# Getting Started

Library to interact with the GEB smart contracts. Manage your safes, mint stablecoins, inspect the system state, and much more.

The library is written in Typescript with full typing support. It allows access to the low level API to directly interact with the contracts.

## Install

```
npm install geb.js
```

## Dependencies

At the moment, Geb.js requires to use [Ether.js](https://www.npmjs.com/package/ethers) V5. In the future we will support Web3.

```
npm install ethers
```

## Documentation

Full API documentation is available [here](https://docs.reflexer.finance/geb-js/gettingstarted).

## Examples

This is a complete example of how you can inspect a SAFE and also open a new one using your own proxy:

```typescript
import { ethers, utils as ethersUtils } from 'ethers'
import { Geb, utils } from 'geb.js'

// Setup Ether.js
const provider = new ethers.providers.JsonRpcProvider(
    'http://kovan.infura.io/<API KEY>'
)
const wallet = new ethers.Wallet('0xdefiisawesome...', provider)

// Create the main GEB object
const geb = new Geb('kovan', provider)

// Get a SAFE
const safe = await geb.getSafe(4)
console.log(`Safe id 4 has: ${utils.wadToFixed(safe.debt).toString()} worth of debt.`)
console.log(`It will get liquidated if ETH price falls below ${(await safe.liquidationPrice())?.toString()} USD.`)

// Open a new SAFE, lock ETH and draw system coins in a single transaction using a proxy
// Note: Before doing this you need to create your own proxy

// We first need to check that the system didn't reach the debt ceiling so that we can
// mint more system coins.
const globalDebt = await geb.contracts.safeEngine.globalDebt()
const debtCeiling = await geb.contracts.safeEngine.globalDebtCeiling()
const systemCoinsToDraw = ethersUtils.parseEther('15')
if(globalDebt.add(systemCoinsToDraw).gt(debtCeiling)) {
    throw new Error('Debt ceiling too low, not possible to draw this amount of system coins.')
}

// We're good to mint some system coins! 
const proxy = await geb.getProxyAction(wallet.address)
const tx = proxy.openLockETHAndGenerateDebt(
    ethersUtils.parseEther('1'), // Lock 1 Ether
    utils.ETH_A,                 // Of collateral type ETH_A
    systemCoinsToDraw            // And draw 15 system coins
)

tx.gasPrice = ethers.BigNumber.from('80').mul('1000000000') // Set the gas price to 80 Gwei
const pending = await wallet.sendTransaction(tx) // Send the transaction
console.log(`Transaction ${pending.hash} waiting to be mined...`)
await pending.wait() // Wait for it to be mined
console.log('Transaction mined, safe opened!')
```

## Additional examples

In the examples below we assume that variables are defined like in the complete example above.

1. [Deploy a new proxy](#deploy-a-new-proxy)
2. [Partial repay of safe debt](#partial-repay-of-safe-debt)
3. [Complete repay of safe debt](#complete-repay-of-safe-debt)
4. [Withdraw Ether collateral](#withdraw-ether-collateral)
5. [Make direct contract calls](#make-direct-contract-calls)
6. [Multicall](#Multicall)

### Deploy a new proxy

```typescript
const tx = geb.deployProxy()
await wallet.sendTransaction(tx)
```

### Partial repayment of safe debt

```typescript
const proxy = await geb.getProxyAction("0xdefidream...")

// You first need to approve your proxy to spend your system coins
let tx =  geb.contracts.coin.approve(proxy.proxyAddress, ethers.constants.MaxUint256)
await wallet.sendTransaction(tx)

// Repay 1 system coin worth of debt for SAFE #4
tx = proxy.repayDebt(4, ethersUtils.parseEther('1'))
await wallet.sendTransaction(tx)
```

### Complete repayment of safe debt

```typescript
const proxy = await geb.getProxyAction("0xdefidream...")

// You first need to approve your proxy to spend your system coins
let tx =  geb.contracts.coin.approve(proxy.proxyAddress, ethers.constants.MaxUint256)
await wallet.sendTransaction(tx)

// Repay all debt of SAFE #4
tx = proxy.repayAllDebt(4)
await wallet.sendTransaction(tx)
```

### Withdraw Ether collateral

```typescript
const proxy = await geb.getProxyAction("0xdefidream...")
// Unlock 1 ETH of collateral from SAFE #4 and transfer it to its owner 
const tx = proxy.freeETH(4, ethersUtils.parseEther('1'))
await wallet.sendTransaction(tx)
```

### Repay all debt and withdraw all collateral

```typescript
const proxy = await geb.getProxyAction("0xdefidream...")
const safe = await geb.getSafe(4)

// You first need to approve your proxy to spend your system coins
let tx =  geb.contracts.coin.approve(proxy.proxyAddress, ethers.constants.MaxUint256)
await wallet.sendTransaction(tx)

// Pay back everything and get your ETH back into your wallet
const tx = proxy.repayAllDebtAndFreeETH(4, safe.collateral)
await wallet.sendTransaction(tx)
```

### Make direct contract calls

Geb.js exposes all contract APIs of all core contracts in the `Geb.contracts` object. Solidity functions that are read-only (`view` or `pure`) return asynchronously the expected value from the chain. State changing functions will return a transaction object to passed to `ether.js` or `web3`.

```typescript
// Fetch some system parameters from their respective contracts
const surplusBuffer = await geb.contracts.accountingEngine.surplusBuffer()
const { stabilityFee } = await geb.contracts.taxCollector.collateralTypes(utils.ETH_A)

// Liquidate a Safe
const tx = geb.contracts.liquidationEngine.liquidateSAFE(utils.ETH_A,"0xdefidream...");
await wallet.sendTransaction(tx)
```

### Multicall

Useful to bundle read-only calls in a single RPC call:

```typescript
const [ globalDebt, collateralInfo ] = await geb.multiCall([
    geb.contracts.safeEngine.globalDebt(true), // !! Note the last parameter set to true.
    geb.contracts.safeEngine.collateralTypes(utils.ETH_A, true),
])
```