feat(api): Add DTSTART equivalent support to spending/funding. (#1329)

Right now we do not store the DTSTART component of the RRule, this has
led to some bugs already where we have to assume the DTSTART based on
some educated guess data. This can lead to wrong calculations in the
future. So going forward I want to support this parameter. This is the
start of the work on that.

pkg/migrations/schema/2023022000_DateStarted.tx.up.sql

@@ -0,0 +1,7 @@
+ALTER TABLE "spending" ADD COLUMN "date_started" TIMESTAMPTZ NULL;
+UPDATE "spending" SET "date_started" = "next_recurrence" WHERE "date_started" IS NULL;
+ALTER TABLE "spending" ALTER COLUMN "date_started" SET NOT NULL;
+
+ALTER TABLE "funding_schedules" ADD COLUMN "date_started" TIMESTAMPTZ NULL;
+UPDATE "funding_schedules" SET "date_started" = "next_occurrence" WHERE "date_started" IS NULL;
+ALTER TABLE "funding_schedules" ALTER COLUMN "date_started" SET NOT NULL;

pkg/models/funding_schedule.go

@@ -5,10 +5,13 @@ import (
 	"time"
 
 	"github.com/getsentry/sentry-go"
+	"github.com/go-pg/pg/v10"
 	"github.com/monetr/monetr/pkg/crumbs"
 	"github.com/monetr/monetr/pkg/util"
 )
 
+var _ pg.BeforeInsertHook = (*FundingSchedule)(nil)
+
 type FundingSchedule struct {
 	tableName string `pg:"funding_schedules"`
 
@@ -25,6 +28,7 @@ type FundingSchedule struct {
 	EstimatedDeposit  *int64       `json:"estimatedDeposit" pg:"estimated_deposit"`
 	LastOccurrence    *time.Time   `json:"lastOccurrence" pg:"last_occurrence"`
 	NextOccurrence    time.Time    `json:"nextOccurrence" pg:"next_occurrence,notnull"`
+	DateStarted       time.Time    `json:"dateStarted" pg:"date_started,notnull"`
 }
 
 func (f *FundingSchedule) GetNumberOfContributionsBetween(start, end time.Time, timezone *time.Location) int64 {
@@ -128,3 +132,13 @@ func (f *FundingSchedule) CalculateNextOccurrence(ctx context.Context, timezone
 
 	return true
 }
+
+func (f *FundingSchedule) BeforeInsert(ctx context.Context) (context.Context, error) {
+	// Make sure when we are creating a funding schedule that we set the date started field for the first instance. This
+	// way subsequent rule evaluations can use this date started as a reference point.
+	if f.DateStarted.IsZero() {
+		f.DateStarted = f.NextOccurrence
+	}
+
+	return ctx, nil
+}

pkg/models/spending.go

@@ -5,6 +5,7 @@ import (
 	"strconv"
 	"time"
 
+	"github.com/go-pg/pg/v10"
 	"github.com/monetr/monetr/pkg/crumbs"
 	"github.com/monetr/monetr/pkg/internal/myownsanity"
 	"github.com/monetr/monetr/pkg/util"
@@ -19,6 +20,8 @@ const (
 	SpendingTypeOverflow
 )
 
+var _ pg.BeforeInsertHook = (*Spending)(nil)
+
 type Spending struct {
 	tableName string `pg:"spending"`
 
@@ -42,6 +45,7 @@ type Spending struct {
 	IsBehind               bool             `json:"isBehind" pg:"is_behind,notnull,use_zero"`
 	IsPaused               bool             `json:"isPaused" pg:"is_paused,notnull,use_zero"`
 	DateCreated            time.Time        `json:"dateCreated" pg:"date_created,notnull"`
+	DateStarted            time.Time        `json:"dateStarted" pg:"date_started,notnull"`
 }
 
 func (e Spending) GetIsStale(now time.Time) bool {
@@ -179,3 +183,13 @@ func (e *Spending) CalculateNextContribution(
 
 	return nil
 }
+
+func (s *Spending) BeforeInsert(ctx context.Context) (context.Context, error) {
+	// Make sure when we are creating a funding schedule that we set the date started field for the first instance. This
+	// way subsequent rule evaluations can use this date started as a reference point.
+	if s.DateStarted.IsZero() {
+		s.DateStarted = s.NextRecurrence
+	}
+
+	return ctx, nil
+}

pkg/repository/expenses.go

@@ -96,6 +96,7 @@ func (r *repositoryBase) CreateSpending(ctx context.Context, spending *models.Sp
 
 	spending.AccountId = r.AccountId()
 	spending.DateCreated = time.Now().UTC()
+	spending.DateStarted = spending.NextRecurrence
 
 	if _, err := r.txn.ModelContext(span.Context(), spending).Insert(spending); err != nil {
 		span.Status = sentry.SpanStatusInternalError

pkg/repository/funding_schedules.go

@@ -74,6 +74,8 @@ func (r *repositoryBase) CreateFundingSchedule(ctx context.Context, fundingSched
 	}
 
 	fundingSchedule.AccountId = r.AccountId()
+	fundingSchedule.DateStarted = fundingSchedule.NextOccurrence
+
 	if _, err := r.txn.ModelContext(span.Context(), fundingSchedule).Insert(fundingSchedule); err != nil {
 		span.Status = sentry.SpanStatusInternalError
 		return errors.Wrap(err, "failed to create funding schedule")