package org.checkerframework.common.wholeprograminference;

import com.sun.tools.javac.code.Type.ArrayType;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.annotation.processing.ProcessingEnvironment;
import javax.lang.model.element.AnnotationMirror;
import javax.lang.model.element.AnnotationValue;
import javax.lang.model.element.ExecutableElement;
import javax.lang.model.element.VariableElement;
import javax.lang.model.type.DeclaredType;
import javax.lang.model.type.TypeMirror;
import org.checkerframework.checker.nullness.qual.Nullable;
import org.checkerframework.javacutil.AnnotationBuilder;
import org.checkerframework.javacutil.AnnotationUtils;
import org.checkerframework.javacutil.BugInCF;
import org.checkerframework.javacutil.TypesUtils;
import org.plumelib.reflection.Signatures;
import org.plumelib.util.CollectionsPlume;
import scenelib.annotations.Annotation;
import scenelib.annotations.el.AnnotationDef;
import scenelib.annotations.field.AnnotationFieldType;
import scenelib.annotations.field.ArrayAFT;
import scenelib.annotations.field.BasicAFT;
import scenelib.annotations.field.ClassTokenAFT;
import scenelib.annotations.field.EnumAFT;
import scenelib.annotations.field.ScalarAFT;

/**
 * This class contains static methods that convert between {@link scenelib.annotations.Annotation}
 * and {@link javax.lang.model.element.AnnotationMirror}.
 */
public class AnnotationConverter {

  /**
   * Converts an {@link javax.lang.model.element.AnnotationMirror} into an {@link
   * scenelib.annotations.Annotation}.
   *
   * @param am the AnnotationMirror
   * @return the Annotation
   */
  public static Annotation annotationMirrorToAnnotation(AnnotationMirror am) {
    @SuppressWarnings("signature:argument") // TODO: bug for inner classes
    AnnotationDef def =
        new AnnotationDef(
            AnnotationUtils.annotationName(am),
            String.format(
                "annotationMirrorToAnnotation %s [%s] keyset=%s",
                am, am.getClass(), am.getElementValues().keySet()));
    Map<String, AnnotationFieldType> fieldTypes = new HashMap<>(am.getElementValues().size());
    // Handling cases where there are fields in annotations.
    for (ExecutableElement ee : am.getElementValues().keySet()) {
      AnnotationFieldType aft = getAnnotationFieldType(ee);
      fieldTypes.put(ee.getSimpleName().toString(), aft);
    }
    def.setFieldTypes(fieldTypes);

    // Now, we handle the values of those types below
    Map<? extends ExecutableElement, ? extends AnnotationValue> values = am.getElementValues();
    Map<String, Object> newValues = new HashMap<>(values.size());
    for (ExecutableElement ee : values.keySet()) {
      Object value = values.get(ee).getValue();
      if (value instanceof List) {
        // If we have a List here, then it is a List of AnnotationValue.
        // Convert each AnnotationValue to its respective Java type.
        @SuppressWarnings("unchecked")
        List<AnnotationValue> valueList = (List<AnnotationValue>) value;
        value = CollectionsPlume.mapList(AnnotationValue::getValue, valueList);
      } else if (value instanceof TypeMirror) {
        try {
          value = Class.forName(TypesUtils.binaryName((TypeMirror) value));
        } catch (ClassNotFoundException e) {
          throw new BugInCF(e, "value = %s [%s]", value, value.getClass());
        }
      }
      newValues.put(ee.getSimpleName().toString(), value);
    }
    Annotation out = new Annotation(def, newValues);
    return out;
  }

  /**
   * Converts an {@link scenelib.annotations.Annotation} into an {@link
   * javax.lang.model.element.AnnotationMirror}.
   *
   * @param anno the Annotation
   * @param processingEnv the ProcessingEnvironment
   * @return the AnnotationMirror
   */
  protected static AnnotationMirror annotationToAnnotationMirror(
      Annotation anno, ProcessingEnvironment processingEnv) {
    final AnnotationBuilder builder =
        new AnnotationBuilder(
            processingEnv, Signatures.binaryNameToFullyQualified(anno.def().name));
    for (String fieldKey : anno.fieldValues.keySet()) {
      addFieldToAnnotationBuilder(fieldKey, anno.fieldValues.get(fieldKey), builder);
    }
    return builder.build();
  }

  /**
   * Returns the type of an element (that is, a field) of an annotation.
   *
   * @param ee an element (that is, a field) of an annotation
   * @return the type of the given annotation field
   */
  protected static @Nullable AnnotationFieldType getAnnotationFieldType(ExecutableElement ee) {
    return typeMirrorToAnnotationFieldType(ee.getReturnType());
  }

  /**
   * Converts a TypeMirror to an AnnotationFieldType.
   *
   * @param tm a type for an annotation element/field: primitive, String, class, enum constant, or
   *     array thereof
   * @return an AnnotationFieldType corresponding to the argument
   */
  protected static AnnotationFieldType typeMirrorToAnnotationFieldType(TypeMirror tm) {
    switch (tm.getKind()) {
      case BOOLEAN:
        return BasicAFT.forType(boolean.class);
        // Primitves
      case BYTE:
        return BasicAFT.forType(byte.class);
      case CHAR:
        return BasicAFT.forType(char.class);
      case DOUBLE:
        return BasicAFT.forType(double.class);
      case FLOAT:
        return BasicAFT.forType(float.class);
      case INT:
        return BasicAFT.forType(int.class);
      case LONG:
        return BasicAFT.forType(long.class);
      case SHORT:
        return BasicAFT.forType(short.class);

      case ARRAY:
        TypeMirror componentType = (((ArrayType) tm).getComponentType());
        AnnotationFieldType componentAFT = typeMirrorToAnnotationFieldType(componentType);
        return new ArrayAFT((ScalarAFT) componentAFT);

      case DECLARED:
        String className = TypesUtils.getQualifiedName((DeclaredType) tm);
        if (className.equals("java.lang.String")) {
          return BasicAFT.forType(String.class);
        } else if (className.equals("java.lang.Class")) {
          return ClassTokenAFT.ctaft;
        } else {
          // This must be an enum constant.
          return new EnumAFT(className);
        }

      default:
        throw new BugInCF(
            "typeMirrorToAnnotationFieldType: unexpected argument %s [%s %s]",
            tm, tm.getKind(), tm.getClass());
    }
  }

  /**
   * Adds a field to an AnnotationBuilder.
   *
   * @param fieldKey is the name of the field
   * @param obj is the value of the field
   * @param builder is the AnnotationBuilder
   */
  @SuppressWarnings("unchecked") // This is actually checked in the first instanceOf call below.
  protected static void addFieldToAnnotationBuilder(
      String fieldKey, Object obj, AnnotationBuilder builder) {
    if (obj instanceof List<?>) {
      builder.setValue(fieldKey, (List<Object>) obj);
    } else if (obj instanceof String) {
      builder.setValue(fieldKey, (String) obj);
    } else if (obj instanceof Integer) {
      builder.setValue(fieldKey, (Integer) obj);
    } else if (obj instanceof Float) {
      builder.setValue(fieldKey, (Float) obj);
    } else if (obj instanceof Long) {
      builder.setValue(fieldKey, (Long) obj);
    } else if (obj instanceof Boolean) {
      builder.setValue(fieldKey, (Boolean) obj);
    } else if (obj instanceof Character) {
      builder.setValue(fieldKey, (Character) obj);
    } else if (obj instanceof Class<?>) {
      builder.setValue(fieldKey, (Class<?>) obj);
    } else if (obj instanceof Double) {
      builder.setValue(fieldKey, (Double) obj);
    } else if (obj instanceof Enum<?>) {
      builder.setValue(fieldKey, (Enum<?>) obj);
    } else if (obj instanceof Enum<?>[]) {
      builder.setValue(fieldKey, (Enum<?>[]) obj);
    } else if (obj instanceof AnnotationMirror) {
      builder.setValue(fieldKey, (AnnotationMirror) obj);
    } else if (obj instanceof Object[]) {
      builder.setValue(fieldKey, (Object[]) obj);
    } else if (obj instanceof TypeMirror) {
      builder.setValue(fieldKey, (TypeMirror) obj);
    } else if (obj instanceof Short) {
      builder.setValue(fieldKey, (Short) obj);
    } else if (obj instanceof VariableElement) {
      builder.setValue(fieldKey, (VariableElement) obj);
    } else if (obj instanceof VariableElement[]) {
      builder.setValue(fieldKey, (VariableElement[]) obj);
    } else {
      throw new BugInCF("Unrecognized type: " + obj.getClass());
    }
  }
}