Add PaymentRequest and Payment messages

[x1m3]

No description provided.

[vmidyllic]

it should be under Iden3Protocol domain name

[x1m3]

Also changed PaymentMessageType to same Iden3Protocol domain.

[vmidyllic]

verifiable.ProofType

[vmidyllic]

do not merge til erc20 payment spec, please

cc: @volodymyr-basiuk

[olomix]

The issue I see here is that if we would try to unmarshal the input json into already initialized object, we would not fullfill that constraint that only one field should be non-empty. What do you think about more explicit unmarshaling by explicitly checking json types instead of base our logic on returned errors?

Suggested change

	func (p *PaymentContext) UnmarshalJSON(data []byte) error {
	var str string
	var strCol []string
	var itemCol []interface{}
	if err := json.Unmarshal(data, &str); err == nil {
	p.str = &str
	return nil
	}
	if err := json.Unmarshal(data, &strCol); err == nil {
	p.strCol = strCol
	return nil
	}
	if err := json.Unmarshal(data, &itemCol); err == nil {
	p.itemCol = itemCol
	return nil
	}
	return errors.Errorf("failed to unmarshal PaymentContext: %s", string(data))
	}
	func (p *PaymentContext) UnmarshalJSON(data []byte) error {
	var o any
	err := json.Unmarshal(data, &o)
	if err != nil {
	return err
	}
	switch v := o.(type) {
	case string:
	p.str = &v
	p.strCol = nil
	p.itemCol = nil
	case []any:
	p.str = nil
	p.itemCol = nil
	p.strCol = make([]string, len(v))
	for i := range v {
	s, ok := v[i].(string)
	if !ok {
	p.strCol = nil
	p.itemCol = v
	break
	}
	p.strCol[i] = s
	}
	default:
	return errors.Errorf("failed to unmarshal PaymentContext: %s",
	string(data))
	}
	return nil
	}

[x1m3]

I agree. I like your proposal. Let me change it.

Done,

[vmidyllic]

I have one doubt regarding that. From the protocol persperctive we can have different proof types here. So we can design structure not to break interfaces later.

What do you think @x1m3 @volodymyr-basiuk ?

[vmidyllic]

also it can be an object, not always an array

[x1m3]

Yes. I agree. We need to handle objects and arrays and change Proof structure in a way that can be extended in the future.

[x1m3]

@vmidyllic Internal representation is a collection, but EthereumEip712Signature2021Col is implementing the json unmarshal interface and accepts and object. Output is always a list. So, it is working with single objects or lists.

Naming is not the best.

Regarding diferent ProfTypes we can always change implementation later but, let me try to do a proposal hidding this prooftype into a superobject

[x1m3]

Fixed. Changed it to class that can be extended in the future with other proof types.

[volodymyr-basiuk]

let's call it railsERC20

[volodymyr-basiuk]

Could we define separate type - iden3comm.PaymentType/PaymentRequestType or similar ?
For this fild Type only one value are possible - Iden3PaymentCryptoV1.
The same for Iden3PaymentRailsV1/Request and Iden3PaymentRailsERC20V1/Request

[x1m3]

Done.