Implement a secure, efficient Marketplace Settlement smart contract using Soroban SDK

[Oluwaseyi89]

Description

Implement a secure, efficient Marketplace Settlement smart contract using Soroban SDK that handles the final stage of NFT transactions within NFTopia. This contract will manage escrow, settlement, royalty distribution, and dispute resolution for NFT sales, auctions, and trades on the Stellar blockchain. The settlement contract ensures atomic swaps, prevents front-running, enforces royalties, and provides a trustless environment for buyers and sellers with minimal fees and maximal security.

Technical Scope

1. Settlement Contract Architecture

• Atomic Swap Engine: Ensure either both sides of transaction succeed or both fail
• Multi-Asset Support: Handle XLM and other Stellar assets as payment
• Escrow Management: Secure holding of funds and NFTs during settlement
• Royalty Distribution: Automatic splitting of payments to creators, sellers, and platform
• Dispute Resolution: Time-based release mechanisms and arbitration support
• Gas Optimization: Minimize transaction costs for high-frequency trading

2. Core Settlement Functions

Transaction Initiation

• initiate_sale: Start fixed-price sale with escrow
• initiate_auction: Begin timed auction with bidding
• initiate_trade: Start NFT-for-NFT swap
• initiate_bundle: Handle multi-item transactions

Execution & Settlement

• execute_sale: Finalize sale and transfer assets
• execute_bid: Process winning auction bid
• cancel_transaction: Cancel pending transaction with penalties
• emergency_withdraw: Admin-only recovery for stuck transactions

Royalty & Fee Management

• calculate_royalties: Compute splits for creator, seller, platform
• distribute_funds: Send payments to all parties
• update_fee_structure: Adjust platform fees dynamically
• withdraw_platform_fees: Collect accumulated platform fees

3. Advanced Settlement Features

Auction Mechanics

• Dutch Auctions: Price decreases over time
• English Auctions: Price increases with bidding
• Reserve Prices: Minimum acceptable prices
• Bid Increments: Minimum bid increases
• Automatic Extensions: Sniping protection with time extensions

Security & Trust Mechanisms

• Front-Running Protection: Commit-reveal schemes for bids
• Reentrancy Guards: Protection against reentrancy attacks
• Withdrawal Patterns: Secure fund withdrawal patterns
• Signature Verification: Multi-signature requirements for high-value transactions
• Cooling Periods: Time delays for certain operations

Dispute Resolution System

• Arbitration Escrow: Funds held for dispute resolution
• Time-Based Releases: Automatic release after timeout
• Multi-Sig Arbitration: Multiple trusted arbitrators
• Evidence Submission: Support for submitting dispute evidence
• Reputation System: Integration with user reputation scores

4. Financial Features

Payment Processing

• Multi-Currency Support: XLM, USDC, other Stellar assets
• Payment Splitting: Automatic distribution to multiple parties
• Installment Payments: Support for payment plans
• Escrow Interest: Optional interest accrual in escrow
• Gas Subsidies: Platform can subsidize transaction fees

Fee Structure

• Platform Fees: Configurable percentage or flat fee
• Creator Royalties: Enforced percentage on secondary sales
• Dynamic Pricing: Fees based on transaction size or user tier
• Fee Waivers: Special conditions for fee exemptions
• Fee Distribution: Transparent allocation of collected fees

Contract Specifications

Data Structures

// Transaction state
pub enum TransactionState {
    Pending,
    Funded,
    Executed,
    Cancelled,
    Disputed,
    Resolved,
}

// Sale transaction
pub struct SaleTransaction {
    pub transaction_id: u64,
    pub seller: Address,
    pub buyer: Option<Address>,
    pub nft_address: Address,
    pub token_id: u64,
    pub price: i128,
    pub currency: Asset, // XLM or other Stellar asset
    pub state: TransactionState,
    pub created_at: u64,
    pub expires_at: u64,
    pub escrow_address: Address,
    pub royalty_info: RoyaltyDistribution,
    pub platform_fee: i128,
}

// Auction transaction
pub struct AuctionTransaction {
    pub auction_id: u64,
    pub seller: Address,
    pub nft_address: Address,
    pub token_id: u64,
    pub starting_price: i128,
    pub reserve_price: i128,
    pub highest_bid: i128,
    pub highest_bidder: Option<Address>,
    pub bid_increment: i128,
    pub start_time: u64,
    pub end_time: u64,
    pub state: TransactionState,
    pub bids: Vec<Bid>,
    pub extension_window: u64, // Time extension for last-minute bids
}

// Bid structure
pub struct Bid {
    pub bidder: Address,
    pub amount: i128,
    pub placed_at: u64,
    pub is_committed: bool, // For commit-reveal schemes
    pub commitment_hash: Option<[u8; 32]>,
}

// Royalty distribution
pub struct RoyaltyDistribution {
    pub creator_address: Address,
    pub creator_percentage: u32, // Basis points
    pub seller_percentage: u32, // Basis points
    pub platform_percentage: u32, // Basis points
    pub total_amount: i128,
    pub amounts: HashMap<Address, i128>, // Final amounts for each party
}

// Dispute information
pub struct Dispute {
    pub dispute_id: u64,
    pub transaction_id: u64,
    pub initiator: Address,
    pub reason: String,
    pub evidence_uri: Option<String>,
    pub arbitrators: Vec<Address>,
    pub votes: HashMap<Address, bool>, // true = for initiator, false = against
    pub required_votes: u32,
    pub created_at: u64,
    pub resolved_at: Option<u64>,
    pub resolution: Option<DisputeResolution>,
}

// Fee configuration
pub struct FeeConfig {
    pub platform_fee_bps: u32, // Basis points
    pub minimum_fee: i128,
    pub maximum_fee: i128,
    pub fee_recipient: Address,
    pub dynamic_fee_enabled: bool,
    pub volume_discounts: Vec<VolumeTier>,
    pub vip_exemptions: Vec<Address>,
}

pub struct VolumeTier {
    pub min_volume: i128,
    pub fee_discount_bps: u32,
}

---

Key Functions Signature

// Transaction initiation
pub fn create_sale(
    env: Env,
    seller: Address,
    nft_address: Address,
    token_id: u64,
    price: i128,
    currency: Asset,
    duration_seconds: u64
) -> Result<u64, SettlementError>;

pub fn create_auction(
    env: Env,
    seller: Address,
    nft_address: Address,
    token_id: u64,
    starting_price: i128,
    reserve_price: i128,
    duration_seconds: u64,
    bid_increment: i128
) -> Result<u64, SettlementError>;

// Transaction execution
pub fn execute_sale(
    env: Env,
    transaction_id: u64,
    buyer: Address,
    payment_amount: i128
) -> Result<ExecutionResult, SettlementError>;

pub fn place_bid(
    env: Env,
    auction_id: u64,
    bid_amount: i128,
    commitment_hash: Option<[u8; 32]>
) -> Result<(), SettlementError>;

pub fn reveal_bid(
    env: Env,
    auction_id: u64,
    bid_amount: i128,
    salt: [u8; 32]
) -> Result<(), SettlementError>;

// Royalty and fee management
pub fn distribute_transaction(
    env: Env,
    transaction_id: u64
) -> Result<DistributionResult, SettlementError>;

pub fn calculate_royalties(
    env: Env,
    nft_address: Address,
    token_id: u64,
    sale_price: i128
) -> Result<RoyaltyDistribution, SettlementError>;

// Dispute resolution
pub fn initiate_dispute(
    env: Env,
    transaction_id: u64,
    reason: String,
    evidence_uri: Option<String>
) -> Result<u64, SettlementError>;

pub fn vote_on_dispute(
    env: Env,
    dispute_id: u64,
    vote: bool
) -> Result<(), SettlementError>;

// Administration
pub fn update_fee_config(
    env: Env,
    new_config: FeeConfig
) -> Result<(), SettlementError>;

pub fn emergency_withdraw(
    env: Env,
    transaction_id: u64,
    reason: EmergencyWithdrawalReason
) -> Result<(), SettlementError>;

---

Implementation Plan

File Structure

nftopia-stellar/
├── contracts/
│   ├── marketplace_settlement/
│   │   ├── src/
│   │   │   ├── lib.rs              # Main contract entry point
│   │   │   ├── settlement_core.rs  # Core settlement logic
│   │   │   ├── auction_engine.rs   # Auction mechanics
│   │   │   ├── escrow_manager.rs   # Escrow fund management
│   │   │   ├── royalty_distributor.rs # Royalty calculation and distribution
│   │   │   ├── dispute_resolution.rs # Dispute handling
│   │   │   ├── fee_manager.rs      # Fee calculation and collection
│   │   │   ├── security/
│   │   │   │   ├── atomic_swap.rs  # Atomic swap guarantees
│   │   │   │   ├── frontrun_protection.rs # Anti-front-running measures
│   │   │   │   └── reentrancy_guard.rs
│   │   │   ├── storage/
│   │   │   │   ├── transaction_store.rs
│   │   │   │   ├── auction_store.rs
│   │   │   │   └── dispute_store.rs
│   │   │   ├── events.rs           # Event emission
│   │   │   ├── error.rs            # Error handling
│   │   │   ├── utils/
│   │   │   │   ├── math_utils.rs   # Safe math operations
│   │   │   │   ├── time_utils.rs   # Time-based calculations
│   │   │   │   └── asset_utils.rs  # Asset handling utilities
│   │   │   └── test/
│   │   │       ├── unit/
│   │   │       │   ├── settlement_tests.rs
│   │   │       │   ├── auction_tests.rs
│   │   │       │   └── royalty_tests.rs
│   │   │       └── integration/
│   │   │           ├── end_to_end_tests.rs
│   │   │           └── cross_contract_tests.rs
│   │   ├── Cargo.toml
│   │   ├── Makefile
│   │   └── README.md
│   └── interfaces/
│       ├── src/
│       │   ├── lib.rs
│       │   ├── i_settlement.rs     # Settlement interface
│       │   ├── i_royalty_enforcement.rs
│       │   └── i_dispute_resolution.rs
│       └── Cargo.toml
├── tests/
│   ├── integration/
│   │   ├── marketplace_settlement_tests.rs
│   │   ├── nft_integration_tests.rs
│   │   └── payment_integration_tests.rs
│   └── e2e/
│       ├── auction_workflow_tests.rs
│       ├── dispute_workflow_tests.rs
│       └── performance_tests.rs
└── scripts/
    ├── deploy_settlement.sh
    ├── load_test_auctions.sh
    └── dispute_simulation.sh

---

Directory to Work on:

nftopia-stellar/contracts/marketplace_settlement

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[mexes20]

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[Oluwaseyi89]

@mexes20 please endeavour to star our repo and deliver a quality job. Thank you.

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