import { Notebook, NotebookPanel } from '@jupyterlab/notebook';
import * as nbformat from '@jupyterlab/nbformat';
import { IDocumentManager } from '@jupyterlab/docmanager';

import { CodeJumper, jumpers } from './jumper';
import { IJump, IJumpPosition } from '../jump';
import { _ensureFocus, _findCell, _findTargetCell } from '../notebook_private';
import { JumpHistory } from '../history';
import { TokenContext } from '../languages/analyzer';
import { Kernel } from '@jupyterlab/services';
import { CodeEditor } from '@jupyterlab/codeeditor';
import { ICodeCellModel } from '@jupyterlab/cells';

export class NotebookJumper extends CodeJumper {
  notebook: Notebook;
  widget: NotebookPanel;

  constructor(
    notebook_widget: NotebookPanel,
    document_manager: IDocumentManager
  ) {
    super();
    this.widget = notebook_widget;
    this.notebook = notebook_widget.content;
    this.history = new JumpHistory(this.notebook.model.modelDB);
    this.document_manager = document_manager;
  }

  get kernel(): Kernel.IKernelConnection {
    return this.widget.context.sessionContext.session?.kernel;
  }

  get cwd() {
    return this.widget.model.modelDB.basePath
      .split('/')
      .slice(0, -1)
      .join('/');
  }

  get editors() {
    return this.notebook.widgets.map(cell => cell.editor);
  }

  get language() {
    let languageInfo = this.notebook.model.metadata.get(
      'language_info'
    ) as nbformat.ILanguageInfoMetadata;
    // TODO: consider version of the language as well
    return languageInfo.name;
  }

  jump(position: IJumpPosition) {
    let { token, index } = position;

    // Prevents event propagation issues
    setTimeout(() => {
      this.notebook.deselectAll();
      this.notebook.activeCellIndex = index;
      _ensureFocus(this.notebook);
      this.notebook.mode = 'edit';

      // find out offset for the element
      let activeEditor = this.notebook.activeCell.editor;

      // place cursor in the line with the definition
      let position = activeEditor.getPositionAt(token.offset);
      activeEditor.setSelection({ start: position, end: position });
    }, 0);
  }

  jump_to_definition(jump: IJump, index?: number) {
    if (index === undefined) {
      // Using `index = this._findCell(editor.host)` does not work,
      // as the host editor has not switched to the clicked cell yet.

      // The mouse event is utilized to workaround Firefox's issue.
      if (jump.mouseEvent !== undefined) {
        index = _findTargetCell(this.notebook, jump.mouseEvent).index;
      } else {
        index = _findCell(this.notebook, jump.origin);
      }
    }

    // if the definition is in a different file:
    // only support cases like:
    //    "from x import y" (clicking on y opens x.py)
    // or
    //    "y.x" (clicking on y opens y.py)
    let cell_of_origin_editor = this.editors[index];
    let cell_of_origin_analyzer = this._getLanguageAnalyzerForCell(
      cell_of_origin_editor
    );

    cell_of_origin_analyzer._maybe_setup_tokens();

    let context = new TokenContext(
      jump.token,
      cell_of_origin_analyzer.tokens,
      cell_of_origin_analyzer._get_token_index(jump.token)
    );

    let after_jump = () => {
      this.history.store({ token: jump.token, index: index });
    };

    if (cell_of_origin_analyzer.isCrossFileReference(context)) {
      this.jump_to_cross_file_reference(context, cell_of_origin_analyzer);
    } else {
      // try to get the location of definition from the kernel (for Python - using inspect)

      // if has location:
      // open tab with the file
      this.inspect_and_jump(
        context,
        cell_of_origin_analyzer,
        () => {
          // TODO when reassigning objects:
          //   def xyz(): pass
          //   a = xyz
          //   x = a
          //  click on the last 'a' will lead to a jump to 'def xyz(): pass' instead to 'a = xyz'
          //  when using kernel for resolution. This may not be the expected behaviour!
          //  maybe we should first try to _findLastDefinition and only jump with kernel if none found
          //  (plus as an option - when user presses a different combination, it could be labeled "deep jump")

          // if it fails, jump to the last definition in the current notebook:
          let { token, cellIndex } = this._findLastDefinition(
            jump.token,
            index
          );

          // nothing found
          if (!token) {
            return;
          }

          this.jump({ token: token, index: cellIndex });
        },
        after_jump
      );
    }
  }

  jump_back() {
    let previous_position = this.history.recollect();
    if (previous_position) {
      this.jump(previous_position);
    }
  }

  getOffset(position: CodeEditor.IPosition, cell: number = 0) {
    return this.editors[cell].getOffsetAt(position);
  }

  getJumpPosition(position: CodeEditor.IPosition, input_number: number) {
    let cells = this.widget.model.cells.iter();
    let cell = cells.next();

    let i = 0;
    let cell_index: number;

    while (cell) {
      if (cell.type === 'code') {
        let code_cell = cell as ICodeCellModel;
        if (code_cell.executionCount === input_number) {
          cell_index = i;
          break;
        }
      }
      cell = cells.next();
      i += 1;
    }

    // TODO: what if we cannot get the cell index?

    return {
      token: {
        offset: this.getOffset(position, cell_index),
        value: ''
      },
      index: cell_index
    };
  }
}

jumpers.set('notebook', NotebookJumper);