// Chapter 34 example: range and if in a template.
// Run with: go run exercises/34/03-range-and-if.go

package main

import (
	"bytes"
	"fmt"
	"html/template"
	"net/http"
)

type item struct {
	Name string
	Rare bool
}

type listPage struct {
	Title string
	Items []item
}

const listText = `<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>{{.Title}}</title>
</head>
<body>
<h1>{{.Title}}</h1>
<ul>
{{range .Items}}
<li>{{.Name}}{{if .Rare}} (rare){{end}}</li>
{{else}}
<li>Nothing here yet.</li>
{{end}}
</ul>
</body>
</html>
`

var listTemplate = template.Must(template.New("list").Parse(listText))

// render builds the page in memory, and sends it only if that worked.
func render(w http.ResponseWriter, data listPage) {
	var page bytes.Buffer
	err := listTemplate.Execute(&page, data)
	if err != nil {
		fmt.Println("Template error:", err)
		http.Error(w, "The page could not be built.", http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	page.WriteTo(w)
}

func handleBag(w http.ResponseWriter, r *http.Request) {
	data := listPage{
		Title: "My bag",
		Items: []item{
			{Name: "sword", Rare: false},
			{Name: "moon stone", Rare: true},
			{Name: "potion", Rare: false},
		},
	}
	render(w, data)
}

func handleEmpty(w http.ResponseWriter, r *http.Request) {
	render(w, listPage{Title: "An empty bag"})
}

func main() {
	http.HandleFunc("GET /{$}", handleBag)
	http.HandleFunc("GET /empty", handleEmpty)

	fmt.Println("Server running at http://localhost:8080")
	fmt.Println("Press Ctrl+C to stop it.")

	err := http.ListenAndServe("localhost:8080", nil)
	if err != nil {
		fmt.Println("Server stopped:", err)
	}
}