fix notification the day before [2]

.claude/settings.local.json

@@ -0,0 +1,9 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(grep:*)",
+      "Bash(go list:*)",
+      "Bash(go tool cover:*)"
+    ]
+  }
+}

cmd/app/main.go

@@ -1,3 +1,5 @@
+// Package main is the entry point for the birthday notification bot web application.
+// It initializes the Telegram bot and HTTP server for the web UI.
 package main
 
 import (
@@ -37,6 +39,9 @@ func main() {
 	}
 }
 
+// initBot creates and starts the Telegram bot from the TELEGRAM_BOT_TOKEN environment variable.
+// It logs a warning if the token is not set and returns nil without error.
+// Returns an error if bot creation or startup fails.
 func initBot() (*bot.Bot, error) {
 	token := os.Getenv("TELEGRAM_BOT_TOKEN")
 	if token == "" {

internal/bot/birthday_notification_test.go

@@ -18,7 +18,7 @@ func TestBirthdayNotificationUniqueness(t *testing.T) {
 	}
 
 	// Simulate first birthday notification
-	shouldSend := bot.shouldSendBirthdayNotification(testBirthday, "BIRTHDAY_TODAY", 0)
+	shouldSend := bot.shouldSendBirthdayNotification(testBirthday, "BIRTHDAY_TODAY")
 	if !shouldSend {
 		t.Error("First birthday notification should be sent")
 	}
@@ -27,16 +27,130 @@ func TestBirthdayNotificationUniqueness(t *testing.T) {
 	testBirthday.LastNotification = time.Now()
 
 	// Simulate second birthday notification on the same day
-	shouldSend = bot.shouldSendBirthdayNotification(testBirthday, "BIRTHDAY_TODAY", 0)
+	shouldSend = bot.shouldSendBirthdayNotification(testBirthday, "BIRTHDAY_TODAY")
 	if shouldSend {
 		t.Error("Second birthday notification on the same day should not be sent")
 	}
 
 	// Simulate birthday notification on a different day
 	futureTime := time.Now().AddDate(0, 0, 1)
 	testBirthday.LastNotification = futureTime
-	shouldSend = bot.shouldSendBirthdayNotification(testBirthday, "BIRTHDAY_TODAY", 0)
+	shouldSend = bot.shouldSendBirthdayNotification(testBirthday, "BIRTHDAY_TODAY")
 	if !shouldSend {
 		t.Error("Birthday notification should be sent on a different day")
 	}
 }
+
+// TestBirthdayDateCalculationAtDifferentTimes tests that birthday date calculation
+// works correctly regardless of the time of day (fixes off-by-one day bug)
+func TestBirthdayDateCalculationAtDifferentTimes(t *testing.T) {
+	testCases := []struct {
+		name         string
+		currentTime  time.Time
+		birthdayMMDD string
+		expectedDiff int
+		description  string
+	}{
+		{
+			name:         "Birthday tomorrow at late evening (8 PM)",
+			currentTime:  time.Date(2025, 12, 15, 20, 0, 0, 0, time.UTC),
+			birthdayMMDD: "12-16",
+			expectedDiff: 1,
+			description:  "Should be 1 day away, not 0 (bug case)",
+		},
+		{
+			name:         "Birthday tomorrow at midnight",
+			currentTime:  time.Date(2025, 12, 15, 0, 0, 0, 0, time.UTC),
+			birthdayMMDD: "12-16",
+			expectedDiff: 1,
+			description:  "Should be 1 day away",
+		},
+		{
+			name:         "Birthday today at late evening (11 PM)",
+			currentTime:  time.Date(2025, 12, 15, 23, 0, 0, 0, time.UTC),
+			birthdayMMDD: "12-15",
+			expectedDiff: 0,
+			description:  "Should be 0 days away (today)",
+		},
+		{
+			name:         "Birthday today at early morning (2 AM)",
+			currentTime:  time.Date(2025, 12, 15, 2, 0, 0, 0, time.UTC),
+			birthdayMMDD: "12-15",
+			expectedDiff: 0,
+			description:  "Should be 0 days away (today)",
+		},
+		{
+			name:         "Birthday in 2 weeks at late evening",
+			currentTime:  time.Date(2025, 12, 1, 20, 0, 0, 0, time.UTC),
+			birthdayMMDD: "12-15",
+			expectedDiff: 14,
+			description:  "Should be exactly 14 days away",
+		},
+		{
+			name:         "Birthday in 4 weeks at late evening",
+			currentTime:  time.Date(2025, 11, 17, 20, 0, 0, 0, time.UTC),
+			birthdayMMDD: "12-15",
+			expectedDiff: 28,
+			description:  "Should be exactly 28 days away",
+		},
+		{
+			name:         "Birthday yesterday at late evening",
+			currentTime:  time.Date(2025, 12, 16, 20, 0, 0, 0, time.UTC),
+			birthdayMMDD: "12-15",
+			expectedDiff: -1,
+			description:  "Should be -1 days (passed yesterday)",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			// Parse the birthday MM-DD using the test case's year
+			thisYearBirthday, err := time.Parse("2006-01-02", tc.currentTime.Format("2006")+"-"+tc.birthdayMMDD)
+			if err != nil {
+				t.Fatalf("Failed to parse birthday date: %v", err)
+			}
+
+			// Normalize current time to start of day (midnight) - this is the fix
+			nowDate := time.Date(tc.currentTime.Year(), tc.currentTime.Month(), tc.currentTime.Day(), 0, 0, 0, 0, time.UTC)
+
+			// Calculate days difference using date-only comparison
+			daysDiff := int(thisYearBirthday.Sub(nowDate).Hours() / 24)
+
+			if daysDiff != tc.expectedDiff {
+				t.Errorf("%s: Expected %d days, got %d days. %s",
+					tc.name, tc.expectedDiff, daysDiff, tc.description)
+				t.Logf("Current time: %s", tc.currentTime.Format("2006-01-02 15:04:05"))
+				t.Logf("Normalized date: %s", nowDate.Format("2006-01-02 15:04:05"))
+				t.Logf("Birthday date: %s", thisYearBirthday.Format("2006-01-02 15:04:05"))
+			}
+		})
+	}
+}
+
+// TestBirthdayDateCalculationBugReproduction specifically tests the original bug scenario
+func TestBirthdayDateCalculationBugReproduction(t *testing.T) {
+	// This is the exact scenario that caused the bug:
+	// Current time: December 15, 2025 at 8 PM (20:00)
+	// Birthday: December 16 (tomorrow)
+	// Bug: Bot would send "Happy Birthday" on Dec 15 instead of Dec 16
+
+	currentTime := time.Date(2025, 12, 15, 20, 0, 0, 0, time.UTC) // 8 PM on Dec 15
+	birthdayMMDD := "12-16"                                       // Birthday is Dec 16
+
+	// Parse the birthday for this year
+	thisYearBirthday, err := time.Parse("2006-01-02", currentTime.Format("2006")+"-"+birthdayMMDD)
+	if err != nil {
+		t.Fatalf("Failed to parse birthday date: %v", err)
+	}
+
+	nowDate := time.Date(currentTime.Year(), currentTime.Month(), currentTime.Day(), 0, 0, 0, 0, time.UTC)
+	daysDiffFixed := int(thisYearBirthday.Sub(nowDate).Hours() / 24)
+
+	if daysDiffFixed != 1 {
+		t.Errorf("Bug still exists! Expected 1 day difference, got %d", daysDiffFixed)
+		t.Logf("Current time: %s", currentTime.Format("2006-01-02 15:04:05 MST"))
+		t.Logf("Normalized date: %s", nowDate.Format("2006-01-02 15:04:05 MST"))
+		t.Logf("Birthday date: %s", thisYearBirthday.Format("2006-01-02 15:04:05 MST"))
+		t.Fatal("The off-by-one day bug has not been fixed!")
+	}
+}