previousCell);
      }

      this._cellMonitor = new ActivityMonitor({
        signal: this.activeCell.model.value.changed,
        timeout: CELL_CHANGED_TIMEOUT
      });

      this._cellMonitor.activityStopped.connect(() => {
        this.sendEditorBreakpoints();
      }, this);

      requestAnimationFrame(() => {
        this.setEditor(this.activeCell);
      });

      this.previousCell = this.activeCell;
    }
  }

  protected sendEditorBreakpoints() {
    const cell = this.activeCell;
    if (!cell || !cell.editor) {
      return;
    }

    const breakpoints = this.getBreakpointsFromEditor(cell).map(lineInfo => {
      return Private.createBreakpoint(
        this._debuggerService.session.client.name,
        this.getEditorId(),
        lineInfo.line + 1
      );
    });

    void this._debuggerService.updateBreakpoints(
      cell.editor.model.value.text,
      breakpoints
    );
  }

  protected setEditor(cell: CodeCell) {
    if (!cell || !cell.editor) {
      return;
    }

    const editor = cell.editor as CodeMirrorEditor;
    this.addBreakpointsToEditor(cell);

    editor.setOption('lineNumbers', true);
    editor.editor.setOption('gutters', [
      'CodeMirror-linenumbers',
      'breakpoints'
    ]);

    editor.editor.on('gutterClick', this.onGutterClick);
  }

  protected removeGutterClick(cell: CodeCell) {
    if (cell.isDisposed) {
      return;
    }
    const editor = cell.editor as CodeMirrorEditor;
    editor.editor.off('gutterClick', this.onGutterClick);
  }

  protected getEditorId(): string {
    return this.activeCell.editor.uuid;
  }

  protected onGutterClick = (editor: Editor, lineNumber: number) => {
    const info = editor.lineInfo(lineNumber);

    if (!info || this._id !== this._debuggerService.session.client.name) {
      return;
    }

    editor.focus();
    CellManager.clearGutter(this.activeCell);

    const isRemoveGutter = !!info.gutterMarkers;
    let breakpoints: Breakpoints.IBreakpoint[] = this.getBreakpoints(
      this._activeCell
    );
    if (isRemoveGutter) {
      breakpoints = breakpoints.filter(ele => ele.line !== info.line + 1);
    } else {
      breakpoints.push(
        Private.createBreakpoint(
          this._debuggerService.session.client.name,
          this.getEditorId(),
          info.line + 1
        )
      );
    }

    void this._debuggerService.updateBreakpoints(
      this._activeCell.model.value.text,
      breakpoints
    );
  };

  private addBreakpointsToEditor(cell: CodeCell) {
    const editor = cell.editor as CodeMirrorEditor;
    const breakpoints = this.getBreakpoints(cell);
    if (
      breakpoints.length === 0 &&
      this._id === this._debuggerService.session.client.name
    ) {
      CellManager.clearGutter(cell);
    } else {
      breakpoints.forEach(breakpoint => {
        editor.editor.setGutterMarker(
          breakpoint.line - 1,
          'breakpoints',
          Private.createMarkerNode()
        );
      });
    }
  }

  private getBreakpointsFromEditor(cell: CodeCell): ILineInfo[] {
    const editor = cell.editor as CodeMirrorEditor;
    let lines = [];
    for (let i = 0; i < editor.doc.lineCount(); i++) {
      const info = editor.editor.lineInfo(i);
      if (info.gutterMarkers) {
        lines.push(info);
      }
    }
    return lines;
  }

  private getBreakpoints(cell: CodeCell): Breakpoints.IBreakpoint[] {
    return this._debuggerModel.breakpointsModel.getBreakpoints(
      this._debuggerService.getCellId(cell.model.value.text)
    );
  }

  private _previousCell: CodeCell;
  private _debuggerModel: Debugger.Model;
  private breakpointsModel: Breakpoints.Model;
  private _activeCell: CodeCell;
  private _debuggerService: IDebugger;
  private _id: string;
  private _cellMonitor: ActivityMonitor<
    IObservableString,
    IObservableString.IChangedArgs
  > = null;
}

export namespace CellManager {
  export interface IOptions {
    debuggerModel: Debugger.Model;
    debuggerService: IDebugger;
    breakpointsModel: Breakpoints.Model;
    activeCell?: CodeCell;
    type: SessionTypes;
  }

  /**
   * Highlight the current line of the frame in the given cell.
   * @param cell The cell to highlight.
   * @param frame The frame with the current line number.
   */
  export function showCurrentLine(cell: Cell, frame: Callstack.IFrame) {
    const editor = cell.editor as CodeMirrorEditor;
    clearHighlight(cell);
    editor.editor.addLineClass(frame.line - 1, 'wrap', LINE_HIGHLIGHT_CLASS);
  }

  /**
   * Remove all line highlighting indicators for the given cell.
   * @param cell The cell to cleanup.
   */
  export function clearHighlight(cell: Cell) {
    if (!cell || cell.isDisposed || !cell.inputArea) {
      return;
    }
    const editor = cell.editor as CodeMirrorEditor;
    editor.doc.eachLine(line => {
      editor.editor.removeLineClass(line, 'wrap', LINE_HIGHLIGHT_CLASS);
    });
  }

  /**
   * Remove line numbers and all gutters from cell.
   * @param cell The cell to cleanup.
   */

  export function clearGutter(cell: Cell) {
    if (!cell || !cell.inputArea) {
      return;
    }
    const editor = cell.editor as CodeMirrorEditor;
    editor.doc.eachLine(line => {
      if ((line as ILineInfo).gutterMarkers) {
        editor.editor.setGutterMarker(line, 'breakpoints', null);
      }
    });
  }
}

export interface ILineInfo {
  line: any;
  handle: any;
  text: string;
  /** Object mapping gutter IDs to marker elements. */
  gutterMarkers: any;
  textClass: string;
  bgClass: string;
  wrapClass: string;
  /** Array of line widgets attached to this line. */
  widgets: any;
}

namespace Private {
  export function createMarkerNode() {
    let marker = document.createElement('div');
    marker.className = 'jp-breakpoint-marker';
    marker.innerHTML = '●';
    return marker;
  }
  export function createBreakpoint(
    session: string,
    type: string,
    line: number
  ) {
    return {
      line,
      active: true,
      verified: true,
      source: {
        name: session
      }
    };
  }
}