api.mustache

package {{package}};

import {{invokerPackage}}.ApiException;
import {{invokerPackage}}.ApiClient;
import {{invokerPackage}}.Configuration;
import {{invokerPackage}}.Pair;

import javax.ws.rs.core.GenericType;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.IOException;

{{#imports}}import {{import}};
{{/imports}}

{{^fullJavaUtil}}
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
{{/fullJavaUtil}}

{{>generatedAnnotation}}
{{#operations}}
public class {{classname}} {
  private ApiClient {{localVariablePrefix}}apiClient;

  public {{classname}}() {
    this(Configuration.getDefaultApiClient());
  }

  public {{classname}}(ApiClient apiClient) {
    this.{{localVariablePrefix}}apiClient = apiClient;
  }

  public ApiClient getApiClient() {
    return {{localVariablePrefix}}apiClient;
  }

  public void setApiClient(ApiClient apiClient) {
    this.{{localVariablePrefix}}apiClient = apiClient;
  }

  {{#operation}}
  {{^responseHeaders.empty}}
  public static class {{operationId}}Response {
    {{#returnType}}
    private final {{{returnType}}} result;
    {{/returnType}}
    {{#responseHeaders}}
    private final {{datatypeWithEnum}} {{name}};
    {{/responseHeaders}}

    private {{operationId}}Response(ApiClient.ResponseResult<{{{returnType}}}> responseResult, ObjectMapper mapper) throws ApiException {
    {{#returnType}}
      this.result = responseResult.getResult();
    {{/returnType}}
      try {
    {{#responseHeaders}}
        this.{{name}} = mapper.readValue("\"" + responseResult.getHeaders().get("{{baseName}}").get(0) + "\"", {{datatypeWithEnum}}.class);
    {{/responseHeaders}}
      } catch (IOException e) {
        throw new ApiException(e);
      }
    }

    {{#returnType}}
    public {{{returnType}}} getResult() {
      return this.result;
    }
    {{/returnType}}

    {{#responseHeaders}}
    public {{datatypeWithEnum}} {{getter}}() {
      return {{name}};
    }
    {{/responseHeaders}}
  }
  {{/responseHeaders.empty}}

  /**
   * {{summary}}
   * {{notes}}{{#allParams}}
   * @param {{paramName}} {{description}}{{#required}} (required){{/required}}{{^required}} (optional{{#defaultValue}}, default to {{{.}}}{{/defaultValue}}){{/required}}{{/allParams}}{{#returnType}}
   * @return {{{returnType}}}{{/returnType}}
   * @throws ApiException if fails to make API call
   */
  public {{#responseHeaders.empty}}{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}void{{/returnType}}{{/responseHeaders.empty}}{{^responseHeaders.empty}}{{operationId}}Response{{/responseHeaders.empty}} {{operationId}}({{#allParams}}{{{dataType}}} {{paramName}}{{#hasMore}}, {{/hasMore}}{{/allParams}}) throws ApiException {
    Object {{localVariablePrefix}}localVarPostBody = {{#bodyParam}}{{paramName}}{{/bodyParam}}{{^bodyParam}}null{{/bodyParam}};
    {{#allParams}}{{#required}}
    // verify the required parameter '{{paramName}}' is set
    if ({{paramName}} == null) {
      throw new ApiException(400, "Missing the required parameter '{{paramName}}' when calling {{operationId}}");
    }
    {{/required}}{{/allParams}}
    // create path and map variables
    String {{localVariablePrefix}}localVarPath = "{{{path}}}".replaceAll("\\{format\\}","json"){{#pathParams}}
      .replaceAll("\\{" + "{{baseName}}" + "\\}", {{localVariablePrefix}}apiClient.escapeString({{{paramName}}}.toString())){{/pathParams}};

    // query params
    {{javaUtilPrefix}}List<Pair> {{localVariablePrefix}}localVarQueryParams = new {{javaUtilPrefix}}ArrayList<Pair>();
    {{javaUtilPrefix}}Map<String, String> {{localVariablePrefix}}localVarHeaderParams = new {{javaUtilPrefix}}HashMap<String, String>();
    {{javaUtilPrefix}}Map<String, Object> {{localVariablePrefix}}localVarFormParams = new {{javaUtilPrefix}}HashMap<String, Object>();

    {{#queryParams}}
    {{localVariablePrefix}}localVarQueryParams.addAll({{localVariablePrefix}}apiClient.parameterToPairs("{{#collectionFormat}}{{{collectionFormat}}}{{/collectionFormat}}", "{{baseName}}", {{paramName}}));
    {{/queryParams}}

    {{#headerParams}}if ({{paramName}} != null)
      {{localVariablePrefix}}localVarHeaderParams.put("{{baseName}}", {{localVariablePrefix}}apiClient.parameterToString({{paramName}}));
    {{/headerParams}}

    {{#formParams}}if ({{paramName}} != null)
      {{localVariablePrefix}}localVarFormParams.put("{{baseName}}", {{paramName}});
    {{/formParams}}

    final String[] {{localVariablePrefix}}localVarAccepts = {
      {{#produces}}"{{mediaType}}"{{#hasMore}}, {{/hasMore}}{{/produces}}
    };
    final String {{localVariablePrefix}}localVarAccept = {{localVariablePrefix}}apiClient.selectHeaderAccept({{localVariablePrefix}}localVarAccepts);

    final String[] {{localVariablePrefix}}localVarContentTypes = {
      {{#consumes}}"{{mediaType}}"{{#hasMore}}, {{/hasMore}}{{/consumes}}
    };
    final String {{localVariablePrefix}}localVarContentType = {{localVariablePrefix}}apiClient.selectHeaderContentType({{localVariablePrefix}}localVarContentTypes);

    String[] {{localVariablePrefix}}localVarAuthNames = new String[] { {{#authMethods}}"{{name}}"{{#hasMore}}, {{/hasMore}}{{/authMethods}} };

    {{#returnType}}
    GenericType<{{{returnType}}}> {{localVariablePrefix}}localVarReturnType = new GenericType<{{{returnType}}}>() {};
    {{#responseHeaders.empty}}
    return {{localVariablePrefix}}apiClient.invokeAPI({{localVariablePrefix}}localVarPath, "{{httpMethod}}", {{localVariablePrefix}}localVarQueryParams, {{localVariablePrefix}}localVarPostBody, {{localVariablePrefix}}localVarHeaderParams, {{localVariablePrefix}}localVarFormParams, {{localVariablePrefix}}localVarAccept, {{localVariablePrefix}}localVarContentType, {{localVariablePrefix}}localVarAuthNames, {{localVariablePrefix}}localVarReturnType).getResult();
    {{/responseHeaders.empty}}
    {{^responseHeaders.empty}}
    return new {{operationId}}Response({{localVariablePrefix}}apiClient.invokeAPI({{localVariablePrefix}}localVarPath, "{{httpMethod}}", {{localVariablePrefix}}localVarQueryParams, {{localVariablePrefix}}localVarPostBody, {{localVariablePrefix}}localVarHeaderParams, {{localVariablePrefix}}localVarFormParams, {{localVariablePrefix}}localVarAccept, {{localVariablePrefix}}localVarContentType, {{localVariablePrefix}}localVarAuthNames, {{localVariablePrefix}}localVarReturnType), apiClient.getJSON().getContext(Void.class));
    {{/responseHeaders.empty}}
    {{/returnType}}{{^returnType}}
    {{localVariablePrefix}}apiClient.invokeAPI({{localVariablePrefix}}localVarPath, "{{httpMethod}}", {{localVariablePrefix}}localVarQueryParams, {{localVariablePrefix}}localVarPostBody, {{localVariablePrefix}}localVarHeaderParams, {{localVariablePrefix}}localVarFormParams, {{localVariablePrefix}}localVarAccept, {{localVariablePrefix}}localVarContentType, {{localVariablePrefix}}localVarAuthNames, null);
    {{/returnType}}
  }
  {{/operation}}
}
{{/operations}}

ApiClient.mustache

package {{invokerPackage}};

import javax.ws.rs.client.Client;
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.client.Entity;
import javax.ws.rs.client.Invocation;
import javax.ws.rs.client.WebTarget;
import javax.ws.rs.core.Form;
import javax.ws.rs.core.GenericType;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.Response.Status;

import org.glassfish.jersey.client.ClientConfig;
import org.glassfish.jersey.client.ClientProperties;
import org.glassfish.jersey.filter.LoggingFilter;
import org.glassfish.jersey.jackson.JacksonFeature;
import org.glassfish.jersey.media.multipart.FormDataBodyPart;
import org.glassfish.jersey.media.multipart.FormDataContentDisposition;
import org.glassfish.jersey.media.multipart.MultiPart;
import org.glassfish.jersey.media.multipart.MultiPartFeature;

import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import java.util.Map.Entry;
import java.util.HashMap;
import java.util.List;
import java.util.ArrayList;
import java.util.Date;
import java.util.TimeZone;

import java.net.URLEncoder;

import java.io.File;
import java.io.UnsupportedEncodingException;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import {{invokerPackage}}.auth.Authentication;
import {{invokerPackage}}.auth.HttpBasicAuth;
import {{invokerPackage}}.auth.ApiKeyAuth;
import {{invokerPackage}}.auth.OAuth;

{{>generatedAnnotation}}
public class ApiClient {

  private Map<String, String> defaultHeaderMap = new HashMap<String, String>();
  private String basePath = "{{basePath}}";
  private boolean debugging = false;
  private int connectionTimeout = 0;

  private Client httpClient;
  private JSON json;
  private String tempFolderPath = null;

  private Map<String, Authentication> authentications;

  private int statusCode;
  private Map<String, List<String>> responseHeaders;

  private DateFormat dateFormat;

  public ApiClient() {
    json = new JSON();
    httpClient = buildHttpClient(debugging);

    // Use RFC3339 format for date and datetime.
    // See http://xml2rfc.ietf.org/public/rfc/html/rfc3339.html#anchor14
    this.dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSXXX");

    // Use UTC as the default time zone.
    this.dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));

    this.json.setDateFormat((DateFormat) dateFormat.clone());

    // Set default User-Agent.
    setUserAgent("{{#httpUserAgent}}{{{.}}}{{/httpUserAgent}}{{^httpUserAgent}}Swagger-Codegen/{{{artifactVersion}}}/java{{/httpUserAgent}}");

    // Setup authentications (key: authentication name, value: authentication).
    authentications = new HashMap<String, Authentication>();{{#authMethods}}{{#isBasic}}
    authentications.put("{{name}}", new HttpBasicAuth());{{/isBasic}}{{#isApiKey}}
    authentications.put("{{name}}", new ApiKeyAuth({{#isKeyInHeader}}"header"{{/isKeyInHeader}}{{^isKeyInHeader}}"query"{{/isKeyInHeader}}, "{{keyParamName}}"));{{/isApiKey}}{{#isOAuth}}
    authentications.put("{{name}}", new OAuth());{{/isOAuth}}{{/authMethods}}
    // Prevent the authentications from being modified.
    authentications = Collections.unmodifiableMap(authentications);
  }

  /**
   * Gets the JSON instance to do JSON serialization and deserialization.
   */
  public JSON getJSON() {
    return json;
  }

  public String getBasePath() {
    return basePath;
  }

  public ApiClient setBasePath(String basePath) {
    this.basePath = basePath;
    return this;
  }

  /**
   * Gets the status code of the previous request
   */
  public int getStatusCode() {
    return statusCode;
  }

  /**
   * Gets the response headers of the previous request
   */
  public Map<String, List<String>> getResponseHeaders() {
    return responseHeaders;
  }

  /**
   * Get authentications (key: authentication name, value: authentication).
   */
  public Map<String, Authentication> getAuthentications() {
    return authentications;
  }

  /**
   * Get authentication for the given name.
   *
   * @param authName The authentication name
   * @return The authentication, null if not found
   */
  public Authentication getAuthentication(String authName) {
    return authentications.get(authName);
  }

  /**
   * Helper method to set username for the first HTTP basic authentication.
   */
  public void setUsername(String username) {
    for (Authentication auth : authentications.values()) {
      if (auth instanceof HttpBasicAuth) {
        ((HttpBasicAuth) auth).setUsername(username);
        return;
      }
    }
    throw new RuntimeException("No HTTP basic authentication configured!");
  }

  /**
   * Helper method to set password for the first HTTP basic authentication.
   */
  public void setPassword(String password) {
    for (Authentication auth : authentications.values()) {
      if (auth instanceof HttpBasicAuth) {
        ((HttpBasicAuth) auth).setPassword(password);
        return;
      }
    }
    throw new RuntimeException("No HTTP basic authentication configured!");
  }

  /**
   * Helper method to set API key value for the first API key authentication.
   */
  public void setApiKey(String apiKey) {
    for (Authentication auth : authentications.values()) {
      if (auth instanceof ApiKeyAuth) {
        ((ApiKeyAuth) auth).setApiKey(apiKey);
        return;
      }
    }
    throw new RuntimeException("No API key authentication configured!");
  }

  /**
   * Helper method to set API key prefix for the first API key authentication.
   */
  public void setApiKeyPrefix(String apiKeyPrefix) {
    for (Authentication auth : authentications.values()) {
      if (auth instanceof ApiKeyAuth) {
        ((ApiKeyAuth) auth).setApiKeyPrefix(apiKeyPrefix);
        return;
      }
    }
    throw new RuntimeException("No API key authentication configured!");
  }

  /**
   * Helper method to set access token for the first OAuth2 authentication.
   */
  public void setAccessToken(String accessToken) {
    for (Authentication auth : authentications.values()) {
      if (auth instanceof OAuth) {
        ((OAuth) auth).setAccessToken(accessToken);
        return;
      }
    }
    throw new RuntimeException("No OAuth2 authentication configured!");
  }

  /**
   * Set the User-Agent header's value (by adding to the default header map).
   */
  public ApiClient setUserAgent(String userAgent) {
    addDefaultHeader("User-Agent", userAgent);
    return this;
  }

  /**
   * Add a default header.
   *
   * @param key The header's key
   * @param value The header's value
   */
  public ApiClient addDefaultHeader(String key, String value) {
    defaultHeaderMap.put(key, value);
    return this;
  }

  /**
   * Check that whether debugging is enabled for this API client.
   */
  public boolean isDebugging() {
    return debugging;
  }

  /**
   * Enable/disable debugging for this API client.
   *
   * @param debugging To enable (true) or disable (false) debugging
   */
  public ApiClient setDebugging(boolean debugging) {
    this.debugging = debugging;
    // Rebuild HTTP Client according to the new "debugging" value.
    this.httpClient = buildHttpClient(debugging);
    return this;
  }

  /**
   * The path of temporary folder used to store downloaded files from endpoints
   * with file response. The default value is <code>null</code>, i.e. using
   * the system's default tempopary folder.
   *
   * @see https://docs.oracle.com/javase/7/docs/api/java/io/File.html#createTempFile(java.lang.String,%20java.lang.String,%20java.io.File)
   */
  public String getTempFolderPath() {
    return tempFolderPath;
  }

  public ApiClient setTempFolderPath(String tempFolderPath) {
    this.tempFolderPath = tempFolderPath;
    return this;
  }

  /**
   * Connect timeout (in milliseconds).
   */
  public int getConnectTimeout() {
    return connectionTimeout;
  }

  /**
   * Set the connect timeout (in milliseconds).
   * A value of 0 means no timeout, otherwise values must be between 1 and
   * {@link Integer#MAX_VALUE}.
   */
  public ApiClient setConnectTimeout(int connectionTimeout) {
    this.connectionTimeout = connectionTimeout;
    httpClient.property(ClientProperties.CONNECT_TIMEOUT, connectionTimeout);
    return this;
  }

  /**
   * Get the date format used to parse/format date parameters.
   */
  public DateFormat getDateFormat() {
    return dateFormat;
  }

  /**
   * Set the date format used to parse/format date parameters.
   */
  public ApiClient setDateFormat(DateFormat dateFormat) {
    this.dateFormat = dateFormat;
    // also set the date format for model (de)serialization with Date properties
    this.json.setDateFormat((DateFormat) dateFormat.clone());
    return this;
  }

  /**
   * Parse the given string into Date object.
   */
  public Date parseDate(String str) {
    try {
      return dateFormat.parse(str);
    } catch (java.text.ParseException e) {
      throw new RuntimeException(e);
    }
  }

  /**
   * Format the given Date object into string.
   */
  public String formatDate(Date date) {
    return dateFormat.format(date);
  }

  /**
   * Format the given parameter object into string.
   */
  public String parameterToString(Object param) {
    if (param == null) {
      return "";
    } else if (param instanceof Date) {
      return formatDate((Date) param);
    } else if (param instanceof Collection) {
      StringBuilder b = new StringBuilder();
      for(Object o : (Collection)param) {
        if(b.length() > 0) {
          b.append(",");
        }
        b.append(String.valueOf(o));
      }
      return b.toString();
    } else {
      return String.valueOf(param);
    }
  }

  /*
    Format to {@code Pair} objects.
  */
  public List<Pair> parameterToPairs(String collectionFormat, String name, Object value){
    List<Pair> params = new ArrayList<Pair>();

    // preconditions
    if (name == null || name.isEmpty() || value == null) return params;

    Collection valueCollection = null;
    if (value instanceof Collection) {
      valueCollection = (Collection) value;
    } else {
      params.add(new Pair(name, parameterToString(value)));
      return params;
    }

    if (valueCollection.isEmpty()){
      return params;
    }

    // get the collection format
    collectionFormat = (collectionFormat == null || collectionFormat.isEmpty() ? "csv" : collectionFormat); // default: csv

    // create the params based on the collection format
    if (collectionFormat.equals("multi")) {
      for (Object item : valueCollection) {
        params.add(new Pair(name, parameterToString(item)));
      }

      return params;
    }

    String delimiter = ",";

    if (collectionFormat.equals("csv")) {
      delimiter = ",";
    } else if (collectionFormat.equals("ssv")) {
      delimiter = " ";
    } else if (collectionFormat.equals("tsv")) {
      delimiter = "\t";
    } else if (collectionFormat.equals("pipes")) {
      delimiter = "|";
    }

    StringBuilder sb = new StringBuilder() ;
    for (Object item : valueCollection) {
      sb.append(delimiter);
      sb.append(parameterToString(item));
    }

    params.add(new Pair(name, sb.substring(1)));

    return params;
  }

  /**
   * Check if the given MIME is a JSON MIME.
   * JSON MIME examples:
   *   application/json
   *   application/json; charset=UTF8
   *   APPLICATION/JSON
   */
  public boolean isJsonMime(String mime) {
    return mime != null && mime.matches("(?i)application\\/json(;.*)?");
  }

  /**
   * Select the Accept header's value from the given accepts array:
   *   if JSON exists in the given array, use it;
   *   otherwise use all of them (joining into a string)
   *
   * @param accepts The accepts array to select from
   * @return The Accept header to use. If the given array is empty,
   *   null will be returned (not to set the Accept header explicitly).
   */
  public String selectHeaderAccept(String[] accepts) {
    if (accepts.length == 0) {
      return null;
    }
    for (String accept : accepts) {
      if (isJsonMime(accept)) {
        return accept;
      }
    }
    return StringUtil.join(accepts, ",");
  }

  /**
   * Select the Content-Type header's value from the given array:
   *   if JSON exists in the given array, use it;
   *   otherwise use the first one of the array.
   *
   * @param contentTypes The Content-Type array to select from
   * @return The Content-Type header to use. If the given array is empty,
   *   JSON will be used.
   */
  public String selectHeaderContentType(String[] contentTypes) {
    if (contentTypes.length == 0) {
      return "application/json";
    }
    for (String contentType : contentTypes) {
      if (isJsonMime(contentType)) {
        return contentType;
      }
    }
    return contentTypes[0];
  }

  /**
   * Escape the given string to be used as URL query value.
   */
  public String escapeString(String str) {
    try {
      return URLEncoder.encode(str, "utf8").replaceAll("\\+", "%20");
    } catch (UnsupportedEncodingException e) {
      return str;
    }
  }

  /**
   * Serialize the given Java object into string entity according the given
   * Content-Type (only JSON is supported for now).
   */
  public Entity<?> serialize(Object obj, Map<String, Object> formParams, String contentType) throws ApiException {
    Entity<?> entity = null;
    if (contentType.startsWith("multipart/form-data")) {
      MultiPart multiPart = new MultiPart();
      for (Entry<String, Object> param: formParams.entrySet()) {
        if (param.getValue() instanceof File) {
          File file = (File) param.getValue();
          FormDataContentDisposition contentDisp = FormDataContentDisposition.name(param.getKey())
              .fileName(file.getName()).size(file.length()).build();
          multiPart.bodyPart(new FormDataBodyPart(contentDisp, file, MediaType.APPLICATION_OCTET_STREAM_TYPE));
        } else {
          FormDataContentDisposition contentDisp = FormDataContentDisposition.name(param.getKey()).build();
          multiPart.bodyPart(new FormDataBodyPart(contentDisp, parameterToString(param.getValue())));
        }
      }
      entity = Entity.entity(multiPart, MediaType.MULTIPART_FORM_DATA_TYPE);
    } else if (contentType.startsWith("application/x-www-form-urlencoded")) {
      Form form = new Form();
      for (Entry<String, Object> param: formParams.entrySet()) {
        form.param(param.getKey(), parameterToString(param.getValue()));
      }
      entity = Entity.entity(form, MediaType.APPLICATION_FORM_URLENCODED_TYPE);
    } else {
      // We let jersey handle the serialization
      entity = Entity.entity(obj, contentType);
    }
    return entity;
  }

  /**
   * Deserialize response body to Java object according to the Content-Type.
   */
  public <T> T deserialize(Response response, GenericType<T> returnType) throws ApiException {
    // Handle file downloading.
    if (returnType.equals(File.class)) {
      @SuppressWarnings("unchecked")
      T file = (T) downloadFileFromResponse(response);
      return file;
    }

    String contentType = null;
    List<Object> contentTypes = response.getHeaders().get("Content-Type");
    if (contentTypes != null && !contentTypes.isEmpty())
      contentType = String.valueOf(contentTypes.get(0));
    if (contentType == null)
      throw new ApiException(500, "missing Content-Type in response");

    return response.readEntity(returnType);
  }

  /**
   * Download file from the given response.
   * @throws ApiException If fail to read file content from response and write to disk
   */
  public File downloadFileFromResponse(Response response) throws ApiException {
    try {
      File file = prepareDownloadFile(response);
      Files.copy(response.readEntity(InputStream.class), file.toPath());
      return file;
    } catch (IOException e) {
      throw new ApiException(e);
    }
  }

  public File prepareDownloadFile(Response response) throws IOException {
    String filename = null;
    String contentDisposition = (String) response.getHeaders().getFirst("Content-Disposition");
    if (contentDisposition != null && !"".equals(contentDisposition)) {
      // Get filename from the Content-Disposition header.
      Pattern pattern = Pattern.compile("filename=['\"]?([^'\"\\s]+)['\"]?");
      Matcher matcher = pattern.matcher(contentDisposition);
      if (matcher.find())
        filename = matcher.group(1);
    }

    String prefix = null;
    String suffix = null;
    if (filename == null) {
      prefix = "download-";
      suffix = "";
    } else {
      int pos = filename.lastIndexOf(".");
      if (pos == -1) {
        prefix = filename + "-";
      } else {
        prefix = filename.substring(0, pos) + "-";
        suffix = filename.substring(pos);
      }
      // File.createTempFile requires the prefix to be at least three characters long
      if (prefix.length() < 3)
        prefix = "download-";
    }

    if (tempFolderPath == null)
      return File.createTempFile(prefix, suffix);
    else
      return File.createTempFile(prefix, suffix, new File(tempFolderPath));
  }

  /**
   * Invoke API by sending HTTP request with the given options.
   *
   * @param path The sub-path of the HTTP URL
   * @param method The request method, one of "GET", "POST", "PUT", and "DELETE"
   * @param queryParams The query parameters
   * @param body The request body object
   * @param headerParams The header parameters
   * @param formParams The form parameters
   * @param accept The request's Accept header
   * @param contentType The request's Content-Type header
   * @param authNames The authentications to apply
   * @param returnType The return type into which to deserialize the response
   * @return The response body in type of string
   */
  public <T> ResponseResult<T> invokeAPI(String path, String method, List<Pair> queryParams, Object body, Map<String, String> headerParams, Map<String, Object> formParams, String accept, String contentType, String[] authNames, GenericType<T> returnType) throws ApiException {
    updateParamsForAuth(authNames, queryParams, headerParams);

    // Not using `.target(this.basePath).path(path)` below,
    // to support (constant) query string in `path`, e.g. "/posts?draft=1"
    WebTarget target = httpClient.target(this.basePath + path);

    if (queryParams != null) {
      for (Pair queryParam : queryParams) {
        if (queryParam.getValue() != null) {
          target = target.queryParam(queryParam.getName(), queryParam.getValue());
        }
      }
    }

    Invocation.Builder invocationBuilder = target.request().accept(accept);

    for (String key : headerParams.keySet()) {
      String value = headerParams.get(key);
      if (value != null) {
        invocationBuilder = invocationBuilder.header(key, value);
      }
    }

    for (String key : defaultHeaderMap.keySet()) {
      if (!headerParams.containsKey(key)) {
        String value = defaultHeaderMap.get(key);
        if (value != null) {
          invocationBuilder = invocationBuilder.header(key, value);
        }
      }
    }

    Entity<?> entity = serialize(body, formParams, contentType);

    Response response = null;

    if ("GET".equals(method)) {
      response = invocationBuilder.get();
    } else if ("POST".equals(method)) {
      response = invocationBuilder.post(entity);
    } else if ("PUT".equals(method)) {
      response = invocationBuilder.put(entity);
    } else if ("DELETE".equals(method)) {
      response = invocationBuilder.delete();
    } else {
      throw new ApiException(500, "unknown method type " + method);
    }

    statusCode = response.getStatusInfo().getStatusCode();
    responseHeaders = buildResponseHeaders(response);

    if (response.getStatus() == Status.NO_CONTENT.getStatusCode()) {
      return new ResponseResult<T>(null, responseHeaders);
    } else if (response.getStatusInfo().getFamily().equals(Status.Family.SUCCESSFUL)) {
      if (returnType == null)
        return new ResponseResult<T>(null, responseHeaders);
      else
        return new ResponseResult<T>(deserialize(response, returnType), responseHeaders);
    } else {
      String message = "error";
      String respBody = null;
      if (response.hasEntity()) {
        try {
          respBody = String.valueOf(response.readEntity(String.class));
          message = respBody;
        } catch (RuntimeException e) {
          // e.printStackTrace();
        }
      }
      throw new ApiException(
        response.getStatus(),
        message,
        buildResponseHeaders(response),
        respBody);
    }
  }

  /**
   * Build the Client used to make HTTP requests.
   */
  private Client buildHttpClient(boolean debugging) {
    final ClientConfig clientConfig = new ClientConfig();
    clientConfig.register(MultiPartFeature.class);
    clientConfig.register(json);
    clientConfig.register(JacksonFeature.class);
    if (debugging) {
      clientConfig.register(LoggingFilter.class);
    }
    return ClientBuilder.newClient(clientConfig);
  }

  private Map<String, List<String>> buildResponseHeaders(Response response) {
    Map<String, List<String>> responseHeaders = new HashMap<String, List<String>>();
    for (Entry<String, List<Object>> entry: response.getHeaders().entrySet()) {
      List<Object> values = entry.getValue();
      List<String> headers = new ArrayList<String>();
      for (Object o : values) {
        headers.add(String.valueOf(o));
      }
      responseHeaders.put(entry.getKey(), headers);
    }
    return responseHeaders;
  }

  /**
   * Update query and header parameters based on authentication settings.
   *
   * @param authNames The authentications to apply
   */
  private void updateParamsForAuth(String[] authNames, List<Pair> queryParams, Map<String, String> headerParams) {
    for (String authName : authNames) {
      Authentication auth = authentications.get(authName);
      if (auth == null) throw new RuntimeException("Authentication undefined: " + authName);
      auth.applyToParams(queryParams, headerParams);
    }
  }

  public static class ResponseResult<T> {
    private final T result;
    private final Map<String, List<String>> headers;

    public ResponseResult(T result, Map<String, List<String>> headers) {
      this.result = result;
      this.headers = headers;
    }

    public T getResult() {
      return result;
    }

    public Map<String, List<String>> getHeaders() {
      return headers;
    }
  }
}