openapi: '3.0.0'
info:
  title: API definition with circular $refs in request bodies
  version: '1.0.0'
servers:
  - url: https://httpbin.org
paths:
  /direct:
    post:
      operationId: directCircular
      summary: 'Direct self-reference (TreeNode.parent → TreeNode)'
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/TreeNode'
      responses:
        '200':
          description: Success
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/TreeNode'
  /indirect:
    post:
      operationId: indirectCircular
      summary: 'Two-hop chain (Person → Company → Person)'
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/Person'
      responses:
        '200':
          description: Success
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Person'
  /polymorphic:
    post:
      operationId: polymorphicCircular
      summary: Circular in oneOf option
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/Expression'
      responses:
        '200':
          description: Success
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Expression'
  /multiple:
    post:
      operationId: multipleCircular
      summary: Multiple self-referencing properties
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/LinkedNode'
      responses:
        '200':
          description: Success
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/LinkedNode'
components:
  schemas:
    TreeNode:
      type: object
      title: TreeNode
      required:
        - id
        - name
        - parent
      properties:
        id:
          type: string
        name:
          type: string
        parent:
          $ref: '#/components/schemas/TreeNode'
        children:
          type: array
          items:
            $ref: '#/components/schemas/TreeNode'
    Person:
      type: object
      title: Person
      required:
        - name
      properties:
        name:
          type: string
        employer:
          $ref: '#/components/schemas/Company'
    Company:
      type: object
      title: Company
      required:
        - name
      properties:
        name:
          type: string
        ceo:
          $ref: '#/components/schemas/Person'
    Expression:
      type: object
      title: Expression
      properties:
        type:
          type: string
          enum:
            - literal
            - binary
        value:
          oneOf:
            - type: string
              title: LiteralValue
            - $ref: '#/components/schemas/Expression'
    LinkedNode:
      type: object
      title: LinkedNode
      required:
        - id
      properties:
        id:
          type: string
        prev:
          $ref: '#/components/schemas/LinkedNode'
        next:
          $ref: '#/components/schemas/LinkedNode'