require('dotenv').config()
const mysql = require('mysql2/promise');
const axios = require('axios')

const rangeStartDate = '2010-01'
const rangeEndDate = '2018-12'

exports.update = async function (startDate = rangeStartDate, endDate = rangeEndDate) {
  console.log('update climate with:', startDate, endDate);
  
  const connection = await mysql.createConnection({
    host: process.env.DB_HOST,
    user: process.env.DB_USER,
    password: process.env.DB_PASSWORD,
    port: process.env.DB_PORT,
    database: 'travopti'
  });
  const [result, fields] = await connection.execute(`SELECT * FROM regions WHERE meteostat_id IS NOT NULL`)

  // let temp = await Promise.all(result.map(x => createClimateObject(x)))
  // let final = temp.reduce((total, element) => total.concat(element), [])

  // await writeToDatabase(connection, final)
  
  let temp2 = await Promise.all(result.map(x => createClimateObjectFrom(x, startDate, endDate)))
  let final2 = temp2.reduce((total, element) => total.concat(element), [])

  await writeToDatabase(connection, final2)

  connection.end();
  let response = 'database update complete. see backend logs for info.'
  console.log(response)
  return response
}

// async function createClimateObject(src) {
//   let response
//   try {
//     response = await axios.get(`https://api.meteostat.net/v1/climate/normals?station=${src.meteostat_id}&key=${process.env.METEOSTAT_API_KEY}`)
//   } catch (error) {
//     console.log("skipping: couldn't find results for following region: ")
//     console.log(src.region + " with meteostat_id " + src.meteostat_id)
//     return []
//   }
//   if (!response.data.data) {
//     console.log("skipping: no data for station meteostat_id " + src.meteostat_id + " (" + src.region + ")")
//     return []
//   }
//   let results = []
//   for (let index = 1; index <= 12; index++) {
//     let result = {
//       region: src.region,
//       region_id: src.id,
//       month: index,
//       temperature: Object.values(response.data.data.temperature)[index - 1] ? Object.values(response.data.data.temperature)[index - 1] : null,
//       temperature_min: Object.values(response.data.data.temperature_min)[index - 1] ? Object.values(response.data.data.temperature_min)[index - 1] : null,
//       temperature_max: Object.values(response.data.data.temperature_max)[index - 1] ? Object.values(response.data.data.temperature_max)[index - 1] : null,
//       precipitation: Object.values(response.data.data.precipitation)[index - 1] ? Object.values(response.data.data.precipitation)[index - 1] : null,
//       sunshine: Object.values(response.data.data.sunshine)[index - 1] ? Object.values(response.data.data.sunshine)[index - 1] : null,
//     }
//     results.push(result)
//   }
//   return results
// }

async function createClimateObjectFrom(src, startDate, endDate) {
  let response
  try {
    response = await axios.get(`https://api.meteostat.net/v1/history/monthly?station=${src.meteostat_id}&start=${startDate}&end=${endDate}&key=${process.env.METEOSTAT_API_KEY}`)
  } catch (error) {
    console.log("skipping createClimateObjectFrom: couldn't find results for following region: ")
    console.log(src.region + " with meteostat_id " + src.meteostat_id)
    console.log(error)
    return []
  }
  if (!response.data.data) {
    console.log("skipping: no data for station meteostat_id " + src.meteostat_id + " (" + src.region + ")")
    return []
  }
  let results = response.data.data.map(element => {
    let result = {
      region: src.region,
      region_id: src.id,
      year: element.month.split("-")[0],
      month: element.month.split("-")[1],
      temperature: element.temperature_mean,
      temperature_min: element.temperature_mean_min,
      temperature_max: element.temperature_mean_max,
      precipitation: element.precipitation,
      raindays: element.raindays,
      sunshine: element.sunshine,
      humidity: element.humidity ? element.humidity : null 
    }
    //console.log(result)
    return result
  })
  return results
}

async function writeToDatabase(dbConnection, climateObjArr) {
  climateObjArr.forEach(async (element) => {
    //console.log(element)
    try {
      if (!element.year) {
        await dbConnection.execute(`
          REPLACE INTO region_climate (region_id, year, month, temperature_mean, temperature_mean_min, temperature_mean_max, percipitation, sunshine)
          VALUES (${element.region_id}, 0, ${element.month}, ${element.temperature}, ${element.temperature_min}, ${element.temperature_max}, ${element.precipitation}, ${element.sunshine});`)
      } else {
        await dbConnection.execute(`
            REPLACE INTO region_climate (region_id, year, month, temperature_mean, temperature_mean_min, temperature_mean_max, percipitation, sunshine, humidity, raindays)
            VALUES (${element.region_id}, ${element.year}, ${element.month}, ${element.temperature}, ${element.temperature_min}, ${element.temperature_max}, ${element.precipitation}, ${element.sunshine}, ${element.humidity}, ${element.raindays});`)
      }
    } catch (error) {
      if (error.code !== 'ER_DUP_ENTRY') {
        console.log("element which causes problems: ")
        console.log(element)
        console.log("query which causes problems: ")
        console.log(error)
      } else {
        console.log(element.region + ": " + error.sqlMessage)
      }
    }
  });
}