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package main
import (
_ "embed"
"encoding/gob"
"html/template"
"io"
"log"
"net/http"
"os"
"os/signal"
"runtime/debug"
"time"
)
// File for persistent storage
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"
// template for /ideas
//
//go:embed ideas.html
var ideas_html string
var Ideas []Idea
// ToDo's
// - [ ] Add a post
// - [ ] Remove a post
// - [ ] 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
// out of 5 rating of the idea
// formatted time string with DateLayout
type Idea struct {
Title string
Text string
Author string
CreatedAt string
Comment []Comment
}
// Represents a comment on an idea
type Comment struct {
Text string
Author string
CreatedAt string
}
// Data passed to the ideas_html template
type PageData struct {
Ideas []Idea
Error string
}
func GetVersion() string {
buildinfo, ok := debug.ReadBuildInfo()
if !ok {
log.Fatalln("Could not read buildinfo to know package version.")
}
return buildinfo.Main.Version
}
func main() {
Version = GetVersion()
// If the .data file does not exist, create it in the cache directory
{
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)
}
// Decode the data and import it into Ideas
dec := gob.NewDecoder(f)
var v string
if err := dec.Decode(&v); err != io.EOF && err != nil {
log.Fatalln("Error while decoding version:", err)
}
if v != Version {
log.Fatalf("Version mismatch for datafile@%s != package@%s\n", v, Version)
}
err = dec.Decode(&Ideas)
if err != nil && err != io.EOF {
log.Fatalln("Error while decoding ideas:", err)
}
log.Printf("Imported @%s: %d ideas\n", v, len(Ideas))
if err := f.Close(); err != nil {
log.Fatalln("Error while closing file:", err)
}
}
// Handle SIGINT
// Save all Ideas into the data file
// NOTE (Luca): This system might seem dumb, but it only adds overhead at startup
// and exit of the program which is fine.
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(Version); err != nil {
log.Fatalln(err)
}
if err := enc.Encode(Ideas); err != nil {
log.Fatalln("Error while saving ideas:", err)
}
log.Println("data saved.")
os.Exit(0)
}()
// Handling http
tmpl, err := template.New("ideas_html").Parse(ideas_html)
if err != nil {
log.Fatalln(err)
}
// TODO (Luca): Make the app more interactive by using websockets instead,
// such that adding, editing or commenting on an idea does not require to
// refresh the page.
// Another approach would be to use htmx?
http.HandleFunc("/ideas/", func(w http.ResponseWriter, r *http.Request) {
tmpl.Execute(w, PageData{Ideas, ""})
})
http.HandleFunc("/create/", func(w http.ResponseWriter, r *http.Request) {
if r.Method != http.MethodPost {
http.Redirect(w, r, "/ideas/", http.StatusMovedPermanently)
return
}
i := Idea{
Title: r.FormValue("title"),
Author: r.FormValue("author"),
CreatedAt: time.Now().Format(DateLayout),
Text: r.FormValue("text"),
}
for _, v := range Ideas {
if i.Title == v.Title {
tmpl.Execute(w, PageData{Ideas, "An idea with title '" + v.Title + "' already exists!"})
return
}
}
Ideas = append(Ideas, i)
log.Println("Added new idea:", i.Title)
http.Redirect(w, r, "/ideas/", http.StatusMovedPermanently)
})
http.HandleFunc("/edit/", func(w http.ResponseWriter, r *http.Request) {
if r.Method != http.MethodPost {
http.Redirect(w, r, "/ideas/", http.StatusMovedPermanently)
return
}
http.Redirect(w, r, "/ideas/", http.StatusMovedPermanently)
})
http.HandleFunc("/delete/", func(w http.ResponseWriter, r *http.Request) {
if r.Method != http.MethodPost {
http.Redirect(w, r, "/ideas/", http.StatusMovedPermanently)
return
}
t := r.FormValue("title")
for i, v := range Ideas {
if t == v.Title {
log.Println("Deleted:", v.Title)
Ideas = append(Ideas[:i], Ideas[i+1:]...)
http.Redirect(w, r, "/ideas/", http.StatusMovedPermanently)
return
}
}
tmpl.Execute(w, PageData{Ideas, "No idea with name '" + t + "'."})
})
http.HandleFunc("/comment/", func(w http.ResponseWriter, r *http.Request) {
if r.Method != http.MethodPost {
http.Redirect(w, r, "/ideas/", http.StatusMovedPermanently)
return
}
http.Redirect(w, r, "/ideas/", http.StatusMovedPermanently)
})
log.Println("Listening on http://localhost:8080")
err = http.ListenAndServe(":8080", nil)
if err != nil {
log.Fatalln(err)
}
}
|
