Prepare for auto-releaser infra (#554)

## Changes
- make `code.Field` always pointers
- added codegen toolchain config
- added changelog template
- refactored code generator to a dedicated package

## Tests
- prepare release for python sdk

.codegen.json

@@ -13,5 +13,14 @@
   },
   "examples": {
     ".codegen/examples_test.go.tmpl": "service/{{.Package}}/{{.SnakeName}}_usage_test.go"
+  },
+  "version": {
+    "version/version.go": "const Version = \"$VERSION\""
+  },
+  "toolchain": {
+    "required": ["go"],
+    "post_generate": [
+      "go test -short ./..."
+    ]
   }
-}
+}

.codegen/changelog.md.tmpl

@@ -0,0 +1,55 @@
+# Version changelog
+
+## {{.Version}}
+
+{{range .Changes -}}
+ * {{.}}.
+{{end}}{{- if .ApiChanges}}
+API Changes:
+{{range .ApiChanges}}
+ * {{.Action}} {{template "what" .}}{{if .Extra}} {{.Extra}}{{with .Other}} {{template "what" .}}{{end}}{{end}}.
+{{- end}}
+
+OpenAPI SHA: {{.Sha}}, Date: {{.Changed}}
+{{- end}}{{if .DependencyUpdates}}
+Dependency updates:
+{{range .DependencyUpdates}}
+ * {{.}}.
+{{- end -}}
+{{end}}
+
+## {{.PrevVersion}}
+
+{{- define "what" -}}
+    {{if eq .X "package" -}}
+        [{{.Package.Name}}](https://pkg.go.dev/github.com/databricks/databricks-sdk-go/service/{{.Package.Name}}) package
+    {{- else if eq .X "service" -}}
+        {{template "service" .Service}}
+    {{- else if eq .X "method" -}}
+        `{{.Method.PascalName}}` method for {{template "service" .Method.Service}}
+    {{- else if eq .X "entity" -}}
+        {{template "entity" .Entity}}
+    {{- else if eq .X "field" -}}
+        `{{.Field.PascalName}}` field for {{template "entity" .Field.Of}}
+    {{- end}}
+{{- end -}}
+
+{{- define "service" -}}
+    [{{if .IsAccounts}}a{{else}}w{{end}}.{{.PascalName}}](https://pkg.go.dev/github.com/databricks/databricks-sdk-go/service/{{.Package.Name}}#{{.PascalName}}API) {{if .IsAccounts}}account{{else}}workspace{{end}}-level service
+{{- end -}}
+
+{{- define "entity" -}}
+    {{- if not . }}any /* ERROR */
+	{{- else if .IsEmpty}}`any`
+	{{- else if .PascalName}}[{{.Package.Name}}.{{.PascalName}}](https://pkg.go.dev/github.com/databricks/databricks-sdk-go/service/{{.Package.Name}}#{{.PascalName}})
+	{{- else if .IsAny}}`any`
+	{{- else if .IsString}}`string`
+	{{- else if .IsBool}}`bool`
+	{{- else if .IsInt64}}`int64`
+	{{- else if .IsFloat64}}`float64`
+	{{- else if .IsInt}}`int`
+	{{- else if .ArrayValue }}[]{{template "entity" .ArrayValue}}
+	{{- else if .MapValue }}map[string]{{template "entity" .MapValue}}
+	{{- else}}[{{.Package.Name}}.{{.PascalName}}](https://pkg.go.dev/github.com/databricks/databricks-sdk-go/service/{{.Package.Name}}#{{.PascalName}})
+	{{- end -}}
+{{- end -}}

openapi/code/entity.go

@@ -62,7 +62,7 @@ type Entity struct {
 
 	// if entity has required fields, this is the order of them
 	RequiredOrder []string
-	fields        map[string]Field
+	fields        map[string]*Field
 
 	// Schema references the OpenAPI schema this entity was created from.
 	Schema *openapi.Schema
@@ -102,7 +102,7 @@ func (e *Entity) Field(name string) *Field {
 		return nil
 	}
 	field.Of = e
-	return &field
+	return field
 }
 
 // Given a list of field names, return the list of *Field objects which result
@@ -136,7 +136,7 @@ func (e *Entity) IsExternal() bool {
 	return e.Package != nil && len(e.Package.types) == 0
 }
 
-func (e *Entity) RequiredFields() (fields []Field) {
+func (e *Entity) RequiredFields() (fields []*Field) {
 	for _, r := range e.RequiredOrder {
 		v := e.fields[r]
 		v.Of = e
@@ -145,7 +145,7 @@ func (e *Entity) RequiredFields() (fields []Field) {
 	return
 }
 
-func (e *Entity) NonRequiredFields() (fields []Field) {
+func (e *Entity) NonRequiredFields() (fields []*Field) {
 	required := map[string]bool{}
 	for _, r := range e.RequiredOrder {
 		required[r] = true
@@ -158,19 +158,19 @@ func (e *Entity) NonRequiredFields() (fields []Field) {
 		v.Of = e
 		fields = append(fields, v)
 	}
-	slices.SortFunc(fields, func(a, b Field) bool {
+	slices.SortFunc(fields, func(a, b *Field) bool {
 		return a.CamelName() < b.CamelName()
 	})
 	return
 }
 
 // Fields returns sorted slice of field representations
-func (e *Entity) Fields() (fields []Field) {
+func (e *Entity) Fields() (fields []*Field) {
 	for _, v := range e.fields {
 		v.Of = e
 		fields = append(fields, v)
 	}
-	slices.SortFunc(fields, func(a, b Field) bool {
+	slices.SortFunc(fields, func(a, b *Field) bool {
 		return a.CamelName() < b.CamelName()
 	})
 	return fields
@@ -252,3 +252,36 @@ func (e *Entity) IsPrivatePreview() bool {
 func (e *Entity) IsPublicPreview() bool {
 	return e.Schema != nil && isPublicPreview(&e.Schema.Node)
 }
+
+func (e *Entity) IsRequest() bool {
+	for _, svc := range e.Package.services {
+		for _, m := range svc.methods {
+			if m.Request == e {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+func (e *Entity) IsResponse() bool {
+	for _, svc := range e.Package.services {
+		for _, m := range svc.methods {
+			if m.Response == e {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+func (e *Entity) IsReferred() bool {
+	for _, t := range e.Package.types {
+		for _, f := range t.fields {
+			if f.Entity == e {
+				return true
+			}
+		}
+	}
+	return false
+}

openapi/code/load.go

@@ -24,6 +24,11 @@ func NewFromFile(name string) (*Batch, error) {
 	if err != nil {
 		return nil, fmt.Errorf("spec from %s: %w", name, err)
 	}
+	return NewFromSpec(spec)
+}
+
+// NewFromSpec converts OpenAPI spec to intermediate representation
+func NewFromSpec(spec *openapi.Specification) (*Batch, error) {
 	batch := Batch{
 		packages: map[string]*Package{},
 	}

openapi/code/method.go

@@ -122,7 +122,7 @@ func (m *Method) rpcSingleFields() (params []Field) {
 		// TODO: explicitly annotate with x-databricks-shortcut
 		return nil
 	}
-	return []Field{m.Request.Fields()[0]}
+	return []Field{*m.Request.Fields()[0]}
 }
 
 func (m *Method) requestShortcutFields() []Field {

openapi/code/package.go

@@ -142,8 +142,9 @@ func (pkg *Package) schemaToEntity(s *openapi.Schema, path []string, hasName boo
 		Named: Named{
 			Description: s.Description,
 		},
-		Schema: s,
-		enum:   map[string]EnumEntry{},
+		Schema:  s,
+		Package: pkg,
+		enum:    map[string]EnumEntry{},
 	}
 	// pull embedded types up, if they can be defined at package level
 	if s.IsDefinable() && !hasName {
@@ -183,7 +184,7 @@ func (pkg *Package) schemaToEntity(s *openapi.Schema, path []string, hasName boo
 
 // makeObject converts OpenAPI Schema into type representation
 func (pkg *Package) makeObject(e *Entity, s *openapi.Schema, path []string) *Entity {
-	e.fields = map[string]Field{}
+	e.fields = map[string]*Field{}
 	required := map[string]bool{}
 	for _, v := range s.Required {
 		required[v] = true
@@ -196,7 +197,7 @@ func (pkg *Package) makeObject(e *Entity, s *openapi.Schema, path []string) *Ent
 			}
 		}
 		named := Named{k, v.Description}
-		e.fields[k] = Field{
+		e.fields[k] = &Field{
 			Named:    named,
 			Entity:   pkg.schemaToEntity(v, append(path, named.PascalName()), false),
 			Required: required[k],

openapi/code/service.go

@@ -135,7 +135,7 @@ func (svc *Service) newRequest(params []openapi.Parameter, op *openapi.Operation
 	if op.RequestBody == nil && len(params) == 0 {
 		return nil
 	}
-	request := &Entity{fields: map[string]Field{}}
+	request := &Entity{fields: map[string]*Field{}}
 	if op.RequestBody != nil {
 		request = svc.Package.schemaToEntity(op.RequestBody.Schema(), []string{op.Name()}, true)
 	}
@@ -155,7 +155,7 @@ func (svc *Service) newRequest(params []openapi.Parameter, op *openapi.Operation
 		}
 		field, exists := request.fields[param.Name]
 		if !exists {
-			field = *param
+			field = param
 		}
 		field.IsPath = param.IsPath
 		field.IsQuery = param.IsQuery
@@ -226,7 +226,7 @@ func (svc *Service) paramPath(path string, request *Entity, params []openapi.Par
 			parts = append(parts, PathPart{prefix, nil, false})
 			continue
 		}
-		parts = append(parts, PathPart{prefix, &field, false})
+		parts = append(parts, PathPart{prefix, field, false})
 	}
 	return
 }

openapi/code/tmpl_util_funcs.go

@@ -39,7 +39,7 @@ var HelperFuncs = template.FuncMap{
 		// via errors.Is(err, code.ErrSkipThisFile)
 		panic(ErrSkipThisFile)
 	},
-	"alphanumOnly": func(in []Field) (out []Field) {
+	"alphanumOnly": func(in []*Field) (out []*Field) {
 		for _, v := range in {
 			if !alphanumRE.MatchString(v.Name) {
 				continue