package main

import (
	"fmt"
	"log"
	"net/http"
	"runtime/debug"
)

func (app *application) serverError(w http.ResponseWriter, r *http.Request, err error) {
	var (
		method = r.Method
		uri    = r.URL.RequestURI()
		trace  = string(debug.Stack())
	)

	app.logger.Error(err.Error(), "method", method, "uri", uri, "trace", trace)
	log.Printf("Crash! %s %s %s", method, uri, trace)
	http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
}

// The clientError helper sends a specific status code and corresponding description
// to the user. We'll use this later in the book to send responses like 400 "Bad
// Request" when there's a problem with the request that the user sent.
func (app *application) clientError(w http.ResponseWriter, status int) {
	http.Error(w, http.StatusText(status), status)
}

// notFound helper is a convenience wrapper around clientError which sends a 404 Not Found response
func (app *application) notFound(w http.ResponseWriter) {
	app.clientError(w, http.StatusNotFound)
}

func (app *application) render(w http.ResponseWriter, r *http.Request, status int, page string, data templateData) {
	// retrieve the appropriate template set from the cache based on the page name.
	// If no entry exists in the cache with the provided name, create a new error
	// and call serverError() helper that we made earlier and return.
	ts, ok := app.templateCache[page]
	if !ok {
		err := fmt.Errorf("the template %s does not exist", page)
		app.serverError(w, r, err)
		return
	}

	// Write out the provided HTTP status code('200 OK', '400 Bad Request', etc).
	w.WriteHeader(status)

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