package ledger

import (
	"slices"
	"testing"
	"time"
)

func TestRegisterPrediction(t *testing.T) {
	t.Run("contribution", func(t *testing.T) {
		input := newTestRegister()

		got, err := RegisterWithContributionPrediction(input, time.Hour*24*365)
		if err != nil {
			t.Fatal(err)
		}
		t.Logf("%+v", got)

		if len(got) != len(input)+13 {
			t.Error(len(got))
		}

		for _, date := range got.Dates() {
			for _, name := range got.Names() {
				t.Logf("%s | %s = %+v", date, name, got[date][name])
				if ti, _ := dateToTime(date); ti.After(time.Now().Add(time.Hour*24*60)) && got[date][name]["XYZ"] == 0 {
					t.Error("predicting future contributions lost unmodified currency", got[date][name])
				}
			}
		}
	})

	t.Run("compounding interest", func(t *testing.T) {
		input := newTestRegister()

		got, err := RegisterWithCompoundingInterestPrediction(input, time.Hour*24*365, "X", .04)
		if err != nil {
			t.Fatal(err)
		}
		t.Logf("%+v", got)

		if len(got) <= len(input) {
			t.Error(len(got))
		}

		for _, date := range got.Dates() {
			for name, balance := range got[date] {
				t.Logf("%s | %s %s", date, name, balance.Debug())
			}
		}
	})
}

func TestBPIPrediction(t *testing.T) {
	t.Run("fixed growth", func(t *testing.T) {
		bpis := BPIs{
			USD: BPI{
				"2001-01": -1000,
				"2001-02": 100,
			},
		}

		got, err := BPIsWithFixedGrowthPrediction(bpis, time.Hour*24*365, string(USD), 0.06)
		if err != nil {
			t.Fatal(err)
		}

		dates := []string{}
		for d := range got[USD] {
			dates = append(dates, d)
		}
		slices.Sort(dates)

		for _, d := range dates {
			t.Logf("%s | %s %.2f", USD, d, got[USD][d])
		}
	})
}

func newTestRegister() map[string]Balances {
	s := func(t time.Time) string {
		return t.Format("2006-01")
	}
	day := time.Hour * 24
	lastYear := time.Now().Add(-1 * day * time.Duration(time.Now().YearDay()))
	return map[string]Balances{
		s(lastYear.Add(day * 0)):   Balances{"X": Balance{USD: 1}},
		s(lastYear.Add(day * 32)):  Balances{"X": Balance{USD: 2}},
		s(lastYear.Add(day * 64)):  Balances{"X": Balance{USD: 3}},
		s(lastYear.Add(day * 94)):  Balances{"X": Balance{USD: 4}},
		s(lastYear.Add(day * 124)): Balances{"X": Balance{USD: 5}},
		s(lastYear.Add(day * 154)): Balances{"X": Balance{USD: 6}},
		s(lastYear.Add(day * 184)): Balances{"X": Balance{USD: 8}},
		s(lastYear.Add(day * 214)): Balances{"X": Balance{USD: 10}},
		s(lastYear.Add(day * 244)): Balances{"X": Balance{USD: 12}},
		s(lastYear.Add(day * 274)): Balances{"X": Balance{USD: 16, "XYZ": 1}},
	}
}