package inflation

import (
	"encoding/csv"
	"fmt"
	"os"
	"sort"
	"strconv"
	"time"
)

func getYearRange(processedData map[string]map[time.Time]float32) (int, int) {
	var startYear, endYear int

	for _, timeData := range processedData {
		for date := range timeData {
			year := date.Year()
			if year < startYear || startYear == 0 {
				startYear = year
			}
			if year > endYear || endYear == 0 {
				endYear = year
			}
		}
	}

	return startYear, endYear
}
func createYearList(startYear, endYear int) []int32 {
	years := make([]int32, 0, endYear-startYear+1)
	for year := startYear; year <= endYear; year++ {
		years = append(years, int32(year))
	}
	return years
}

func aggregateDataByYear(data map[time.Time]float32) map[int32]float32 {
	yearlyData := make(map[int]float32)

	for k, v := range data {
		if _, exists := yearlyData[k.Year()]; !exists {
			yearlyData[k.Year()] = 0
		}
		yearlyData[k.Year()] += v
	}

	aggregatedData := make(map[int32]float32)
	for k, v := range yearlyData {
		aggregatedData[int32(k)] = v
	}

	return aggregatedData
}

func toPercent(m map[time.Time]float32) map[time.Time]float32 {
	var times []time.Time
	for t := range m {
		times = append(times, t)
	}
	sort.Slice(times, func(i, j int) bool {
		return times[i].Before(times[j])
	})
	percentageChanges := make(map[time.Time]float32)
	var previousValue float32
	for i, t := range times {
		currentValue := m[t]
		if i == 0 {
			percentageChanges[t] = 0
		} else {
			percentageChange := ((currentValue - previousValue) / previousValue) * 100
			percentageChanges[t] = percentageChange
		}
		previousValue = currentValue
	}

	return percentageChanges
}

func readCSV(filePath string) (map[time.Time]float32, error) {
	file, err := os.Open(filePath)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	csvReader := csv.NewReader(file)
	records, err := csvReader.ReadAll()
	if err != nil {
		return nil, err
	}

	dataMap := make(map[time.Time]float32)

	for i, record := range records {
		if i == 0 {
			continue
		}

		if len(record) < 2 || record[1] == "." {
			continue
		}

		date, err := time.Parse("2006-01-02", record[0])
		if err != nil {
			return nil, fmt.Errorf("error parsing date on line %d: %v", i+1, err)
		}

		value, err := strconv.ParseFloat(record[1], 32)
		if err != nil {
			return nil, fmt.Errorf("error parsing float on line %d: %v", i+1, err)
		}

		dataMap[date] = float32(value)
	}

	return dataMap, nil
}