xdr: add helper functions for contract events

[DavidLiedle]

This commit addresses TODOs in the contract events processor by moving frequently-used helper functions to the XDR package where they belong.

Changes:

• Add GetTopics() and GetData() methods to ContractEventBody
• Add ToContractAddress() method to Hash for contract ID conversion
• Add Serialize() method to ScVal for consistent serialization
• Add SerializeScValArray() for array serialization
• Update contract_events.go and contract_data.go to use new XDR methods
• Remove duplicate code from processors

These changes improve code reusability and maintainability by centralizing XDR-related functionality in the appropriate package.

🤖 Generated with Claude Code

[Copilot]

Pull Request Overview

This PR addresses technical debt by moving XDR-related helper functions from processor packages to the XDR package where they logically belong, improving code organization and reusability.

• Adds helper methods to XDR types for extracting contract event data and serialization
• Moves contract event processing utilities from processors to the XDR package
• Updates processors to use the new centralized XDR methods

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
xdr/scval_helpers.go	Adds ScVal serialization methods moved from processors
xdr/hash.go	Adds ToContractAddress() method for converting Hash to contract address
xdr/event.go	Adds GetTopics() and GetData() methods to ContractEventBody
processors/contract/contract_events.go	Updates to use new XDR methods and removes duplicated functions
processors/contract/contract_data.go	Updates to use new ScVal.Serialize() method

[Copilot]

The panic message uses string concatenation with fmt.Sprintf which is inefficient. Consider using fmt.Sprintf directly: panic(fmt.Sprintf("unsupported event body version: %d", eb.V))

Suggested change

	panic("unsupported event body version: " + fmt.Sprintf("%d", eb.V))
	panic(fmt.Sprintf("unsupported event body version: %d", eb.V))

[Copilot]

The panic message uses string concatenation with fmt.Sprintf which is inefficient. Consider using fmt.Sprintf directly: panic(fmt.Sprintf("unsupported event body version: %d", eb.V))

Suggested change

	panic("unsupported event body version: " + fmt.Sprintf("%d", eb.V))
	panic(fmt.Sprintf("unsupported event body version: %d", eb.V))

[Copilot]

Consider returning an error instead of panicking to allow callers to handle unsupported versions gracefully. Panicking can crash the application and makes error handling more difficult.

Suggested change

	func (eb ContractEventBody) GetTopics() []ScVal {
	switch eb.V {
	case 0:
	return eb.MustV0().Topics
	default:
	panic("unsupported event body version: " + fmt.Sprintf("%d", eb.V))
	}
	}
	// GetData extracts the data from a contract event body.
	// This is a helper function to abstract the versioning of ContractEventBody.
	func (eb ContractEventBody) GetData() ScVal {
	switch eb.V {
	case 0:
	return eb.MustV0().Data
	default:
	panic("unsupported event body version: " + fmt.Sprintf("%d", eb.V))
	func (eb ContractEventBody) GetTopics() ([]ScVal, error) {
	switch eb.V {
	case 0:
	return eb.MustV0().Topics, nil
	default:
	return nil, errors.New("unsupported event body version: " + fmt.Sprintf("%d", eb.V))
	}
	}
	// GetData extracts the data from a contract event body.
	// This is a helper function to abstract the versioning of ContractEventBody.
	func (eb ContractEventBody) GetData() (ScVal, error) {
	switch eb.V {
	case 0:
	return eb.MustV0().Data, nil
	default:
	return ScVal{}, errors.New("unsupported event body version: " + fmt.Sprintf("%d", eb.V))

[Copilot]

Consider returning an error instead of panicking to allow callers to handle unsupported versions gracefully. Panicking can crash the application and makes error handling more difficult.

Suggested change

	func (eb ContractEventBody) GetTopics() []ScVal {
	switch eb.V {
	case 0:
	return eb.MustV0().Topics
	default:
	panic("unsupported event body version: " + fmt.Sprintf("%d", eb.V))
	}
	}
	// GetData extracts the data from a contract event body.
	// This is a helper function to abstract the versioning of ContractEventBody.
	func (eb ContractEventBody) GetData() ScVal {
	switch eb.V {
	case 0:
	return eb.MustV0().Data
	default:
	panic("unsupported event body version: " + fmt.Sprintf("%d", eb.V))
	func (eb ContractEventBody) GetTopics() ([]ScVal, error) {
	switch eb.V {
	case 0:
	return eb.MustV0().Topics, nil
	default:
	return nil, fmt.Errorf("unsupported event body version: %d", eb.V)
	}
	}
	// GetData extracts the data from a contract event body.
	// This is a helper function to abstract the versioning of ContractEventBody.
	func (eb ContractEventBody) GetData() (ScVal, error) {
	switch eb.V {
	case 0:
	return eb.MustV0().Data, nil
	default:
	return ScVal{}, fmt.Errorf("unsupported event body version: %d", eb.V)