From 37c3b2a78017e3acfb36664d74062a100c7b8f90 Mon Sep 17 00:00:00 2001
From: Tim Wundenberg <tim@wundenbergs.de>
Date: Mon, 9 Sep 2024 23:16:27 +0200
Subject: [PATCH] feat: inc generic metric if error occurs #161

---
 service/auth.go    | 23 +++++++++++------------
 service/workout.go |  3 +--
 utils/http.go      | 21 +++++++++++++++++++++
 3 files changed, 33 insertions(+), 14 deletions(-)

diff --git a/service/auth.go b/service/auth.go
index f2d1820..3853e9d 100644
--- a/service/auth.go
+++ b/service/auth.go
@@ -5,7 +5,6 @@ import (
 	"crypto/subtle"
 	"database/sql"
 	"encoding/base64"
-	"log/slog"
 	"net/http"
 	"net/mail"
 	"strings"
@@ -96,12 +95,12 @@ func HandleSignUpVerifyResponsePage(db *sql.DB) http.HandlerFunc {
 		`, token)
 
 		if err != nil {
-			slog.Error("Could not update user: " + err.Error())
+			utils.LogError("Could not update user", err)
 			return
 		}
 		i, err := result.RowsAffected()
 		if err != nil {
-			slog.Error("Could not get rows affected: " + err.Error())
+			utils.LogError("Could not get rows affected", err)
 			return
 		}
 
@@ -144,7 +143,7 @@ func HandleSignUpComp(db *sql.DB) http.HandlerFunc {
 
 		userId, err := uuid.NewRandom()
 		if err != nil {
-			slog.Error("Could not generate UUID: %v", err)
+			utils.LogError("Could not generate UUID", err)
 			auth.Error("Internal Server Error").Render(r.Context(), w)
 			return
 		}
@@ -152,7 +151,7 @@ func HandleSignUpComp(db *sql.DB) http.HandlerFunc {
 		salt := make([]byte, 16)
 		_, err = rand.Read(salt)
 		if err != nil {
-			slog.Error("Could not generate salt: %v", err)
+			utils.LogError("Could not generate salt", err)
 			auth.Error("Internal Server Error").Render(r.Context(), w)
 			return
 		}
@@ -172,7 +171,7 @@ func HandleSignUpComp(db *sql.DB) http.HandlerFunc {
 			}
 
 			auth.Error("Internal Server Error").Render(r.Context(), w)
-			slog.Error("Could not insert user: %v", err)
+			utils.LogError("Could not insert user", err)
 			return
 		}
 
@@ -250,7 +249,7 @@ func HandleSignOutComp(db *sql.DB) http.HandlerFunc {
 		if user != nil {
 			_, err := db.Exec("DELETE FROM session WHERE session_id = ?", user.SessionId)
 			if err != nil {
-				slog.Error("Could not delete session: %v", err)
+				utils.LogError("Could not delete session%v", err)
 				http.Error(w, err.Error(), http.StatusInternalServerError)
 				return
 			}
@@ -289,14 +288,14 @@ func sendVerificationEmail(db *sql.DB, r *http.Request, userId string, email str
 	var b []byte = make([]byte, 32)
 	_, err := rand.Reader.Read(b)
 	if err != nil {
-		slog.Error("Could not generate token: " + err.Error())
+		utils.LogError("Could not generate token", err)
 		return
 	}
 	token := base64.StdEncoding.EncodeToString(b)
 
 	_, err = db.Exec("INSERT INTO user_token (user_uuid, type, token, created_at) VALUES (?, 'email_verify', ?, datetime())", userId, token)
 	if err != nil {
-		slog.Error("Could not insert token: " + err.Error())
+		utils.LogError("Could not insert token", err)
 		return
 	}
 
@@ -310,7 +309,7 @@ func tryCreateSessionAndSetCookie(r *http.Request, w http.ResponseWriter, db *sq
 	var session_id_bytes []byte = make([]byte, 32)
 	_, err := rand.Reader.Read(session_id_bytes)
 	if err != nil {
-		slog.Error("Could not generate session ID: " + err.Error())
+		utils.LogError("Could not generate session ID", err)
 		auth.Error("Internal Server Error").Render(r.Context(), w)
 		return false
 	}
@@ -319,12 +318,12 @@ func tryCreateSessionAndSetCookie(r *http.Request, w http.ResponseWriter, db *sq
 	// Delete old inactive sessions
 	_, err = db.Exec("DELETE FROM session WHERE created_at < datetime('now','-8 hours') AND user_uuid = ?", user_uuid)
 	if err != nil {
-		slog.Error("Could not delete old sessions: " + err.Error())
+		utils.LogError("Could not delete old sessions", err)
 	}
 
 	_, err = db.Exec("INSERT INTO session (session_id, user_uuid, created_at) VALUES (?, ?, datetime())", session_id, user_uuid)
 	if err != nil {
-		slog.Error("Could not insert session: " + err.Error())
+		utils.LogError("Could not insert session", err)
 		auth.Error("Internal Server Error").Render(r.Context(), w)
 		return false
 	}
diff --git a/service/workout.go b/service/workout.go
index 3c67e09..a43cea6 100644
--- a/service/workout.go
+++ b/service/workout.go
@@ -1,7 +1,6 @@
 package service
 
 import (
-	"log/slog"
 	"me-fit/template"
 	"me-fit/template/workout"
 	"me-fit/utils"
@@ -66,7 +65,7 @@ func HandleWorkoutNewComp(db *sql.DB) http.HandlerFunc {
 		var rowId int
 		err = db.QueryRow("INSERT INTO workout (user_id, date, type, sets, reps) VALUES (?, ?, ?, ?, ?) RETURNING rowid", user.Id, date, typeStr, sets, reps).Scan(&rowId)
 		if err != nil {
-			slog.Error(err.Error())
+			utils.LogError("Could not insert workout", err)
 			http.Error(w, err.Error(), http.StatusInternalServerError)
 			return
 		}
diff --git a/utils/http.go b/utils/http.go
index 8dd3b31..72f1a79 100644
--- a/utils/http.go
+++ b/utils/http.go
@@ -6,6 +6,9 @@ import (
 	"me-fit/types"
 	"net/http"
 	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
 )
 
 type ContextKey string
@@ -14,6 +17,24 @@ const (
 	ContextKeyUser ContextKey = "user_id"
 )
 
+var (
+	errorMetric = promauto.NewCounter(
+		prometheus.CounterOpts{
+			Name: "mefit_error_total",
+			Help: "The total number of errors during processing",
+		},
+	)
+)
+
+func LogError(message string, err error) {
+	slog.Error(message + ": " + err.Error())
+	errorMetric.Inc()
+}
+func LogErrorMsg(message string) {
+	slog.Error(message)
+	errorMetric.Inc()
+}
+
 func DoRedirect(w http.ResponseWriter, r *http.Request, url string) {
 	isHtmx := r.Header.Get("HX-Request") == "true"
 	if isHtmx {