mv /ana, /ledger to /src/

src/ana/predictor.go

@@ -0,0 +1,159 @@
+package ana
+
+import (
+	"maps"
+	"math"
+	"regexp"
+	"slices"
+	"time"
+
+	"gogs.inhome.blapointe.com/ana-ledger/src/ledger"
+)
+
+const (
+	month = time.Hour * 24 * 365 / 12
+)
+
+type Predictor func(ledger.Balances, time.Duration) ledger.Balances
+
+func NewInterestPredictor(namePattern string, currencyPattern string, apy float64) Predictor {
+	nameMatcher := regexp.MustCompile(namePattern)
+	currencyMatcher := regexp.MustCompile(currencyPattern)
+	return func(given ledger.Balances, delta time.Duration) ledger.Balances {
+		result := maps.Clone(given)
+		for k, v := range result {
+			result[k] = maps.Clone(v)
+		}
+
+		monthsPassed := float64(delta) / float64(month)
+		scalar := math.Pow(1.0+apy/12.0, monthsPassed)
+		for name := range result {
+			if !nameMatcher.MatchString(name) {
+				continue
+			}
+			for currency := range result[name] {
+				if !currencyMatcher.MatchString(string(currency)) {
+					continue
+				}
+				result[name][currency] *= scalar
+			}
+		}
+		return result
+	}
+}
+
+func NewAutoContributionPredictor(reg ledger.Register) Predictor {
+	monthlyRate := getMonthlyAutoContributionRates(reg)
+	return NewContributionPredictor(monthlyRate)
+}
+
+func NewContributionPredictor(monthlyRate ledger.Balances) Predictor {
+	return func(given ledger.Balances, delta time.Duration) ledger.Balances {
+		months := float64(delta) / float64(month)
+		result := make(ledger.Balances)
+		for k, v := range given {
+			result[k] = maps.Clone(v)
+		}
+		for name := range monthlyRate {
+			if _, ok := result[name]; !ok {
+				result[name] = make(ledger.Balance)
+			}
+			for currency := range monthlyRate[name] {
+				result[name][currency] += monthlyRate[name][currency] * months
+			}
+		}
+		return result
+	}
+}
+
+func getMonthlyAutoContributionRates(reg ledger.Register) map[string]ledger.Balance {
+	window := 6 * month
+	window = 12 * month
+	contributions := getRecentContributions(reg, window)
+	result := make(map[string]ledger.Balance)
+	for name := range contributions {
+		result[name] = getMonthlyAutoContributionRate(contributions[name], window)
+	}
+	return result
+}
+
+func getMonthlyAutoContributionRate(contributions []ledger.Balance, window time.Duration) ledger.Balance {
+	currencies := map[ledger.Currency]int{}
+	for _, balance := range contributions {
+		for currency := range balance {
+			currencies[currency] = 1
+		}
+	}
+	result := make(ledger.Balance)
+	for currency := range currencies {
+		result[currency] = getMonthlyAutoContributionRateForCurrency(contributions, window, currency)
+	}
+	return result
+}
+
+func getMonthlyAutoContributionRateForCurrency(contributions []ledger.Balance, window time.Duration, currency ledger.Currency) float64 {
+	values := []float64{}
+	for i := range contributions {
+		if v, ok := contributions[i][currency]; ok {
+			values = append(values, v)
+		}
+	}
+	slices.Sort(values)
+	if len(values) < 3 {
+		return 0
+	}
+
+	start := int(len(values) / 4)
+	end := min(1+max(0, len(values)-len(values)/4), len(values))
+	subvalues := values[start:end]
+	sum := 0.0
+	for _, v := range subvalues {
+		sum += v
+	}
+	standard := sum / float64(end-start)
+	standard = subvalues[len(subvalues)/2]
+	totalIfAllWereStandard := standard * float64(len(contributions))
+	result := totalIfAllWereStandard / float64(window) * float64(month)
+	//log.Printf("%s: %v contributions of about %.2f over %v can TLDR as %.2f per month from %v", currency, len(contributions), standard, window, result, values[start:end])
+	return result
+}
+
+func getRecentContributions(reg ledger.Register, window time.Duration) map[string][]ledger.Balance {
+	return getContributions(reg.Between(time.Now().Add(-1*window), time.Now()))
+}
+
+func getContributions(reg ledger.Register) map[string][]ledger.Balance {
+	contributions := make(map[string][]ledger.Balance)
+	for _, name := range reg.Names() {
+		contributions[name] = getContributionsFor(reg, name)
+	}
+	return contributions
+}
+
+func getContributionsFor(reg ledger.Register, name string) []ledger.Balance {
+	result := make([]ledger.Balance, 0)
+	var last ledger.Balance
+	for _, date := range reg.Dates() {
+		if _, ok := reg[date][name]; !ok {
+			continue
+		}
+
+		if last == nil {
+			last = reg[date][name]
+			continue
+		}
+
+		result = append(result, make(ledger.Balance))
+		this := result[len(result)-1]
+
+		for k, v := range last {
+			this[k] = -1 * v
+		}
+		for k, v := range reg[date][name] {
+			this[k] += v
+		}
+
+		last = reg[date][name]
+	}
+	return result
+}