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Symphony Java BDK Template API module

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package com.symphony.bdk.template.api;

import org.apiguardian.api.API;

import java.util.List;
import java.util.ServiceLoader;
import java.util.stream.Collectors;
import java.util.stream.StreamSupport;

/**
 * Interface to represent a specific template engine backed by a specific technology.
 * It creates {@link Template} instances based on a file provided in the file system, in the classpath or as a URL
 */
@API(status = API.Status.STABLE)
public interface TemplateEngine {

  /**
   * Create a {@link Template} instance from a file on the file system
   * @param templatePath path to a template file on the file system
   * @return a new {@link Template} instantiated from the provided file
   * @throws TemplateException when template cannot be loaded, e.g. file not accessible
   */
  Template newTemplateFromFile(String templatePath) ;

  /**
   * Create a {@link Template} instance from a file in the classpath
   *
   * @param templatePath full path to a template file in the classpath
   * @return a new {@link Template} instantiated from the provided classpath resource
   * @throws TemplateException when template cannot be loaded, e.g. resource not accessible
   */
  Template newTemplateFromClasspath(String templatePath);

  /**
   * Create a {@link Template} instance from a string
   *
   * @param template inline template string
   * @return a new {@link Template} instantiated from the provided inline string
   * @throws TemplateException when template cannot be loaded.
   */
  Template newTemplateFromString(String template);

  static TemplateEngine getDefaultImplementation() {
    final ServiceLoader engineServiceLoader = ServiceLoader.load(TemplateEngine.class);

    final List templateEngines = StreamSupport.stream(engineServiceLoader.spliterator(), false)
        .collect(Collectors.toList());

    if (templateEngines.isEmpty()) {
      throw new IllegalStateException("No TemplateEngine implementation found in classpath. "
          + "Please add a symphony-bdk-template-* (freemarker or handlebars) dependency to your project.");
    } else if (templateEngines.size() > 1) {
      throw new IllegalStateException("More than 1 TemplateEngine implementation found in classpath. "
          + "Please remove the extra symphony-bdk-template-* dependency from your project");
    }
    return templateEngines.stream().findFirst().get();
  }
}