package org.devtcg.testwebservices;

import java.lang.reflect.Field;

/**
 * On Dalvik, reflection methods cannot be trusted to perform lookups with
 * reasonable efficiency. All of the methods return deep copies of the
 * underlying cached structures and methods that lookup by name perform a linear
 * search for a match. So, we need our own custom class cache here to ensure
 * maximum performance reading our data binding classes.
 */
public class ClassCache<T> {
    private final Class<T> mClazz;

    private HashMap<String, AnnotationCache<Field>> mFieldsByName;
    private AnnotationCache<Field>[] mFieldsWithAnnotations;
    private Field[] mFields;

    public ClassCache(Class<T> clazz) {
        mClazz = clazz;
    }

    public AnnotationCache<Field> getFieldWithAnnotations(String name) throws NoSuchFieldException {
        if (mFieldsByName == null) {
            mFieldsByName = getFieldsByName();
        }
        AnnotationCache<Field> field = mFieldsByName.get(name);
        if (field == null) {
            throw new NoSuchFieldException(name);
        } else {
            return field;
        }
    }

    public Field getField(String name) throws NoSuchFieldException {
        return getFieldWithAnnotations(name).getElement();
    }

    public AnnotationCache<Field>[] getFieldsWithAnnotations() {
        if (mFieldsWithAnnotations == null) {
            Field[] fields = getFields();
            int N = fields.length;
            AnnotationCache<Field>[] fieldsWithAnnotations = new AnnotationCache[N];
            for (int i = 0; i < N; i++) {
                fieldsWithAnnotations[i] = new AnnotationCache<Field>(fields[i]);
            }
            mFieldsWithAnnotations = fieldsWithAnnotations;
        }
        return mFieldsWithAnnotations;
    }

    public Field[] getFields() {
        if (mFields == null) {
            mFields = mClazz.getFields();
        }
        return mFields;
    }

    private HashMap<String, AnnotationCache<Field>> getFieldsByName() {
        HashMap<String, AnnotationCache<Field>> map =
                new HashMap<String, AnnotationCache<Field>>();
        Field[] array = getFields();
        int N = array.length;
        for (int i = 0; i < N; i++) {
            Field field = array[i];
            map.put(field.getName(), new AnnotationCache<Field>(field));
        }
        return map;
    }
}