> For the complete documentation index, see [llms.txt](https://docs.capsulelabs.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.capsulelabs.xyz/capsulenft/developer-walkthroughs/contracts/capsule.sol.md).

# Capsule.sol

## The Capsule NFT Contract

The Capsule NFT contract ("Capsule contract") is the base ERC-721 NFT utilized by the Capsule Protocol. The other contracts (CapsuleFactory.sol and CapsuleMinter.sol) mint, burn, and interact with this contract. Any NFT generated from the Capsule Protocol is of this type.

A new instance of this contract is deployed each time a Capsule Collection is created. 

> [View an example of Capsule.sol verified contract code on Etherscan](https://etherscan.io/address/0x4ced59c19f1f3a9eebd670f746b737acf504d1eb)

### User Interactable Methods

#### lockCollectionCount

```solidity
function lockCollectionCount(uint256 _nftCount) external virtual
```

**Usage**: Lock the collection at a provided NFT count (the collection total Capsule NFT count), preventing any further minting past the given number. The set `maxId` of this collection will be the provided NFT count minus one, for clarity (without subtracting 1, a lock count of `15` would provide for `16` NFTs, as it includes the `0` count).

**Parameters**:

* `_name`: (uint256) - the count at which to lock the Capsule Collection from further minting

***

#### isCollectionLocked

```solidity
function isCollectionLocked() public view returns (bool)
```

**Usage**: Check if the Capsule Collection is locked. This is checked by ensuring the `maxId` is less than the counter.

**Parameters**: (none)

***

#### transferOwnership

```solidity
function transferOwnership(address _newOwner) public virtual
```

**Usage**: Transfer ownership of the Capsule to `_newOwner`. The new owner of the Capsule NFT will be able to call any owner-only methods from the contract.

**Parameters**:

* `_account`: (address) - The address (account) to pass ownership onto. This can also be the zero address.

***

#### tokenURI

```solidity
function tokenURI(uint256 tokenId) public view returns (string)
```

**Usage**: Check the tokenURI of a Capsule at id `tokenId`. The tokenURI will map to the NFT metadata.

**Parameters**:

* `_tokenId`: (uint256) - the id of the NFT

***

#### setTokenURI

```solidity
function setTokenURI(uint256 _tokenId, string _newTokenURI) external
```

**Usage**: Set new token URI for a given tokenId. Only the tokenURI owner, also known as the Metamaster, can set a new URI.

**Parameters**:

* `_tokenId`: (uint256) - the id of the NFT to burn
* `_newTokenURI`: (string) - the new NFT at `_tokenId`'s tokenURI

***

#### updateTokenURIOwner

```solidity
function updateTokenURIOwner(address _newTokenURIOwner) external
```

**Usage**: Update the tokenURIowner. Only the tokenURIOwner, also known as the Metamaster, can call this function.

**Parameters**:

* `_account`: (address) - The new address to become the tokenURIOwner (Metamaster)

***

#### isCollectionMinter

```solidity
function isCollectionMinter(address _account) external view returns (bool)
```

**Usage**: Check if the passed in address of `_account` is allowed to mint from the collection.

**Parameters**:

* `_account`: (address) - The address (account) to check

***

#### exists

```solidity
function exists(uint256 tokenId) external view returns (bool)
```

**Usage**: Check if a Capsule (at id `tokenId`) of the current collection exists.

**Parameters**:

* `_tokenId`: (uint256) - the id of the NFT

***

### User Non-Interactable Methods

#### constructor

```solidity
constructor(string _name, string _symbol, address _tokenURIOwner, bool _isCollectionPrivate) public
```

**Usage**: Called upon creation of Capsule. The CapsuleFactory calls the constructor upon creation of a Capsule Collection.

**Parameters**:

* `_name`: (string) - the name of the Capsule Collection
* `_symbol`: (string) - the symbol of the Capsule Collection
* `_tokenURIOwner`: (address) - the address of the Capsule Collection tokenURIOwner (also known as the Metamaster)
* `_isCollectionPrivate`: (boolean) - whether the Capsule Collection is designated as private

***

#### mint

```solidity
function mint(address _account, string _uri) external
```

**Usage**: Create an NFT from this collection. This method is uneditable by users, as only the CapsuleMinter may mint NFTs from this collection. Users interact with this mint through the CapsuleMinter's `mintCapsule` methods.

**Parameters**:

* `_account`: (address) - the account to receive the NFT
* `_uri`: (string) - the set NFT tokenURI

***

#### burn

```solidity
function burn(address _account, uint256 _tokenId) external
```

**Usage**: Burn an NFT from this collection. This method is uneditable by users, as only the CapsuleMinter may burn NFTs from this collection. Users interact with this burn through the CapsuleMinter's `burnCapsule` methods.

**Parameters**:

* `_account`: (address) - the account that is burning the NFT
* `_tokenId`: (uint256) - the id of the NFT to burn

***

### Key Constants

#### VERSION

```solidity
string VERSION
```

**Usage**: The current version.

***

#### counter

```solidity
uint256 counter
```

**Usage**: The current Capsule Collection counter (used as an id).

***

#### maxId

```solidity
uint256 maxId
```

**Usage**: The maximum id the collection is allowed to mint up to (this may also be set to the `MaxUInt256` to signify no maximum). The maxId may be set to a number lower than the current `counter` or id, in which case no further Capsules may be minted from this collection.

***

#### factory

```solidity
contract ICapsuleFactory factory
```

**Usage**: The address of the CapsuleFactory this Capsule is attached to.

***

#### tokenURIOwner

```solidity
address tokenURIOwner
```

**Usage**: The current tokenURIOwner of the collection - this parameter may also be known as the 'Metamaster'.

***

#### isCollectionPrivate

```solidity
bool isCollectionPrivate
```

**Usage**: A boolean which designates whether the collection is private (`true`) or public (`false`).

***

### Lesser Interesting Functions

#### supportsInterface

```solidity
function supportsInterface(bytes4 interfaceId) public view returns (bool)
```

***

#### \_beforeTokenTransfer

```solidity
function _beforeTokenTransfer(address from, address to, uint256 tokenId) internal
```

***

#### \_burn

```solidity
function _burn(uint256 tokenId) internal
```

***

### Modifiers

#### onlyMinter

```solidity
modifier onlyMinter()
```

***

### Key Events

#### TokenURIOwnerUpdated

```solidity
event TokenURIOwnerUpdated(address oldOwner, address newOwner)
```

***

#### TokenURIUpdated

```solidity
event TokenURIUpdated(uint256 tokenId, string oldTokenURI, string newTokenURI)
```