> For the complete documentation index, see [llms.txt](https://docs.ashswap.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ashswap.io/developers/smart-contracts/stable-pool.md).

# Stable Pool

## Contract Interface

### 1. Notations & Structs

#### 1.1. PoolResultType

```rust
pub type PoolResultType<BigUint> = ManagedVec<BigUint, EsdtTokenPayment<BigUint>>;
```

#### 1.2. TokenAttributes

```rust
pub struct TokenAttributes<M: ManagedTypeApi> {
    pub reserve: BigUint<M>,
    pub rate: BigUint<M>,
}
```

#### 1.3. AddLiquidityAttributes

```rust
pub struct AddLiquidityAttributes<M: ManagedTypeApi> {
    pub token: TokenIdentifier<M>,
    pub attribute: TokenAttributes<M>,
    pub amount_added: BigUint<M>,
    pub total_fee: BigUint<M>,
    pub admin_fee: BigUint<M>,
}
```

#### 1.4. AddLiquidityEvent

```rust
pub struct AddLiquidityEvent<M: ManagedTypeApi> {
    lp_token_amount: BigUint<M>,
    lp_token_supply: BigUint<M>,
    tokens: ManagedVec<M, AddLiquidityAttributes<M>>,
}
```

#### 1.5. RemoveLiquidityAttributes

```rust
pub struct RemoveLiquidityAttributes<M: ManagedTypeApi> {
    pub token: TokenIdentifier<M>,
    pub attribute: TokenAttributes<M>,
    pub amount_removed: BigUint<M>,
}
```

#### 1.6. RemoveLiquidityEvent

```rust
pub struct RemoveLiquidityEvent<M: ManagedTypeApi> {
    lp_token_amount: BigUint<M>,
    lp_token_supply: BigUint<M>,
    tokens: ManagedVec<M, RemoveLiquidityAttributes<M>>,
}
```

#### 1.7. RemoveLiquidityOneCoinEvent

```rust
pub struct RemoveLiquidityOneCoinEvent<M: ManagedTypeApi> {
    lp_token_amount: BigUint<M>,
    lp_token_supply: BigUint<M>,
    total_fee: BigUint<M>,
    admin_fee: BigUint<M>,
    token_out: RemoveLiquidityAttributes<M>,
}
```

#### 1.8. ExchangeAttributes

```rust
pub struct ExchangeAttributes<M: ManagedTypeApi> {
    pub token: TokenIdentifier<M>,
    pub attribute: TokenAttributes<M>,
    pub final_amount: BigUint<M>,
}
```

#### 1.9. ExchangeEvent

```rust
pub struct ExchangeEvent<M: ManagedTypeApi> {
    total_fee: BigUint<M>,
    admin_fee: BigUint<M>,
    token_in: ExchangeAttributes<M>,
    token_out: ExchangeAttributes<M>,
}
```

### 2. Write functions

#### 2.1. Add liquidity

```rust
#[payable("*")]
#[endpoint(addLiquidity)]
fn add_liquidity(&self, mint_amount_min: BigUint, lp_token_receiver: &ManagedAddress) -> PoolResultType<Self::Api>

```

#### 2.2. Remove liquidity

```rust
#[payable("*")]
#[endpoint(removeLiquidity)]
fn remove_liquidity(&self, token_amount_min: MultiValueEncoded<BigUint>) -> PoolResultType<Self::Api>
```

#### 2.3. Exchange

```rust
#[payable("*")]
#[endpoint(exchange)]
fn exchange(&self, token_out: TokenIdentifier, amount_out_min: BigUint) -> PoolResultType<Self::Api>
```

`token_out`: The token id that you want to receive after exchanging.

`amount_out_min`: The minimum amount of `token_out` that you will receive. If the pool returns an amount that is smaller than `amount_out_min` the transaction will be reverted.

### 3. Read functions

#### 3.1. Estimate the exchange output

```rust
#[derive(TopEncode, TopDecode, NestedEncode, NestedDecode, PartialEq, TypeAbi, Clone, ManagedVecItem)]
pub struct TokenAttributes<M: ManagedTypeApi> {
    pub reserve: BigUint<M>,
    pub rate: BigUint<M>,
}

#[derive(TopEncode, TopDecode, NestedEncode, NestedDecode, PartialEq, TypeAbi, Clone, ManagedVecItem)]
pub struct ExchangeAttributes<M: ManagedTypeApi> {
    pub token: TokenIdentifier<M>,
    pub attribute: TokenAttributes<M>,
    pub final_amount: BigUint<M>,
}

#[derive(TopEncode, TopDecode, NestedEncode, NestedDecode, PartialEq, TypeAbi, Clone)]
pub struct ExchangeResultType<M: ManagedTypeApi> {
    pub total_fee: BigUint<M>,
    pub admin_fee: BigUint<M>,
    pub token_in: ExchangeAttributes<M>,
    pub token_out: ExchangeAttributes<M>,
}

#[view(estimateAmountOut)]
fn get_amount_out(&self, token_in: &TokenIdentifier, token_out: &TokenIdentifier, amount_in: BigUint) -> ExchangeResultType<Self::Api>
```

#### 3.2. Estimate add liquidity

```rust
#[derive(TopEncode, TopDecode, NestedEncode, NestedDecode, PartialEq, TypeAbi, Clone)]
pub struct AddLiquidityResultType<M: ManagedTypeApi> {
    pub mint_amount: BigUint<M>,
    pub tokens: ManagedVec<M, AddLiquidityAttributes<M>>,
}

#[view(estimateAddLiquidity)]
fn pool_add_liquidity(&self, token_amount_added: &ManagedVec<BigUint>) -> AddLiquidityResultType<Self::Api>
```

#### 3.3. Estimate remove liquidity

```rust
#[derive(TopEncode, TopDecode, NestedEncode, NestedDecode, PartialEq, TypeAbi, Clone)]
pub struct RemoveLiquidityResultType<M: ManagedTypeApi> {
    pub burn_amount: BigUint<M>,
    pub tokens: ManagedVec<M, RemoveLiquidityAttributes<M>>,
}

#[view(estimateRemoveLiquidity)]
fn pool_remove_liquidity(&self, burn_amount: BigUint) -> RemoveLiquidityResultType<Self::Api>
```

#### 3.4. Get AMP factor

```rust
#[view(getAmpFactor)]
fn get_amp_factor(&self) -> u64
```

#### 3.5. Get pool state

```rust
#[derive(TopEncode, TopDecode, PartialEq, TypeAbi, Debug)]
pub enum State { Inactive, Active, ActiveNoSwaps }

#[view(getState)]
fn state(&self) -> State;
```

#### 3.6. Get LP token identifier

```rust
#[view(getLpTokenIdentifier)]
fn get_lp_token_identifier(&self) -> TokenIdentifier
```

#### 3.7. Get LP token supply

```rust
#[view(getTotalSupply)]
fn get_lp_token_supply(&self) -> BigUint
```

#### 3.8. Get pool tokens

```rust
#[view(getTokens)]
fn get_tokens(&self) -> ManagedVec<TokenIdentifier>
```

#### 3.9. Get token balances

```rust
#[view(getBalances)]
fn get_balances(&self, token: &TokenIdentifier) -> BigUint
```

#### 3.10. Get swap fee

```rust
#[view(getSwapFeePercent)]
fn swap_fee_percent(&self) -> u64;
```

#### 3.11. Get admin fee

```rust
#[view(getAdminFeePercent)]
fn admin_fee_percent(&self) -> u64;
```

### 4. Events

#### 4.1. Add liquidity

```rust
#[event("add_liquidity")]
fn add_liquidity_event(
    &self,
    #[indexed] timestamp: u64,
    #[indexed] caller: &ManagedAddress,
    add_liquidity_event: &AddLiquidityEvent<Self::Api>,
);
```

#### 4.2. Remove liquidity

```rust
#[event("remove_liquidity")]
fn remove_liquidity_event(
    &self,
    #[indexed] timestamp: u64,
    #[indexed] caller: &ManagedAddress,
    remove_liquidity_event: &RemoveLiquidityEvent<Self::Api>,
);
```

#### 4.3. Remove liquidity one coin

```rust
#[event("remove_liquidity_one_coin")]
fn remove_liquidity_one_coin_event(
    &self,
    #[indexed] timestamp: u64,
    #[indexed] caller: &ManagedAddress,
    remove_liquidity_one_coin_event: &RemoveLiquidityOneCoinEvent<Self::Api>,
);
```

#### 4.4. Exchange

```rust
#[event("exchange")]
fn exchange_event(
    &self,
    #[indexed] timestamp: u64,
    #[indexed] caller: &ManagedAddress,
    exchange_event: &ExchangeEvent<Self::Api>,
);
```