openapi: 3.0.0
info:
  title: OAuth Token API
  description: >
    This API provides an OAuth 2.0 **Client Credentials** flow to obtain access
    tokens

    that are required to call secured endpoints.  

    The token is a JWT (JSON Web Token) with a limited lifetime.
  version: '1.0'
  contact:
    name: SQR
    email: support@sqr.id
    url: https://sqr.id
servers:
  - url: https://api.sqr-group.com
tags:
  - name: OAuth Token
    description: >-
      — This API allows clients to obtain access tokens using the client
      credentials flow.
paths:
  /oauth2/token:
    post:
      summary: Get access token
      description: |
        Request an access token using the **Client Credentials Grant**.  
        The access token is required for calling all secured APIs.
      operationId: getAccessToken
      tags:
        - OAuth Token
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/TokenRequestDto'
      responses:
        '200':
          description: Access token successfully generated.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/TokenResponseDto'
        '400':
          description: Invalid request or missing fields.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/TokenErrorDto'
        '401':
          description: Authentication failed.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/TokenErrorDto'
        5XX:
          description: Internal error during authentication.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/InternalErrorDto'
components:
  schemas:
    TokenRequestDto:
      type: object
      required:
        - client_id
        - client_secret
        - grant_type
      properties:
        client_id:
          type: string
          description: The client identifier issued during registration.
          example: 354z244b-2b83-4721-922b-9f9b4ba13059
        client_secret:
          type: string
          description: The client secret issued during registration.
          example: secret
        grant_type:
          type: string
          description: Must be `client_credentials` for this flow.
          example: client_credentials
    TokenResponseDto:
      type: object
      properties:
        access_token:
          type: string
          description: The JWT access token issued by the server.
          example: eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9...
        token_type:
          type: string
          description: Type of the token issued.
          example: Bearer
        expires_in:
          type: integer
          description: Lifetime of the access token in seconds.
          example: 3600
        scope:
          type: string
          description: Granted scopes.
          example: read:users write:logs
      required:
        - access_token
        - token_type
        - expires_in
    TokenErrorDto:
      type: object
      properties:
        error:
          type: string
          description: Error type identifier.
          example: invalid_client
        error_description:
          type: string
          description: Human-readable error explanation.
          example: Client authentication failed
      required:
        - error
        - error_description
    InternalErrorDto:
      type: object
      properties:
        code:
          type: number
          example: 503
        timestamp:
          type: string
          format: date-time
          example: '2025-07-11T06:51:25.202Z'
        path:
          type: string
          example: /oauth2/token
        method:
          type: string
          example: POST
        error:
          type: string
          example: INTERNAL_SERVER_ERROR
        message:
          type: string
          example: Internal Server Error
      required:
        - code
        - timestamp
        - path
        - method
        - error
        - message
