package main

import (
	"bytes"
	"fmt"
	"net/http"
	"path"
	"runtime/debug"
	"strings"
)

func (app *application) serverError(w http.ResponseWriter, err error) {
    trace := fmt.Sprintf("%s\n%s", err.Error(), debug.Stack())
    app.errorLog.Print(trace)

    http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
}

func (app *application) clientError(w http.ResponseWriter, status int) {
    http.Error(w, http.StatusText(status), status)
}

func (app *application) notFound(w http.ResponseWriter) {
    app.clientError(w, http.StatusNotFound)
}

func (app *application) cleanUrl(url string) string {
    s := strings.TrimPrefix(url, "http://")
    s = strings.TrimPrefix(s, "https://")
    s = path.Base(path.Clean(s))
    s = "http://" + s
    return s
}

func (app *application) renderPage(w http.ResponseWriter, status int, page string, data *templateData) {
    ts, ok := app.templateCache[page]
    if !ok {
        err := fmt.Errorf("the template %s does not exist", page)
        app.serverError(w, err)
        return
    }

    // a buffer to attempt to write the template to
    // before writing it to the ResponseWriter w
    buf := new(bytes.Buffer)

    err := ts.ExecuteTemplate(buf, "base", data)
    if err != nil {
        app.serverError(w, err)
        return
    }

    w.WriteHeader(status)

    buf.WriteTo(w)
}

func (app *application) renderElem(w http.ResponseWriter, status int, elem string, data *templateData) {
    ts, ok := app.templateCache[elem]
    if !ok {
        err := fmt.Errorf("the template %s does not exist", elem)
        app.serverError(w, err)
        return
    }

    // a buffer to attempt to write the template to
    // before writing it to the ResponseWriter w
    buf := new(bytes.Buffer)

    err := ts.Execute(buf, data)
    if err != nil {
        app.serverError(w, err)
        return
    }

    w.WriteHeader(status)

    buf.WriteTo(w)
}