package logfile

import (
	"os"
	"path/filepath"
	"sort"
	"time"

	"github.com/go-flucky/flucky/pkg/types"
)

// AppendTemperatures with temperature values from a logfile. As additional option it's possible to compress the temperature data.
func AppendTemperatures(logfile Logfile, compression bool, temperatures []*types.Temperature) error {

	allTemperatures := make([]*types.Temperature, 0)

	if _, err := os.Stat(logfile.GetLogfile()); err == nil {
		temperaturesFromLogfile, err := logfile.ReadTemperatures()
		if err != nil {
			return err
		}

		allTemperatures = append(allTemperatures, temperaturesFromLogfile...)
	}

	allTemperatures = append(allTemperatures, temperatures...)

	if compression {
		allTemperatures = CompressTemperature(allTemperatures)
	}

	err := logfile.WriteTemperatures(allTemperatures)
	if err != nil {
		return err
	}
	return nil
}

// CompressTemperature compresses the temperatures from an array. It is checked
// whether the measured temperature of a value corresponds to that of the
// predecessor. If this is the case, the current value is discarded and the
// validity date of the predecessor value is set to that of the current value.
// No information is lost as a result. The validity period of the measured value
// is thereby exclusively increased.
func CompressTemperature(temperatures []*types.Temperature) []*types.Temperature {
	compressedTemperatures := make([]*types.Temperature, 0)
	lastTemperatureBySensors := make(map[string]*types.Temperature, 0)

	// Sort all measured temperatures beforehand by the starting validity date to
	// avoid errors when compressing the temperatures.
	SortTemperatures(temperatures)

	for _, temperature := range temperatures {
		if lastTemperatureBySensor, ok := lastTemperatureBySensors[temperature.SensorID]; ok {
			if lastTemperatureBySensor.TemperatureValue == temperature.TemperatureValue {

				lastTemperatureBySensors[temperature.SensorID].TemperatureTillDate = temperature.TemperatureTillDate

				now := time.Now()
				lastTemperatureBySensors[temperature.SensorID].UpdateDate = &now
			} else {
				compressedTemperatures = append(compressedTemperatures, lastTemperatureBySensors[temperature.SensorID])
				lastTemperatureBySensors[temperature.SensorID] = temperature
			}
		} else {
			lastTemperatureBySensors[temperature.SensorID] = temperature
		}
	}

	// Copy all remaining entries from the map into the array
	for _, lastTemperatureBySensor := range lastTemperatureBySensors {
		compressedTemperatures = append(compressedTemperatures, lastTemperatureBySensor)
	}

	return compressedTemperatures
}

// New returns a log file with basic functions for reading and writing data.
// The file extension of the logfile is taken into account to format the logfile
// into the correct format.
func New(logfile string) Logfile {

	ext := filepath.Ext(logfile)

	switch ext {
	case ".csv":
		return &csvLogfile{
			logfile: logfile,
		}
	case ".json":
		return &jsonLogfile{
			logfile: logfile,
		}
	case ".xml":
		return &xmlLogfile{
			logfile: logfile,
		}
	default:
		return &jsonLogfile{
			logfile: logfile,
		}
	}
}

// SplittTemperatures into multiple arrays. The Size can be defined by
// temperatureSplitBy parameter.
func SplittTemperatures(temperatures []*types.Temperature, templeratureSplitBy int) [][]*types.Temperature {
	splittedTemperatures := make([][]*types.Temperature, 0)
	newTemperatures := make([]*types.Temperature, 0)
	for _, temperature := range temperatures {
		if len(newTemperatures) == templeratureSplitBy {
			splittedTemperatures = append(splittedTemperatures, newTemperatures)
			newTemperatures = make([]*types.Temperature, 0)
		}
		newTemperatures = append(newTemperatures, temperature)
	}
	splittedTemperatures = append(splittedTemperatures, newTemperatures)
	return splittedTemperatures
}

// SortTemperatures by TemperatureFromDate
func SortTemperatures(temperatures []*types.Temperature) {
	sort.SliceStable(temperatures, func(i int, j int) bool {
		return temperatures[i].TemperatureFromDate.Before(temperatures[j].TemperatureFromDate)
	})
}