> For the complete documentation index, see [llms.txt](https://docs-v4.venus.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs-v4.venus.io/technical-reference/reference-core-pool/prime/prime-lens.md).

# Prime lens

## PrimeLens

PrimeLens is a read-only helper contract for off-chain APR queries against PrimeV2. It is kept separate from PrimeV2 to stay within the EVM contract-size limit. It holds an immutable reference to a PrimeV2 instance and derives values from PrimeV2 and PrimeLiquidityProvider state.

## Solidity API

#### primeV2

The PrimeV2 instance this lens reads from (set in the constructor)

```solidity
contract IPrimeV2WithStorage primeV2
```

***

#### constructor

```solidity
constructor(address primeV2_)
```

**Parameters**

| Name      | Type    | Description                     |
| --------- | ------- | ------------------------------- |
| primeV2\_ | address | Address of the PrimeV2 contract |

**❌ Errors**

* Throw InvalidAddress if primeV2\_ is the zero address

***

#### calculateAPR

Returns supply and borrow APR for a user in a given market, based on current state.

```solidity
function calculateAPR(address market, address user) external view returns (struct IPrimeV2.APRInfo aprInfo)
```

**Parameters**

| Name   | Type    | Description                           |
| ------ | ------- | ------------------------------------- |
| market | address | The market for which to fetch the APR |
| user   | address | The account for which to get the APR  |

**Return Values**

| Name    | Type                    | Description                                      |
| ------- | ----------------------- | ------------------------------------------------ |
| aprInfo | struct IPrimeV2.APRInfo | APR information for the user in the given market |

The `APRInfo` struct contains:

```solidity
struct APRInfo {
  uint256 supplyAPR;          // supply APR of the user in BPS
  uint256 borrowAPR;          // borrow APR of the user in BPS
  uint256 totalScore;         // total score of the market
  uint256 userScore;          // score of the user
  uint256 xvsBalanceForScore; // XVS balance of the user used for score
  uint256 capital;            // capital of the user
  uint256 cappedSupply;       // capped supply of the user
  uint256 cappedBorrow;       // capped borrow of the user
  uint256 supplyCapUSD;       // supply cap of the user in USD
  uint256 borrowCapUSD;       // borrow cap of the user in USD
}
```

***

#### estimateAPR

Returns supply and borrow APR for a user in a given market based on hypothetical supply, borrow and XVS staked amounts. The user's score is recomputed from the supplied inputs (subtracting their existing market score and re-adding the estimated one), so the result reflects what the APR would be under the provided position.

```solidity
function estimateAPR(address market, address user, uint256 borrow, uint256 supply, uint256 xvsStaked) external view returns (struct IPrimeV2.APRInfo aprInfo)
```

**Parameters**

| Name      | Type    | Description                           |
| --------- | ------- | ------------------------------------- |
| market    | address | The market for which to fetch the APR |
| user      | address | The account for which to get the APR  |
| borrow    | uint256 | Hypothetical borrow amount            |
| supply    | uint256 | Hypothetical supply amount            |
| xvsStaked | uint256 | Hypothetical staked XVS amount        |

**Return Values**

| Name    | Type                    | Description                                                                                |
| ------- | ----------------------- | ------------------------------------------------------------------------------------------ |
| aprInfo | struct IPrimeV2.APRInfo | APR information for the user in the given market (same `APRInfo` struct as `calculateAPR`) |

***

#### incomeDistributionYearly

The total income that will be distributed to Prime token holders for a market over a year. Computed as the PrimeLiquidityProvider effective distribution speed for the market's underlying multiplied by `blocksOrSecondsPerYear`.

```solidity
function incomeDistributionYearly(address vToken) public view returns (uint256 amount)
```

**Parameters**

| Name   | Type    | Description                                    |
| ------ | ------- | ---------------------------------------------- |
| vToken | address | The market for which to fetch the total income |

**Return Values**

| Name   | Type    | Description                        |
| ------ | ------- | ---------------------------------- |
| amount | uint256 | The annualized distribution income |

***


---

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