From 505e5aae755fb5c1e46b744deac33c1c0562f54b Mon Sep 17 00:00:00 2001
From: Bhasher <github.it@bhasher.com>
Date: Thu, 4 Jan 2024 14:13:27 +0100
Subject: [PATCH] Server side If-Modified-Since cache

---
 backend/handlers/projects.go | 18 +++++++++++++++++-
 backend/main.go              |  3 +--
 backend/utils/cache.go       | 21 +++++++++++++++++++++
 3 files changed, 39 insertions(+), 3 deletions(-)
 create mode 100644 backend/utils/cache.go

diff --git a/backend/handlers/projects.go b/backend/handlers/projects.go
index 9f24e64..2c67c70 100644
--- a/backend/handlers/projects.go
+++ b/backend/handlers/projects.go
@@ -3,9 +3,11 @@ package handlers
 import (
 	"fmt"
 	"strconv"
+	"time"
 
 	"git.bhasher.com/bhasher/focus/backend/db"
 	"git.bhasher.com/bhasher/focus/backend/types"
+	"git.bhasher.com/bhasher/focus/backend/utils"
 	"github.com/gofiber/fiber/v2"
 )
 
@@ -21,8 +23,16 @@ func projectsRouter(router fiber.Router) error {
 	return nil
 }
 
+var projectsLastEdit time.Time;
+
 func GetAllProjects(c *fiber.Ctx) error {
+	isCached, err := utils.Cache(c, projectsLastEdit);
+	if err == nil && isCached {
+		return nil;
+	}
+
 	projects, err := db.GetAllProjects()
+	currentTime := time.Now();
 	if err != nil {
 		return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{
 			"error": "Cannot retrieve projects",
@@ -30,7 +40,13 @@ func GetAllProjects(c *fiber.Ctx) error {
 		})
 	}
 
-	return c.Status(fiber.StatusOK).JSON(projects)
+	err = c.Status(fiber.StatusOK).JSON(projects)
+	if err != nil {
+		return err;
+	}
+
+	projectsLastEdit = currentTime;
+	return nil;
 }
 
 func GetProject(c *fiber.Ctx) error {
diff --git a/backend/main.go b/backend/main.go
index df17f12..a8a9727 100644
--- a/backend/main.go
+++ b/backend/main.go
@@ -6,7 +6,6 @@ import (
 	"os"
 
 	"github.com/gofiber/fiber/v2"
-	"github.com/gofiber/fiber/v2/middleware/cache"
 	"github.com/gofiber/fiber/v2/middleware/cors"
 	_ "github.com/mattn/go-sqlite3"
 
@@ -37,7 +36,7 @@ func main() {
 		AllowHeaders: "Origin, Content-Type, Accept",
 	}))
 
-	app.Use(cache.New())
+	// app.Use(cache.New())
 
 	handlers.APIRouter(app.Group("/api"))
 
diff --git a/backend/utils/cache.go b/backend/utils/cache.go
new file mode 100644
index 0000000..280cb64
--- /dev/null
+++ b/backend/utils/cache.go
@@ -0,0 +1,21 @@
+package utils
+
+import (
+	"time"
+
+	"github.com/gofiber/fiber/v2"
+)
+
+func Cache(c *fiber.Ctx, lastEdit time.Time) (bool, error) {
+	clientLast, err := time.Parse(time.RFC1123, c.Get("If-Modified-Since"))
+	if err != nil {
+		return false, err
+	}
+	
+	if clientLast.Before(lastEdit) {
+		c.SendStatus(fiber.StatusNotModified)
+		return true, nil
+	}
+
+	return false, nil
+}
\ No newline at end of file