package com.atlassian.sal.core.component;
   
   import com.atlassian.sal.api.component.ComponentLocator;
   import com.atlassian.sal.spi.HostContextAccessor;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import java.util.Collection;
   import java.util.Map;
  
  public class DefaultComponentLocator extends ComponentLocator {
      private static final Logger log = LoggerFactory.getLogger(DefaultComponentLocator.class);
  
      private final HostContextAccessor hostContextAccessor;
  
      public DefaultComponentLocator(final HostContextAccessor accessor) {
          this.hostContextAccessor = accessor;
          ComponentLocator.setComponentLocator(this);
      }
  
      @Override
      protected <T> T getComponentInternal(final Class<T> iface) {
          final Map<String, T> beansOfType = hostContextAccessor.getComponentsOfType(iface);
  
          if (beansOfType == null || beansOfType.isEmpty()) {
              return null;
          } else if (beansOfType.size() > 1) {
              // we have multiple implementations of this interface, choose one with name that looks like iface name
              final String shortClassName = convertClassToName(iface);
              final T implementation = beansOfType.get(shortClassName);
              if (implementation == null) {
                  log.warn("More than one instance of " + iface.getName() + " found but none of them has key " + shortClassName);
              }
              return implementation;
          }
          return beansOfType.values().iterator().next();
      }
  
      @Override
      protected <T> T getComponentInternal(final Class<T> iface, final String componentId) {
          final Map<String, T> beansOfType = hostContextAccessor.getComponentsOfType(iface);
  
          return beansOfType.get(componentId);
      }
  
      @Override
      protected <T> Collection<T> getComponentsInternal(final Class<T> iface) {
          final Map<String, T> beansOfType = hostContextAccessor.getComponentsOfType(iface);
          return (beansOfType != null ? beansOfType.values() : null);
      }
  }