import Web3 from 'web3'
import { constants } from './constants'

const errorMsgNoMetamaskAccount = `You haven't chosen any account in MetaMask.
Please choose your initial key in MetaMask and reload the page.
Check POA Network <a href='https://github.com/poanetwork/wiki' target='blank'>wiki</a> for more info.`

const errorMsgDeniedAccess = 'You have denied access to your accounts'

function generateElement(msg) {
  let errorNode = document.createElement('div')
  errorNode.innerHTML = `<div style="line-height: 1.6;">
    ${msg}
  </div>`
  return errorNode
}

async function getAccounts(web3) {
  let accounts
  if (window.ethereum) {
    accounts = await window.ethereum.request({ method: 'eth_accounts' })
  } else {
    accounts = await web3.eth.getAccounts()
  }
  return accounts
}

async function getNetId(web3) {
  let netId
  if (window.ethereum) {
    const { chainId } = window.ethereum
    netId = web3.utils.isHex(chainId) ? web3.utils.hexToNumber(chainId) : chainId
  } else {
    netId = await web3.eth.net.getId()
  }
  return netId
}

let getWeb3 = (onAccountChanged) => {
  return new Promise(function(resolve, reject) {
    // Wait for loading completion to avoid race conditions with web3 injection timing.
    window.addEventListener('load', async function() {
      let web3

      // Checking if Web3 has been injected by the browser (Mist/MetaMask)
      if (window.ethereum) {
        web3 = new Web3(window.ethereum)
        console.log('Injected web3 detected.')
        if (!window.ethereum.autoRefreshOnNetworkChange) {
          window.ethereum.on('chainChanged', () => {
            window.location.reload()
          })
        }
        try {
          await window.ethereum.request({ method: 'eth_requestAccounts' })
        } catch (e) {
          reject({
            msg: errorMsgDeniedAccess,
            node: generateElement(errorMsgDeniedAccess)
          })
          return
        }
      } else if (window.web3) {
        web3 = new Web3(window.web3.currentProvider)
        console.log('Injected web3 detected.')
      } else {
        console.error('Metamask not found')
        reject({
          msg: errorMsgNoMetamaskAccount,
          node: generateElement(errorMsgNoMetamaskAccount)
        })
        return
      }

      const netId = await getNetId(web3)
      console.log('netId', netId)

      let netIdName
      let errorMsg = null

      if (netId in constants.NETWORKS) {
        netIdName = constants.NETWORKS[netId].NAME
        console.log(`This is ${netIdName}`)
      } else {
        netIdName = 'ERROR'
        errorMsg = `You aren't connected to POA Network.
            Please switch on Metamask and refresh the page.
            Check POA Network <a href='https://github.com/poanetwork/wiki' target='blank'>wiki</a> for more info.
            <b>Current Network ID</b> is <i>${netId}</i>`
        console.log('This is an unknown network.')
      }

      document.title = `${netIdName} - DApp Keys Generation`

      if (errorMsg !== null) {
        reject({ msg: errorMsg, node: generateElement(errorMsg) })
        return
      }

      const accounts = await getAccounts(web3)
      const defaultAccount = accounts[0] || null

      let currentAccount = defaultAccount ? defaultAccount.toLowerCase() : null
      function onUpdateAccount(account) {
        if (account && account !== currentAccount) {
          currentAccount = account
          onAccountChanged(account)
        }
      }
      if (window.ethereum) {
        window.ethereum.on('accountsChanged', accs => {
          const account = accs && accs.length > 0 ? accs[0].toLowerCase() : null
          onUpdateAccount(account)
        })
      } else if (web3.currentProvider.publicConfigStore) {
        web3.currentProvider.publicConfigStore.on('update', obj => {
          const account = obj.selectedAddress ? obj.selectedAddress.toLowerCase() : null
          onUpdateAccount(account)
        })
      }

      if (defaultAccount === null) {
        reject({
          msg: errorMsgNoMetamaskAccount,
          node: generateElement(errorMsgNoMetamaskAccount)
        })
        return
      }

      resolve({
        web3Instance: web3,
        netIdName,
        netId,
        defaultAccount
      })
    })
  })
}

export default getWeb3