/**
 * Copyright © 2016-2018 The Thingsboard Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.thingsboard.server.extensions.core.filter;

import jdk.nashorn.api.scripting.NashornScriptEngineFactory;
import lombok.extern.slf4j.Slf4j;
import org.thingsboard.server.common.data.kv.AttributeKvEntry;
import org.thingsboard.server.common.data.kv.KvEntry;
import org.thingsboard.server.common.msg.core.UpdateAttributesRequest;
import org.thingsboard.server.extensions.api.device.DeviceAttributes;

import javax.script.*;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @author Andrew Shvayka
 */
@Slf4j
public class NashornJsEvaluator {

    public static final String CLIENT_SIDE = "cs";
    public static final String SERVER_SIDE = "ss";
    public static final String SHARED = "shared";
    private static NashornScriptEngineFactory factory = new NashornScriptEngineFactory();

    private CompiledScript engine;

    public NashornJsEvaluator(String script) {
        engine = compileScript(script);
    }

    private static CompiledScript compileScript(String script) {
        ScriptEngine engine = factory.getScriptEngine(new String[]{"--no-java"});
        Compilable compEngine = (Compilable) engine;
        try {
            return compEngine.compile(script);
        } catch (ScriptException e) {
            log.warn("Failed to compile filter script: {}", e.getMessage(), e);
            throw new IllegalArgumentException("Can't compile script: " + e.getMessage());
        }
    }

    public static Bindings convertListEntries(Bindings bindings, String attributesVarName, Collection<AttributeKvEntry> attributes) {
        Map<String, Object> attrMap = new HashMap<>();
        for (AttributeKvEntry attr : attributes) {
            if (!CLIENT_SIDE.equalsIgnoreCase(attr.getKey()) && !SERVER_SIDE.equalsIgnoreCase(attr.getKey())
                    && !SHARED.equalsIgnoreCase(attr.getKey())) {
                bindings.put(attr.getKey(), getValue(attr));
            }
            attrMap.put(attr.getKey(), getValue(attr));
        }
        bindings.put(attributesVarName, attrMap);
        return bindings;
    }

    public static Bindings updateBindings(Bindings bindings, UpdateAttributesRequest msg) {
        Map<String, Object> attrMap = (Map<String, Object>) bindings.get(CLIENT_SIDE);
        for (AttributeKvEntry attr : msg.getAttributes()) {
            if (!CLIENT_SIDE.equalsIgnoreCase(attr.getKey()) && !SERVER_SIDE.equalsIgnoreCase(attr.getKey())
                    && !SHARED.equalsIgnoreCase(attr.getKey())) {
                bindings.put(attr.getKey(), getValue(attr));
            }
            attrMap.put(attr.getKey(), getValue(attr));
        }
        bindings.put(CLIENT_SIDE, attrMap);
        return bindings;
    }

    protected static Object getValue(KvEntry attr) {
        switch (attr.getDataType()) {
            case STRING:
                return attr.getStrValue().orElse(null);
            case LONG:
                return attr.getLongValue().orElse(null);
            case DOUBLE:
                return attr.getDoubleValue().orElse(null);
            case BOOLEAN:
                return attr.getBooleanValue().orElse(null);
        }
        return null;
    }

    public static Bindings toBindings(List<KvEntry> entries) {
        return toBindings(new SimpleBindings(), entries);
    }

    public static Bindings toBindings(Bindings bindings, List<KvEntry> entries) {
        for (KvEntry entry : entries) {
            bindings.put(entry.getKey(), getValue(entry));
        }
        return bindings;
    }

    public static Bindings getAttributeBindings(DeviceAttributes attributes) {
        Bindings bindings = new SimpleBindings();
        convertListEntries(bindings, CLIENT_SIDE, attributes.getClientSideAttributes());
        convertListEntries(bindings, SERVER_SIDE, attributes.getServerSideAttributes());
        convertListEntries(bindings, SHARED, attributes.getServerSidePublicAttributes());
        return bindings;
    }

    public Boolean execute(Bindings bindings) throws ScriptException {
        Object eval = engine.eval(bindings);
        if (eval instanceof Boolean) {
            return (Boolean) eval;
        } else {
            log.warn("Wrong result type: {}", eval);
            throw new ScriptException("Wrong result type: " + eval);
        }
    }

    public void destroy() {
        engine = null;
    }
}
