feat: Add mode to inject templates after marker (#153)

* Add fake enum

* Add test

* Add implementation

* Fixed toolchain not available

* lint

* Update injector.go

* refactor

* update docs

* support skipping empty/null injections

* more test cases

* update linter

---------

Co-authored-by: Anthony Chung <anthony.chung@coinbase.com>

app/commands/cmd_lint.go

@@ -43,6 +43,8 @@ func (ctrl *Controller) Lint(ctx *cli.Context) error {
 			q.Prompt.IsConfirm(),
 			q.Prompt.IsSelect(),
 			q.Prompt.IsMultiSelect(),
+			q.Prompt.IsInputLoop(),
+			q.Prompt.IsTextInput(),
 		}
 
 		isAny := false
@@ -84,6 +86,15 @@ func (ctrl *Controller) Lint(ctx *cli.Context) error {
 		}
 	}
 
+	// Validate injectjons
+	for _, injection := range pf.Inject {
+		if injection.Mode != "" {
+			if injection.Mode != "before" && injection.Mode != "after" {
+				errs = append(errs, fmt.Errorf("invalid injection mode: %s", injection.Mode))
+			}
+		}
+	}
+
 	for _, err := range errs {
 		log.Error().Err(err).Msg("")
 	}

app/scaffold/injector.go

@@ -2,6 +2,7 @@ package scaffold
 
 import (
 	"bufio"
+	"bytes"
 	"errors"
 	"io"
 	"strings"
@@ -23,38 +24,50 @@ func indentation(b string) string {
 // Inject will read the reader line by line and find the line
 // that contains the string "at". It will then insert the data
 // before that line.
-func Inject(r io.Reader, data string, at string) ([]byte, error) {
-	bldr := strings.Builder{}
-	newline := func(s string) {
-		bldr.WriteString(s)
-		bldr.WriteString("\n")
+func Inject(r io.Reader, data string, at string, mode Mode) ([]byte, error) {
+	var buf bytes.Buffer
+
+	// Write a line to the buffer
+	writeLine := func(line string) {
+		buf.WriteString(line)
+		buf.WriteString("\n")
+	}
+
+	// Write multiple lines with indentation to the buffer
+	writeLines := func(lines []string, indent string) {
+		for _, l := range lines {
+			if l != "" {
+				writeLine(indent + l)
+			}
+		}
 	}
 
-	found := false
+	var (
+		inserted      = false
+		found         = false
+		scanner       = bufio.NewScanner(r)
+		linesToInsert = strings.Split(data, "\n")
+	)
 
-	scanner := bufio.NewScanner(r)
+	// Loop through each line in the reader
 	for scanner.Scan() {
 		line := scanner.Text()
 
 		if strings.Contains(line, at) {
-			// Found the line, insert the data
-			// before this line
-			indent := indentation(line)
-
-			lines := strings.Split(data, "\n")
-
-			for _, l := range lines {
-				if l == "" {
-					continue
-				}
-
-				newline(indent + l)
+			if mode != After {
+				writeLines(linesToInsert, indentation(line))
+				inserted = true
 			}
-
 			found = true
 		}
 
-		newline(line)
+		writeLine(line)
+
+		// If in 'after' mode and the insertion point is found, insert after it
+		if mode == After && found && !inserted {
+			writeLines(linesToInsert, indentation(line))
+			inserted = true
+		}
 	}
 
 	if err := scanner.Err(); err != nil {
@@ -65,5 +78,5 @@ func Inject(r io.Reader, data string, at string) ([]byte, error) {
 		return nil, ErrInjectMarkerNotFound
 	}
 
-	return []byte(bldr.String()), nil
+	return buf.Bytes(), nil
 }

app/scaffold/injector_test.go

@@ -7,25 +7,19 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-var t1 = `---
-hello world
-    indented line
-    # Inject Marker
-`
-
-var t1Want = `---
+func TestInject(t *testing.T) {
+	const Marker = "# Inject Marker"
+	const Input = `---
 hello world
     indented line
-    injected line 1
-    injected line 2
     # Inject Marker
 `
 
-func TestInject(t *testing.T) {
 	type args struct {
 		s    string
 		data string
 		at   string
+		mode Mode
 	}
 	tests := []struct {
 		name    string
@@ -36,25 +30,80 @@ func TestInject(t *testing.T) {
 		{
 			name: "inject",
 			args: args{
-				s:    t1,
+				s:    Input,
 				data: "injected line 1\ninjected line 2",
-				at:   "# Inject Marker",
+				at:   Marker,
 			},
-			want: t1Want,
+			want: `---
+hello world
+    indented line
+    injected line 1
+    injected line 2
+    # Inject Marker
+`,
 		},
 		{
-			name: "inject no marker",
+			name: "inject after",
 			args: args{
-				s:    t1,
+				s:    Input,
 				data: "injected line 1\ninjected line 2",
-				at:   "# Inject Marker 2",
+				at:   Marker,
+				mode: After,
+			},
+			want: `---
+hello world
+    indented line
+    # Inject Marker
+    injected line 1
+    injected line 2
+`,
+		},
+		{
+			name: "don't inject empty data",
+			args: args{
+				s:    Input,
+				data: "",
+				at:   Marker,
+			},
+			want: Input,
+		},
+		{
+			name: "don't inject empty lines",
+			args: args{
+				s:    Input,
+				data: "\n\n\n\n",
+				at:   Marker,
+			},
+			want: Input,
+		},
+		{
+			name: "inject no marker",
+			args: args{
+				s:    Input,
+				data: "injected",
+				at:   Marker + "invalid",
 			},
 			wantErr: true,
 		},
+		{
+			name: "preserve manual indentation",
+			args: args{
+				s:    Input,
+				data: "    injected",
+				at:   Marker,
+				mode: After,
+			},
+			want: `---
+hello world
+    indented line
+    # Inject Marker
+        injected
+`,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			got, err := Inject(strings.NewReader(tt.args.s), tt.args.data, tt.args.at)
+			got, err := Inject(strings.NewReader(tt.args.s), tt.args.data, tt.args.at, tt.args.mode)
 
 			switch {
 			case tt.wantErr:

app/scaffold/project_scaffold_file.go

@@ -38,10 +38,18 @@ type Rewrite struct {
 	To   string `yaml:"to"`
 }
 
+type Mode string
+
+const (
+	Before Mode = "before"
+	After  Mode = "after"
+)
+
 type Injectable struct {
 	Name     string `yaml:"name"`
 	Path     string `yaml:"path"`
 	At       string `yaml:"at"`
+	Mode     Mode   `yaml:"mode"`
 	Template string `yaml:"template"`
 }
 

app/scaffold/render_funcs.go

@@ -334,7 +334,12 @@ func RenderRWFS(eng *engine.Engine, args *RWFSArgs, vars engine.Vars) error {
 			return err
 		}
 
-		outbytes, err := Inject(f, out, injection.At)
+		// Assume that empty string or only whitespace is not a valid injection.
+		if out == "" || strings.TrimSpace(out) == "" {
+			continue
+		}
+
+		outbytes, err := Inject(f, out, injection.At, injection.Mode)
 		if err != nil {
 			return err
 		}

docs/docs/.vitepress/config.mts

@@ -6,7 +6,7 @@ export default withMermaid(
     base: "/scaffold/",
     title: "Scaffold",
     description: "A Project and Template Scaffolding Tool",
-    head: [["link", { rel: "icon", href: "/favicon.webp" }]],
+    head: [["link", { rel: "icon", href: "/scaffold/favicon.webp" }]],
     themeConfig: {
       search: {
         provider: "local",