Add date format option with tests

- Add Date struct with DateOnly flag
- Implement custom date formatting for Notion API
- Add comprehensive test coverage
- Fix timezone formatting in FormatForNotion
- Handle null values in UnmarshalJSON
- Closes #177

date_test.go

@@ -0,0 +1 @@
+package notionapi

pkg/models/date.go

@@ -0,0 +1,71 @@
+package models
+
+import (
+	"encoding/json"
+	"time"
+)
+
+type Date struct {
+	time.Time
+	DateOnly bool
+}
+
+// Format returns the date in the specified format based on DateOnly flag
+func (d Date) Format() string {
+	if d.DateOnly {
+		return d.Time.Format("2006-01-02")
+	}
+	return d.Time.Format(time.RFC3339)
+}
+
+// FormatForNotion returns the date in Notion's expected format
+func (d Date) FormatForNotion() string {
+	if d.DateOnly {
+		return d.Time.Format("2006-01-02")
+	}
+	// Notion expects RFC3339 format without explicit timezone
+	return d.Time.UTC().Format("2006-01-02T15:04:05Z")
+}
+
+// MarshalJSON adds error handling and validation
+func (d Date) MarshalJSON() ([]byte, error) {
+	if d.Time.IsZero() {
+		return []byte("null"), nil
+	}
+	return json.Marshal(d.FormatForNotion())
+}
+
+// UnmarshalJSON adds better error handling
+func (d *Date) UnmarshalJSON(data []byte) error {
+	// Handle null value
+	if string(data) == "null" {
+		d.Time = time.Time{}
+		d.DateOnly = false
+		return nil
+	}
+
+	var rawValue string
+	if err := json.Unmarshal(data, &rawValue); err != nil {
+		return err
+	}
+
+	// Try both formats
+	formats := []string{
+		"2006-01-02",           // Date only
+		"2006-01-02T15:04:05Z", // Full datetime
+		time.RFC3339,           // Fallback
+	}
+
+	var lastErr error
+	for _, format := range formats {
+		if t, err := time.Parse(format, rawValue); err == nil {
+			d.Time = t
+			d.DateOnly = format == "2006-01-02"
+			return nil
+		} else {
+			lastErr = err
+		}
+	}
+
+	return lastErr
+}

pkg/models/date_object.go

@@ -0,0 +1,46 @@
+package models
+
+import "fmt"
+
+type DateObject struct {
+	Start    *Date `json:"start"`
+	End      *Date `json:"end"`
+	DateOnly bool  `json:"date_only,omitempty"`
+}
+
+// NewDateObject creates a new DateObject with validation
+func NewDateObject(start, end *Date, dateOnly bool) (*DateObject, error) {
+	// Validation: end date should not be before start date
+	if start != nil && end != nil && end.Time.Before(start.Time) {
+		return nil, fmt.Errorf("end date cannot be before start date")
+	}
+
+	if start != nil {
+		start.DateOnly = dateOnly
+	}
+	if end != nil {
+		end.DateOnly = dateOnly
+	}
+
+	return &DateObject{
+		Start:    start,
+		End:      end,
+		DateOnly: dateOnly,
+	}, nil
+}
+
+// FormatForNotion formats both dates with error handling
+func (do DateObject) FormatForNotion() (map[string]interface{}, error) {
+	result := make(map[string]interface{})
+
+	if do.Start == nil {
+		return nil, fmt.Errorf("start date is required")
+	}
+
+	result["start"] = do.Start.FormatForNotion()
+	if do.End != nil {
+		result["end"] = do.End.FormatForNotion()
+	}
+
+	return result, nil
+}

pkg/models/date_test.go

@@ -0,0 +1,242 @@
+package models
+
+import (
+	"encoding/json"
+	"testing"
+	"time"
+)
+
+func TestDate_MarshalJSON(t *testing.T) {
+	tests := []struct {
+		name    string
+		date    Date
+		want    string
+		wantErr bool
+	}{
+		{
+			name: "date only format",
+			date: Date{
+				Time:     time.Date(2024, 3, 14, 0, 0, 0, 0, time.UTC),
+				DateOnly: true,
+			},
+			want:    `"2024-03-14"`,
+			wantErr: false,
+		},
+		{
+			name: "datetime format",
+			date: Date{
+				Time:     time.Date(2024, 3, 14, 15, 30, 0, 0, time.UTC),
+				DateOnly: false,
+			},
+			want:    `"2024-03-14T15:30:00Z"`,
+			wantErr: false,
+		},
+		{
+			name: "zero time",
+			date: Date{
+				Time:     time.Time{},
+				DateOnly: false,
+			},
+			want:    "null",
+			wantErr: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := json.Marshal(tt.date)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("Date.MarshalJSON() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if string(got) != tt.want {
+				t.Errorf("Date.MarshalJSON() = %v, want %v", string(got), tt.want)
+			}
+		})
+	}
+}
+
+func TestDate_UnmarshalJSON(t *testing.T) {
+	tests := []struct {
+		name    string
+		json    string
+		want    Date
+		wantErr bool
+	}{
+		{
+			name: "date only format",
+			json: `"2024-03-14"`,
+			want: Date{
+				Time:     time.Date(2024, 3, 14, 0, 0, 0, 0, time.UTC),
+				DateOnly: true,
+			},
+			wantErr: false,
+		},
+		{
+			name: "datetime format",
+			json: `"2024-03-14T15:30:00Z"`,
+			want: Date{
+				Time:     time.Date(2024, 3, 14, 15, 30, 0, 0, time.UTC),
+				DateOnly: false,
+			},
+			wantErr: false,
+		},
+		{
+			name:    "invalid format",
+			json:    `"invalid-date"`,
+			wantErr: true,
+		},
+		{
+			name: "null value",
+			json: "null",
+			want: Date{
+				Time:     time.Time{},
+				DateOnly: false,
+			},
+			wantErr: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var got Date
+			err := json.Unmarshal([]byte(tt.json), &got)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("Date.UnmarshalJSON() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !tt.wantErr {
+				if !got.Time.Equal(tt.want.Time) {
+					t.Errorf("Date.UnmarshalJSON() Time = %v, want %v", got.Time, tt.want.Time)
+				}
+				if got.DateOnly != tt.want.DateOnly {
+					t.Errorf("Date.UnmarshalJSON() DateOnly = %v, want %v", got.DateOnly, tt.want.DateOnly)
+				}
+			}
+		})
+	}
+}
+
+func TestDateObject_FormatForNotion(t *testing.T) {
+	tests := []struct {
+		name    string
+		obj     DateObject
+		want    map[string]interface{}
+		wantErr bool
+	}{
+		{
+			name: "valid date range",
+			obj: DateObject{
+				Start: &Date{
+					Time:     time.Date(2024, 3, 14, 0, 0, 0, 0, time.UTC),
+					DateOnly: true,
+				},
+				End: &Date{
+					Time:     time.Date(2024, 3, 15, 0, 0, 0, 0, time.UTC),
+					DateOnly: true,
+				},
+				DateOnly: true,
+			},
+			want: map[string]interface{}{
+				"start": "2024-03-14",
+				"end":   "2024-03-15",
+			},
+			wantErr: false,
+		},
+		{
+			name: "start date only",
+			obj: DateObject{
+				Start: &Date{
+					Time:     time.Date(2024, 3, 14, 15, 30, 0, 0, time.UTC),
+					DateOnly: false,
+				},
+				DateOnly: false,
+			},
+			want: map[string]interface{}{
+				"start": "2024-03-14T15:30:00Z",
+			},
+			wantErr: false,
+		},
+		{
+			name: "missing start date",
+			obj: DateObject{
+				End: &Date{
+					Time:     time.Date(2024, 3, 15, 0, 0, 0, 0, time.UTC),
+					DateOnly: true,
+				},
+				DateOnly: true,
+			},
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := tt.obj.FormatForNotion()
+			if (err != nil) != tt.wantErr {
+				t.Errorf("DateObject.FormatForNotion() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !tt.wantErr {
+				for k, v := range tt.want {
+					if got[k] != v {
+						t.Errorf("DateObject.FormatForNotion() = %v, want %v", got[k], v)
+					}
+				}
+			}
+		})
+	}
+}
+
+func TestNewDateObject(t *testing.T) {
+	tests := []struct {
+		name     string
+		start    *Date
+		end      *Date
+		dateOnly bool
+		wantErr  bool
+	}{
+		{
+			name: "valid date range",
+			start: &Date{
+				Time:     time.Date(2024, 3, 14, 0, 0, 0, 0, time.UTC),
+				DateOnly: true,
+			},
+			end: &Date{
+				Time:     time.Date(2024, 3, 15, 0, 0, 0, 0, time.UTC),
+				DateOnly: true,
+			},
+			dateOnly: true,
+			wantErr:  false,
+		},
+		{
+			name: "end before start",
+			start: &Date{
+				Time:     time.Date(2024, 3, 15, 0, 0, 0, 0, time.UTC),
+				DateOnly: true,
+			},
+			end: &Date{
+				Time:     time.Date(2024, 3, 14, 0, 0, 0, 0, time.UTC),
+				DateOnly: true,
+			},
+			dateOnly: true,
+			wantErr:  true,
+		},
+		{
+			name:     "start date only",
+			start:    &Date{Time: time.Now()},
+			end:      nil,
+			dateOnly: false,
+			wantErr:  false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			_, err := NewDateObject(tt.start, tt.end, tt.dateOnly)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("NewDateObject() error = %v, wantErr %v", err, tt.wantErr)
+			}
+		})
+	}
+}