private updateSnakeBondPath()

in packages/ketcher-core/src/application/render/renderers/PolymerBondRenderer/SnakeModePolymerBondRenderer.ts [457:655]
195 lines of code
24 McCabe index (conditional complexity)

  private updateSnakeBondPath(
    startPosition: Vec2,
    endPosition: Vec2,
    reCheckAttachmentPoint = true,
  ): void {
    const isR1TheCurrentAttachmentPointOfFirstMonomer =
      this.polymerBond.firstMonomer.getAttachmentPointByBond(
        this.polymerBond,
      ) === 'R1' ||
      this.polymerBond.firstMonomer.getPotentialAttachmentPointByBond(
        this.polymerBond,
      ) === 'R1';

    // check if there is nucleotide in current row
    const isBondConnectedWithNucleotide =
      this.polymerBond.firstMonomer.isMonomerInRnaChainRow;
    const verticalLineLength = this.polymerBond.firstMonomer.monomerItem
      .isAntisense
      ? RNA_ANTISENSE_CHAIN_VERTICAL_LINE_LENGTH
      : this.polymerBond.firstMonomer.monomerItem.isSense &&
        (this.polymerBond.restOfRowsWithAntisense || 0) > 0
      ? RNA_SENSE_CHAIN_VERTICAL_LINE_LENGTH
      : isBondConnectedWithNucleotide
      ? RNA_CHAIN_VERTICAL_LINE_LENGTH
      : VERTICAL_LINE_LENGTH + 5;

    if (this.isSecondMonomerBottomRight(startPosition, endPosition)) {
      if (
        isR1TheCurrentAttachmentPointOfFirstMonomer &&
        reCheckAttachmentPoint
      ) {
        this.updateSnakeBondPath(endPosition, startPosition, false);
        return;
      }
      this.addLine(
        LineDirection.Horizontal,
        LINE_FROM_MONOMER_LENGTH + this.getMonomerWidth() / 2,
        startPosition,
      );
      this.addLineFromLeftToBottom();
      this.addLine(
        LineDirection.Vertical,
        endPosition.y - startPosition.y - CORNER_LENGTH * 2,
      );
      this.addLineFromTopToRight();
      this.addLine(
        LineDirection.Horizontal,
        endPosition.x -
          startPosition.x -
          CORNER_LENGTH * 2 -
          LINE_FROM_MONOMER_LENGTH -
          this.getMonomerWidth() / 2,
      );
    } else if (this.isSecondMonomerTopRight(startPosition, endPosition)) {
      if (
        isR1TheCurrentAttachmentPointOfFirstMonomer &&
        reCheckAttachmentPoint
      ) {
        this.updateSnakeBondPath(endPosition, startPosition, false);
        return;
      }
      this.addLine(
        LineDirection.Horizontal,
        LINE_FROM_MONOMER_LENGTH + this.getMonomerWidth() / 2,
        startPosition,
      );
      this.addLineFromLeftToTop();
      this.addLine(
        LineDirection.Vertical,
        endPosition.y -
          startPosition.y -
          CORNER_LENGTH * 2 +
          this.getMonomerHeight() / 2,
      );
      this.addLineFromBottomToRight();
      this.addLine(
        LineDirection.Horizontal,
        endPosition.x -
          startPosition.x -
          CORNER_LENGTH * 2 -
          LINE_FROM_MONOMER_LENGTH -
          this.getMonomerWidth() / 2,
      );
    } else if (this.isSecondMonomerBottomLeft(startPosition, endPosition)) {
      if (
        isR1TheCurrentAttachmentPointOfFirstMonomer &&
        reCheckAttachmentPoint
      ) {
        this.updateSnakeBondPath(endPosition, startPosition, false);
        return;
      }
      this.addLine(
        LineDirection.Horizontal,
        LINE_FROM_MONOMER_LENGTH -
          (this.polymerBond.firstMonomer.monomerItem.isAntisense ? 10 : 0) +
          this.getMonomerWidth() / 2,
        startPosition,
      );
      this.addLineFromLeftToBottom();
      this.addLine(LineDirection.Vertical, verticalLineLength);
      this.addLineFromTopToLeft();
      this.addLine(
        LineDirection.Horizontal,
        -(
          startPosition.x -
          endPosition.x +
          LINE_FROM_MONOMER_LENGTH * 2 +
          this.getMonomerWidth()
        ),
      );
      this.addLineFromRightToBottom();
      this.addLine(
        LineDirection.Vertical,
        endPosition.y -
          startPosition.y -
          CORNER_LENGTH * 4 -
          verticalLineLength,
      );
      this.addLineFromTopToRight();
      this.addLine(
        LineDirection.Horizontal,
        LINE_FROM_MONOMER_LENGTH + this.getMonomerWidth() / 2,
      );
    } else if (this.isSecondMonomerTopLeft(startPosition, endPosition)) {
      if (
        isR1TheCurrentAttachmentPointOfFirstMonomer &&
        reCheckAttachmentPoint
      ) {
        this.updateSnakeBondPath(endPosition, startPosition, false);
        return;
      }
      this.addLine(
        LineDirection.Horizontal,
        LINE_FROM_MONOMER_LENGTH + this.getMonomerWidth() / 2,
        startPosition,
      );
      this.addLineFromLeftToBottom();
      this.addLine(LineDirection.Vertical, this.getMonomerHeight());
      this.addLineFromTopToLeft();
      this.addLine(
        LineDirection.Horizontal,
        -(
          startPosition.x -
          endPosition.x +
          LINE_FROM_MONOMER_LENGTH * 2 +
          this.getMonomerWidth()
        ),
      );

      this.addLineFromRightToTop();
      this.addLine(
        LineDirection.Vertical,
        endPosition.y - startPosition.y - this.getMonomerHeight(),
      );
      this.addLineFromBottomToRight();
      this.addLine(
        LineDirection.Horizontal,
        LINE_FROM_MONOMER_LENGTH + this.getMonomerWidth() / 2,
      );
    } else if (this.isSecondMonomerLeft(startPosition, endPosition)) {
      if (
        isR1TheCurrentAttachmentPointOfFirstMonomer &&
        reCheckAttachmentPoint
      ) {
        this.updateSnakeBondPath(endPosition, startPosition, false);
        return;
      }
      this.addLine(
        LineDirection.Horizontal,
        LINE_FROM_MONOMER_LENGTH + this.getMonomerWidth() / 2,
        startPosition,
      );
      this.addLineFromLeftToBottom();
      this.addLine(
        LineDirection.Vertical,
        endPosition.y - startPosition.y + this.getMonomerHeight(),
      );
      this.addLineFromTopToLeft();
      this.addLine(
        LineDirection.Horizontal,
        -(
          startPosition.x -
          endPosition.x +
          LINE_FROM_MONOMER_LENGTH * 2 +
          this.getMonomerWidth()
        ),
      );

      this.addLineFromRightToTop();
      this.addLine(LineDirection.Vertical, -this.getMonomerHeight());
      this.addLineFromBottomToRight();
      this.addLine(
        LineDirection.Horizontal,
        LINE_FROM_MONOMER_LENGTH + this.getMonomerWidth() / 2,
      );
    } else {
      this.addRandomLine(startPosition, endPosition);
    }
  }