/**

 * Back 2 Browser Bytecode Translator

 * Copyright (C) 2012 Jaroslav Tulach <jaroslav.tulach@apidesign.org>

 *

 * This program is free software: you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation, version 2 of the License.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program. Look for COPYING file in the top folder.

 * If not, see http://opensource.org/licenses/GPL-2.0.

 */

package org.apidesign.bck2brwsr.htmlpage;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.lang.reflect.Method;

import java.util.logging.Level;

import java.util.logging.Logger;

import javafx.scene.web.WebEngine;

import netscape.javascript.JSObject;

import org.apidesign.bck2brwsr.core.ExtraJavaScript;

import org.apidesign.bck2brwsr.core.JavaScriptBody;

/** Provides binding between models and 

 *

 * @author Jaroslav Tulach <jtulach@netbeans.org>

 */

@ExtraJavaScript(resource = "/org/apidesign/bck2brwsr/htmlpage/knockout-2.2.1.js")

public class Knockout {

    private static final Logger LOG = Logger.getLogger(Knockout.class.getName());

    /** used by tests */

    static Knockout next;

    static {

        BufferedReader r = new BufferedReader(new InputStreamReader(Knockout.class.getResourceAsStream("knockout-2.2.1.js")));

        StringBuilder sb = new StringBuilder();

        for (;;) {

            try {

                String l = r.readLine();

                if (l == null) {

                    break;

                }

                sb.append(l).append('\n');

            } catch (IOException ex) {

                throw new IllegalStateException(ex);

            }

        }

        web().executeScript(sb.toString());

        Object ko = web().executeScript("ko");

        assert ko != null : "Knockout library successfully defined 'ko'";

    }

    private final Object bindings;

    Knockout(Object bindings) {

        this.bindings = bindings;

    }

    public static <M> Knockout applyBindings(

        Class<M> modelClass, M model, String[] propsGettersAndSetters

    ) {

        Object bindings = next;

        next = null;

        if (bindings == null) {

            bindings = web().executeScript("new Object()");

        }

        for (int i = 0; i < propsGettersAndSetters.length; i += 4) {

            try {

                Method getter = modelClass.getMethod(propsGettersAndSetters[i + 3]);

                bind(bindings, model, propsGettersAndSetters[i],

                    propsGettersAndSetters[i + 1],

                    propsGettersAndSetters[i + 2],

                    getter.getReturnType().isPrimitive()

                );

            } catch (NoSuchMethodException ex) {

                throw new IllegalStateException(ex.getMessage());

            }

        }

        applyBindings(bindings);

        return new Knockout(bindings);

    }

    @JavaScriptBody(args = { "prop" }, body =

        "this[prop].valueHasMutated();"

    )

    public void valueHasMutated(String prop) {

        LOG.log(Level.INFO, "property mutated: {0}", prop);

        JSObject koProp = (JSObject) ((JSObject)bindings).getMember(prop);

        koProp.call("valueHasMutated");

    }

    @JavaScriptBody(args = { "id", "ev" }, body = "ko.utils.triggerEvent(window.document.getElementById(id), ev.substring(2));")

    public static void triggerEvent(String id, String ev) {

    }

    @JavaScriptBody(args = { "bindings", "model", "prop", "getter", "setter", "primitive" }, body =

          "var bnd = {\n"

        + "  read: function() {\n"

        + "    var v = model[getter]();\n"

        + "    return v;\n"

        + "  },\n"

        + "  owner: bindings\n"

        + "};\n"

        + "if (setter != null) {\n"

        + "  bnd.write = function(val) {\n"

        + "    model[setter](primitive ? new Number(val) : val);\n"

        + "  };\n"

        + "}\n"

        + "bindings[prop] = ko.computed(bnd);"

    )

    private static void bind(

        Object bindings, Object model, String prop, String getter, String setter, boolean primitive

    ) {

        WebEngine e = web();

        JSObject bnd = (JSObject) e.executeScript("var x = {}; x.bnd = "

        + "new Function('ko', 'bindings', 'model', 'prop', 'getter', 'setter', 'primitive', '"

        + "var bnd = {"

        + "  read: function() {"

        + "    try {"

        + "      return model[getter]();"

        + "    } catch (e) {"

        + "      alert(\"Cannot call \" + getter + \" on \" + model + \" error: \" + e);"

        + "    }"

        + "  },"

        + "  owner: bindings"

        + "};"

        + "if (setter != null) {"

        + "  bnd.write = function(val) {"

        + "    model[setter](primitive ? new Number(val) : val);"

        + "  };"

        + "};"

        + "bindings[prop] = ko.computed(bnd);'"

        + "); x;");

        Object ko = e.executeScript("ko");

        bnd.call("bnd", ko, bindings, model, prop, strip(getter), strip(setter), primitive);

        LOG.log(Level.INFO, "binding defined for {0}: {1}", new Object[]{prop, ((JSObject)bindings).getMember(prop)});

    }

    private static String strip(String mangled) {

        if (mangled == null) {

            return null;

        }

        int under = mangled.indexOf("__");

        return mangled.substring(0, under);

    }

    @JavaScriptBody(args = { "bindings" }, body = "ko.applyBindings(bindings);")

    private static void applyBindings(Object bindings) {

        JSObject ko = (JSObject) web().executeScript("ko");

        ko.call("applyBindings", bindings);

    }

    private static WebEngine web() {

        return (WebEngine) System.getProperties().get("webEngine");

    }

}