Refactor scheduleAdaptiveNextDueDate function for improved readability and fix bug, Add New Tests for it

2 files changed, 247 insertions, 12 deletions

diff --git a/internal/chore/scheduler.go b/internal/chore/scheduler.go
index 5413447..cec120d 100644
--- a/internal/chore/scheduler.go
+++ b/internal/chore/scheduler.go
@@ -3,6 +3,7 @@ package chore
 import (
 	"encoding/json"
 	"fmt"
+	"math"
 	"math/rand"
 	"strings"
 	"time"
@@ -141,11 +142,15 @@ func scheduleNextDueDate(chore *chModel.Chore, completedDate time.Time) (*time.T
 	return &nextDueDate, nil
 
 }
-
 func scheduleAdaptiveNextDueDate(chore *chModel.Chore, completedDate time.Time, history []*chModel.ChoreHistory) (*time.Time, error) {
-	//  will generate due date base on history and the different between the completed date and the due date
-	// the more recent the higher weight
-	if len(history) <= 1 {
+
+	history = append([]*chModel.ChoreHistory{
+		{
+			CompletedAt: &completedDate,
+		},
+	}, history...)
+
+	if len(history) < 2 {
 		if chore.NextDueDate != nil {
 			diff := completedDate.UTC().Sub(chore.NextDueDate.UTC())
 			nextDueDate := completedDate.UTC().Add(diff)
@@ -153,22 +158,23 @@ func scheduleAdaptiveNextDueDate(chore *chModel.Chore, completedDate time.Time,
 		}
 		return nil, nil
 	}
-	var weight float64
+
+	var totalDelay float64
 	var totalWeight float64
-	var nextDueDate time.Time
+	decayFactor := 0.5 // Adjust this value to control the decay rate
+
 	for i := 0; i < len(history)-1; i++ {
 		delay := history[i].CompletedAt.UTC().Sub(history[i+1].CompletedAt.UTC()).Seconds()
-		weight = delay * float64(len(history)-i)
+		weight := math.Pow(decayFactor, float64(i))
+		totalDelay += delay * weight
 		totalWeight += weight
 	}
-	// calculate the average delay
-	averageDelay := totalWeight / float64(len(history)-1)
-	// calculate the difference between the completed date and the due date
-	nextDueDate = completedDate.UTC().Add(time.Duration(averageDelay) * time.Second)
+
+	averageDelay := totalDelay / totalWeight
+	nextDueDate := completedDate.UTC().Add(time.Duration(averageDelay) * time.Second)
 
 	return &nextDueDate, nil
 }
-
 func RemoveAssigneeAndReassign(chore *chModel.Chore, userID int) {
 	for i, assignee := range chore.Assignees {
 		if assignee.UserID == userID {
diff --git a/internal/chore/scheduler_test.go b/internal/chore/scheduler_test.go
new file mode 100644
index 0000000..21d064a
--- /dev/null
+++ b/internal/chore/scheduler_test.go
@@ -0,0 +1,229 @@
+package chore
+
+import (
+	"encoding/json"
+	"testing"
+	"time"
+
+	chModel "donetick.com/core/internal/chore/model"
+)
+
+func TestScheduleNextDueDateBasic(t *testing.T) {
+	choreTime := time.Now()
+	freqencyMetadataBytes := `{"time":"2024-07-07T14:30:00-04:00"}`
+
+	testTable := []struct {
+		chore    *chModel.Chore
+		expected time.Time
+	}{
+		{
+			chore: &chModel.Chore{
+				FrequencyType:     chModel.FrequancyTypeDaily,
+				NextDueDate:       &choreTime,
+				FrequencyMetadata: &freqencyMetadataBytes,
+			},
+			expected: choreTime.AddDate(0, 0, 1),
+		},
+		{
+			chore: &chModel.Chore{
+				FrequencyType:     chModel.FrequancyTypeWeekly,
+				NextDueDate:       &choreTime,
+				FrequencyMetadata: &freqencyMetadataBytes,
+			},
+			expected: choreTime.AddDate(0, 0, 7),
+		},
+		{
+			chore: &chModel.Chore{
+				FrequencyType:     chModel.FrequancyTypeMonthly,
+				NextDueDate:       &choreTime,
+				FrequencyMetadata: &freqencyMetadataBytes,
+			},
+			expected: choreTime.AddDate(0, 1, 0),
+		},
+		{
+			chore: &chModel.Chore{
+				FrequencyType:     chModel.FrequancyTypeYearly,
+				NextDueDate:       &choreTime,
+				FrequencyMetadata: &freqencyMetadataBytes,
+			},
+			expected: choreTime.AddDate(1, 0, 0),
+		},
+
+		//
+	}
+	for _, tt := range testTable {
+		t.Run(string(tt.chore.FrequencyType), func(t *testing.T) {
+
+			actual, err := scheduleNextDueDate(tt.chore, choreTime)
+			if err != nil {
+				t.Errorf("Error: %v", err)
+			}
+			if actual != nil && actual.UTC().Format(time.RFC3339) != tt.expected.UTC().Format(time.RFC3339) {
+				t.Errorf("Expected: %v, Actual: %v", tt.expected, actual)
+			}
+		})
+	}
+}
+
+func TestScheduleNextDueDateDayOfTheWeek(t *testing.T) {
+	choreTime := time.Now()
+
+	Monday := "monday"
+	Wednesday := "wednesday"
+
+	timeOfChore := "2024-07-07T16:30:00-04:00"
+	getExpectedTime := func(choreTime time.Time, timeOfChore string) time.Time {
+		t, err := time.Parse(time.RFC3339, timeOfChore)
+		if err != nil {
+			return time.Time{}
+		}
+		return time.Date(choreTime.Year(), choreTime.Month(), choreTime.Day(), t.Hour(), t.Minute(), 0, 0, t.Location())
+	}
+	nextSaturday := choreTime.AddDate(0, 0, 1)
+	for nextSaturday.Weekday() != time.Saturday {
+		nextSaturday = nextSaturday.AddDate(0, 0, 1)
+	}
+
+	nextMonday := choreTime.AddDate(0, 0, 1)
+	for nextMonday.Weekday() != time.Monday {
+		nextMonday = nextMonday.AddDate(0, 0, 1)
+	}
+
+	nextTuesday := choreTime.AddDate(0, 0, 1)
+	for nextTuesday.Weekday() != time.Tuesday {
+		nextTuesday = nextTuesday.AddDate(0, 0, 1)
+	}
+
+	nextWednesday := choreTime.AddDate(0, 0, 1)
+	for nextWednesday.Weekday() != time.Wednesday {
+		nextWednesday = nextWednesday.AddDate(0, 0, 1)
+	}
+
+	nextThursday := choreTime.AddDate(0, 0, 1)
+	for nextThursday.Weekday() != time.Thursday {
+		nextThursday = nextThursday.AddDate(0, 0, 1)
+	}
+
+	testTable := []struct {
+		chore             *chModel.Chore
+		frequencyMetadata *chModel.FrequencyMetadata
+		expected          time.Time
+	}{
+		{
+			chore: &chModel.Chore{
+				FrequencyType: chModel.FrequancyTypeDayOfTheWeek,
+				NextDueDate:   &nextSaturday,
+			},
+			frequencyMetadata: &chModel.FrequencyMetadata{
+				Time: timeOfChore,
+				Days: []*string{&Monday, &Wednesday},
+			},
+
+			expected: getExpectedTime(nextMonday, timeOfChore),
+		},
+		{
+			chore: &chModel.Chore{
+				FrequencyType: chModel.FrequancyTypeDayOfTheWeek,
+				NextDueDate:   &nextMonday,
+			},
+			frequencyMetadata: &chModel.FrequencyMetadata{
+				Time: timeOfChore,
+				Days: []*string{&Monday, &Wednesday},
+			},
+			expected: getExpectedTime(nextWednesday, timeOfChore),
+		},
+	}
+	for _, tt := range testTable {
+		t.Run(string(tt.chore.FrequencyType), func(t *testing.T) {
+			bytesFrequencyMetadata, err := json.Marshal(tt.frequencyMetadata)
+			stringFrequencyMetadata := string(bytesFrequencyMetadata)
+
+			if err != nil {
+				t.Errorf("Error: %v", err)
+			}
+			tt.chore.FrequencyMetadata = &stringFrequencyMetadata
+			actual, err := scheduleNextDueDate(tt.chore, choreTime)
+
+			if err != nil {
+				t.Errorf("Error: %v", err)
+			}
+			if actual != nil && actual.UTC().Format(time.RFC3339) != tt.expected.UTC().Format(time.RFC3339) {
+				t.Errorf("Expected: %v, Actual: %v", tt.expected, actual)
+			}
+		})
+	}
+}
+func TestScheduleAdaptiveNextDueDate(t *testing.T) {
+	getTimeFromDate := func(timeOfChore string) *time.Time {
+		t, err := time.Parse(time.RFC3339, timeOfChore)
+		if err != nil {
+			return nil
+		}
+		return &t
+	}
+	testTable := []struct {
+		description  string
+		history      []*chModel.ChoreHistory
+		chore        *chModel.Chore
+		expected     *time.Time
+		completeDate *time.Time
+	}{
+		{
+			description: "Every Two days",
+			chore: &chModel.Chore{
+				NextDueDate: getTimeFromDate("2024-07-13T01:30:00-00:00"),
+			},
+			history: []*chModel.ChoreHistory{
+				{
+					CompletedAt: getTimeFromDate("2024-07-11T01:30:00-00:00"),
+				},
+				// {
+				// 	CompletedAt: getTimeFromDate("2024-07-09T01:30:00-00:00"),
+				// },
+				// {
+				// 	CompletedAt: getTimeFromDate("2024-07-07T01:30:00-00:00"),
+				// },
+			},
+			expected: getTimeFromDate("2024-07-15T01:30:00-00:00"),
+		},
+		{
+			description: "Every 8 days",
+			chore: &chModel.Chore{
+				NextDueDate: getTimeFromDate("2024-07-13T01:30:00-00:00"),
+			},
+			history: []*chModel.ChoreHistory{
+				{
+					CompletedAt: getTimeFromDate("2024-07-05T01:30:00-00:00"),
+				},
+				{
+					CompletedAt: getTimeFromDate("2024-06-27T01:30:00-00:00"),
+				},
+			},
+			expected: getTimeFromDate("2024-07-21T01:30:00-00:00"),
+		},
+		{
+			description: "40 days with limit Data",
+			chore: &chModel.Chore{
+				NextDueDate: getTimeFromDate("2024-07-13T01:30:00-00:00"),
+			},
+			history: []*chModel.ChoreHistory{
+				{CompletedAt: getTimeFromDate("2024-06-03T01:30:00-00:00")},
+			},
+			expected: getTimeFromDate("2024-08-22T01:30:00-00:00"),
+		},
+	}
+	for _, tt := range testTable {
+		t.Run(tt.description, func(t *testing.T) {
+			expectedNextDueDate := tt.expected
+
+			actualNextDueDate, err := scheduleAdaptiveNextDueDate(tt.chore, *tt.chore.NextDueDate, tt.history)
+			if err != nil {
+				t.Errorf("Error: %v", err)
+			}
+
+			if actualNextDueDate == nil || !actualNextDueDate.Equal(*expectedNextDueDate) {
+				t.Errorf("Expected: %v, Actual: %v", expectedNextDueDate, actualNextDueDate)
+			}
+		})
+	}
+}