rules:

  # ─── INFO / METADATA ───────────────────────────────────────────────────────

  info-title-required:
    message: API info title is required
    severity: error
    given: $.info
    then:
      field: title
      function: truthy

  info-title-contains-union-pacific:
    message: API title should reference Union Pacific
    severity: warn
    given: $.info.title
    then:
      function: pattern
      functionOptions:
        match: "(?i)union.pacific"

  info-description-required:
    message: API info description is required
    severity: warn
    given: $.info
    then:
      field: description
      function: truthy

  info-version-required:
    message: API info version is required
    severity: error
    given: $.info
    then:
      field: version
      function: truthy

  # ─── OPENAPI VERSION ────────────────────────────────────────────────────────

  openapi-version-3:
    message: OpenAPI version must be 3.x
    severity: error
    given: $
    then:
      field: openapi
      function: pattern
      functionOptions:
        match: "^3\\."

  # ─── SERVERS ────────────────────────────────────────────────────────────────

  servers-defined:
    message: At least one server must be defined
    severity: error
    given: $
    then:
      field: servers
      function: truthy

  servers-https-only:
    message: Server URLs must use HTTPS
    severity: error
    given: $.servers[*].url
    then:
      function: pattern
      functionOptions:
        match: "^https://"

  # ─── PATHS — NAMING CONVENTIONS ─────────────────────────────────────────────

  paths-camel-case-convention:
    message: Paths use camelCase or lowercase for resource names (Union Pacific convention)
    severity: info
    given: $.paths[*]~
    then:
      function: pattern
      functionOptions:
        match: "^(/[a-zA-Z0-9_{}/-]+)+$"

  paths-no-trailing-slash:
    message: Paths must not end with a trailing slash
    severity: warn
    given: $.paths[*]~
    then:
      function: pattern
      functionOptions:
        notMatch: "/$"

  # ─── OPERATIONS ─────────────────────────────────────────────────────────────

  operation-id-required:
    message: Every operation must have an operationId
    severity: error
    given: $.paths[*][get,post,put,patch,delete,head,options]
    then:
      field: operationId
      function: truthy

  operation-id-camel-case:
    message: operationId should use camelCase (Union Pacific convention)
    severity: warn
    given: $.paths[*][get,post,put,patch,delete,head,options].operationId
    then:
      function: pattern
      functionOptions:
        match: "^[a-z][a-zA-Z0-9]+$"

  operation-summary-required:
    message: Every operation must have a summary
    severity: error
    given: $.paths[*][get,post,put,patch,delete,head,options]
    then:
      field: summary
      function: truthy

  operation-summary-title-case:
    message: Operation summaries should use Title Case
    severity: warn
    given: $.paths[*][get,post,put,patch,delete,head,options].summary
    then:
      function: pattern
      functionOptions:
        match: "^[A-Z]"

  operation-description-required:
    message: Every operation should have a description
    severity: warn
    given: $.paths[*][get,post,put,patch,delete,head,options]
    then:
      field: description
      function: truthy

  operation-tags-required:
    message: Every operation should have at least one tag
    severity: warn
    given: $.paths[*][get,post,put,patch,delete,head,options]
    then:
      field: tags
      function: truthy

  # ─── PARAMETERS ─────────────────────────────────────────────────────────────

  parameter-description-required:
    message: All parameters should have descriptions
    severity: warn
    given: $.paths[*][get,post,put,patch,delete].parameters[*]
    then:
      field: description
      function: truthy

  parameter-schema-required:
    message: All parameters must have a schema
    severity: error
    given: $.paths[*][get,post,put,patch,delete].parameters[*]
    then:
      field: schema
      function: truthy

  # ─── REQUEST BODIES ──────────────────────────────────────────────────────────

  request-body-json:
    message: Request bodies should use application/json content type
    severity: warn
    given: $.paths[*][post,put,patch].requestBody.content
    then:
      function: schema
      functionOptions:
        schema:
          type: object
          minProperties: 1

  request-body-description:
    message: Request bodies should have a description
    severity: warn
    given: $.paths[*][post,put,patch].requestBody
    then:
      field: description
      function: truthy

  # ─── RESPONSES ───────────────────────────────────────────────────────────────

  response-success-defined:
    message: Every operation must define at least one 2xx success response
    severity: error
    given: $.paths[*][get,post,put,patch,delete]
    then:
      field: responses
      function: truthy

  response-description-required:
    message: All responses must have a description
    severity: error
    given: $.paths[*][get,post,put,patch,delete].responses[*]
    then:
      field: description
      function: truthy

  response-401-unauthorized:
    message: Protected operations should define 401 Unauthorized response
    severity: warn
    given: $.paths[*][get,post,put,patch,delete]
    then:
      field: responses.401
      function: truthy

  response-400-bad-request:
    message: Write operations should define 400 Bad Request response
    severity: info
    given: $.paths[*][post,put,patch]
    then:
      field: responses.400
      function: truthy

  # ─── SCHEMAS — PROPERTY NAMING ───────────────────────────────────────────────

  schema-property-camel-case:
    message: Schema properties should use camelCase (Union Pacific convention)
    severity: warn
    given: $.components.schemas[*].properties[*]~
    then:
      function: pattern
      functionOptions:
        match: "^[a-z][a-zA-Z0-9]*$"

  schema-description-required:
    message: Top-level component schemas should have descriptions
    severity: warn
    given: $.components.schemas[*]
    then:
      field: description
      function: truthy

  # ─── SECURITY ────────────────────────────────────────────────────────────────

  security-schemes-defined:
    message: Security schemes must be defined
    severity: error
    given: $.components
    then:
      field: securitySchemes
      function: truthy

  security-oauth2-present:
    message: Union Pacific uses OAuth 2.0 Client Credentials authentication
    severity: warn
    given: $.components.securitySchemes[*]
    then:
      field: type
      function: enumeration
      functionOptions:
        values:
          - oauth2

  # ─── HTTP METHOD CONVENTIONS ─────────────────────────────────────────────────

  get-no-request-body:
    message: GET operations must not have a request body
    severity: error
    given: $.paths[*].get
    then:
      field: requestBody
      function: falsy

  rpc-style-post:
    message: >-
      RPC-style action operations (releaseShipment, orderEquipment, cancelRequest)
      should use POST method
    severity: info
    given: $.paths[?(@property =~ /release|order|cancel/)][*]
    then:
      function: truthy

  # ─── GENERAL QUALITY ─────────────────────────────────────────────────────────

  no-empty-descriptions:
    message: Descriptions must not be empty strings
    severity: warn
    given: $..description
    then:
      function: pattern
      functionOptions:
        match: ".+"

  components-schemas-defined:
    message: Components schemas section should be defined
    severity: error
    given: $.components
    then:
      field: schemas
      function: truthy