import debug from 'debug'
import ETHProvider from 'eth-provider'
import fs from 'fs-extra'
import json from 'jsonfile'
import Level from 'level'
import ora from 'ora'
import os from 'os'
import path from 'path'
import shell from 'shelljs'
import contractor from 'truffle-contract'
import Web3 from 'web3'
import GitHelper from './lib/git'
import IPLDHelper from './lib/ipld'
import LineHelper from './lib/line'

const _timeout = async (duration: any): Promise<void> => {
  return new Promise<any>((resolve, reject) => {
    setTimeout(() => {
      resolve()
    }, duration)
  })
}

export default class Helper {
  // name and url
  public name: string
  public url: string
  // address and path shortcuts
  public address: string
  public path: string
  // config
  public config: any
  // lib
  public debug: any
  public line: LineHelper
  public git: GitHelper
  public ipld: IPLDHelper
  // db
  private _db: any
  // provider and web3
  private _provider: any
  private _web3: any
  // artifacts and contracts
  private _repo!: any
  private _kernel!: any

  constructor(name: string = '_', url: string) {
    // name and url
    this.name = name
    this.url = url
    // address and path shortcuts
    this.address = this.url.split('://')[1]
    this.path = path.resolve(process.env.GIT_DIR as string)
    // config
    this.config = this._config()
    // lib
    this.debug = debug('pando')
    this.line = new LineHelper()
    this.git = new GitHelper(this)
    this.ipld = new IPLDHelper(this)
  }

  // OK
  public async initialize(): Promise<void> {
    // create dirs
    fs.ensureDirSync(path.join(this.path, 'refs', 'remotes', this.name))
    fs.ensureDirSync(path.join(this.path, 'pando', 'refs'))
    // load db
    this._db = Level(path.join(this.path, 'pando', 'refs', this.address))
    // initialize web3
    this._provider = await this._ethConnect()
    this._web3 = new Web3(this._provider)
    // initialize repo contract
    this._repo = { artifact: undefined, contract: undefined }
    // tslint:disable-next-line:no-submodule-imports
    this._repo.artifact = contractor(require('@pando/repository/abi/PandoRepository.json'))
    this._repo.artifact.setProvider(this._provider)
    this._repo.artifact.defaults({ from: this.config.ethereum.account })
    this._repo.artifact.autoGas = true
    this._repo.artifact.gasMultiplier = 3
    this._repo.contract = await this._repo.artifact.at(this.address)
    // initialize kernel contract
    this._kernel = { artifact: undefined, contract: undefined }
    // tslint:disable-next-line:no-submodule-imports
    this._kernel.artifact = contractor(require('@pando/repository/abi/Kernel.json'))
    this._kernel.artifact.setProvider(this._provider)
    this._kernel.artifact.defaults({ from: this.config.ethereum.account })
    this._kernel.artifact.autoGas = true
    this._kernel.artifact.gasMultiplier = 3
    this._kernel.contract = await this._kernel.artifact.at(await this._repo.contract.kernel())
  }

  // OK
  public async run(): Promise<void> {
    while (true) {
      const cmd = await this.line.next()

      switch (this._cmd(cmd)) {
        case 'capabilities':
          await this._handleCapabilities()
          break
        case 'list for-push':
          await this._handleList({ forPush: true })
          break
        case 'list':
          await this._handleList()
          break
        case 'fetch':
          await this._handleFetch(cmd)
          break
        case 'push':
          await this._handlePush(cmd)
          break
        case 'end':
          this._exit()
        case 'unknown':
          throw new Error('Unknown command: ' + cmd)
      }
    }
  }

  /***** commands handling methods *****/

  // OK
  private async _handleCapabilities(): Promise<void> {
    this.debug('cmd', 'capabilities')
    // this._send('option')
    this._send('fetch')
    this._send('push')
    this._send('')
  }

  // OK
  private async _handleList({ forPush = false }: { forPush?: boolean } = {}): Promise<void> {
    forPush ? this.debug('cmd', 'list', 'for-push') : this.debug('cmd, list')

    const refs = await this._fetchRefs()

    // tslint:disable-next-line:forin
    for (const ref in refs) {
      this._send(this.ipld.cidToSha(refs[ref]) + ' ' + ref)
    }

    // force HEAD to master and update once pando handle symbolic refs
    this._send('@refs/heads/master' + ' ' + 'HEAD')
    this._send('')
  }

  // OK
  private async _handleFetch(line: string): Promise<void> {
    this.debug('cmd', line)

    while (true) {
      const [cmd, oid, name] = line.split(' ')
      await this._fetch(oid, name)
      line = await this.line.next()

      if (line === '') break
    }

    this._send('')
  }

  // OK
  private async _handlePush(line: string): Promise<void> {
    this.debug('cmd', line)

    while (true) {
      const [src, dst] = line.split(' ')[1].split(':')

      if (src === '') {
        await this._delete(dst)
      } else {
        await this._push(src, dst)
      }

      line = await this.line.next()

      if (line === '') break
    }

    this._send('')
  }

  /***** refs db methods *****/

  // OK
  private async _fetchRefs(): Promise<object> {
    this.debug('fetching remote refs from chain')

    let start
    let block
    let events
    const ops: object[] = []
    const updates: object = {}
    const spinner = ora('Fetching remote refs from chain [this may take a while]').start()

    try {
      start = await this._db.get('@block')
    } catch (err) {
      if (err.message === 'Key not found in database [@block]') {
        start = 0
      } else {
        throw err
      }
    }

    try {
      block = await this._web3.eth.getBlockNumber()
      events = await this._repo.contract.getPastEvents('UpdateRef', {
        fromBlock: start,
        toBlock: 'latest',
      })

      for (const event of events) {
        updates[event.args.ref] = event.args.hash
      }

      // tslint:disable-next-line:forin
      for (const ref in updates) {
        ops.push({ type: 'put', key: ref, value: updates[ref] })
      }

      ops.push({ type: 'put', key: '@block', value: block })

      await this._db.batch(ops)

      spinner.succeed('Remote refs fetched from chain')

      return this._getRefs()
    } catch (err) {
      spinner.fail('Failed to fetch remote refs from chain')
      throw err
    }
  }

  // OK
  private async _getRefs(): Promise<object> {
    this.debug('reading refs from local db')

    const refs: any = {}

    return new Promise<object>((resolve, reject) => {
      this._db
        .createReadStream()
        .on('data', ref => {
          if (ref.key !== '@block') refs[ref.key] = ref.value
        })
        .on('error', err => {
          reject(err)
        })
        .on('end', () => {
          //
        })
        .on('close', () => {
          resolve(refs)
        })
    })
  }

  /***** core methods *****/

  // OK
  private async _fetch(oid: string, ref: string): Promise<void> {
    this.debug('fetching', ref, oid, this.ipld.shaToCid(oid))
    await this.git.download(oid)
  }

  // OK
  private async _push(src: string, dst: string): Promise<void> {
    this.debug('pushing', src, 'to', dst)

    return new Promise<void>(async (resolve, reject) => {
      let spinner
      let head
      let txHash
      let mapping: any = {}
      const puts: any = []
      const pins: any = []

      try {
        const refs = await this._getRefs()
        const remote: any = refs[dst]

        const srcBranch = src.split('/').pop()
        const dstBranch = dst.split('/').pop()

        const revListCmd = remote ? `git rev-list --left-only ${srcBranch}...${this.name}/${dstBranch}` : 'git rev-list --all'

        const commits = shell
          .exec(revListCmd, { silent: true })
          .stdout.split('\n')
          .slice(0, -1)

        // checking permissions
        try {
          spinner = ora(`Checking permissions over ${this.address}`).start()

          if (process.env.PANDO_OPEN_PR) {
            if (await this._kernel.contract.hasPermission(this.config.ethereum.account, this.address, await this._repo.contract.OPEN_PR_ROLE(), '0x0')) {
              spinner.succeed(`You have open PR permission over ${this.address}`)
            } else {
              spinner.fail(`You do not have open PR permission over ${this.address}`)
              this._die()
            }
          } else {
            if (await this._kernel.contract.hasPermission(this.config.ethereum.account, this.address, await this._repo.contract.PUSH_ROLE(), '0x0')) {
              spinner.succeed(`You have push permission over ${this.address}`)
            } else {
              spinner.fail(`You do not have push permission over ${this.address}. Try to run 'git pando pr open' to open a push request.`)
              this._die()
            }
          }
        } catch (err) {
          spinner.fail(`Failed to check permissions over ${this.address}: ` + err.message)
          this._die()
        }

        // collect git objects
        try {
          spinner = ora('Collecting git objects [this may take a while]').start()

          for (const commit of commits) {
            const _mapping = await this.git.collect(commit, mapping)
            mapping = { ...mapping, ..._mapping }
          }

          head = this.ipld.shaToCid(commits[0])

          // tslint:disable-next-line:forin
          for (const entry in mapping) {
            puts.push(this.ipld.put(mapping[entry]))
          }

          spinner.succeed('Git objects collected')
        } catch (err) {
          spinner.fail('Failed to collect git objects: ' + err.message)
          this._die()
        }

        // upload git objects
        try {
          spinner = ora('Uploading git objects to IPFS').start()
          await Promise.all(puts)
          spinner.succeed('Git objects uploaded to IPFS')
        } catch (err) {
          spinner.fail('Failed to upload git objects to IPFS: ' + err.message)
          this._die()
        }

        // pin git objects
        try {
          // tslint:disable-next-line:forin
          for (const entry in mapping) {
            pins.push(this.ipld.pin(entry))
          }
          spinner = ora('Pinning git objects to IPFS').start()
          await Promise.all(pins)
          spinner.succeed('Git objects pinned to IPFS')
        } catch (err) {
          spinner.fail('Failed to pin git objects to IPFS: ' + err.message)
          this._die()
        }

        // register on chain
        if (!process.env.PANDO_OPEN_PR) {
          try {
            spinner = ora(`Registering ref ${dst} ${head} on-chain`).start()
            this._repo.contract
              .push(dst, head)
              .on('error', err => {
                if (!err.message.includes('Failed to subscribe to new newBlockHeaders to confirm the transaction receipts')) {
                  spinner.fail(`Failed to register ref ${dst} ${head} on-chain: ` + err.message)
                  this._die()
                }
              })
              .on('transactionHash', hash => {
                txHash = hash
                spinner.text = `Registering ref ${dst} ${head} on-chain through tx ${txHash}`
              })
              .then(receipt => {
                spinner.succeed(`Ref ${dst} ${head} registered on-chain through tx ${txHash}`)
                this._send(`ok ${dst}`)
                resolve()
              })
              .catch(err => {
                spinner.fail(`Failed to register ref ${dst} ${head} on-chain: ` + err.message)
                this._die()
              })
          } catch (err) {
            spinner.fail(`Failed to register ref ${dst} ${head} on-chain: ` + err.message)
            this._die()
          }
        } else {
          try {
            spinner = ora(`Opening PR for ${dst} ${head} on-chain`).start()
            this._repo.contract
              .openPR(process.env.PANDO_PR_TITLE, process.env.PANDO_PR_DESCRIPTION || '', dst, head)
              .on('error', err => {
                if (!err.message.includes('Failed to subscribe to new newBlockHeaders to confirm the transaction receipts')) {
                  spinner.fail(`Failed to open PR for ${dst} ${head} on-chain: ` + err.message)
                  this._die()
                }
              })
              .on('transactionHash', hash => {
                txHash = hash
                spinner.text = `Opening PR for ${dst} ${head} on-chain through tx ${txHash}`
              })
              .then(receipt => {
                const id = receipt.logs.filter(l => l.event === 'OpenPR')[0].args.id
                spinner.succeed(`PR #${id} for ${dst} ${head} opened on-chain through tx ${txHash}`)
                this._send(`error ${dst} Relax! This is because you do not have push permission: PR #${id} has been opened for you instead`)
                resolve()
              })
              .catch(err => {
                spinner.fail(`Failed to open PR for ${dst} ${head} on-chain: ` + err.message)
                this._die()
              })
          } catch (err) {
            spinner.fail(`Failed to open PR for ${dst} ${head} on-chain: ` + err.message)
            this._die()
          }
        }
      } catch (err) {
        this._die(err.message)
      }
    })
  }

  // TODO
  private async _delete(dst: string): Promise<void> {
    this.debug('deleting', dst)
  }

  /***** utility methods *****/

  // OK
  private async _ethConnect(): Promise<any> {
    this.debug('connecting to gateway', this.config.ethereum.gateway)

    const provider = ETHProvider(this.config.ethereum.gateway)
    const spinner = ora('Connecting to Ethereum').start()

    while (true) {
      try {
        const accounts = await provider.send('eth_accounts')
        spinner.stop()
        for (const account of accounts) {
          if (account === this.config.ethereum.account) return provider
        }
        this._die("Failed to access your Ethereum account. Update your gateway configuration or run 'git pando config' to select another account.")
      } catch (err) {
        if (err.code === 4100 || err.code === 4001) {
          spinner.text = `Error connecting to Ethereum. ${err.message}.`
          await _timeout(2000)
        } else {
          spinner.stop()
          this._die('Failed to connect to Ethereum. Make sure your Ethereum gateway is running.')
        }
      }
    }
  }

  // OK
  private _config(): any {
    const LOCAL = path.join(this.path, 'pando', '.pandorc')
    const GLOBAL = path.join(os.homedir(), '.pandorc')

    if (fs.pathExistsSync(LOCAL)) return json.readFileSync(LOCAL)
    if (fs.pathExistsSync(GLOBAL)) return json.readFileSync(GLOBAL)

    this._die("No configuration file found. Run 'git-pando config' and come back to us.")
  }

  // OK
  private _cmd(line: string): string {
    if (line === 'capabilities') {
      return 'capabilities'
    } else if (line === 'list for-push') {
      return 'list for-push'
    } else if (line === 'list') {
      return 'list'
    } else if (line.startsWith('option')) {
      return 'option'
    } else if (line.startsWith('fetch')) {
      return 'fetch'
    } else if (line.startsWith('push')) {
      return 'push'
    } else if (line === '') {
      return 'end'
    } else {
      return 'unknown'
    }
  }

  // OK
  private _send(message): void {
    // tslint:disable-next-line:no-console
    console.log(message)
  }

  // OK
  private _die(message?: string): void {
    // tslint:disable-next-line:no-console
    if (message) console.error(message)
    process.exit(1)
  }

  // OK
  private _exit(): void {
    process.exit(0)
  }
}