const _ = require('lodash')
const fs = require('fs')


exports.transform = (data) => {
  // get data
  // let data = JSON.parse(fs.readFileSync('transformer-test.json'));
  const types = Object.keys(data[0].scores)

  // STEP 1  Create Response Array with region names from first climate object
  let byRegion = data[0].climate.map(el => {
    return {
      region_id: el.region_id,
      country_id: el.country_id,
      name: el.name,
    }
  })

  // STEP 2  Prepare flat scoreobject array and set days property
  scoreObjs = _.flatten(_.map(data, (period) => {
    return _.reduce(period.scores, (arr, el) => {
      return arr.concat(el)
    }).map(element => {
      element.days = period.days
      return element
    })
  }))

  // STEP 3  Collect scoreobjects for each region
  let results = byRegion.map(region => {
    let scores = []
    types.forEach(typ => {
      let tempScores = _.filter(scoreObjs, { 'region_id': region.region_id, 'type': typ })
      if (_.some(tempScores, { 'score': null })) {
        console.log("found 'null' scores! skipping...")
        //console.log(tempScores)
        return
      }
      let averagedScore = {
        region_id: region.region_id,
        type: typ,
        value: 0,
        score: 0,
        days: 0
      }
      tempScores.forEach(el => {
        averagedScore.value += (el.value * el.days)
        averagedScore.score += (el.score * el.days)
        averagedScore.days += (el.days)
      })

      averagedScore.value = _.round(averagedScore.value / averagedScore.days, 1)
      averagedScore.score = _.round(averagedScore.score / averagedScore.days, 1)
      delete averagedScore.region_id
      delete averagedScore.days
      scores.push(averagedScore)

    })
    region.scores = scores

    // STEP 4  Calculate Average Score
    region.score = calculateAverage(region.scores)
    //console.log(region)
    return region
  })
  
  // console.log(results)
  return _.orderBy(results, 'score', 'desc')
  //end
}

function calculateAverage(scores) {
  let sum = 0
  scores.forEach(el => sum += el.score)
  //console.log(sum)
  return _.round(sum / scores.length, 2)
}