add projects and metrics routes

api/routes/metrics.go

@@ -0,0 +1,77 @@
+package routes
+
+import (
+	"time"
+
+	"github.com/gofiber/fiber/v2"
+	"github.com/ngn13/website/api/database"
+	"github.com/ngn13/website/api/util"
+)
+
+type visitor_cache_entry struct {
+	Addr   string // SHA1 hash of visitor's IP
+	Number uint64 // number of the visitor
+}
+
+const VISITOR_CACHE_MAX = 30            // store 30 visitor data at most
+var visitor_cache []visitor_cache_entry // in memory cache for the visitor
+
+func GET_Metrics(c *fiber.Ctx) error {
+	var (
+		err    error
+		result map[string]uint64 = map[string]uint64{
+			"number": 0, // visitor number of the current visitor
+			"total":  0, // total number of visitors
+			"since":  0, // metric collection start date (UNIX timestamp)
+		}
+	)
+
+	db := c.Locals("database").(*database.Type)
+	new_addr := util.GetSHA1(util.IP(c))
+
+	for i := range visitor_cache {
+		if new_addr == visitor_cache[i].Addr {
+			result["number"] = visitor_cache[i].Number
+			break
+		}
+	}
+
+	if result["total"], err = db.MetricsGet("visitor_count"); err != nil {
+		return util.ErrInternal(c, err)
+	}
+
+	if result["number"] == 0 {
+		result["total"]++
+		result["number"] = result["total"]
+
+		if len(visitor_cache) > VISITOR_CACHE_MAX {
+			util.Debg("visitor cache is full, removing the oldest entry")
+			visitor_cache = visitor_cache[1:]
+		}
+
+		visitor_cache = append(visitor_cache, visitor_cache_entry{
+			Addr:   new_addr,
+			Number: result["number"],
+		})
+
+		if err = db.MetricsSet("visitor_count", result["total"]); err != nil {
+			return util.ErrInternal(c, err)
+		}
+	}
+
+	if result["since"], err = db.MetricsGet("start_date"); err != nil {
+		return util.ErrInternal(c, err)
+	}
+
+	if result["since"] == 0 {
+		result["since"] = uint64(time.Now().Truncate(24 * time.Hour).Unix())
+
+		if err = db.MetricsSet("since", result["since"]); err != nil {
+			return util.ErrInternal(c, err)
+		}
+	}
+
+	return util.JSON(c, 200, fiber.Map{
+		"result": result,
+	})
+}