mousedown()

in packages/ketcher-react/src/script/editor/tool/bond.ts [58:144]
83 lines of code
24 McCabe index (conditional complexity)

  mousedown(event) {
    if (this.dragCtx) return;
    if (isBondingWithMacroMolecule(this.editor, event)) {
      return;
    }
    const struct = this.editor.render.ctab;
    const molecule = struct.molecule;
    const functionalGroups = molecule.functionalGroups;
    const ci = this.editor.findItem(event, [
      'atoms',
      'bonds',
      'functionalGroups',
    ]);
    const atomResult: Array<number> = [];
    const bondResult: Array<number> = [];
    const result: Array<number> = [];
    if (ci && functionalGroups.size && ci.map === 'atoms') {
      const atomId = FunctionalGroup.atomsInFunctionalGroup(
        functionalGroups,
        ci.id,
      );
      if (atomId !== null) atomResult.push(atomId);
    }
    if (ci && functionalGroups.size && ci.map === 'bonds') {
      const bondId = FunctionalGroup.bondsInFunctionalGroup(
        molecule,
        functionalGroups,
        ci.id,
      );
      if (bondId !== null) bondResult.push(bondId);
    }
    if (atomResult.length > 0) {
      for (const id of atomResult) {
        const fgId = FunctionalGroup.findFunctionalGroupByAtom(
          functionalGroups,
          id,
        );
        if (fgId !== null && !result.includes(fgId)) {
          result.push(fgId);
        }
      }
      if (result.length) {
        this.editor.event.removeFG.dispatch({ fgIds: result });
        return;
      }
    } else if (bondResult.length > 0) {
      for (const id of bondResult) {
        const fgId = FunctionalGroup.findFunctionalGroupByBond(
          molecule,
          functionalGroups,
          id,
        );
        if (fgId !== null && !result.includes(fgId)) {
          result.push(fgId);
        }
      }
      if (result.length) {
        this.editor.event.removeFG.dispatch({ fgIds: result });
        return;
      }
    }

    let attachmentAtomId: number | undefined;
    if (ci?.map === 'functionalGroups') {
      const sgroup = molecule.sgroups.get(ci.id);
      attachmentAtomId = sgroup?.getAttachmentAtomId();
    }

    const rnd = this.editor.render;
    this.editor.hover(null);
    this.editor.selection(null);
    this.dragCtx = {
      xy0: rnd.page2obj(event),
      item:
        attachmentAtomId === undefined
          ? ci
          : {
              map: 'atoms',
              id: attachmentAtomId,
            },
    };

    if (!this.dragCtx.item)
      // ci.type == 'Canvas'
      delete this.dragCtx.item;
    return true;
  }