Feat: Implement tba acc contract

[Otaiki1]

TBA Account Contract Implementation

This PR closes #1

Summary

This PR implements the core TBA (Token Bound Account) Account contract, completing the foundational infrastructure for the Token Bound Account system on Stellar/Soroban. The contract enables NFTs to have their own smart accounts that can hold assets and execute transactions.

Changes

Core Functionality

1. Nonce Tracking

• Added Nonce to the DataKey enum for transaction nonce storage
• Implemented get_nonce() and increment_nonce() helper functions
• Added public nonce() getter function to query the current nonce
• Nonce starts at 0 and increments with each transaction execution

2. Transaction Execution

• Implemented execute() function that allows the TBA account to execute transactions on other contracts
• Function signature: execute(env: Env, to: Address, func: Symbol, args: Vec<Val>) -> Vec<Val>
• Includes proper authorization checks (only NFT owner can execute)
• Automatically increments nonce on each execution
• Emits TransactionExecutedEvent for transaction tracking

3. Event Emission

• Added TransactionExecutedEvent struct with fields:
  • to: Address - Target contract address
  • func: Symbol - Function name being called
  • nonce: u64 - Transaction nonce
• Events are emitted via Soroban's native event system

4. Authorization

• Maintained existing __check_auth() implementation for CustomAccountInterface
• Updated to use correct Soroban SDK types (BytesN<64> for signatures)
• Fixed imports to use soroban_sdk::auth::Context
• Proper authorization flow ensures only NFT owner can control the account

Code Quality

Fixes

• Fixed import statements for Context and signature types
• Corrected invoke_contract usage with proper type annotations
• Fixed Val conversion for require_auth_for_args
• Updated token() function to handle chain_id (set to 0 as placeholder)

Test Suite

• Created comprehensive test suite in contracts/tba_account/src/test.rs
• Tests cover:
  • ✅ Initialization (success case)
  • ✅ Re-initialization prevention (panic test)
  • ✅ Getter functions (token_contract, token_id, token, nonce)
  • ✅ Nonce initial value verification
  • ✅ Execute before initialization (panic test)
• All 5 tests passing

Files Modified

• contracts/tba_account/src/lib.rs

  • Added Nonce storage and helper functions
  • Added TransactionExecutedEvent struct
  • Implemented execute() function
  • Fixed imports and type conversions
  • Added nonce() getter function

• contracts/tba_account/src/test.rs (new file)

  • Comprehensive test suite with 5 test cases
  • Mock NFT contract for testing
  • Tests for initialization, getters, and error cases

Technical Details

Storage

• Uses instance storage for all data (nonce, token contract, token ID, etc.)
• Nonce stored as u64 type
• All storage keys defined in DataKey enum

Authorization Flow

1. execute() verifies contract is initialized
2. Queries NFT contract for current owner
3. Requires authorization from NFT owner via require_auth()
4. Increments nonce
5. Emits event
6. Executes target contract call

Soroban-Specific Implementation

• Uses env.invoke_contract() for contract calls (not raw calls like Solidity)
• Uses env.events().publish() for event emission
• Uses require_auth() for Stellar's native authorization
• Uses Symbol for function names
• Uses Vec<Val> for function arguments (Soroban's universal value type)

Testing

cargo test --package tba_account

Results:

• ✅ 5 tests passing
• ✅ 0 tests failing
• ✅ Contract compiles without errors
• ✅ No linter errors

Compatibility

• Compatible with ERC-6551 pattern (token() returns chain_id, contract, token_id tuple)
• Follows Soroban best practices
• Integrates with CustomAccountInterface for native Stellar account abstraction

Next Steps

This implementation completes the core TBA Account contract. Future enhancements could include:

• Support for batch transactions
• Delegate functionality
• Enhanced event tracking
• Integration with TBA Registry contract

Notes

• Warnings about unused get_implementation_hash() and get_salt() functions are expected - these may be used by the Registry contract or future features
• Chain ID is currently set to 0 as a placeholder (Soroban doesn't expose chain_id in the same way as Ethereum)

[manoahLinks]

Thanks for your contribution @Otaiki1