fyp/handler.go

package main

import (
	"fmt"
	"html/template"
	"log"
	"net/http"
	"strings"
)

func baseLoadTemplate(base string, path string) (*template.Template, any) {
	return template.New(base).ParseFiles(
		"./views/"+base,
		"./views/"+path,
		"./views/partials/header.html",
	)
}

func loadTemplate(path string) (*template.Template, any) {
	return baseLoadTemplate("layout.html", path)
}

func LoadView(writer http.ResponseWriter, path string, data interface{}) {
	tmpl, err := loadTemplate(path)
	if err != nil {
		fmt.Printf("Failed to load view %s\n", path)
		fmt.Println(err)
		if path == "500.html" {
			writer.Write([]byte("<h1>Failed to load 500.html check console for more info</h1>"))
		} else {
			LoadView(writer, "500.html", nil)
		}
		return
	}

	if err := tmpl.Execute(writer, data); err != nil {
		fmt.Printf("Failed to load view %s\n", path)
		fmt.Println(err)
		writer.WriteHeader(http.StatusInternalServerError)
		if path == "500.html" {
			writer.Write([]byte("<h1>Failed to load 500.html check console for more info</h1>"))
		} else {
			LoadView(writer, "500.html", nil)
		}
		return
	}
}

/** Only returns the html without template */
func LoadHtml(writer http.ResponseWriter, path string, data interface{}) {
	tmpl, err := baseLoadTemplate("html.html", path)
	if err != nil {
		fmt.Printf("Failed to load template %s\n", path)
		fmt.Println(err)
		writer.WriteHeader(http.StatusInternalServerError)
		if path == "500.html" {
			writer.Write([]byte("<h1>Failed to load 500.html check console for more info</h1>"))
		} else {
			LoadHtml(writer, "500.html", nil)
		}
		return
	}

	if err := tmpl.Execute(writer, data); err != nil {
		fmt.Printf("Failed to execute template %s\n", path)
		fmt.Println(err)
		writer.WriteHeader(http.StatusInternalServerError)
		if path == "500.html" {
			writer.Write([]byte("<h1>Failed to load 500.html check console for more info</h1>"))
		} else {
			LoadHtml(writer, "500.html", nil)
		}
		return
	}
}

type Error struct {
	code int
	msg  *string
}

type AnswerType int

const (
	NORMAL AnswerType = 1 << iota
	HTML
	JSON
	HTMLFULL
)

func LoadBasedOnAnswer(ans AnswerType, w http.ResponseWriter, path string, data map[string]interface{}) {
	if ans == NORMAL {
		LoadView(w, path, nil)
		return
	} else if ans == HTML {
		LoadHtml(w, path, nil)
		return
	} else if ans == HTMLFULL {
		if data == nil {
			LoadHtml(w, path, map[string]interface{}{
				"App": true,
			})
		} else {
			data["App"] = true
			LoadHtml(w, path, data)
		}
		return
	} else if ans == JSON {
		panic("TODO JSON!")
	} else {
		panic("unreachable")
	}

}

type HandleFunc struct {
	path string
	mode AnswerType
	fn   func(mode AnswerType, w http.ResponseWriter, r *http.Request) *Error
}

type Handler interface {
	New()
	Startup()
	Get(fn func(mode AnswerType, w http.ResponseWriter, r *http.Request) *Error)
	Post(fn func(mode AnswerType, w http.ResponseWriter, r *http.Request) *Error)
}

type Handle struct {
	gets  []HandleFunc
	posts []HandleFunc
}

func handleError(err *Error, answerType AnswerType, w http.ResponseWriter) {
	if err != nil {
		w.WriteHeader(err.code)
		if err.code == 404 {
			LoadBasedOnAnswer(answerType, w, "404.html", nil)
			return
		}
		if err.msg != nil {
			w.Write([]byte(*err.msg))
		}
	}
}

func (x *Handle) Get(path string, fn func(mode AnswerType, w http.ResponseWriter, r *http.Request) *Error) {
	nhandler :=
		HandleFunc{
			fn:   fn,
			path: path,
			mode: NORMAL | HTML | HTMLFULL | JSON,
		}

	x.gets = append(x.gets, nhandler)
}

func (x *Handle) GetHTML(path string, fn func(mode AnswerType, w http.ResponseWriter, r *http.Request) *Error) {
	nhandler :=
		HandleFunc{
			fn:   fn,
			path: path,
			mode: NORMAL | HTML | HTMLFULL,
		}

	x.gets = append(x.gets, nhandler)
}

func (x *Handle) GetJSON(path string, fn func(mode AnswerType, w http.ResponseWriter, r *http.Request) *Error) {
	nhandler :=
		HandleFunc{
			fn:   fn,
			path: path,
			mode: JSON,
		}

	x.gets = append(x.gets, nhandler)
}

func (x *Handle) Post(path string, fn func(mode AnswerType, w http.ResponseWriter, r *http.Request) *Error) {
	nhandler :=
		HandleFunc{
			fn:   fn,
			path: path,
			mode: NORMAL | HTML | HTMLFULL | JSON,
		}

	x.posts = append(x.posts, nhandler)
}

func (x *Handle) PostHTML(path string, fn func(mode AnswerType, w http.ResponseWriter, r *http.Request) *Error) {
	nhandler :=
		HandleFunc{
			fn:   fn,
			path: path,
			mode: NORMAL | HTML | HTMLFULL,
		}

	x.posts = append(x.posts, nhandler)
}

func (x *Handle) PostJSON(path string, fn func(mode AnswerType, w http.ResponseWriter, r *http.Request) *Error) {
	nhandler :=
		HandleFunc{
			fn:   fn,
			path: path,
			mode: JSON,
		}

	x.posts = append(x.posts, nhandler)
}

func (x *Handle) handleGets(ans AnswerType, w http.ResponseWriter, r *http.Request) {
	for _, s := range x.gets {
		fmt.Printf("target: %s, paths: %s\n", s.path, r.URL.Path)
		if s.path == r.URL.Path && ans&s.mode != 0 {
			s.fn(ans, w, r)
			return
		}
	}
	w.WriteHeader(http.StatusNotFound)
	LoadBasedOnAnswer(ans, w, "404.html", nil)
}

func (x *Handle) handlePosts(ans AnswerType, w http.ResponseWriter, r *http.Request) {
	for _, s := range x.posts {
		if s.path == r.URL.Path && ans&s.mode != 0 {
			s.fn(ans, w, r)
			return
		}
	}
	w.WriteHeader(http.StatusNotFound)
	LoadBasedOnAnswer(ans, w, "404.html", nil)
}

func AnswerTemplate(path string, data interface{}) func(mode AnswerType, w http.ResponseWriter, r *http.Request) *Error {
	return func(mode AnswerType, w http.ResponseWriter, r *http.Request) *Error {
		LoadBasedOnAnswer(mode, w, path, nil)
		return nil
	}
}

func NewHandler() *Handle {

	x := &Handle{}

	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		ans := NORMAL

		if r.Header.Get("Request-Type") == "htmlfull" {
			ans = HTMLFULL
		}
		if r.Header.Get("Request-Type") == "html" {
			ans = HTML
		}
		//TODO JSON

		if r.Method == "GET" {
			x.handleGets(ans, w, r)
			return
		}
		if r.Method == "POST" {
			x.handlePosts(ans, w, r)
			return
		}
		panic("TODO handle: " + r.Method)
	})

	// TODO Handle this in other way
	http.HandleFunc("/styles/", func(w http.ResponseWriter, r *http.Request) {
		path := r.URL.Path[len("/styles/"):]
		if !strings.HasSuffix(path, ".css") {
			w.WriteHeader(http.StatusNotFound)
			w.Write([]byte("File not found"))
			return
		}

		t, err := template.ParseFiles("./views/styles/" + path)

		if err != nil {
			w.WriteHeader(http.StatusInternalServerError)
			w.Write([]byte("Failed to load template"))
			fmt.Println("Error:")
			fmt.Println(err)
			return
		}

		w.Header().Set("Content-Type", "text/css; charset=utf-8")
		t.Execute(w, nil)
	})

	// TODO Handle this in other way
	http.HandleFunc("/js/", func(w http.ResponseWriter, r *http.Request) {
		path := r.URL.Path[len("/js/"):]
		if !strings.HasSuffix(path, ".js") {
			w.WriteHeader(http.StatusNotFound)
			w.Write([]byte("File not found"))
			return
		}

		t, err := template.ParseFiles("./views/js/" + path)

		if err != nil {
			w.WriteHeader(http.StatusInternalServerError)
			w.Write([]byte("Failed to load template"))
			fmt.Println("Error:")
			fmt.Println(err)
			return
		}

		w.Header().Set("Content-Type", "text/javascript; charset=utf-8")
		t.Execute(w, nil)
	})

	return x
}

func (x Handle) Startup() {
	fmt.Printf("Starting up!\n")
	log.Fatal(http.ListenAndServe(":8000", nil))
}