Implement a comprehensive, standards-compliant NFT contract using Soroban SDK

[Oluwaseyi89]

Description

Implement a comprehensive, standards-compliant NFT contract using Soroban SDK that serves as the core digital asset representation within the NFTopia ecosystem. This contract will define the fundamental NFT standard for Stellar, supporting token minting, transfers, ownership management, metadata storage, and royalty enforcement while ensuring security, efficiency, and interoperability with existing NFT marketplaces and wallets.

Technical Scope

1. NFT Contract Architecture

• Standards Compliance: Implement ERC-721 equivalent with Stellar optimizations
• Gas-Efficient Design: Optimize for Stellar's fee structure and transaction costs
• Upgradeable Pattern: Support for contract upgrades via transparent proxy
• Batch Operations: Enable efficient batch transfers and approvals
• Metadata Flexibility: Support for on-chain and off-chain (IPFS) metadata
• Royalty Standard: Implement EIP-2981 equivalent for universal royalty support

2. Core Contract Functions

Token Management

• mint: Create new NFT with specified owner and metadata
• burn: Destroy NFT with proper authorization checks
• transfer: Transfer ownership between addresses
• safe_transfer_from: Secure transfer with receiver contract validation
• batch_transfer: Transfer multiple tokens in single transaction

Ownership & Approvals

• owner_of: Query token owner
• balance_of: Get token count for address
• approve: Grant transfer permission for specific token
• set_approval_for_all: Grant/revoke transfer permissions for all tokens
• get_approved: Check approved address for token
• is_approved_for_all: Check global approval status

Metadata Management

• token_uri: Retrieve metadata URI
• token_metadata: Get structured metadata (on-chain)
• set_token_uri: Update metadata URI (owner/admin only)
• set_base_uri: Update base URI for collection (admin only)
• freeze_metadata: Permanently lock metadata (immutable mode)

3. Advanced NFT Features

Royalty & Secondary Sales

• set_royalty_info: Configure royalty percentage and recipient
• get_royalty_info: Query royalty information for token
• Royalty Distribution: Automatic royalty calculation on transfers
• Marketplace Compatibility: Support for OpenSea, Rarible, etc. royalty standards
• Secondary Sale Tracking: Record sale history for provenance

Access Control & Security

• Role-Based Access Control: Owner, admin, minter, burner roles
• Pausable Functionality: Ability to pause minting/transfers
• Time-locked Operations: Scheduled reveals and releases
• Whitelist Management: Controlled access for minting
• Anti-Sniping Protection: Measures against last-minute bidding attacks

Interoperability Features

• Cross-Contract Support: Integration with marketplace, auction contracts
• Stellar Asset Wrapping: Convert between Stellar native assets and NFTs
• Event Emission: Comprehensive event system for indexers
• Interface Compliance: ERC-165 equivalent for interface detection
• Metadata Standards: OpenSea metadata standard support

4. Security & Compliance

Security Measures

• Reentrancy Protection: Guard against reentrancy attacks
• Input Validation: Comprehensive parameter validation
• Safe Math Operations: Overflow/underflow protection
• Access Control Validation: Role-based permission checks
• Gas Limit Considerations: Prevent out-of-gas attacks

Compliance Features

• Provenance Tracking: Maintain immutable creation/transfer history
• Licensing Integration: Support for NFT licenses (CC0, proprietary)
• Regulatory Considerations: Support for jurisdictional requirements
• Anti-Money Laundering: Optional transaction monitoring hooks
• Data Privacy: GDPR-compliant data handling where applicable

Contract Specifications

Data Structures

// Core NFT data
pub struct TokenData {
    pub id: u64,
    pub owner: Address,
    pub approved: Option<Address>,
    pub metadata_uri: String,
    pub created_at: u64,
    pub creator: Address,
    pub royalty_percentage: u32, // Basis points (0-10000)
    pub royalty_recipient: Address,
    pub attributes: Vec<TokenAttribute>,
    pub edition_number: Option<u32>, // For limited editions
    pub total_editions: Option<u32>, // For limited editions
}

// Token attribute for on-chain metadata
pub struct TokenAttribute {
    pub trait_type: String,
    pub value: String,
    pub display_type: Option<String>, // "number", "date", "boost_percentage"
}

// Collection configuration
pub struct CollectionConfig {
    pub name: String,
    pub symbol: String,
    pub base_uri: String,
    pub max_supply: Option<u64>,
    pub mint_price: Option<i128>, // Optional mint cost in stroops
    pub is_revealed: bool,
    pub royalty_default: RoyaltyInfo,
    pub metadata_is_frozen: bool,
}

// Royalty information
pub struct RoyaltyInfo {
    pub recipient: Address,
    pub percentage: u32, // Basis points
}

// Role-based access control
pub enum Role {
    Owner,
    Admin,
    Minter,
    Burner,
    MetadataUpdater,
}

---

Key Functions Signature

// Core NFT functions
pub fn mint(
    env: Env,
    to: Address,
    metadata_uri: String,
    attributes: Vec<TokenAttribute>,
    royalty_override: Option<RoyaltyInfo>
) -> Result<u64, ContractError>;

pub fn safe_transfer_from(
    env: Env,
    from: Address,
    to: Address,
    token_id: u64,
    data: Option<Bytes>
) -> Result<(), ContractError>;

pub fn burn(
    env: Env,
    token_id: u64,
    confirm: bool
) -> Result<(), ContractError>;

// Royalty functions
pub fn get_royalty_info(
    env: Env,
    token_id: u64,
    sale_price: i128
) -> Result<(Address, i128), ContractError>;

pub fn set_default_royalty(
    env: Env,
    recipient: Address,
    percentage: u32
) -> Result<(), ContractError>;

// Batch operations
pub fn batch_mint(
    env: Env,
    recipients: Vec<Address>,
    metadata_uris: Vec<String>,
    attributes: Vec<Vec<TokenAttribute>>
) -> Result<Vec<u64>, ContractError>;

pub fn batch_transfer(
    env: Env,
    from: Address,
    to: Address,
    token_ids: Vec<u64>
) -> Result<(), ContractError>;

---

Implementation Plan

File Structure

nftopia-stellar/
├── contracts/
│   ├── nft_contract/
│   │   ├── src/
│   │   │   ├── lib.rs              # Main contract entry point
│   │   │   ├── token.rs            # Token data structures and logic
│   │   │   ├── transfer.rs         # Transfer and approval logic
│   │   │   ├── metadata.rs         # Metadata management
│   │   │   ├── royalty.rs          # Royalty calculation and enforcement
│   │   │   ├── access_control.rs   # Role-based access control
│   │   │   ├── storage.rs          # Storage layout and management
│   │   │   ├── events.rs           # Event definitions and emission
│   │   │   ├── error.rs            # Error types and handling
│   │   │   ├── utils.rs            # Utility functions
│   │   │   ├── interface.rs        # Contract interface definitions
│   │   │   └── test/
│   │   │       ├── unit_tests.rs
│   │   │       └── integration_tests.rs
│   │   ├── Cargo.toml
│   │   ├── Makefile
│   │   └── README.md
│   └── interfaces/
│       ├── src/
│       │   ├── lib.rs
│       │   ├── i_nft.rs            # Core NFT interface
│       │   ├── i_royalty.rs        # Royalty interface
│       │   ├── i_metadata.rs       # Metadata interface
│       │   └── i_access_control.rs # Access control interface
│       └── Cargo.toml
├── tests/
│   ├── integration/
│   │   ├── nft_workflow_tests.rs
│   │   ├── royalty_tests.rs
│   │   └── batch_operation_tests.rs
│   └── e2e/
│       ├── marketplace_integration.rs
│       └── wallet_integration.rs
└── scripts/
    ├── deploy_nft.sh
    ├── verify_metadata.sh
    └── upgrade_contract.sh

---

Directory to Work on:

nftopia-stellar/contracts/nft_contract

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[raizo07]

@raizo07 has applied to work on this issue as part of the Stellar Wave Program's 1st wave.

I'd like to work on this

ℹ️ Repo Maintainers: To accept this application, review their application or assign @raizo07 to this issue.

[Oluwaseyi89]

@raizo07 please endeavour to star our repo and deliver a quality job. Thank you.

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Congratulations, @raizo07! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on January 31, 2026.

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