/*******************************************************************************
 * Copyright (c) 2010 György Orosz.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     György Orosz - initial API and implementation
 ******************************************************************************/
package org.erlide.wrangler.refactoring.backend;

import org.eclipse.core.resources.IFile;
import org.erlide.runtime.rpc.IOtpRpc;
import org.erlide.runtime.rpc.RpcResult;
import org.erlide.util.ErlLogger;
import org.erlide.wrangler.refactoring.backend.SyntaxInfo.Type;
import org.erlide.wrangler.refactoring.util.GlobalParameters;

import com.ericsson.otp.erlang.OtpErlangAtom;
import com.ericsson.otp.erlang.OtpErlangInt;
import com.ericsson.otp.erlang.OtpErlangList;
import com.ericsson.otp.erlang.OtpErlangLong;
import com.ericsson.otp.erlang.OtpErlangObject;
import com.ericsson.otp.erlang.OtpErlangTuple;

/**
 * Wranglers syntax backend, which is for determining about a selection its type
 *
 * @author Gyorgy Orosz
 * @version %I%, %G%
 */
public class WranglerSyntaxBackend implements IWranglerBackend {
    protected IOtpRpc backend;
    protected static final String MODULE = "wrangler_ast_server";
    protected static final String INTERFACE_MODULE = "api_interface";
    protected static final String PARSE_FUNCTION = "parse_annotate_file";
    protected static final String VAR_FUNCTION = "pos_to_var_name";

    /**
     * @param backend
     *            Backend object
     */
    public WranglerSyntaxBackend(final IOtpRpc backend) {
        this.backend = backend;
    }

    protected OtpErlangTuple parseFile(final IFile f) {
        final String filePath = f.getLocation().toOSString();
        final RpcResult res = backend.call_noexception(MODULE, PARSE_FUNCTION, "sax",
                filePath, "true",
                GlobalParameters.getWranglerSelection().getSearchPath());
        return parseParserResult(res.getValue());
    }

    protected OtpErlangTuple parseParserResult(final OtpErlangObject value) {
        final OtpErlangTuple backendResult = (OtpErlangTuple) value;
        if (!((OtpErlangAtom) backendResult.elementAt(0)).atomValue().equals("ok")) {
            return null;
        }
        final OtpErlangTuple wranglerResult = (OtpErlangTuple) backendResult.elementAt(1);

        return (OtpErlangTuple) wranglerResult.elementAt(0);

    }

    protected SyntaxInfo varToPos(final OtpErlangTuple syntaxTree, final int line,
            final int col) {
        final OtpErlangInt[] position = new OtpErlangInt[2];
        position[0] = new OtpErlangInt(line);
        position[1] = new OtpErlangInt(col);
        final RpcResult res = backend.call_noexception(INTERFACE_MODULE, VAR_FUNCTION,
                "xx", syntaxTree, new OtpErlangTuple(position));
        return parseVarInfo(res.getValue());
    }

    private SyntaxInfo parseVarInfo(final OtpErlangObject value) {
        try {
            final OtpErlangTuple result = (OtpErlangTuple) value;
            if (!((OtpErlangAtom) result.elementAt(0)).atomValue().equals("ok")) {
                return new SyntaxInfo(Type.NONE, -1, -1);
            }
            SyntaxInfo ret;
            final OtpErlangTuple res = (OtpErlangTuple) result.elementAt(1);
            final OtpErlangTuple position = (OtpErlangTuple) ((OtpErlangList) res
                    .elementAt(1)).elementAt(0);
            OtpErlangLong line, col;
            line = (OtpErlangLong) position.elementAt(0);
            col = (OtpErlangLong) position.elementAt(0);
            ret = new SyntaxInfo(Type.VARIABLE, line.intValue(), col.intValue());
            return ret;
        } catch (final Exception e) {
            ErlLogger.debug(e);
            return null;
        }
    }

    /**
     * Returns syntax information about a selection
     *
     * @param f
     *            selected file
     * @param line
     *            selected line
     * @param pos
     *            selected position
     * @return syntax information
     */
    public SyntaxInfo getSyntaxInfo(final IFile f, final int line, final int pos) {
        return varToPos(parseFile(f), line, pos);
    }

    // TODO:: implement expression checking
}