# Fixed-Term Teller

The  Fixed Term Teller is an implementation of the Bond Base Teller contract specific to handling user bond transactions and tokenizing bond markets where purchases vest in a fixed amount of time (rounded to the day) as ERC1155 tokens.It implements the functions required by the [Fixed-Term Teller Interface](https://dev.bondprotocol.finance/smart-contracts/bond-system/teller-interfaces#fixed-term-teller-interface) and the [Base Teller](https://dev.bondprotocol.finance/smart-contracts/bond-system/teller/base-teller) Abstract Contract. 

It also inherits the ERC1155 standard and is itself the contract which provides information on the Bond Tokens it issues. 

Specifically, it implements the `_handlePayout` function to mint ERC1155 tokens to the user to represent their bond position during a purchase. 

Additionally, it implements the `deploy` (*i.e. stores the metadata for a new ERC1155 token if one does not exist for a combination of underlying token and the maturity date*), `create` (*allows anyone to mint ERC1155 Bond Tokens for a combination of an underlying token and maturity date by paying a fee to the protocol*), and `redeem` (*redeems ERC1155 Bond Tokens that have vested for the underlying token*). 

By design, the tokenization of the Teller is not permissioned. This allows other market participants  to use the same Bond Tokens that Bond Protocol is issuing to create a standard in the market and drive additional liquidity (*less likely for ERC1155, but it is an option*).

## Methods

This section only includes methods not inherited from [Base Teller](https://dev.bondprotocol.finance/smart-contracts/bond-system/teller/base-teller) or [ERC1155](https://github.com/transmissions11/solmate/blob/bff24e835192470ed38bf15dbed6084c2d723ace/src/tokens/ERC1155.sol).

### batchRedeem

```solidity
function batchRedeem(uint256[] tokenIds_, uint256[] amounts_) external nonpayable
```

Redeem multiple fixed-term bond tokens for the underlying tokens (bond tokens must have matured)

#### Parameters

| Name       | Type       | Description                               |
| ---------- | ---------- | ----------------------------------------- |
| tokenIds\_ | uint256\[] | Array of bond token ids                   |
| amounts\_  | uint256\[] | Array of amounts of bond tokens to redeem |

### create

```solidity
function create(contract ERC20 underlying_, uint48 expiry_, uint256 amount_) external nonpayable returns (uint256, uint256)
```

Deposit an ERC20 token and mint a future-dated ERC1155 bond token

#### Parameters

| Name         | Type           | Description                                                                |
| ------------ | -------------- | -------------------------------------------------------------------------- |
| underlying\_ | contract ERC20 | ERC20 token redeemable when the bond token vests                           |
| expiry\_     | uint48         | Timestamp at which the bond token can be redeemed for the underlying token |
| amount\_     | uint256        | Amount of underlying tokens to deposit                                     |

#### Returns

| Name      | Type    | Description                               |
| --------- | ------- | ----------------------------------------- |
| tokenId   | uint256 | ID of the ERC1155 bond token received     |
| amountOut | uint256 | Amount of the ERC1155 bond token received |

### createFeeDiscount

```solidity
function createFeeDiscount() external view returns (uint48)
```

'Create' function fee discount. Amount standard fee is reduced by for partners who just want to use the 'create' function to issue bond tokens. Configurable by policy.

#### Returns

| Name        | Type   | Description |
| ----------- | ------ | ----------- |
| feeDiscount | uint48 | undefined   |

### deploy

```solidity
function deploy(contract ERC20 underlying_, uint48 expiry_) external nonpayable returns (uint256)
```

"Deploy" a new ERC1155 bond token for an (underlying, expiry) pair and return its ID.

#### Parameters

| Name         | Type           | Description                                                                |
| ------------ | -------------- | -------------------------------------------------------------------------- |
| underlying\_ | contract ERC20 | ERC20 token redeemable when the bond token vests                           |
| expiry\_     | uint48         | Timestamp at which the bond token can be redeemed for the underlying token |

#### Returns

| Name    | Type    | Description                                |
| ------- | ------- | ------------------------------------------ |
| tokenId | uint256 | ID of the ERC1155 bond token being created |

### getTokenId

```solidity
function getTokenId(contract ERC20 underlying_, uint48 expiry_) external pure returns (uint256)
```

Get token ID from token and expiry

#### Parameters

| Name         | Type           | Description                     |
| ------------ | -------------- | ------------------------------- |
| underlying\_ | contract ERC20 | Address of the underlying token |
| expiry\_     | uint48         | Expiry of the bond              |

#### Returns

| Name    | Type    | Description          |
| ------- | ------- | -------------------- |
| tokenId | uint256 | ID of the bond token |

### getTokenNameAndSymbol

```solidity
function getTokenNameAndSymbol(uint256 tokenId_) external view returns (string, string)
```

Get the token name and symbol for a bond token

#### Parameters

| Name      | Type    | Description          |
| --------- | ------- | -------------------- |
| tokenId\_ | uint256 | ID of the bond token |

#### Returns

| Name   | Type   | Description       |
| ------ | ------ | ----------------- |
| name   | string | Bond token name   |
| symbol | string | Bond token symbol |

### redeem

```solidity
function redeem(uint256 tokenId_, uint256 amount_) external nonpayable
```

Redeem a fixed-term bond token for the underlying token (bond token must have matured)

#### Parameters

| Name      | Type    | Description                    |
| --------- | ------- | ------------------------------ |
| tokenId\_ | uint256 | ID of the bond token to redeem |
| amount\_  | uint256 | Amount of bond token to redeem |

### tokenMetadata

```solidity
function tokenMetadata(uint256) external view returns (bool active, contract ERC20 payoutToken, uint48 expiry, uint256 supply)
```

#### Parameters

| Name      | Type    | Description          |
| --------- | ------- | -------------------- |
| tokenId\_ | uint256 | ID of the bond token |

#### Returns

| Name        | Type           | Description                                                             |
| ----------- | -------------- | ----------------------------------------------------------------------- |
| active      | bool           | Whether the bond token has been created                                 |
| payoutToken | contract ERC20 | Address of the underlying token                                         |
| expiry      | uint48         | Timestamp when the bond token can be exchanged for the underlying token |
| supply      | uint256        | Total supply of the bond token                                          |

## Events

### ERC1155BondTokenCreated

```solidity
event ERC1155BondTokenCreated(uint256 tokenId, contract ERC20 indexed payoutToken, uint48 indexed expiry)
```

#### Parameters

| Name                  | Type           | Description                                                            |
| --------------------- | -------------- | ---------------------------------------------------------------------- |
| tokenId               | uint256        | ID of the ERC1155 bond token                                           |
| payoutToken `indexed` | contract ERC20 | Address of the underlying token                                        |
| expiry `indexed`      | uint48         | Timestamp when the bond token can be redeemed for the underlying token |