superherohub/internal/router/router.go

package router

import (
	"encoding/json"
	"github.com/eslider/superherohub/pkg/deesee"
	"log"
	"net/http"
	"strings"

	"github.com/gorilla/mux"
)

// Router is a custom router that encapsulates the mux.Router
type Router struct {
	store  Storage     // The store where superheroes are stored
	router *mux.Router // Encapsulated mux router
	logger *log.Logger // The logger to use for this router
	key    int         // The key to use for DeeSee encryption
}

type Storage interface {
	// List  of superheroes
	List() []*deesee.Superhero

	// Put stores a superhero in the store.
	Put(*deesee.Superhero) error
}

// New creates a new encapsulated router.
//
// The pattern I use is to define a custom router structure
// that has a `mux.Router` as the field and also encapsulates things
// like the JSON store to load, encryption-keys, database connection,
// application configuration, and so on.
//
// This makes it easy to update routes as they
// require different resources and development progresses.
//
// And handlers shouldn't have prefix like "handle", course they are methods of the Router
func New(store Storage, key int, logger *log.Logger) *Router {
	// Set the logger
	if logger == nil {
		logger = log.Default()
	}

	r := &Router{
		store:  store,
		key:    key,
		logger: logger,
		router: mux.NewRouter(),
	}

	r.router.Use(r.loggingMiddleware)

	// Set a custom 404 handler
	r.router.NotFoundHandler = http.HandlerFunc(r.HandleNotFound)

	// Set `getSuperHeroes` as the handler for the route
	r.router.HandleFunc("/superheroes", r.GetSuperHeroes).Methods(http.MethodGet)

	// Set `putSuperHero` as the handler for the route
	r.router.HandleFunc("/superheroes", r.StoreSuperHero).Methods(http.MethodPut)

	// Enable CORS by uncommenting the following line
	// router.Use(mux.CORSMethodMiddleware(router))

	// Maybe better to use /api prefix for all routes?
	// subrouter := router.PathPrefix("/api").Subrouter()
	return r
}

// GetHandler returns the encapsulated router
func (r *Router) GetHandler() http.Handler {
	return r.router
}

// GetSuperHeroes returns a list of superheroes
// with optional filtering and encryption of identities.
//
// Usage:
//
//   - Retrieve all superheroes
//
//     GET /superheroes
//
//   - Retrieve all superheroes with encrypted identities:
//
//     GET /superheroes?encrypted=true
//
//   - Retrieve superheroes that match given superpower(s)
//
//     GET /superheroes?superpowers=flight,super-strength
//
//   - Retrieve superheroes that match given superpower(s) with encrypted identities
//
//     GET /superheroes?superpowers=flight,super-strength&encrypted=true
func (r *Router) GetSuperHeroes(w http.ResponseWriter, req *http.Request) {
	var (
		// Resulting
		heroes = r.store.List()
		// Get query parameter values
		params = req.URL.Query()
		err    error
	)

	// Filter superheroes by superpowers?
	// The name of the power should be long enough to search for, at least 3 chars.
	if powerFilter := params.Get("superpowers"); len(powerFilter) > 2 {

		// Here we use the `strings` package to split comma-separated power names.
		// Maybe it's better to prevent send special chars by remove with regular expression.
		powers := strings.Split(powerFilter, ",")
		heroes = deesee.SearchByPowers(heroes, powers)
	}

	// Encrypt identities with DeeSee encryption algorithm?
	if strings.EqualFold(params.Get("encrypted"), "true") {
		// Encrypt identities
		heroes = deesee.EncryptHerosIdentities(heroes, r.key)
	}

	w.Header().Set("Content-Type", "application/json")

	// Return JSON
	if err = json.NewEncoder(w).Encode(heroes); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
}

// StoreSuperHero saves one superhero
func (r *Router) StoreSuperHero(w http.ResponseWriter, req *http.Request) {
	var (
		err  error
		hero = &deesee.Superhero{}
	)

	// Decode JSON
	if err = json.NewDecoder(req.Body).Decode(hero); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	// Put superhero
	if err = r.store.Put(hero); err != nil {
		http.Error(w, err.Error(), http.StatusConflict)
		return
	}

	// Return JSON
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusCreated)

	// Response body
	_, err = w.Write([]byte(`{
	  "message": "Superhero stored successfully.",
	  "status": "success"
	}`))

	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
}

// HandleNotFound is a custom 404 handler
func (r *Router) HandleNotFound(w http.ResponseWriter, _ *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusNotFound)
	_, err := w.Write([]byte(`{"error": "not found"}`))
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
}

// loggingMiddleware is a middleware that logs all requests
func (r *Router) loggingMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
		r.logger.Printf("Request: %s %s", req.Method, req.RequestURI)
		next.ServeHTTP(w, req)
	})
}