feature/Add JSON Schema generation support and corresponding tests

- Introduced `OBPResourceDocJson` for generating Draft-04 JSON Schema from case classes.
- Updated `ResourceDocJson` to utilize Circe JSON types for request and response bodies.
- Added unit tests in `OBPResourceDocJsonSpec` to validate schema generation for sample case classes.

Author: hongwei1

build.sbt

@@ -15,6 +15,9 @@ ThisBuild / organizationHomepage := Some(url("https://www.openbankproject.com/")
 libraryDependencies ++= Seq(
   "io.circe" %% "circe-core" % "0.14.10",
   "io.circe" %% "circe-parser" % "0.14.10",
+  // JSON Schema generation
+  "com.github.andyglow" %% "scala-jsonschema" % "0.7.11",
+  "com.github.andyglow" %% "scala-jsonschema-circe-json" % "0.7.11",
   "org.scalatest" %% "scalatest" % "3.2.19" % Test
 )
 

src/main/scala/com/openbankproject/resourcedocs/core/model/ResourceDocJson.scala

@@ -1,6 +1,9 @@
 package com.openbankproject.resourcedocs.core.model
 
-import io.circe.Json
+import io.circe.{Json => CirceJson}
+import com.github.andyglow.jsonschema.AsCirce._
+import json._
+import json.schema.Version.Draft04
 
 /** JSON-friendly DTO for API resource documentation. This structure avoids framework types and uses primitive-friendly
   * fields.
@@ -17,6 +20,21 @@ final case class ImplementedByJson(
     function: String // The val / partial function that implements the call e.g. "getBanks"
 )
 
+object OBPResourceDocJson {
+  /** Helper to generate Schema JSON from a Case Class type.
+    *
+    * @tparam T
+    *   The case class type to generate schema for
+    * @return
+    *   Circe JSON representing the Draft-04 JSON Schema
+    */
+  def generateSchema[T: Schema]: CirceJson = {
+    // Instantiate the final class directly
+    val v = new json.schema.Version.Draft04()
+    Json.schema[T].asCirce(v)
+  }
+}
+
 /** Extended JSON-friendly DTO for API resource documentation that matches OBP-API structure. This structure includes
   * all fields from OBP-API's ResourceDocJson for compatibility. Field names use snake_case to match OBP-API's
   * ResourceDocJson structure.
@@ -29,14 +47,16 @@ final case class OBPResourceDocJson(
     summary: String,
     description: String, // HTML format
     description_markdown: String, // Markdown format
-    example_request_body: Option[Json] = None,
-    success_response_body: Option[Json] = None,
+    example_request_body: Option[CirceJson] = None,
+    success_response_body: Option[CirceJson] = None,
 
     error_response_bodies: List[String] = List.empty,
     tags: List[String] = List.empty,
 
-    typed_request_body: Option[Json] = None, 
-    typed_success_response_body: Option[Json] = None,
+    // Schema for request body (Draft-04 JSON Schema)
+    typed_request_body: Option[CirceJson] = None, 
+    // Schema for success response (Draft-04 JSON Schema)
+    typed_success_response_body: Option[CirceJson] = None,
 
     roles: Option[List[RoleInfoJson]] = None,
     is_featured: Boolean = false,

src/test/scala/com/openbankproject/resourcedocs/core/model/OBPResourceDocJsonSpec.scala

@@ -0,0 +1,70 @@
+package com.openbankproject.resourcedocs.core.model
+
+import io.circe.{Json => CirceJson}
+import org.scalatest.flatspec.AnyFlatSpec
+import org.scalatest.matchers.should.Matchers
+import json._
+
+case class SampleRequest(id: String, quantity: Int, tags: List[String])
+case class SampleResponse(success: Boolean, message: Option[String])
+
+class OBPResourceDocJsonSpec extends AnyFlatSpec with Matchers {
+
+  // Define implicits using the macro
+  implicit val sampleRequestSchema: Schema[SampleRequest] = Json.schema[SampleRequest]
+  implicit val sampleResponseSchema: Schema[SampleResponse] = Json.schema[SampleResponse]
+
+  "OBPResourceDocJson.generateSchema" should "generate correct Draft-04 schema for a case class" in {
+    val schema: CirceJson = OBPResourceDocJson.generateSchema[SampleRequest]
+
+    val schemaObj = schema.asObject.get
+    
+    // Handle Schema with Definitions (Draft-04 style)
+    // The root might contain $ref, and properties are in definitions
+    val properties = if (schemaObj.contains("definitions")) {
+      val definitions = schemaObj("definitions").flatMap(_.asObject).get
+      // Assuming only one definition is generated for the simple case class
+      definitions.values.head.asObject.get("properties").flatMap(_.asObject).get
+    } else {
+      schemaObj("properties").flatMap(_.asObject).get
+    }
+    
+    properties("id").flatMap(_.asObject).flatMap(_("type").flatMap(_.asString)) should be(Some("string"))
+    properties("quantity").flatMap(_.asObject).flatMap(_("type").flatMap(_.asString)) should be(Some("integer"))
+    
+    // Verify array handling
+    val tagsProp = properties("tags").flatMap(_.asObject).get
+    tagsProp("type").flatMap(_.asString) should be(Some("array"))
+    tagsProp("items").flatMap(_.asObject).flatMap(_("type").flatMap(_.asString)) should be(Some("string"))
+    
+    // Verify required fields
+    // If using definitions, 'required' is inside the definition
+    val requiredSource = if (schemaObj.contains("definitions")) {
+       val definitions = schemaObj("definitions").flatMap(_.asObject).get
+       definitions.values.head.asObject.get
+    } else {
+       schemaObj
+    }
+    val required = requiredSource("required").flatMap(_.asArray).getOrElse(Vector.empty).flatMap(_.asString)
+    required should contain allOf ("id", "quantity", "tags")
+  }
+
+  it should "handle Option types as optional fields in schema" in {
+    val schema: CirceJson = OBPResourceDocJson.generateSchema[SampleResponse]
+    
+    val schemaObj = schema.asObject.get
+    
+    val requiredSource = if (schemaObj.contains("definitions")) {
+       val definitions = schemaObj("definitions").flatMap(_.asObject).get
+       definitions.values.head.asObject.get
+    } else {
+       schemaObj
+    }
+    
+    val required = requiredSource("required").flatMap(_.asArray).map(_.flatMap(_.asString)).getOrElse(Vector.empty)
+    
+    // 'success' should be required, 'message' should NOT be in required list
+    required should contain("success")
+    required should not contain "message"
+  }
+}