From d46dbbce6a279c1b8c469c7a78e1bba491eb2557 Mon Sep 17 00:00:00 2001
From: Shreyas Goenka <shreyas.goenka@databricks.com>
Date: Fri, 13 Jan 2023 04:52:25 +0100
Subject: [PATCH] WIP json schema support for bundles

---
 bundle/schema/generator.go | 125 +++++++++++++++++++++++++++++++++++++
 1 file changed, 125 insertions(+)
 create mode 100644 bundle/schema/generator.go

diff --git a/bundle/schema/generator.go b/bundle/schema/generator.go
new file mode 100644
index 00000000..a6ffcaa2
--- /dev/null
+++ b/bundle/schema/generator.go
@@ -0,0 +1,125 @@
+package schema
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+)
+
+// TODO: should omit empty denote non required fields in the json schema
+type Schema struct {
+	Type        JsType               `json:"type"`
+	Properities map[string]*Property `json:"properities,omitempty"`
+}
+
+type Property struct {
+	// TODO: Add a enum for json types
+	Type        JsType               `json:"type"`
+	Items       *Item                `json:"item,omitempty"`
+	Properities map[string]*Property `json:"properities,omitempty"`
+}
+
+type Item struct {
+	Type JsType `json:"type"`
+}
+
+func NewSchema(goType reflect.Type) (*Schema, error) {
+	rootProp, err := properity(goType)
+	if err != nil {
+		return nil, err
+	}
+	return &Schema{
+		Type:        rootProp.Type,
+		Properities: rootProp.Properities,
+	}, nil
+}
+
+type JsType string
+
+const (
+	Invalid JsType = "invalid"
+	Boolean        = "boolean"
+	String         = "string"
+	Number         = "number"
+	Object         = "object"
+	Array          = "array"
+)
+
+// TODO: add support for pointers
+func jsType(goType reflect.Type) (JsType, error) {
+	switch goType.Kind() {
+	case reflect.Bool:
+		return Boolean, nil
+	case reflect.String:
+		return String, nil
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Float32, reflect.Float64:
+		return Number, nil
+	case reflect.Struct:
+		return Object, nil
+	// TODO: add support for pattern properities to account for maps
+	case reflect.Map:
+		if goType.Key().Kind() != reflect.String {
+			return Invalid, fmt.Errorf("only strings map keys are valid. key type: ", goType.Key().Kind())
+		}
+		return Object, nil
+	case reflect.Array, reflect.Slice:
+		return Array, nil
+	default:
+		return Invalid, fmt.Errorf("unhandled golang type: %s", goType)
+	}
+}
+
+// TODO: handle case of self referential pointers in structs
+
+// TODO: add support for lower case field name if json tag is missing
+func properity(goType reflect.Type) (*Property, error) {
+	// *Struct and Struct generate identical json schemas
+	if goType.Kind() == reflect.Pointer {
+		return properity(goType.Elem())
+	}
+
+	rootJsType, err := jsType(goType)
+
+	// TODO: recursive debugging can be a pain. Make sure the error localtion
+	// floats up
+	if err != nil {
+		return nil, err
+	}
+
+	var items *Item
+	if goType.Kind() == reflect.Array || goType.Kind() == reflect.Slice {
+		elemJsType, err := jsType(goType.Elem())
+		if err != nil {
+			// TODO: float up error in case of deep recursion
+			return nil, err
+		}
+		items = &Item{
+			// TODO: what if there is an array of objects?
+			Type: elemJsType,
+		}
+	}
+
+	properities := map[string]*Property{}
+	if goType.Kind() == reflect.Struct {
+		for i := 0; i < goType.NumField(); i++ {
+			field := goType.Field(i)
+			fieldProps, err := properity(field.Type)
+			// TODO: make sure this error floats up with context
+			if err != nil {
+				return nil, err
+			}
+			fieldJsonTags := field.Tag.Get("json")
+			// TODO: test if this split is needed
+			fieldName := strings.Split(fieldJsonTags, ",")[0]
+
+			properities[fieldName] = fieldProps
+		}
+	}
+
+	return &Property{
+		Type:        rootJsType,
+		Items:       items,
+		Properities: properities,
+	}, nil
+
+}