# Liquidity Provision

* Mint
  * Function: `mint`
  * Pull liquidity of a token pair from `msg.sender` (should have approved enough amount), provide liquidity to Uniswap v3 pool, keep the liquidity position NFT in Particle contract. At the same time, create `LiquidityPosition.Info` to bookkeep the ownership of `tokenId` to `msg.sender`.
* Increase liquidity
  * Function: `increaseLiquidity`
  * Increase liquidity to existing `tokenId` via Uniswap’s NonfungiblePositionManager.
  * Note: there are two internal functions of `increaseLiquidity`. The external facing one (takes `lps` storage as calldata input) authenticates the caller. The inner function is used in two cases: (1) this external facing function for an LP to add liquidity and (2) returning liquidity back to LP when closing a position in `_closePosition`.
* Decrease liquidity
  * Function: `decreaseLiquidity`
  * Decrease liquidity from existing `tokenId` via Uniswap’s NonfungiblePositionManager.
  * Note: the decreased liquidity is stored in owed tokens. Withdrawing the actual amount needs the `collectLiquidity` function below.
  * Note: similar to `increaseLiquidity`, there are two internal functions of `decreaseLiquidity`. The external one (takes `lps` storage as calldata input) authenticates the caller. The inner function is used in two cases: (1) this external facing function for an LP to decrease liquidity and (2) borrowing liquidity from an LP position in `openPosition`.
* Collect liquidity
  * Function: `collectLiquidity`
  * Collect fees and liquidity from owed tokens to the caller (LP) wallet.
  * Note: there are two internal functions of `collectLiquidity`. The external one (takes `lps` storage as calldata input) authenticates the caller. The inner function is used in two cases: (1) this external facing function for an LP to collect fees and (2) borrowing liquidity from an LP position in `openPosition`.
  * Note: this function imposes `amountMax` such that borrowing liquidity wouldn’t withdraw more amounts than requested.