feat(api): Add endpoint to retrieve response time (#1070)

Add in the API the ability to get Response Times

Co-authored-by: Adrian Almenar <adrian@tecnocratica.net>

api/raw.go

@@ -41,3 +41,35 @@ func UptimeRaw(c *fiber.Ctx) error {
 	c.Set("Expires", "0")
 	return c.Status(200).Send([]byte(fmt.Sprintf("%f", uptime)))
 }
+
+func ResponseTimeRaw(c *fiber.Ctx) error {
+	duration := c.Params("duration")
+	var from time.Time
+	switch duration {
+	case "30d":
+		from = time.Now().Add(-30 * 24 * time.Hour)
+	case "7d":
+		from = time.Now().Add(-7 * 24 * time.Hour)
+	case "24h":
+		from = time.Now().Add(-24 * time.Hour)
+	case "1h":
+		from = time.Now().Add(-2 * time.Hour) // Because uptime metrics are stored by hour, we have to cheat a little
+	default:
+		return c.Status(400).SendString("Durations supported: 30d, 7d, 24h, 1h")
+	}
+	key := c.Params("key")
+	responseTime, err := store.Get().GetAverageResponseTimeByKey(key, from, time.Now())
+	if err != nil {
+		if errors.Is(err, common.ErrEndpointNotFound) {
+			return c.Status(404).SendString(err.Error())
+		} else if errors.Is(err, common.ErrInvalidTimeRange) {
+			return c.Status(400).SendString(err.Error())
+		}
+		return c.Status(500).SendString(err.Error())
+	}
+
+	c.Set("Content-Type", "text/plain")
+	c.Set("Cache-Control", "no-cache, no-store, must-revalidate")
+	c.Set("Expires", "0")
+	return c.Status(200).Send([]byte(fmt.Sprintf("%d", responseTime)))
+}