const _ = require('lodash')
const app = require('./app')

app.service('statistics', function(api) {
  const chart = ({
    rows,
    seriesField,
    dataField,
    labelsField
  }) => {
    const labels = _.chain(rows).map(x => x[labelsField]).uniq().value()
    const series = _.chain(rows).map(x => x[seriesField]).uniq().value()
    const seriesData = _.chain(rows)
      .groupBy(x => x[seriesField])
      .toPairs()
      .map(([key, rows]) => [
        key,
        _.chain(rows)
          .map(row => [row[labelsField], row[dataField]])
          .fromPairs()
          .value()
      ])
      .fromPairs()
      .value()
    data = series.map(s => {
      const sdata = seriesData[s]
      return labels.map(l => sdata[l])
    })

    return {labels, series, data}
  }


  this.efficiency = async () => {
    const rows = await api.statistics()
    return {
      delivery: chart({
        rows,
        seriesField: 'key',
        dataField: 'delivered',
        labelsField: 'date'
      }),
      efficiency: chart({
        rows,
        seriesField: 'key',
        dataField: 'efficiency',
        labelsField: 'date'
      })
    }
  }
})