feat: support file server in rest (#4244)

rest/internal/fileserver/filehandler.go

@@ -0,0 +1,39 @@
+package fileserver
+
+import (
+	"net/http"
+	"strings"
+)
+
+func Middleware(path, dir string) func(http.HandlerFunc) http.HandlerFunc {
+	fileServer := http.FileServer(http.Dir(dir))
+	pathWithTrailSlash := ensureTrailingSlash(path)
+	pathWithoutTrailSlash := ensureNoTrailingSlash(path)
+
+	return func(next http.HandlerFunc) http.HandlerFunc {
+		return func(w http.ResponseWriter, r *http.Request) {
+			if r.Method == http.MethodGet && strings.HasPrefix(r.URL.Path, pathWithTrailSlash) {
+				r.URL.Path = strings.TrimPrefix(r.URL.Path, pathWithoutTrailSlash)
+				fileServer.ServeHTTP(w, r)
+			} else {
+				next(w, r)
+			}
+		}
+	}
+}
+
+func ensureTrailingSlash(path string) string {
+	if strings.HasSuffix(path, "/") {
+		return path
+	}
+
+	return path + "/"
+}
+
+func ensureNoTrailingSlash(path string) string {
+	if strings.HasSuffix(path, "/") {
+		return path[:len(path)-1]
+	}
+
+	return path
+}

rest/internal/fileserver/filehandler_test.go

@@ -0,0 +1,99 @@
+package fileserver
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMiddleware(t *testing.T) {
+	tests := []struct {
+		name            string
+		path            string
+		dir             string
+		requestPath     string
+		expectedStatus  int
+		expectedContent string
+	}{
+		{
+			name:            "Serve static file",
+			path:            "/static/",
+			dir:             "./testdata",
+			requestPath:     "/static/example.txt",
+			expectedStatus:  http.StatusOK,
+			expectedContent: "1",
+		},
+		{
+			name:           "Pass through non-matching path",
+			path:           "/static/",
+			dir:            "./testdata",
+			requestPath:    "/other/path",
+			expectedStatus: http.StatusNotFound,
+		},
+		{
+			name:            "Directory with trailing slash",
+			path:            "/assets",
+			dir:             "testdata",
+			requestPath:     "/assets/sample.txt",
+			expectedStatus:  http.StatusOK,
+			expectedContent: "2",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			middleware := Middleware(tt.path, tt.dir)
+			nextHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				w.WriteHeader(http.StatusNotFound)
+			})
+
+			handlerToTest := middleware(nextHandler)
+
+			req := httptest.NewRequest("GET", tt.requestPath, nil)
+			rr := httptest.NewRecorder()
+
+			handlerToTest.ServeHTTP(rr, req)
+
+			assert.Equal(t, tt.expectedStatus, rr.Code)
+			if len(tt.expectedContent) > 0 {
+				assert.Equal(t, tt.expectedContent, rr.Body.String())
+			}
+		})
+	}
+}
+
+func TestEnsureTrailingSlash(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected string
+	}{
+		{"path", "path/"},
+		{"path/", "path/"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.input, func(t *testing.T) {
+			result := ensureTrailingSlash(tt.input)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+func TestEnsureNoTrailingSlash(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected string
+	}{
+		{"path", "path"},
+		{"path/", "path"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.input, func(t *testing.T) {
+			result := ensureNoTrailingSlash(tt.input)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}

rest/internal/fileserver/testdata/example.txt

@@ -0,0 +1 @@
+1

rest/internal/fileserver/testdata/sample.txt

@@ -0,0 +1 @@
+2