Prompt for template variables values based on the available manifest

internal/template/copy.go

@@ -9,7 +9,7 @@ import (
 	"strings"
 	"text/template"
 
-	"gitlab.com/wpetit/scaffold/internal/fs"
+	"forge.cadoles.com/wpetit/scaffold/internal/fs"
 	"gopkg.in/src-d/go-billy.v4"
 
 	"github.com/Masterminds/sprig"
@@ -60,8 +60,6 @@ func CopyDir(vfs billy.Filesystem, baseDir string, dst string, opts *Option) err
 
 		dstPath := filepath.Join(dst, relSrcPath)
 
-		log.Printf("relSrcPath: %s, dstPath: %s", relSrcPath, dstPath)
-
 		if info.IsDir() {
 			log.Printf("creating dir '%s'", dstPath)
 			if err := os.MkdirAll(dstPath, 0755); err != nil {

internal/template/manifest.go

@@ -1,11 +1,158 @@
 package template
 
+import (
+	"io"
+	"io/ioutil"
+
+	"github.com/antonmedv/expr"
+	"github.com/antonmedv/expr/vm"
+	"github.com/manifoldco/promptui"
+	"github.com/pkg/errors"
+	"gopkg.in/yaml.v2"
+)
+
+const (
+	ManifestVersion1 = "1"
+	VarTypeString    = "string"
+	VarTypeSelect    = "select"
+)
+
+type Data map[string]interface{}
+
 type Manifest struct {
 	Version string `yaml:"version"`
 	Vars    []Var  `yaml:"vars"`
 }
 
 type Var struct {
-	Type string `yaml:"type"`
-	Name string `yaml:"name"`
+	Type        string       `yaml:"type"`
+	Name        string       `yaml:"name"`
+	Description string       `yaml:"description"`
+	Default     string       `yaml:"default"`
+	Constraints []Constraint `yaml:"constraints"`
+	Items       []string     `yaml:"items"`
+}
+
+type Constraint struct {
+	Rule    string `yaml:"rule"`
+	Message string `yaml:"message"`
+}
+
+func (m *Manifest) Validate() error {
+	if m.Version != ManifestVersion1 {
+		return errors.Errorf("unexpected manifest version: '%s'", m.Version)
+	}
+
+	return nil
+}
+
+func Load(r io.Reader) (*Manifest, error) {
+	data, err := ioutil.ReadAll(r)
+	if err != nil {
+		return nil, errors.Wrap(err, "could not read manifest")
+	}
+
+	manifest := &Manifest{}
+
+	if err := yaml.Unmarshal(data, manifest); err != nil {
+		return nil, errors.Wrap(err, "could not unmarshal manifest")
+	}
+
+	return manifest, nil
+}
+
+func Prompt(manifest *Manifest, data Data) error {
+	for _, v := range manifest.Vars {
+		var (
+			value string
+			err   error
+		)
+
+		switch v.Type {
+		case VarTypeString:
+			value, err = promptString(v)
+
+		case VarTypeSelect:
+			value, err = promptSelect(v)
+
+		default:
+			err = errors.Errorf("unexpected variable type '%s'", v.Type)
+		}
+
+		if err != nil {
+			return err
+		}
+
+		data[v.Name] = value
+	}
+
+	return nil
+}
+
+func promptString(v Var) (string, error) {
+	var validate func(string) error
+
+	if len(v.Constraints) > 0 {
+		rules := make([]*vm.Program, 0, len(v.Constraints))
+
+		for _, c := range v.Constraints {
+			r, err := expr.Compile(c.Rule)
+			if err != nil {
+				return "", errors.Wrapf(err, "invalid constraint syntax: '%s'", c.Rule)
+			}
+
+			rules = append(rules, r)
+		}
+
+		validate = func(input string) error {
+			env := struct {
+				Input string
+			}{input}
+
+			for i, r := range rules {
+				result, err := expr.Run(r, env)
+				if err != nil {
+					return errors.Wrapf(err, "could not run constraint rule (constraint #%d)", i)
+				}
+
+				match, ok := result.(bool)
+				if !ok {
+					return errors.Errorf("unexpected constraint rule result '%v' (constraint #%d)", result, i)
+				}
+
+				if match {
+					return errors.New(v.Constraints[i].Message)
+				}
+			}
+
+			return nil
+		}
+	}
+
+	prompt := promptui.Prompt{
+		Label:    v.Description,
+		Validate: validate,
+		Default:  v.Default,
+	}
+
+	value, err := prompt.Run()
+	if err != nil {
+		return "", errors.Wrapf(err, "could not prompt for variable '%s'", v.Name)
+	}
+
+	return value, nil
+}
+
+func promptSelect(v Var) (string, error) {
+	prompt := promptui.Select{
+		Label: v.Description,
+		Items: v.Items,
+	}
+
+	_, value, err := prompt.Run()
+	if err != nil {
+		return "", errors.Wrapf(err, "could not prompt for variable '%s'", v.Name)
+	}
+
+	return value, nil
 }

internal/template/option.go

@@ -2,6 +2,6 @@ package template
 
 type Option struct {
 	IgnorePatterns []string
-	TemplateData   map[string]interface{}
+	TemplateData   Data
 	TemplateExt    string
 }