index.js

module.exports = convert;

function convert(parameters) {
  var parametersSchema = {};
  var bodySchema = getBodySchema(parameters);
  var formDataSchema = getSchema(parameters, 'formData');
  var headerSchema = getSchema(parameters, 'header');
  var pathSchema = getSchema(parameters, 'path');
  var querySchema = getSchema(parameters, 'query');

  if (bodySchema) {
    parametersSchema.body = bodySchema;
  }

  if (formDataSchema) {
    parametersSchema.formData = formDataSchema;
  }

  if (headerSchema) {
    parametersSchema.headers = headerSchema;
  }

  if (pathSchema) {
    parametersSchema.path = pathSchema;
  }

  if (querySchema) {
    parametersSchema.query = querySchema;
  }

  return parametersSchema;
}

var VALIDATION_KEYWORDS = [
  'additionalItems',
  'default',
  'description',
  'enum',
  'exclusiveMaximum',
  'exclusiveMinimum',
  'format',
  'items',
  'maxItems',
  'maxLength',
  'maximum',
  'minItems',
  'minLength',
  'minimum',
  'multipleOf',
  'pattern',
  'title',
  'type',
  'uniqueItems'
];

function copyValidationKeywords(src, dst) {
  if (src && dst) {
    for (var i = 0, keys = Object.keys(src), len = keys.length; i < len; i++) {
      var keyword = keys[i];

      if (VALIDATION_KEYWORDS.indexOf(keyword) > -1 || keyword.slice(0,2) === 'x-') {
        dst[keyword] = src[keyword];
      }
    }
  }
}

function getBodySchema(parameters) {
  var bodySchema = parameters.filter(function(param) {
    return param.in === 'body' && param.schema;
  })[0];

  if (bodySchema) {
    bodySchema = bodySchema.schema;
  }

  return bodySchema;
}

function getSchema(parameters, type) {
  var params = parameters.filter(byIn(type));
  var schema;

  if (params.length) {
    schema = {properties: {}};

    params.forEach(function(param) {
      var paramSchema = {};

      schema.properties[param.name] = paramSchema;

      copyValidationKeywords(param, paramSchema);
    });

    schema.required = getRequiredParams(params);
  }

  return schema;
}

function getRequiredParams(parameters) {
  return parameters.filter(byRequired).map(toName);
}

function byIn(str) {
  return function(param) {
    return param.in === str;
  };
}

function byRequired(param) {
  return !!param.required;
}

function toName(param) {
  return param.name;
}