package meteo

import (
	"encoding/csv"
	"fmt"
	"io"
	"strconv"
	"strings"
	"time"
)

func (mt *MeteoData) validate() error {
	if mt.MaxTemp > 60 {
		return ErrMaxTempOutOfRange
	}

	if mt.MinTemp < -20 {
		return ErrMinTempOutOfRange
	}

	if mt.Rainfall < 0 || mt.Rainfall > 80 {
		return ErrRainfallOutOfRange
	}

	if mt.Cloudiness < 0 || mt.Cloudiness > 100 {
		return ErrCloudinessOutOfRange
	}

	return nil
}

type FileIngest interface {
	Parse(io io.Reader, fs *FileStats) ([]MeteoData, []RejectedMeteoData, error)
}

type CSV struct{}

var _ FileIngest = (*CSV)(nil)

func (c *CSV) Parse(r io.Reader, fs *FileStats) ([]MeteoData, []RejectedMeteoData, error) {
	reader := csv.NewReader(r)
	reader.Comma = ';'
	reader.TrimLeadingSpace = true

	header, err := reader.Read()
	if err != nil {
		return nil, nil, fmt.Errorf("%w: %v", ErrReadingCSVHeader, err)
	}

	var meteoDataList []MeteoData
	var rejectedDataList []RejectedMeteoData

	for {
		row, err := reader.Read()
		if err == io.EOF {
			break
		}
		if err != nil {
			return nil, nil, fmt.Errorf("%w: %v", ErrReadingCSVRow, err)
		}

		if len(row) == 0 || (len(row) == 1 && row[0] == "") {
			continue
		}

		rowValue := strings.Join(row, ";")

		record := make(H)
		for i, value := range row {
			if i < len(header) {
				record[header[i]] = value
			}
		}

		meteoData, err := normalize(record)
		if err != nil {
			fs.RowsRejected++
			rejectedDataList = append(rejectedDataList, RejectedMeteoData{
				RowValue: rowValue,
				Reason:   err.Error(),
			})
			continue
		}

		if err := meteoData.validate(); err != nil {
			fs.RowsRejected++
			rejectedDataList = append(rejectedDataList, RejectedMeteoData{
				RowValue: rowValue,
				Reason:   err.Error(),
			})
			continue
		}

		meteoDataList = append(meteoDataList, *meteoData)
		fs.RowsInserted++
	}

	return meteoDataList, rejectedDataList, nil
}

func normalize(record H) (*MeteoData, error) {
	meteoData := &MeteoData{}

	if dateStr, ok := record["Fecha"].(string); ok {
		t, err := time.Parse("2006/01/02", dateStr)
		if err != nil {
			return nil, fmt.Errorf("%w: %v", ErrInvalidDateFormat, err)
		}
		meteoData.Timestamp = t
	} else {
		return nil, ErrMissingDateField
	}

	if location, ok := record["Ciudad"].(string); ok {
		meteoData.Location = location
	} else {
		return nil, ErrMissingCityField
	}

	if maxTempStr, ok := record["Temperatura Máxima (C)"].(string); ok {
		maxTemp, err := parseFloat(maxTempStr)
		if err != nil {
			return nil, fmt.Errorf("%w: %v", ErrInvalidMaxTemp, err)
		}
		meteoData.MaxTemp = maxTemp
	} else {
		return nil, ErrMissingMaxTempField
	}

	if minTempStr, ok := record["Temperatura Mínima (C)"].(string); ok {
		minTemp, err := parseFloat(minTempStr)
		if err != nil {
			return nil, fmt.Errorf("%w: %v", ErrInvalidMinTemp, err)
		}
		meteoData.MinTemp = minTemp
	} else {
		return nil, ErrMissingMinTempField
	}

	if rainfallStr, ok := record["Precipitación (mm)"].(string); ok {
		rainfall, err := parseFloat(rainfallStr)
		if err != nil {
			return nil, fmt.Errorf("%w: %v", ErrInvalidRainfall, err)
		}
		meteoData.Rainfall = rainfall
	} else {
		return nil, ErrMissingRainfallField
	}

	if cloudinessStr, ok := record["Nubosidad (%)"].(string); ok {
		cloudiness, err := parseFloat(cloudinessStr)
		if err != nil {
			return nil, fmt.Errorf("%w: %v", ErrInvalidCloudiness, err)
		}
		meteoData.Cloudiness = cloudiness
	} else {
		return nil, ErrMissingCloudinessField
	}

	return meteoData, nil
}

func parseFloat(s string) (float32, error) {
	s = strings.Replace(s, ",", ".", 1)
	f, err := strconv.ParseFloat(s, 32)
	if err != nil {
		return 0, err
	}
	return float32(f), nil
}