Support subresolvers

[ross-weir]

Support subresolvers, something like:

• Add flag to Resolver box including parent nft id Probably no need for this, would still need to manually verify ids off-chain
  • For a root resolver the parent will be the Registry nft id
  • For subresolvers the parent will be the parent Resolver nft id
• Resolver should maintain a avl tree of subresolvers similar to Registry
• When trading ownership of the Resolver
  • subresolver tree should be cleared
  • maybe also support the current owner burning the subresolver boxes in some way

    
    ### Tasks

• [ ] Combine label & tld registers into single collection of labels (and update contracts accordingly) why did I want to do this? xD
• [ ] Add AVL tree to Resolver contract for subresolvers
• [ ] Add mintSubResolver action to Resolver contract
• [ ] Clear Resolver subresolvers AVL tree when Resolver is sold

[ross-weir]

Traditionally I think subresolvers would be added via the Registry, consider adding subresolver minting as a registry action instead of a resolver action

Some random ideas:

• label register of resolver box becomes a Coll[Coll[Byte]] and can contain multiple labels
• A subdomain is added to the Registry AVLTree alongside regular domains
• When minting a subdomain with the registry you need to provide the resolver box of the domain of the previous level to prove ownership (how would this work when we transfer ownership of a resolver? all subdomains would need to be invalidated, maybe need a way to burn subdomains)

[ross-weir]

Another potential benefit of using the registry to store sub resolvers is offchain code would only need to track one avl tree instead of one avl tree per resolver

Not sure how big a deal this is though

Downside: It would require txns to be submitted by bots since we are interacting with the Registry (with current design)

[ross-weir]

I think each resolver should be responsible for subresolvers for the following reasons:

Pros:

• Minting new subresolvers is simplified, no need for bots to submit transactions
• Selling resolvers is simplified, just clear the subresolver tree (optionally burn subresolvers? could maybe claim back some funds and be a good blockchain citizen by keeping utxos clean). Unclear how this would work if subresolvers were stored in registry

Cons:

• Need to keep track of an AVL tree for each resolver (including every single sub resolver), this is a BIG con. For example if I wanted to resolver the domain pay.me.example.erg I would need to first replay all avl tree actions in example.erg to ensure the me.example.erg exists with a valid nft, then replay all avl tree actions in me.example.erg to validate pay.me.example.erg exists with a valid nft and so on.

[ross-weir]

2 difficult questions depending on which approach we take. Still lean towards Resolver managing subresolvers but we could explore more solutions.

Registry tracking subresolvers

How do we ensure subresolvers of a domain are removed from the registry when a resolver is traded/sold?

Resolver tracking subresolvers

How do we efficiently resolve a chain of subresolvers? It requires processing all AVL trees for ALL resolvers and their subresolvers, not sure if this is practical. May need some specialised indexing.