[Create Peptide Structure] As a Ketcher user, I want to add peptide bond linking the monomers presented on canvas

As	I want	so that
Ketcher polymer editor user	to add peptide bond linking the monomers presented on the canvas	I can represent the monomers added to the canvas as a united entity that is a peptide molecule
Ketcher polymer editor user	for Ketcher to select exact connection point if possible when linking the monomers	I can represent the correct peptide bond when creating complex structures with amino acids that have 3 polarized groups

1. Context

Glossary: polymer Glossary

3. Assumptions

ID	Assumption
1	Peptide bond should be represented as a single line on the canvas hiding its actual internal structure

4. Additional information (optional)

Use Polymer Business rules from here: Polymer Business Rules

8. Acceptance Criteria

#	User Group	GIVEN	WHEN	THEN
1	Ketcher polymer editor User	Polymer editor mode of the Ketcher enabled	viewing on the tool panel	I see the Peptide bond tool icon AND tooltip appears when I hover on the icon AND I can click on the icon
2			clicking on the bond tool icon	bond tool icon is highlighted in the tool panel
3		Polymer editor mode of the Ketcher enabled AND there is highlighted bond tool in the tool panel	clicking on the empty canvas place AND moving a cursor with the mouse button pressed (dragging) AND then stopping pressing the mouse button (dropping)	Ketcher visualize the line representing the bond on the canvas starting from the place of the first click to the place of the actual cursor position while dragging AND Ketcher stops representing the line on the canvas when dropping
4		Polymer editor mode of the Ketcher enabled AND there is at least 1 monomer added to the canvas AND there is highlighted bond tool in the	clicking on the monomer on the canvas AND dragging AND dropping on the empty space of the canvas	Ketcher visualize the line representing the bond on the canvas starting from the monomer to the place of the actual cursor position while dragging AND Ketcher stops representing the line on the canvas when dropping
5		Polymer editor mode of the Ketcher enabled AND there are at least 2 chains on the canvas with at least one monomer in each one of them having Free connection points AND there is highlighted bond tool in the tool panel	dragging from a monomer with a free connection point in the first chain AND dropping on a monomer with a free connection point in the second chain	Ketcher visualize the line representing the peptide bond on the canvas when dragging AND when dropping Ketcher visualize the line from one monomer to the other on the canvas with the ends attached to monomers AND Ketcher aligns the monomers in accordance with the Business Rules table AND Ketcher enumerates the peptide chain and monomers in this chain in accordance with the business rules tables AND Ketcher creates bonds AND Ketcher selects connection points of the monomers in participating in the bond and marks them as Occupied
5.1		conditions from no.5 AND at least one of the chains in question has at least 2 monomers in it	dragging on the monomer at the beginning of one chain AND dropping on the monomer at the end of other chains	Ketcher turns those 2 chains into one single chain AND enumerates the chains on the canvas with the beginning set on the beginning of the second chain and end set to the end of the first chain AND bond is created using Carboxyl end of the end monomer from the second chain and Amino end from the monomer at the beginning of the first chain
5.2		conditions from no.5 AND both chains have only 1 monomer in it	dragging from monomer in the first chain AND dropping on the monomer in the second chain	Ketcher turns those 2 chains into one single chain with the monomer that was placed more on the left on the canvas as the beginning and the monomer that was placed more on the right on the canvas as the end AND bond is created using Carboxyl end of the beginning monomer from the chain and Amino end from the monomer the end of the chain
5.3		conditions from no.5 AND having monomer with free connection in the middle of one chain (this means the chain should be at least 3 monomers long) AND having monomer with 1 free connection in any place of another chain	dragging from a monomer with free connection in the middle of the chain AND dropping at the monomer having a 1 free connection in another chain (if maybe the end or not)	Ketcher does not change chain arrangement on the canvas AND bond is created using free connection points in each connected monomer
5.4		conditions from no.5 AND having monomer with at least 1 free connection in the middle of one chain (this means the chain should be at least 3 monomers long) AND having monomer with at least 2 free connections in any place of another chain	dragging from a monomer with free connection in the middle of the chain AND dropping at the monomer having at least 2 free connections in another chain	Ketcher displays the message for the user with the ability to select the connection points for bond creation AND Ketcher displays: monomers names and structure and provides the ability to select from the free connection points of each of the monomer AND when the user confirms the selection THEN Ketcher does not change chain arrangement on the canvas AND creates the bond using the connection points selected by the user
5.5		conditions from no.5ANDboth chains have at least 2 monomers in them and there is only 1 free connection point at the end (or beginning) of both chains	dragging from the end (beginning) of one chain AND dropping on the end (beginning) of another chain	Ketcher does not change chain arrangement on the canvas AND bond is created using free connection points in each connected monomer
5.6		conditions from no.5 AND both chains have at least 2 monomers in them and there are at least 2 free connection points on the end (or beginning) of one of the chain	dragging from the end (beginning) of one chain AND dropping on the end (beginning) of another chain	Ketcher displays the message for the user with the ability to select the connection points for bond creation AND Ketcher displays: monomers names and structure and provides the ability to select from the free connection points of each of the monomer AND when the user confirms the selection THEN Ketcher does not change chain arrangement on the canvas AND creates the bond using the connection points selected by the user
6		Polymer editor mode of the Ketcher enabled AND there is a chain on the canvas with at least 3 monomers with at least 2 of them having free connection points and separated by at least one monomer between them AND there is highlighted bond tool in the tool panel	dragging from one of the monomers with free connection points AND dropping on the other monomer with a free connection point	Ketcher displays the bond on the canvas AND Ketcher does not change chain & monomers enumeration AND creates a bond with the monomers in question AND represent a chain as on a canvas in accordance with rules for chains with cycle
6.1		conditions from no.6	dragging from the end (beginning) of the chain AND dropping on the beginning (end) of the chain	Ketcher creates a bond using free Amino connection end from the beginning of the chain and Carboxyl connection end from the end of the chain
6.2		conditions from no.6 AND there are 2 monomers with free connection points not at the ends of the chain separated by at least one monomer between them	dragging from one of the monomers with a free connection point in the middle of the chain AND dropping on the other monomer with a free connection point in the middle of the chain	Ketcher creates a bond using a single free connection point of each of the monomer(there can't be 2 free connection points for the monomers in the middle of the chain)
6.3		conditions from no.6 AND here is a monomer with 2 free connection points at the end or beginning of the chain AND there is a monomer with a free connection point in the middle of the chain	dragging from the monomer at the end of the beginning of the chain AND dropping on the monomer in the middle of the chain (or vice versa)	Ketcher displays the message for the user with the ability to select the connection points for bond creation AND Ketcher displays: monomers names and structure and provides the ability to select from the free connection points of each of the monomer AND when the user confirms the selection THEN creates the bond using the connection points selected by the user
7		Polymer editor mode of the Ketcher enabled AND there is at least one monomer on the canvas without a free connection point and at least one other monomer AND there is highlighted bond tool in the	dragging from the monomer with a free connection point to monomer without a free connection point OR dragging from the monomer without free connection points to the monomer with a free connection point OR dragging from monomer without connection point to the monomer without connection point	Ketcher visualize the line representing the peptide bond on the canvas when dragging AND when dropping Ketcher removes the line from the canvas AND indicates that there are no connection points available with the mention of exact monomer on the canvas not having the connection points available with the text "We can't connect those monomers: \name of the monomer without free connection point\ does not have free connection points"