// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.search.query.profile;

import com.yahoo.processing.request.CompoundName;
import com.yahoo.protect.Validator;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * <p>A wrapper of a query profile where overrides to the values in the referenced
 * profile can be set.</p>
 *
 * <p>This is used to allow configured overrides (in a particular referencing profile) of a referenced query profile.
 *
 * <p>Properties which are defined as not overridable in the type (if any) of the referenced query profile
 * cannot be set.</p>
 *
 * @author bratseth
 */
public class BackedOverridableQueryProfile extends OverridableQueryProfile implements Cloneable {

    /** The backing read only query profile, or null if this is not backed */
    private QueryProfile backingProfile;

    /**
     * Creates an overridable profile from the given backing profile. The backing profile will never be
     * written to.
     *
     * @param backingProfile the backing profile, which is assumed read only, never null
     */
    public BackedOverridableQueryProfile(QueryProfile backingProfile) {
        Validator.ensureNotNull("An overridable query profile must be backed by a real query profile",backingProfile);
        setType(backingProfile.getType());
        this.backingProfile=backingProfile;
    }

    @Override
    public synchronized void freeze() {
        super.freeze();
        backingProfile.freeze();
    }

    @Override
    protected Object localLookup(String localName, DimensionBinding dimensionBinding) {
        Object valueInThis=super.localLookup(localName,dimensionBinding);
        if (valueInThis!=null) return valueInThis;
        return backingProfile.localLookup(localName,dimensionBinding);
    }

    protected Boolean isLocalInstanceOverridable(String localName) {
        Boolean valueInThis=super.isLocalInstanceOverridable(localName);
        if (valueInThis!=null) return valueInThis;
        return backingProfile.isLocalInstanceOverridable(localName);
    }

    @Override
    protected QueryProfile createSubProfile(String name,DimensionBinding dimensionBinding) {
        Object backing=backingProfile.lookup(new CompoundName(name),true,dimensionBinding.createFor(backingProfile.getDimensions()));
        if (backing!=null && backing instanceof QueryProfile)
            return new BackedOverridableQueryProfile((QueryProfile)backing);
        else
            return new OverridableQueryProfile(); // Nothing is set in this branch, so nothing to override, but need override checking
    }

    /** Returns a clone of this which can be independently overridden, but which refers to the same backing profile */
    @Override
    public BackedOverridableQueryProfile clone() {
        BackedOverridableQueryProfile clone=(BackedOverridableQueryProfile)super.clone();
        return clone;
    }

    /** Returns the query profile backing this */
    public QueryProfile getBacking() { return backingProfile; }

    @Override
    public void addInherited(QueryProfile inherited) {
        backingProfile.addInherited(inherited);
    }

    void addInheritedHere(QueryProfile inherited) {
        super.addInherited(inherited);
    }

    @Override
    protected void visitVariants(boolean allowContent,QueryProfileVisitor visitor,DimensionBinding dimensionBinding) {
        super.visitVariants(allowContent, visitor, dimensionBinding);
        if (visitor.isDone()) return;
        backingProfile.visitVariants(allowContent, visitor, dimensionBinding);
    }

    @Override
    protected void visitInherited(boolean allowContent,QueryProfileVisitor visitor,DimensionBinding dimensionBinding, QueryProfile owner) {
        super.visitInherited(allowContent,visitor,dimensionBinding, owner);
        if (visitor.isDone()) return;
        backingProfile.visitInherited(allowContent,visitor,dimensionBinding,owner);
    }

    /** Returns a value from the content of this: The value in this, or the value from the backing if not set in this */
    protected Object getContent(String localKey) {
        Object value=super.getContent(localKey);
        if (value!=null) return value;
        return backingProfile.getContent(localKey);
    }

    /**
     * Returns all the content from this:
     * All the values in this, and all values in the backing where an overriding value is not set in this
     */
    @Override
    protected Map<String,Object> getContent() {
        Map<String,Object> thisContent=super.getContent();
        Map<String,Object> backingContent=backingProfile.getContent();
        if (thisContent.isEmpty()) return backingContent; // Shortcut
        if (backingContent.isEmpty()) return thisContent; // Shortcut
        Map<String,Object> content=new HashMap<>(backingContent);
        content.putAll(thisContent);
        return content;
    }

    @Override
    public String toString() {
        return "overridable wrapper of " + backingProfile.toString();
    }

    @Override
    public boolean isExplicit() {
        return backingProfile.isExplicit();
    }

    @Override
    public List<String> getDimensions() {
        List<String> dimensions=super.getDimensions();
        if (dimensions!=null) return dimensions;
        return backingProfile.getDimensions();
    }

}