package main

import (
  "os"
  "fmt"
  "errors"
  "html/template"
  "log"
  "net/http"
  "regexp"
)

type ApiReq struct {
  endpoint string
}

type Page struct {
  Title string
  Content []byte
}

func (p *Page) save() error {
    filename := p.Title + ".txt"
    return os.WriteFile(filename, p.Content, 0600)
}

func loadPage(title string) ( *Page, error ) {
    filename := title + ".txt"
    body, err := os.ReadFile(filename)
    if err != nil {
      return nil, err
    }
    return &Page{Title: title, Content: body}, nil
}

func renderTemplate(w http.ResponseWriter, tmpl string, p *Page) {
  t, err := template.ParseFiles( "views/" + tmpl + ".html" )
  if err != nil {
    http.Error( w, err.Error(), http.StatusInternalServerError )
    return
  }
  err = t.Execute( w, p )
  if err != nil {
    http.Error( w, err.Error(), http.StatusInternalServerError )
    return
  }
}

func apiHandler(w http.ResponseWriter, r *http.Request) {
  endpoint, _ := getTitle( w, r )
  log.Printf(`API Request: %s`, endpoint )
}

func errorViewHandler(w http.ResponseWriter, r *http.Request) {
  title, _ := getTitle( w, r )
  log.Printf( `Rendering error page: %s`, title )
  p := &Page{ Title: title }
  renderTemplate( w, "error", p )
}
func viewHandler(w http.ResponseWriter, r *http.Request) {
  title, err := getTitle( w, r )
  if err != nil { title = "404" }
  log.Printf( `Rendering page: %s`, title )
  p, err := loadPage( title )
  if err != nil {
    http.Redirect( w, r, "/error/404", http.StatusFound )
    return
  }
  renderTemplate( w, "test", p )
}

var validPath = regexp.MustCompile( "^/(view|error|api)/([a-zA-Z0-9]+)$" )
func getTitle( w http.ResponseWriter, r *http.Request ) ( string, error ) {
  m := validPath.FindStringSubmatch( r.URL.Path )
  if m == nil {
    http.NotFound( w, r )
    return "", errors.New("Unsupported Route")
  }
  return m[2], nil
}

func main() {
    http.HandleFunc("/view/", viewHandler)
    http.HandleFunc("/error/", errorViewHandler)
    http.HandleFunc("/api/", apiHandler)

    fmt.Printf("Server Running")

    log.Fatal(http.ListenAndServe(":8080", nil))
}