cards/src/server/server.go

package main

import (
	"encoding/json"
	"fmt"
	"local/router"
	"local/storage"
	"log"
	"net/http"
	"strings"
)

type Server struct {
	config Config
	gm     *GameMaster
	*router.Router
}

func NewServer(config Config, gm *GameMaster) *Server {
	return &Server{
		config: config,
		gm:     gm,
		Router: router.New(),
	}
}

func (server *Server) Routes() error {
	cases := map[string]map[string]http.HandlerFunc{
		fmt.Sprintf("%s/%s%s", server.config.Server.File.Prefix, router.Wildcard, router.Wildcard): map[string]http.HandlerFunc{
			http.MethodGet: server.File,
		},
		fmt.Sprintf("%s/games", server.config.Server.API.Prefix): map[string]http.HandlerFunc{
			http.MethodGet: server.GameList,
		},
		fmt.Sprintf("%s/games/%s", server.config.Server.API.Prefix, router.Wildcard): map[string]http.HandlerFunc{
			http.MethodGet:  server.GameGet,
			http.MethodPost: server.GameInsert,
			http.MethodPut:  server.GameReplace,
		},
	}

	for path, spec := range cases {
		log.Println("listening for:", path)
		handler := server.ByMethod(spec)
		if err := server.Add(path, handler); err != nil {
			return err
		}
	}

	return nil
}

func (server *Server) ByMethod(m map[string]http.HandlerFunc) http.HandlerFunc {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		foo, ok := m[r.Method]
		if ok {
			foo(w, r)
		} else {
			http.NotFound(w, r)
		}
	})
}

func (server *Server) File(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		http.NotFound(w, r)
		return
	}
	s := http.FileServer(http.Dir(server.config.Server.File.Root))
	r.URL.Path = strings.TrimPrefix(r.URL.Path, server.config.Server.File.Prefix)
	s.ServeHTTP(w, r)
}

func (server *Server) GameList(w http.ResponseWriter, r *http.Request) {
	resp, err := server.gm.ListGames()
	if err != nil {
		internalError(w, err.Error())
		return
	}
	json.NewEncoder(w).Encode(resp)
}

func (server *Server) GameGet(w http.ResponseWriter, r *http.Request) {
	var gameID string
	err := router.Params(r, &gameID)
	if err != nil {
		badRequest(w, err.Error())
		return
	}
	resp, err := server.gm.GetGame(gameID)
	if err != nil {
		internalError(w, err.Error())
		return
	}
	json.NewEncoder(w).Encode(resp)
}

func (server *Server) GameReplace(w http.ResponseWriter, r *http.Request) {
	var gameID string
	err := router.Params(r, &gameID)
	if err != nil {
		badRequest(w, err.Error())
		return
	}
	var game Game
	err = json.NewDecoder(r.Body).Decode(&game)
	if err != nil {
		badRequest(w, err.Error())
		return
	}
	err = server.gm.ReplaceGame(gameID, game)
	if err != nil {
		internalError(w, err.Error())
		return
	}
	json.NewEncoder(w).Encode(game)
}

func (server *Server) GameInsert(w http.ResponseWriter, r *http.Request) {
	var gameID string
	err := router.Params(r, &gameID)
	if err != nil {
		badRequest(w, err.Error())
		return
	}
	err = server.gm.CreateGame(gameID)
	if err != nil {
		internalError(w, err.Error())
		return
	}
	json.NewEncoder(w).Encode(Game{})
}

func notImpl(w http.ResponseWriter) {
	errHandler(w, http.StatusNotImplemented, http.StatusText(http.StatusNotImplemented))
}

func internalError(w http.ResponseWriter, message string) {
	errHandler(w, http.StatusInternalServerError, message)
}

func badRequest(w http.ResponseWriter, message string) {
	errHandler(w, http.StatusBadRequest, message)
}

func errHandler(w http.ResponseWriter, status int, message string) {
	if message == storage.ErrNotFound.Error() {
		status = http.StatusNotFound
	}
	w.WriteHeader(status)
	json.NewEncoder(w).Encode(map[string]interface{}{
		"status":     http.StatusText(status),
		"statusCode": status,
		"error":      message,
	})
}