package main

import (
	"errors"
	"fmt"
	"time"
)

type CacheEntry struct {
	Date                       int64
	GreenEnergyPercentage      float32
	PolledSmartEnergySummation float32
}
type CacheData []CacheEntry

func (config Config) updateCache() {

	greenEnergyPercentage, err := config.historyAverageAndConvertToGreen(config.Sensors.FossilPercentage, time.Now())
	if err != nil {
		return
	}
	historyPolledSmartEnergySummation, err := config.historyDelta(config.Sensors.PolledSmartEnergySummation, time.Now())
	if err != nil {
		return
	}

	config.db.Exec("INSERT INTO cache(time,green_energy_percentage,energy_consumption) VALUES (?,?,?);", dayStart(time.Now()).Unix(), greenEnergyPercentage.Value, historyPolledSmartEnergySummation.Value)

	cached, err := config.readCache()
	if err != nil {
		return
	}
	if len(cached) != 8 && time.Now().Sub(config.HomeAssistant.InstallationDate) > 8*time.Hour*24 {
		err := config.refreshCacheFromPast(time.Now().Add(-8 * time.Hour * 24))
		if err != nil {
			fmt.Println("Error refreshing cache", err.Error())
			return
		}
	}

}

func (config Config) refreshCacheFromInstall() error {
	return config.refreshCacheFromPast(config.HomeAssistant.InstallationDate)
}

func (config Config) refreshCacheFromPast(pastTime time.Time) error {

	// in order to avoid querying and storing each day's data from 0001-01-01 in future versions
	if config.HomeAssistant.InstallationDate.IsZero() {
		return errors.New("installation date not set")
	}

	greenEnergyPercentage, err := config.historyBulkAverageAndConvertToGreen(config.Sensors.FossilPercentage, pastTime, time.Now())
	if err != nil {
		return err
	}
	historyPolledSmartEnergySummation, err := config.historyBulkDelta(config.Sensors.PolledSmartEnergySummation, pastTime, time.Now())
	if err != nil {
		return err
	}

	_, err = config.db.Exec("DELETE FROM cache")
	if err != nil {
		return err
	}

	for key, day := range greenEnergyPercentage {
		_, err := config.db.Exec("INSERT INTO cache(time,green_energy_percentage,energy_consumption) VALUES (?,?,?);", day.DayTime.Unix(), greenEnergyPercentage[key].Value, historyPolledSmartEnergySummation[key].Value)
		if err != nil {
			return err
		}
	}

	return nil

}

func (config Config) readCache() (CacheData, error) {

	start := dayStart(time.Now()).AddDate(0, 0, -8)

	rows, err := config.db.Query("SELECT time, green_energy_percentage, energy_consumption FROM cache WHERE time > ?", start.Unix())
	if err != nil {
		return CacheData{}, err
	}
	defer rows.Close()
	var ret CacheData

	for rows.Next() {
		var (
			date                         int64
			greenEnergyPercentage        float32
			polledSmartEnergyConsumption float32
		)
		err = rows.Scan(&date, &greenEnergyPercentage, &polledSmartEnergyConsumption)
		ret = append(ret, CacheEntry{date, greenEnergyPercentage, polledSmartEnergyConsumption})
	}

	return ret, nil

}