const _ = require('lodash')
const sequelize = require('./sequelize')
const Sequelize = require('sequelize')
const migrations = require('./migrations')
const chalk = require('chalk')

const Version = sequelize.define('_version', {
  key: {
    type: Sequelize.STRING,
    primaryKey: true
  },
  value: Sequelize.DOUBLE
}, {
  tableName: '_version',
  timestamps: false
})

const getVersion = async (namespace, queryInterface) => {
  const defaultVersion = migrations[namespace].defaultVersion || migrations[namespace].map(x => x.version).reduce((a, b) => Math.max(a, b), 0.0)
  const tables = await queryInterface.showAllTables()
  if (!tables.includes('_version')) {
    return defaultVersion
  } else {
    const result = await Version.findOne({where: {key: namespace}})
    if (result) {
      return result.value
    } else {
      return defaultVersion
    }
  }
}

const setVersion = async (namespace, version, queryInterface) => {
  await Version.upsert({key: namespace, value: version}, { where: { key: namespace }})
}

const migrate = async (namespace, targetVersion) => {
  const queryInterface = sequelize.getQueryInterface()
  const currentVersion = await getVersion(namespace, queryInterface)
  let migs = _.sortBy(migrations[namespace], 'version')
  if (!targetVersion) targetVersion = migs.map(x => x.version).reduce((a, b) => Math.max(a, b), 0)
  console.log(chalk.green(`Migrating ${namespace}`))
  console.log(chalk.yellow(`Current version: ${currentVersion}`))
  console.log(chalk.yellow(`Target version:  ${targetVersion}`))
  // Sanity check
  for (let mig of migs) {
    if (!mig.version) throw new Error(`All migrations require versions`)
    if (!mig.up) throw new Error('All migrations require `up`')
  }
  // Filter to relevant migrations
  migs = migs.filter(mig => mig.version > currentVersion && mig.version <= targetVersion)
  console.log(`Migrations to run: ${migs.map(x => x.version).join(', ')}`)
  let lastVersion = currentVersion
  for (let mig of migs) {
    if (mig.version > lastVersion) {
      console.log(chalk.blue(`Running migration ${mig.version}: ${mig.name}`))
      mig.description && console.log(chalk.blue(mig.description))
      let newVersion = await mig.up(queryInterface, Sequelize)
      if (!Number.isFinite(newVersion)) throw new Error(`All migrations must return the resulting version`)
      if (newVersion < lastVersion) throw new Error(`Up migration downgraded database: ${mig.version} -> ${newVersion}`)
      await setVersion(namespace, newVersion, queryInterface)
      console.log(`Database now at version ${newVersion}`)
      lastVersion = newVersion
    } else {
      console.log(chalk.blue(`Skipping migration ${mig.version}: ${mig.name}`))
    }
  }
  console.log(chalk.cyan(`Migration complete. Current database version: ${await getVersion(namespace, queryInterface)}`))
}

const migrateAll = async () => {
  const namespaces = _.keys(_.omit(migrations, 'material-framework'))
  await migrate('material-framework')
  console.log(_.keys(migrations))
  for (let namespace of namespaces) {
    await migrate(namespace)
  }
}

module.exports = {
  getVersion,
  migrate,
  migrateAll,
  migrations,
  setVersion
}