import Web3 from 'web3'
import namehash from 'eth-ens-namehash'
import { BigNumber as BN } from 'bignumber.js'
import { toChecksumAddress, isAddress } from 'web3-utils'

import networkConfig from '@/networkConfig'
import { REGISTRY_DEPLOYED_BLOCK } from '@/constants'
import { sleep, flattenNArray } from '@/utils'

import AggregatorABI from '@/abis/Aggregator.abi.json'
import RelayerRegistryABI from '@/abis/RelayerRegistry.abi.json'

const MIN_STAKE_BALANCE = '0X1B1AE4D6E2EF500000' // 500 TORN

const subdomains = Object.values(networkConfig).map(({ ensSubdomainKey }) => ensSubdomainKey)

class RelayerRegister {
  constructor(provider) {
    this.provider = provider
    this.$indexedDB = window.$nuxt.$indexedDB(1)

    const { registryContract, aggregatorContract } = networkConfig.netId1

    this.aggregator = new this.provider.Contract(AggregatorABI, aggregatorContract)
    this.relayerRegistry = new this.provider.Contract(RelayerRegistryABI, registryContract)
  }

  fetchEvents = ({ fromBlock, toBlock }, shouldRetry = false) => {
    return new Promise((resolve, reject) => {
      if (fromBlock <= toBlock) {
        this.relayerRegistry
          .getPastEvents('RelayerRegistered', { fromBlock, toBlock })
          .then((events) => resolve(events))
          .catch((_) => {
            if (shouldRetry) {
              sleep(500).then(() =>
                this.fetchEvents({ fromBlock, toBlock })
                  .then((events) => resolve(events))
                  .catch((_) => resolve(undefined))
              )
            } else {
              resolve(undefined)
            }
          })
      } else {
        resolve(undefined)
      }
    })
  }

  batchFetchEvents = async ({ fromBlock, toBlock }) => {
    const batchSize = 10
    const blockRange = 10000
    const blockDifference = toBlock - fromBlock
    const chunkCount = Math.ceil(blockDifference / blockRange)
    const blockDenom = Math.ceil(blockDifference / chunkCount)
    const chunkSize = Math.ceil(chunkCount / batchSize)

    let failed = []
    let events = []
    let lastBlock = fromBlock

    for (let batchIndex = 0; batchIndex < chunkSize; batchIndex++) {
      const params = new Array(batchSize).fill('').map((_, i) => {
        const toBlock = (i + 1) * blockDenom + lastBlock
        const fromBlock = toBlock - blockDenom
        return { fromBlock, toBlock }
      })
      const promises = new Array(batchSize).fill('').map(
        (_, i) =>
          new Promise((resolve) =>
            sleep(i * 20).then(() => {
              this.fetchEvents(params[i], true).then((batch) => {
                if (!batch) {
                  resolve([{ isFailedBatch: true, fromBlock, toBlock }])
                } else {
                  resolve(batch)
                }
              })
            })
          )
      )
      const requests = flattenNArray(await Promise.all(promises))
      const failedIndexes = requests
        .filter((e) => e.isFailedBatch)
        .map((e) => {
          const reqIndex = requests.indexOf(e)
          return params[reqIndex]
        })

      failed = failed.concat(failedIndexes || [])
      events = events.concat(requests.filter((e) => !e.isFailedBatch))
      lastBlock = params[batchSize - 1].toBlock
    }

    if (failed.length !== 0) {
      const failedReqs = failed.map((e) => this.fetchEvents(e))
      const failedBatch = flattenNArray(await Promise.all(failedReqs))

      events = events.concat(failedBatch || [])
    }

    events = events.map((e) => ({ ...e.returnValues }))

    if (events.length === 0) {
      throw new Error('Failed to fetch registry events')
    }

    return events
  }

  saveEvents = async ({ events, lastSyncBlock, storeName }) => {
    try {
      if (this.$indexedDB.isBlocked) {
        return
      }

      await this.$indexedDB.putItem({
        data: {
          blockNumber: lastSyncBlock,
          name: storeName
        },
        storeName: 'lastEvents'
      })

      if (events.length) {
        this.$indexedDB.createMultipleTransactions({ data: events, storeName })
      }
    } catch (err) {
      console.error(`saveEvents has error: ${err.message}`)
    }
  }

  getCachedData = async () => {
    let blockFrom = REGISTRY_DEPLOYED_BLOCK[1]

    try {
      const blockTo = await this.provider.getBlockNumber()

      const cachedEvents = await this.$indexedDB.getAll({
        storeName: 'register_events'
      })

      const lastBlock = await this.$indexedDB.getFromIndex({
        indexName: 'name',
        key: 'register_events',
        storeName: 'lastEvents'
      })

      if (lastBlock) {
        blockFrom = blockTo >= lastBlock.blockNumber ? lastBlock.blockNumber + 1 : blockTo
      }

      return { blockFrom, blockTo, cachedEvents }
    } catch {
      return { blockFrom, blockTo: 'latest', cachedEvents: [] }
    }
  }

  getENSAddress = async (ensName) => {
    const { url } = Object.values(networkConfig.netId1.rpcUrls)[0]
    const provider = new Web3(url)

    const ensAddress = await provider.eth.ens.getAddress(ensName)

    return ensAddress
  }

  fetchRelayers = async () => {
    const blockRange = 10000
    // eslint-disable-next-line prefer-const
    let { blockTo, cachedEvents } = await this.getCachedData()
    let allRelayers = cachedEvents

    const currentBlockNumber = await this.provider.getBlockNumber()
    const fromBlock = cachedEvents.length === 0 ? REGISTRY_DEPLOYED_BLOCK[1] : blockTo
    const blockDifference = currentBlockNumber - fromBlock

    try {
      let toBlock
      let registerRelayerEvents
      let lastSyncBlock = blockTo

      if (cachedEvents.length > 0 || blockDifference === 0) {
        return cachedEvents
      } else if (blockDifference >= blockRange) {
        toBlock = currentBlockNumber
        registerRelayerEvents = await this.batchFetchEvents({ fromBlock, toBlock })
        lastSyncBlock = toBlock
      } else {
        toBlock = fromBlock + blockRange
        registerRelayerEvents = await this.fetchEvents({ fromBlock, toBlock }, true)
        lastSyncBlock = toBlock
      }

      const relayerEvents = cachedEvents.concat(registerRelayerEvents || [])
      const events = []

      for (let x = 0; x < relayerEvents.length; x++) {
        const { ensName, relayerAddress } = relayerEvents[x]
        let ensAddress

        if (!isAddress(relayerAddress)) {
          ensAddress = await this.getENSAddress(ensName)
          ensAddress = toChecksumAddress(ensAddress)
        } else {
          ensAddress = relayerAddress
        }

        events.push({ ensName, relayerAddress: ensAddress })
      }

      await this.saveEvents({ storeName: 'register_events', lastSyncBlock, events })

      allRelayers = allRelayers.concat(events)
    } catch (err) {
      console.log(err)
    }
    return allRelayers
  }

  filterRelayer = (acc, curr, ensSubdomainKey, relayer) => {
    const subdomainIndex = subdomains.indexOf(ensSubdomainKey)
    const mainnetSubdomain = curr.records[0]
    const hostname = curr.records[subdomainIndex]
    const isHostWithProtocol = hostname.includes('http')

    const isOwner = relayer.relayerAddress === curr.owner
    const hasMinBalance = new BN(curr.balance).gte(MIN_STAKE_BALANCE)

    if (
      hostname &&
      isOwner &&
      mainnetSubdomain &&
      curr.isRegistered &&
      hasMinBalance &&
      !isHostWithProtocol
    ) {
      acc.push({
        hostname,
        ensName: relayer.ensName,
        stakeBalance: curr.balance,
        relayerAddress: relayer.relayerAddress
      })
    } else {
      console.error(`${relayer.ensName} invalid: `, {
        isOwner,
        hasTXT: Boolean(hostname),
        isHasMinBalance: hasMinBalance,
        isRegistered: curr.isRegistered,
        isHostWithoutProtocol: !isHostWithProtocol,
        isMainnetSubdomain: Boolean(mainnetSubdomain)
      })
    }

    return acc
  }

  getValidRelayers = async (relayers, ensSubdomainKey) => {
    const relayerNameHashes = relayers.map((r) => namehash.hash(r.ensName))

    const relayersData = await this.aggregator.methods.relayersData(relayerNameHashes, subdomains).call()

    const validRelayers = relayersData.reduce(
      (acc, curr, index) => this.filterRelayer(acc, curr, ensSubdomainKey, relayers[index]),
      []
    )

    return validRelayers
  }

  getRelayers = async (ensSubdomainKey) => {
    const relayers = await this.fetchRelayers()
    const validRelayers = await this.getValidRelayers(relayers, ensSubdomainKey)

    return validRelayers
  }
}

export const relayerRegisterService = (provider) => new RelayerRegister(provider.eth)