Added datafile for persistent ideas

The data file uses a version number for debugging and is serialized into
a data file, for now this is good enough but because of encapsulating
the data in a struct there is no convenient way of appending to the
Ideas slice.
- Removed the Rating as it is not really constructive.
- Added handling of SIGINT to keep the data even on exit from air of
  Ctrl-c
- Removed example data
- Use log instaed of fmt everywhere
- Removed Makefile

1 files changed, 81 insertions, 44 deletions

diff --git a/main.go b/main.go
index 9f1383b..8d07d58 100644
--- a/main.go
+++ b/main.go
@@ -2,14 +2,21 @@ package main
 
 import (
 	_ "embed"
-	"fmt"
+	"encoding/gob"
 	"html/template"
+	"io"
 	"log"
 	"net/http"
+	"os"
+	"os/signal"
+	"runtime/debug"
 )
 
 // File for persistent storage
-const DataFilename = "main.data"
+var DataFilename = "ideas.data"
+
+// Version number used for debugging compatibility with the .data file
+var Version string
 
 // layout for how the date should be output in html
 var DateLayout string = "02/01/2006 on 15:04"
@@ -19,13 +26,15 @@ var DateLayout string = "02/01/2006 on 15:04"
 //go:embed ideas.html
 var ideas_html string
 
+var data Store
+
 // ToDo's
 // - [ ] Add a post
-// - [ ] Serialize data to a  file
 // - [ ] Remove a post
-// - [x] Change the date format printing
 // - [ ] work with funcmaps in templates
 // - [ ] Put a reaction on a post
+// - [x] Store ideas to a file (encoder/gob)
+// - [x] Change the date format printing
 
 // Represents an idea
 // CreatedAt is a formatted date string
@@ -38,59 +47,87 @@ type Idea struct {
 	CreatedAt   string
 }
 
-func main() {
-	var ideas []Idea
+// Data needed through the programm, this data is written to DataFilename for persistent storage
+// Is also the format for the Data file
+type Store struct {
+	Version string
+	Ideas   []Idea
+}
 
-	// Create a .data file  in the cache directory
-	{
-		// data := os.Getenv("XDG_CACHE_HOME")
-		// if data == "" {
-		// 	data = "."
-		// }
-		// data = data + ""
-		//
-		// file, err := os.Create(data + "/" + DataFilename)
-		// if err != nil {
-		// 	panic(err)
-		// }
+func GetVersion() string {
+	buildinfo, ok := debug.ReadBuildInfo()
+	if !ok {
+		log.Fatalln("Could not read buildinfo to know package version.")
 	}
-	// hardcoded data
+	return buildinfo.Main.Version
+}
+
+func main() {
+	Version = GetVersion()
+
+	// Create a .data file  in the cache directory and decode eventual ideas from it
 	{
-		ideas = []Idea{
-			{
-				Title:       "Better Keylogger",
-				Description: "Keylogger which records statistics about your typing.",
-				Author:      "Me",
-				CreatedAt:   "26/09/2024 on 14:51",
-			},
-			{
-				Title:       "music tracker",
-				Description: "An app that can track music across multiple music apps such as spotify, apple music, deezer, etc.",
-				Author:      "Me",
-				CreatedAt:   "24/09/2024 on 14:32",
-			},
-			{
-				Title:       "automated hosting",
-				Description: "Service to host a website where people can drag&drop their files and they are hosted, it also provides a subdomain automatically.",
-				Author:      "Him",
-			},
+		p := os.Getenv("XDG_CACHE_HOME")
+		// TODO: remove for testing
+		p = ""
+		if p == "" {
+			p = "."
+		}
+		DataFilename = p + "/" + DataFilename
+
+		f, err := os.OpenFile(DataFilename, os.O_RDONLY|os.O_CREATE, 0666)
+		if err != nil {
+			log.Fatalln("Error while opening data file:", err)
+		}
+
+		dec := gob.NewDecoder(f)
+		if err := dec.Decode(&data); err != io.EOF && err != nil {
+			log.Fatalln("Error while decoding ideas:", err)
+		}
+		log.Println(data)
+
+		if data.Version != Version {
+			log.Fatalf("Version mismatch for datafile@%s != package@%s\n", data.Version, Version)
+		}
+
+		log.Printf("Imported @%s: %d ideas\n", data.Version, len(data.Ideas))
+		if err := f.Close(); err != nil {
+			log.Fatalln("Error while closing file:", err)
 		}
 	}
-	// // Example of parsing a string into time with the layout
-	// CreatedAt: func() string {
-	// 	t, _ := time.Parse(DateLayout, "24/09/2024 on 14:40")
-	// 	return t.Format(DateLayout)
 
-	tmpl, err := template.New("mytemplate").Parse(ideas_html)
+	// Handle SIGINT
+	// On program exit it should write all its data to the datafile
+	// TODO: Instead of recreating the file the new ideas should be appended, a way to achieve this would be that every time a new idea is added it is appended to the file, this way there is no need to ensure this.
+	go func() {
+		c := make(chan os.Signal, 1)
+		signal.Notify(c, os.Interrupt)
+		<-c
+
+		f, err := os.Create(DataFilename)
+		if err != nil {
+			log.Fatalln(err)
+		}
+		defer f.Close()
+
+		enc := gob.NewEncoder(f)
+		if err := enc.Encode(data); err != nil {
+			log.Fatalln(err)
+		}
+		log.Println("data saved.")
+		os.Exit(0)
+	}()
+
+	tmpl, err := template.New("ideas_html").Parse(ideas_html)
 	if err != nil {
 		log.Fatalln(err)
 	}
 
 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
-		tmpl.Execute(w, struct{ Ideas []Idea }{ideas})
+		tmpl.Execute(w, data)
 	})
 
-	fmt.Println("Listening on http://localhost:8080")
+	log.Println("Listening on http://localhost:8080")
 	err = http.ListenAndServe(":8080", nil)
 	if err != nil {
 		log.Fatalln(err)