Redesign state communication

[lichenma]

Context

Currently, everything works by sending the state variable to the server and then once the server replies we change the state to match the state kept in the server. There problems with this due to heroku having a 2 second delay at times communicating from client to server and over to another client. We want to move to a state where we keep the client states and only perform updates when the server replies to us - figure out a logic for combining states in a way that makes sense.

• implement state combination logic on frontend (separate issue file on server side as well)

[lichenma]

• we do not even need to pass the entire state object all the time -> this may end up saving the speed of some calls and makes the logic and debugging easier since we are only passing the board around

• In order to do this we can keep a complex data object on the backend that stores board, puzzle and history

[lichenma]

The initial implementation will feature state being passed with the following schema:

We will be adding the parameters lastUpdated and lastUpdatedUser -> next step of the process would be to introduce methods to the frontend and backend which only accepts changes that are more recent than the current changes.

In the future for most use cases, only the puzzle object is utilized so we will aim to only pass this aspect of the state to websockets -> to be visited in a future PR

{
   board : Map {

      puzzle: List [
         List [
            Map {
              value: Integer 
              prefilled: Boolean 
              notes: Array
              -->    lastUpdated: Date
              -->    lastUpdatedUser: String
           } 
        ]
      ]

      groupSelected: Array
      choices: Map
      selected: Array
   }

   history : List 
   historyOffset: Integer 
   solution: Array[Array[9]]
}