private/apigen: Resolve import issues

This change resolves several issues:
* Imports can no longer be duplicated
* The import statement now conforms to Storj's code style requirements
* Packages are imported as needed, eliminating extraneous imports

Change-Id: Ie021e06bb0d472c65aa3575db94bc81ccac108e3

private/apigen/gogen.go

@@ -9,6 +9,7 @@ import (
 	"net/http"
 	"os"
 	"reflect"
+	"sort"
 	"strings"
 	"time"
 
@@ -45,57 +46,55 @@ func (a *API) generateGo() ([]byte, error) {
 		return pathPackages[len(pathPackages)-1]
 	}
 
-	p("// AUTOGENERATED BY private/apigen")
-	p("// DO NOT EDIT.")
-	p("")
+	imports := struct {
+		All      map[string]bool
+		Standard []string
+		External []string
+		Internal []string
+	}{
+		All: make(map[string]bool),
+	}
 
-	p("package %s", a.PackageName)
-	p("")
+	i := func(paths ...string) {
+		for _, path := range paths {
+			if getPackageName(path) == a.PackageName {
+				return
+			}
 
-	p("import (")
-	p(`"context"`)
-	p(`"encoding/json"`)
-	p(`"net/http"`)
-	p(`"time"`)
-	p("")
-	p(`"github.com/gorilla/mux"`)
-	p(`"github.com/zeebo/errs"`)
-	p(`"go.uber.org/zap"`)
-	p("")
+			if _, ok := imports.All[path]; ok {
+				return
+			}
+			imports.All[path] = true
 
-	p(`"storj.io/common/uuid"`)
-	p(`"storj.io/storj/private/api"`)
+			var slice *[]string
+			switch {
+			case !strings.Contains(path, "."):
+				slice = &imports.Standard
+			case strings.HasPrefix(path, "storj.io"):
+				slice = &imports.Internal
+			default:
+				slice = &imports.External
+			}
+			*slice = append(*slice, path)
+		}
+	}
 
 	for _, group := range a.EndpointGroups {
 		for _, method := range group.Endpoints {
 			if method.Request != nil {
-				path := reflect.TypeOf(method.Request).Elem().PkgPath()
-				pn := getPackageName(path)
-				if pn == a.PackageName {
-					continue
-				}
-
-				p(`"%s"`, path)
+				i(reflect.TypeOf(method.Request).Elem().PkgPath())
 			}
 			if method.Response != nil {
-				path := reflect.TypeOf(method.Response).Elem().PkgPath()
-				pn := getPackageName(path)
-				if pn == a.PackageName {
-					continue
-				}
-
-				p(`"%s"`, path)
+				i(reflect.TypeOf(method.Response).Elem().PkgPath())
 			}
 		}
 	}
 
-	p(")")
-	p("")
-
 	p("const dateLayout = \"2006-01-02T15:04:05.000Z\"")
 	p("")
 
 	for _, group := range a.EndpointGroups {
+		i("github.com/zeebo/errs")
 		p("var Err%sAPI = errs.Class(\"%s %s api\")", cases.Title(language.Und).String(group.Prefix), a.PackageName, group.Prefix)
 	}
 
@@ -109,6 +108,7 @@ func (a *API) generateGo() ([]byte, error) {
 				params += param.Type.String() + ", "
 			}
 
+			i("context", "storj.io/storj/private/api")
 			if e.Response != nil {
 				responseType := reflect.TypeOf(e.Response)
 				p("%s(context.Context, "+params+") (%s, api.HTTPError)", e.MethodName, a.handleTypesPackage(responseType))
@@ -121,6 +121,7 @@ func (a *API) generateGo() ([]byte, error) {
 	}
 
 	for _, group := range a.EndpointGroups {
+		i("go.uber.org/zap")
 		p("// %sHandler is an api handler that exposes all %s related functionality.", group.Name, group.Prefix)
 		p("type %sHandler struct {", group.Name)
 		p("log *zap.Logger")
@@ -131,6 +132,7 @@ func (a *API) generateGo() ([]byte, error) {
 	}
 
 	for _, group := range a.EndpointGroups {
+		i("github.com/gorilla/mux")
 		p(
 			"func New%s(log *zap.Logger, service %sService, router *mux.Router, auth api.Auth) *%sHandler {",
 			group.Name,
@@ -156,6 +158,7 @@ func (a *API) generateGo() ([]byte, error) {
 
 	for _, group := range a.EndpointGroups {
 		for pathMethod, endpoint := range group.Endpoints {
+			i("net/http")
 			p("")
 			handlerName := "handle" + endpoint.MethodName
 			p("func (h *%sHandler) %s(w http.ResponseWriter, r *http.Request) {", group.Name, handlerName)
@@ -168,15 +171,7 @@ func (a *API) generateGo() ([]byte, error) {
 			p("")
 
 			if !endpoint.NoCookieAuth || !endpoint.NoAPIAuth {
-				if !endpoint.NoCookieAuth && !endpoint.NoAPIAuth {
-					p("ctx, err = h.auth.IsAuthenticated(ctx, r, true, true)")
-				}
-				if endpoint.NoCookieAuth && !endpoint.NoAPIAuth {
-					p("ctx, err = h.auth.IsAuthenticated(ctx, r, false, true)")
-				}
-				if !endpoint.NoCookieAuth && endpoint.NoAPIAuth {
-					p("ctx, err = h.auth.IsAuthenticated(ctx, r, true, false)")
-				}
+				p("ctx, err = h.auth.IsAuthenticated(ctx, r, %v, %v)", !endpoint.NoCookieAuth, !endpoint.NoAPIAuth)
 				p("if err != nil {")
 				if !endpoint.NoCookieAuth {
 					p("h.auth.RemoveAuthCookie(w)")
@@ -192,9 +187,11 @@ func (a *API) generateGo() ([]byte, error) {
 				for _, param := range endpoint.Params {
 					switch param.Type {
 					case reflect.TypeOf(uuid.UUID{}):
+						i("storj.io/common/uuid")
 						handleUUIDQuery(p, param)
 						continue
 					case reflect.TypeOf(time.Time{}):
+						i("time")
 						handleTimeQuery(p, param)
 						continue
 					case reflect.TypeOf(""):
@@ -262,6 +259,7 @@ func (a *API) generateGo() ([]byte, error) {
 			p("return")
 			p("}")
 
+			i("encoding/json")
 			p("")
 			p("err = json.NewEncoder(w).Encode(retVal)")
 			p("if err != nil {")
@@ -271,6 +269,34 @@ func (a *API) generateGo() ([]byte, error) {
 		}
 	}
 
+	fileBody := result
+	result = ""
+
+	p("// AUTOGENERATED BY private/apigen")
+	p("// DO NOT EDIT.")
+	p("")
+
+	p("package %s", a.PackageName)
+	p("")
+
+	p("import (")
+	slices := [][]string{imports.Standard, imports.External, imports.Internal}
+	for sn, slice := range slices {
+		sort.Strings(slice)
+		for pn, path := range slice {
+			p(`"%s"`, path)
+			if pn == len(slice)-1 && sn < len(slices)-1 {
+				p("")
+			}
+		}
+	}
+	p(")")
+	p("")
+
+	result += fileBody
+
+	fmt.Printf("\n\n\nHERE:%v\n\n\n", result)
+
 	output, err := format.Source([]byte(result))
 	if err != nil {
 		return nil, err