import fs from 'fs'
import assert from 'assert'
import clone from 'clone'
import pify from 'pify'
import Migrator from '../../../app/scripts/lib/migrator'
import liveMigrations from '../../../app/scripts/migrations'

const stubMigrations = [
  {
    version: 1,
    migrate: (data) => {
      // clone the data just like we do in migrations
      const clonedData = clone(data)
      clonedData.meta.version = 1
      return Promise.resolve(clonedData)
    },
  },
  {
    version: 2,
    migrate: (data) => {
      const clonedData = clone(data)
      clonedData.meta.version = 2
      return Promise.resolve(clonedData)
    },
  },
  {
    version: 3,
    migrate: (data) => {
      const clonedData = clone(data)
      clonedData.meta.version = 3
      return Promise.resolve(clonedData)
    },
  },
]
const versionedData = { meta: { version: 0 }, data: { hello: 'world' } }

import data from '../../../app/scripts/first-time-state'

const firstTimeState = {
  meta: { version: 0 },
  data,
}
describe('liveMigrations require list', () => {
  it('should include all the migrations', async () => {
    const fileNames = await pify(cb => fs.readdir('./app/scripts/migrations/', cb))()
    const migrationNumbers = fileNames.reduce((agg, filename) => {
      const name = filename.split('.')[0]
      if (/^\d+$/.test(name)) {
        agg.push(name)
      }
      return agg
    }, []).map((num) => parseInt(num))

    migrationNumbers.forEach((num) => {
      const migration = liveMigrations.find((m) => m.version === num)
      assert(migration, `migration should be include in the index missing migration ${num}`)
    })
  })
})

describe('Migrator', () => {
  const migrator = new Migrator({ migrations: stubMigrations })
  it('migratedData version should be version 3', async () => {
    const migratedData = await migrator.migrateData(versionedData)
    assert.equal(migratedData.meta.version, stubMigrations[2].version)
  })

  it('should match the last version in live migrations', async () => {
    const migrator = new Migrator({ migrations: liveMigrations })
    const migratedData = await migrator.migrateData(firstTimeState)
    const last = liveMigrations.length - 1
    assert.equal(migratedData.meta.version, liveMigrations[last].version)
  })

  it('should emit an error', async () => {
    const migrator = new Migrator({
      migrations: [{
        version: 1,
        async migrate () {
          throw new Error('test')
        },
      }],
    })
    await assert.rejects(migrator.migrateData({ meta: { version: 0 } }))
  })
})