package ledger

import (
	"fmt"
	"io"
	"log"
	"maps"
	"time"
)

func RegisterWithContributionPrediction(reg map[string]Balances, windowAsPercentOfTotalDuration float64) (map[string]Balances, error) {
	return reg, io.EOF
}

func BPIWithFixedGrowthPrediction(reg map[string]Balances, windowAsPercentOfTotalDuration float64, pattern string, rate float64) (map[string]Balances, error) {
	result := make(map[string]Balances)
	return result, io.EOF
}

func RegisterWithCompoundingInterestPrediction(reg map[string]Balances, windowAsPercentOfTotalDuration float64, pattern string, rate float64) (map[string]Balances, error) {
	nameToLastDate := func() map[string]string {
		result := map[string]string{}
		for date, balances := range reg {
			for name := range balances {
				if result[name] < date {
					result[name] = date
				}
			}
		}
		return result
	}()
	firstTime, lastTime := func() (time.Time, time.Time) {
		var latest time.Time
		first := time.Now()
		for _, v := range nameToLastDate {
			v2, _ := dateToTime(v)
			if latest.Before(v2) {
				latest = v2
			}
			if first.Before(v2) {
				first = v2
			}
		}
		return first, latest
	}()
	log.Println("first", firstTime, "last time", lastTime, "nameToDate", nameToLastDate)

	lastPrediction := lastTime
	for lastPrediction.Before(lastTime.Add(lastTime.Sub(firstTime) * time.Duration(windowAsPercentOfTotalDuration))) {
		lastPrediction = lastPrediction.Add(time.Hour * 24 * (45 - lastPrediction.Day()))
      TODO ^
	}

	result := maps.Clone(reg)
	return result, io.EOF
}

func dateToTime(s string) (time.Time, error) {
	for _, layout := range []string{
		"2006-01-02",
		"2006-01",
	} {
		if t, err := time.ParseInLocation(layout, s, time.Local); err == nil {
			return t, err
		}
	}
	return time.Time{}, fmt.Errorf("no layout matching %q", s)
}