package org.robolectric.annotation.processing.validator;

import org.robolectric.annotation.processing.RobolectricModel;

import java.util.List;

import javax.annotation.processing.ProcessingEnvironment;
import javax.lang.model.element.TypeElement;
import javax.lang.model.element.TypeParameterElement;
import javax.lang.model.element.VariableElement;
import javax.lang.model.type.DeclaredType;
import javax.lang.model.type.TypeMirror;
import javax.lang.model.type.TypeVisitor;
import javax.lang.model.util.SimpleTypeVisitor6;
import javax.tools.Diagnostic.Kind;

/**
 * Validator that checks usages of {@link org.robolectric.annotation.RealObject}.
 */
public class RealObjectValidator extends FoundOnImplementsValidator {

  public RealObjectValidator(RobolectricModel model, ProcessingEnvironment env) {
    super(model, env, "org.robolectric.annotation.RealObject");
  }

  public static String join(List<?> params) {
    StringBuffer retval = new StringBuffer();
    boolean comma = false;
    for (Object p : params) {
      if (comma) {
        retval.append(',');
      }
      comma = true;
      retval.append(p);
    }
    return retval.toString();
  }
  
  TypeVisitor<Void,VariableElement> typeVisitor = new SimpleTypeVisitor6<Void,VariableElement>() {
    @Override
    public Void visitDeclared(DeclaredType t, VariableElement v) {
      List<? extends TypeMirror> typeParams = t.getTypeArguments();
      List<? extends TypeParameterElement> parentTypeParams = parent.getTypeParameters();

      if (!parentTypeParams.isEmpty() && typeParams.isEmpty()) {
        messager.printMessage(Kind.ERROR, "@RealObject is missing type parameters", v);
      } else {
        String typeString = join(typeParams);
        String parentString = join(parentTypeParams);
        if (!typeString.equals(parentString)) {
          messager.printMessage(Kind.ERROR, "Parameter type mismatch: expecting <" + parentString + ">, was <" + typeString + '>', v);
        }
      }
      return null;
    }
    
    
  };
  
  TypeElement parent;
  
  @Override
  public Void visitVariable(VariableElement elem, TypeElement parent) {
    this.parent = parent;
    TypeMirror impClass = model.getImplementedClass(imp);
    if (impClass != null) {
      TypeMirror elemType = elem.asType();
      if (!types.isAssignable(impClass, elemType)) {
        error("@RealObject with type <" + elemType + ">; expected <" + impClass + '>');
      }
      typeVisitor.visit(elemType, elem);
    }
    return null;
  }
}