package org.jboss.windup.reporting.renderer.graphviz;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Map;

import javax.script.Bindings;
import javax.script.Compilable;
import javax.script.CompiledScript;
import javax.script.ScriptContext;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.builder.ReflectionToStringBuilder;
import org.apache.tinkerpop.gremlin.structure.Graph;
import org.jboss.windup.reporting.renderer.dot.DotWriter;
import java.util.logging.Logger;
import org.jboss.windup.util.Logging;

public class GraphvizWriter extends DotWriter
{
    private static final Logger LOG = Logging.get(GraphvizWriter.class);

    private final CompiledScript vizJsCompiled;

    public GraphvizWriter(Graph graph) throws ScriptException, IOException
    {
        super(graph);
        if (true)
        {
            throw new RuntimeException(
                        "Not yet implemented; this is unstable.  The javascript requires Int32Array, which isn't currently provided by Rhino.");
        }

        // precompile the javascript.
        StringBuilder builder = new StringBuilder();
        builder.append(IOUtils.toString(this.getClass().getClassLoader().getResourceAsStream("vizjs/viz.js")));

        builder = new StringBuilder();
        builder.append("function Viz() { console.log('Hello World'); }");

        ScriptEngineManager manager = new ScriptEngineManager();
        ScriptEngine engine = manager.getEngineByName("JavaScript");

        String script = builder.toString();
        Compilable compilingEngine = (Compilable) engine;
        vizJsCompiled = compilingEngine.compile(builder.toString());
    }

    @Override
    public void writeGraph(OutputStream os) throws IOException
    {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        super.writeGraph(baos);

        try
        {
            StringBuilder builder = new StringBuilder();
            builder.append(IOUtils.toString(this.getClass().getClassLoader().getResourceAsStream("vizjs/viz.js")));
            builder.append("var result = new Viz(dotGraph);");

            String script = builder.toString();
            ScriptEngine engine = new ScriptEngineManager().getEngineByName("JavaScript");
            Compilable compilingEngine = (Compilable) engine;
            CompiledScript cscript = compilingEngine.compile(script);

            // Bindings bindings = cscript.getEngine().createBindings();
            Bindings bindings = engine.getBindings(ScriptContext.ENGINE_SCOPE);
            for (Map.Entry me : bindings.entrySet())
            {
                System.out.printf("%s: %s\n", me.getKey(), String.valueOf(me.getValue()));
            }
            bindings.put("dotGraph", baos.toString());
            // cscript.eval();
            Object result = cscript.eval(bindings);
            LOG.info("Result:" + ReflectionToStringBuilder.toString(result));
        }
        catch (Exception e)
        {
            throw new IOException("Exception generating graph.", e);
        }
    }
}
