feat: http router, command api

internal/router/command.go

@@ -0,0 +1,49 @@
+package router
+
+import (
+	"errors"
+	"net/http"
+
+	"github.com/iliadenisov/galaxy/internal/game"
+
+	"github.com/gin-gonic/gin"
+	"github.com/iliadenisov/galaxy/internal/controller"
+	"github.com/iliadenisov/galaxy/internal/model/rest"
+)
+
+var (
+	ErrCommandNotProcessed = errors.New("command was not processed by executor")
+)
+
+func CommandHandler(c *gin.Context, executor Executor) {
+	var cmd rest.Command
+	if err := c.ShouldBindJSON(&cmd); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+	err := executor(cmd)
+	switch {
+	case err == nil:
+		c.Status(http.StatusOK)
+	case errors.Is(err, ErrCommandNotProcessed):
+		c.Status(http.StatusInternalServerError)
+	default:
+		// TODO: separate bad value errors and game state errors
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+	}
+}
+
+func Execute(cmd rest.Command) error {
+	p := func(p *controller.Param) {
+		// TODO: initialize base controller settings
+		p.StoragePath = ""
+	}
+	switch {
+	case cmd.DeclareWar != nil:
+		return game.DeclareWar(p, cmd.Race, cmd.DeclareWar.Opponent)
+	case cmd.DeclarePeace != nil:
+		return game.DeclarePeace(p, cmd.Race, cmd.DeclareWar.Opponent)
+	default:
+		return ErrCommandNotProcessed
+	}
+}

internal/router/middleware.go

@@ -0,0 +1,28 @@
+package router
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/gin-gonic/gin"
+)
+
+// LimitMiddleware limits number of concurrent connections using a buffered channel with limit spaces
+func LimitMiddleware(limit int) gin.HandlerFunc {
+	if limit <= 0 {
+		panic("limit must be greater than 0")
+	}
+	semaphore := make(chan bool, limit)
+	t := time.NewTimer(time.Millisecond * 100)
+
+	return func(c *gin.Context) {
+		t.Reset(time.Millisecond * 100)
+		select {
+		case semaphore <- true:
+			c.Next()
+			<-semaphore
+		case <-t.C:
+			c.Status(http.StatusGatewayTimeout)
+		}
+	}
+}

internal/router/router.go

@@ -0,0 +1,40 @@
+package router
+
+import (
+	"github.com/gin-gonic/gin"
+	"github.com/gin-gonic/gin/binding"
+	"github.com/go-playground/validator/v10"
+	"github.com/iliadenisov/galaxy/internal/model/rest"
+)
+
+type Executor func(rest.Command) error
+
+type Router struct {
+	r        *gin.Engine
+	executor Executor
+}
+
+func (r Router) Run() error {
+	return r.r.Run()
+}
+
+func NewRouter() Router {
+	return NewRouterExecutor(Execute)
+}
+
+func NewRouterExecutor(executor Executor) Router {
+	return Router{r: setupRouter(executor)}
+}
+
+func setupRouter(executor Executor) *gin.Engine {
+	gin.SetMode(gin.ReleaseMode)
+	r := gin.New()
+	r.Use(gin.Recovery())
+
+	if v, ok := binding.Validator.Engine().(*validator.Validate); ok {
+		v.RegisterValidation("notblank", notBlankStringValidator)
+	}
+
+	r.PUT("/api/v1/command", LimitMiddleware(1), func(ctx *gin.Context) { CommandHandler(ctx, executor) })
+	return r
+}

internal/router/router_export_test.go

@@ -0,0 +1,10 @@
+package router
+
+import (
+	"github.com/gin-gonic/gin"
+	"github.com/iliadenisov/galaxy/internal/model/rest"
+)
+
+func SetupRouter() *gin.Engine {
+	return setupRouter(func(c rest.Command) error { return nil })
+}

internal/router/router_test.go

@@ -0,0 +1,126 @@
+package router_test
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"testing"
+
+	"github.com/gin-gonic/gin"
+	"github.com/iliadenisov/galaxy/internal/model/rest"
+	"github.com/iliadenisov/galaxy/internal/router"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRouter(t *testing.T) {
+	r := router.SetupRouter()
+
+	exampleCommand := rest.Command{
+		Race: "SomeRace",
+		Vote: &rest.CommandVote{
+			Recipient: "AnotherRace",
+		},
+	}
+
+	w := httptest.NewRecorder()
+	req, _ := http.NewRequest("PUT", "/api/v1/command", cmdBody(exampleCommand))
+	r.ServeHTTP(w, req)
+
+	assert.Equal(t, 200, w.Code, w.Body)
+
+	// error: notblank validator
+	exampleCommand.Race = ""
+	w = httptest.NewRecorder()
+	req, _ = http.NewRequest("PUT", "/api/v1/command", cmdBody(exampleCommand))
+	r.ServeHTTP(w, req)
+
+	assert.Equal(t, http.StatusBadRequest, w.Code, w.Body)
+
+	exampleCommand.Race = "       "
+	w = httptest.NewRecorder()
+	req, _ = http.NewRequest("PUT", "/api/v1/command", cmdBody(exampleCommand))
+	r.ServeHTTP(w, req)
+
+	assert.Equal(t, http.StatusBadRequest, w.Code, w.Body)
+
+	// error: no commands
+	exampleCommand = rest.Command{
+		Race: "SomeRace",
+	}
+
+	w = httptest.NewRecorder()
+	req, _ = http.NewRequest("PUT", "/api/v1/command", cmdBody(exampleCommand))
+	r.ServeHTTP(w, req)
+
+	assert.Equal(t, http.StatusBadRequest, w.Code, w.Body)
+
+	// error: more than one command
+	exampleCommand = rest.Command{
+		Race: "SomeRace",
+		Vote: &rest.CommandVote{
+			Recipient: "AnotherRace",
+		},
+		DeclarePeace: &rest.CommandDeclarePeace{
+			Opponent: "OpponentRace",
+		},
+	}
+
+	w = httptest.NewRecorder()
+	req, _ = http.NewRequest("PUT", "/api/v1/command", cmdBody(exampleCommand))
+	r.ServeHTTP(w, req)
+
+	assert.Equal(t, http.StatusBadRequest, w.Code, w.Body)
+}
+
+func TestLimitConnections(t *testing.T) {
+	r := limitTestingRouter()
+
+	wg := sync.WaitGroup{}
+	lock := sync.WaitGroup{}
+	lock.Add(1)
+	for range 1000 {
+		wg.Go(func() {
+			w := httptest.NewRecorder()
+			lock.Wait()
+			req, _ := http.NewRequest("GET", "/limited", nil)
+			r.ServeHTTP(w, req)
+			assert.Equal(t, 200, w.Code, w.Body)
+		})
+	}
+	lock.Done()
+	wg.Wait()
+}
+
+func cmdBody(cmd rest.Command) *strings.Reader {
+	commandJson, _ := json.Marshal(cmd)
+	return strings.NewReader(string(commandJson))
+}
+
+func limitTestingRouter() *gin.Engine {
+	gin.SetMode(gin.ReleaseMode)
+	r := gin.New()
+	r.Use(gin.Recovery())
+
+	counter := atomic.Int32{}
+	r.GET("/limited",
+		// limiting all ingoing connections
+		router.LimitMiddleware(1),
+		// storing counter value and testing increment after executing Next handlers
+		func(c *gin.Context) {
+			expected := counter.Load() + 1
+			c.Next()
+			current := counter.Load()
+			if current != expected {
+				c.String(http.StatusConflict, "expected: %d, got: %d", expected, current)
+			}
+		},
+		// increment counter
+		func(c *gin.Context) {
+			counter.Add(1)
+			c.Status(http.StatusOK)
+		})
+	return r
+}

internal/router/validator.go

@@ -0,0 +1,17 @@
+package router
+
+import (
+	"strings"
+
+	"github.com/go-playground/validator/v10"
+)
+
+var notBlankStringValidator validator.Func = func(fl validator.FieldLevel) bool {
+	s, ok := fl.Field().Interface().(string)
+	if ok {
+		if len(strings.TrimSpace(s)) == 0 {
+			return false
+		}
+	}
+	return true
+}