remove liquidity example (#1290)

* remove liquidity example

* remove liquidity exmaple

* remove liquidity exmaple

* remove liquidity exmaple

* chore: tidy up remove-liquidity example

* chore: fix typo

Co-authored-by: ankit <ankitgci1@gamil.com>
Co-authored-by: Georgios Konstantopoulos <me@gakonst.com>

examples/remove_liquidity.rs

@@ -0,0 +1,88 @@
+use ethers::prelude::*;
+use eyre::Result;
+use std::{convert::TryFrom, sync::Arc};
+
+abigen!(
+    UniswapV2Router,
+    r#"[
+        removeLiquidity(address tokenA,address tokenB, uint liquidity,uint amountAMin, uint amountBMin, address to, uint ) external returns (uint amountA, uint amountB)
+    ]"#,
+);
+
+abigen!(
+    UniswapV2Pair,
+    r#"[
+        approve(address,uint256)(bool)
+        getReserves()(uint112,uint112,uint32)
+        token0()(address)
+        token1()(address)
+    ]"#
+);
+
+// Remove liquidity from uniswap V2.
+// This example will remove 500 liquidity of 2 test tokens, TA and TB on Rinkeby testnet.
+// This example uses pair contract and uniswap swap contract to remove liquidity.
+#[tokio::main]
+async fn main() -> Result<()> {
+    let provider = Arc::new({
+        // connect to the network
+        let provider = Provider::<Http>::try_from(
+            "https://rinkeby.infura.io/v3/a111fcada47746d990e0e2b7df50d00a",
+        )?;
+        let chain_id = provider.get_chainid().await?;
+
+        // this wallet's private key
+        let wallet = "725fd1619b2653b7ff1806bf29ae11d0568606d83777afd5b1f2e649bd5132a9"
+            .parse::<LocalWallet>()?
+            .with_chain_id(chain_id.as_u64());
+
+        SignerMiddleware::new(provider, wallet)
+    });
+
+    let pair = "0xA6108E4d436bE592bAc12F9A0aB7D9A10d821176".parse::<Address>()?;
+    let pair = UniswapV2Pair::new(pair, provider.clone());
+
+    let router = "0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D".parse::<Address>()?;
+    let router = UniswapV2Router::new(router, provider.clone());
+
+    let (reserve0, reserve1, _) = pair.get_reserves().call().await?;
+
+    println!("Reserves (token A, Token B): ({}, {})", reserve0, reserve1);
+
+    let price =
+        if reserve0 > reserve1 { 1000 * reserve0 / reserve1 } else { 1000 * reserve1 / reserve0 }
+            / 1000;
+    println!("token0 / token1 price = {}", price);
+
+    let liquidity = 100.into();
+
+    println!("Approving the transaction!");
+    let receipt =
+        pair.approve(router.address(), liquidity).send().await?.await?.expect("no receipt found");
+    println!("contract approved succesfully!");
+    println!("{:?}", receipt);
+
+    println!("Removing {} liquidity!", liquidity);
+
+    let token0 = pair.token_0().call().await?;
+    let token1 = pair.token_1().call().await?;
+
+    let receipt = router
+        .remove_liquidity(
+            token0,
+            token1,
+            liquidity,
+            0.into(),
+            0.into(),
+            provider.address(),
+            U256::MAX,
+        )
+        .send()
+        .await?
+        .await?
+        .expect("no receipt for remove_liquidity");
+    println!("liquidity removed succesfully!");
+    println!("{:?}", receipt);
+
+    Ok(())
+}