# Get started with UniRep

Build your own application with UniRep is easy. Here are the guides for you to follow:
- Getting started with [create-unirep-app](https://developer.unirep.io/docs/getting-started/create-unirep-app)
- Getting started with [typescript/javascript](https://developer.unirep.io/docs/getting-started/ts-js)

## Need idea?

- Get some inspiration for what you can you build:
- [What I can build with UniRep?](https://developer.unirep.io/docs/next/what-can-i-build)
- [Applications built by UniRep core contributors](https://developer.unirep.io/docs/next/welcome#-design--deploy-a-customized-attester)

## Questions?
We are at discord! https://discord.gg/VzMMDJmYc5

# Code examples
## Installation

yarn add @unirep/core

## deploy

import { ethers } from 'ethers'
import { deployUnirep } from '@unirep/contracts/deploy'

// connect to a wallet
const privateKey = 'YOUR/PRIVATE/KEY'
const provider = 'YOUR/ETH/PROVIDER'
const deployer = new ethers.Wallet(privateKey, provider)

// deploy unirep contract
const unirepContract = await deployUnirep(deployer)

## connect deployed unirep contract

import { getUnirepContract } from '@unirep/contracts'

const address = 'UNIREP/ADDRESS'
const provider = 'YOUR/ETH/PROVIDER'
const unirep = getUnirepContract(address, provider)

## attester sign up with wallet

// attester wallet
const attester = new ethers.Wallet(privateKey, provider)
// define epoch length
const epochLength = 300 // 300 seconds
// send transaction
const tx = await unirepContract
    .connect(attester)
    .attesterSignUp(epochLength)
await tx.wait()

## user sign up
**User**

import { UserState } from '@unirep/core'
import { defaultProver } from '@unirep/circuits/provers/defaultProver'
import { Identity } from "@semaphore-protocol/identity"

// semaphore Identity
const identity = new Identity()
// generate user state
const userState = new UserState({
  prover: defaultProver, // a circuit prover
  unirepAddress: unirepContract.address,
  provider: provider, // an ethers.js provider
  id: identity
})

// start and sync
await userState.start()
await userState.waitForSync()

// generate signup proof
const { proof, publicSignals } = await userState.genUserSignUpProof()

// stop sync
userState.stop()

**Attester**

// attester sends the tx
const tx = await unirepContract
    .connect(attester)
    .userSignUp(publicSignals, proof)
await tx.wait()

> user can check if he signs up successfully
> **User**
> ```typescript
> await userState.waitForSync()
> console.log(await userState.hasSignedUp()) // true
> ```

## attest
**User**

import { genEpochKey } from '@unirep/utils'
// get epoch from contract
const epoch = await unirepContract.attesterCurrentEpoch(attester.address)
// define nonce
const nonce = 0 // it could be 0 to (NUM_EPOCH_KEY_NONCE - 1) per user
// generate an epoch key
const epochKey = genEpochKey(
    identity.secret,
    BigInt(attester.address),
    epoch,
    nonce
)

**Attester**

// attester sends the tx
const fieldIndex = 0 // the data field that the attester chooses to change
const change = 5 // the amount of the change
// know more about data
// https://developer.unirep.io/docs/protocol/data
const tx = await unirepContract
    .connect(attester)
    .attest(epochKey, epoch, fieldIndex, change)
await tx.wait()

## user state transition
when epoch ends (e.g. 300 seconds finish)
**User**

// calling this to make sure the state is updated
await userState.waitForSync()
// generate the user state transition proof
const { proof, publicSignals } = await userState.genUserStateTransitionProof()
userState.stop()

// sends the tx
const key = 'RELAYER/PRIVATE/KEY'
const signer = new ethers.Wallet(key, provider)
// it doesn't need to be the attester
const tx = await unirepContract
    .connect(signer)
    .userStateTransition(publicSignals, proof)
await tx.wait()

## Prove data

// calling this to make sure the state is updated
await userState.waitForSync()
// the data user wants to prove
// If the user has 5, then he can choose to prove it is more than 3
// see: https://developer.unirep.io/docs/circuits-api/reputation-proof
const proof = await userState.genProveReputationProof({
    minRep: 3
})
// check if proof is valid
console.log(await proof.verify()) // true