//
// $Id$
//
// Narya library - tools for developing networked games
// Copyright (C) 2002-2004 Three Rings Design, Inc., All Rights Reserved
// http://www.threerings.net/code/narya/
//
// This library is free software; you can redistribute it and/or modify it
// under the terms of the GNU Lesser General Public License as published
// by the Free Software Foundation; either version 2.1 of the License, or
// (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

package com.threerings.presents.tools;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.StringWriter;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;

import java.util.regex.Pattern;
import java.util.regex.Matcher;

import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang.StringUtils;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.DirectoryScanner;
import org.apache.tools.ant.Task;
import org.apache.tools.ant.types.FileSet;
import org.apache.tools.ant.types.Reference;
import org.apache.tools.ant.util.ClasspathUtils;

import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.VelocityEngine;

import com.samskivert.util.ObjectUtil;
import com.samskivert.util.SortableArrayList;
import com.samskivert.util.StringUtil;
import com.samskivert.velocity.VelocityUtil;

import com.threerings.presents.dobj.DObject;
import com.threerings.presents.dobj.DSet;
import com.threerings.presents.dobj.OidList;

/**
 * Generates necessary additional distributed object declarations and
 * methods.
 */
public class GenDObjectTask extends Task
{
    /**
     * Adds a nested <fileset> element which enumerates service
     * declaration source files.
     */
    public void addFileset (FileSet set)
    {
        _filesets.add(set);
    }

    /** Configures our classpath which we'll use to load service classes. */
    public void setClasspathref (Reference pathref)
    {
        _cloader = ClasspathUtils.getClassLoaderForPath(
            getProject(), pathref);
    }

    /** Performs the actual work of the task. */
    public void execute () throws BuildException
    {
        if (_cloader == null) {
            String errmsg = "This task requires a 'classpathref' attribute " +
                "to be set to the project's classpath.";
            throw new BuildException(errmsg);
        }

        try {
            _velocity = VelocityUtil.createEngine();
        } catch (Exception e) {
            throw new BuildException("Failure initializing Velocity", e);
        }

        // resolve the DObject class using our classloader
        try {
            _doclass = _cloader.loadClass(DObject.class.getName());
            _dsclass = _cloader.loadClass(DSet.class.getName());
            _olclass = _cloader.loadClass(OidList.class.getName());
        } catch (Exception e) {
            throw new BuildException("Can't resolve InvocationListener", e);
        }

        ArrayList files = new ArrayList();
        for (Iterator iter = _filesets.iterator(); iter.hasNext(); ) {
            FileSet fs = (FileSet)iter.next();
            DirectoryScanner ds = fs.getDirectoryScanner(getProject());
            File fromDir = fs.getDir(getProject());
            String[] srcFiles = ds.getIncludedFiles();
            for (int f = 0; f < srcFiles.length; f++) {
                processObject(new File(fromDir, srcFiles[f]));
            }
        }
    }

    /** Processes a distributed object source file. */
    protected void processObject (File source)
    {
        // System.err.println("Processing " + source + "...");
        // load up the file and determine it's package and classname
        String name = null;
        try {
            name = GenUtil.readClassName(source);
        } catch (Exception e) {
            System.err.println(
                "Failed to parse " + source + ": " + e.getMessage());
        }

        try {
            processObject(source, _cloader.loadClass(name));
        } catch (ClassNotFoundException cnfe) {
            System.err.println(
                "Failed to load " + name + ".\n" +
                "Missing class: " + cnfe.getMessage());
            System.err.println(
                "Be sure to set the 'classpathref' attribute to a classpath\n" +
                "that contains your projects invocation service classes.");
        } catch (Exception e) {
            e.printStackTrace(System.err);
        }
    }

    /** Processes a resolved distributed object class instance. */
    protected void processObject (File source, Class oclass)
    {
        // make sure we extend distributed object
        if (!_doclass.isAssignableFrom(oclass) || _doclass.equals(oclass)) {
            // System.err.println("Skipping " + oclass.getName() + "...");
            return;
        }

        // determine which fields we need to deal with
        ArrayList flist = new ArrayList();
        Field[] fields = oclass.getDeclaredFields();
        for (int ii = 0; ii < fields.length; ii++) {
            Field f = fields[ii];
            int mods = f.getModifiers();
            if (!Modifier.isPublic(mods) ||
                Modifier.isStatic(mods) ||
                Modifier.isTransient(mods)) {
                continue;
            }
            flist.add(f);
        }

        // slurp our source file into newline separated strings
        String[] lines = null;
        try {
            BufferedReader bin = new BufferedReader(new FileReader(source));
            ArrayList llist = new ArrayList();
            String line = null;
            while ((line = bin.readLine()) != null) {
                llist.add(line);
            }
            lines = (String[])llist.toArray(new String[llist.size()]);
            bin.close();
        } catch (IOException ioe) {
            System.err.println("Error reading '" + source + "': " + ioe);
            return;
        }

        // now determine where to insert our static field declarations and
        // our generated methods
        int bstart = -1, bend = -1;
        int nstart = -1, nend = -1;
        int mstart = -1, mend = -1;
        for (int ii = 0; ii < lines.length; ii++) {
            String line = lines[ii].trim();

            // look for the start of the class body
            if (GenUtil.NAME_PATTERN.matcher(line).find()) {
                if (line.endsWith("{")) {
                    bstart = ii+1;
                } else {
                    // search down a few lines for the open brace
                    for (int oo = 1; oo < 10; oo++) {
                        if (get(lines, ii+oo).trim().endsWith("{")) {
                            bstart = ii+oo+1;
                            break;
                        }
                    }
                }

            // track the last } on a line by itself and we'll call that
            // the end of the class body
            } else if (line.equals("}")) {
                bend = ii;

            // look for our field and method markers
            } else if (line.equals(FIELDS_START)) {
                nstart = ii;
            } else if (line.equals(FIELDS_END)) {
                nend = ii+1;
            } else if (line.equals(METHODS_START)) {
                mstart = ii;
            } else if (line.equals(METHODS_END)) {
                mend = ii+1;
            }
        }

        // sanity check the markers
        if (check(source, "fields start", nstart, "fields end", nend) ||
            check(source, "fields end", nend, "fields start", nstart) ||
            check(source, "methods start", mstart, "methods end", mend) ||
            check(source, "methods end", mend, "methods start", mstart)) {
            return;
        }

        // we have no previous markers then stuff the fields at the top of
        // the class body and the methods at the bottom
        if (nstart == -1) {
            nstart = bstart;
            nend = bstart;
        }
        if (mstart == -1) {
            mstart = bend;
            mend = bend;
        }

        // generate our fields section and our methods section
        StringBuffer fsection = new StringBuffer();
        StringBuffer msection = new StringBuffer();
        for (int ii = 0; ii < flist.size(); ii++) {
            Field f = (Field)flist.get(ii);
            Class ftype = f.getType();
            String fname = f.getName();

            // create our velocity context
            VelocityContext ctx = new VelocityContext();
            ctx.put("field", fname);
            ctx.put("type", GenUtil.simpleName(ftype));
            ctx.put("wrapfield", GenUtil.boxArgument(ftype, "value"));
            ctx.put("wrapofield", GenUtil.boxArgument(ftype, "ovalue"));
            ctx.put("clonefield",
                    GenUtil.cloneArgument(_dsclass, ftype, "value"));
            ctx.put("capfield", StringUtil.unStudlyName(fname).toUpperCase());
            ctx.put("upfield", StringUtils.capitalize(fname));
            if (ftype.isArray()) {
                Class etype = ftype.getComponentType();
                ctx.put("elemtype", GenUtil.simpleName(etype));
                ctx.put("wrapelem", GenUtil.boxArgument(etype, "value"));
                ctx.put("wrapoelem", GenUtil.boxArgument(etype, "ovalue"));
            }

            // now figure out which template to use
            String tname = "field.tmpl";
            if (_dsclass.isAssignableFrom(ftype)) {
                tname = "set.tmpl";
            } else if (_olclass.isAssignableFrom(ftype)) {
                tname = "oidlist.tmpl";
            }

            // now generate our bits
            StringWriter fwriter = new StringWriter();
            StringWriter mwriter = new StringWriter();
            try {
                _velocity.mergeTemplate(NAME_TMPL, "UTF-8", ctx, fwriter);
                _velocity.mergeTemplate(
                    BASE_TMPL + tname, "UTF-8", ctx, mwriter);
            } catch (Exception e) {
                System.err.println("Failed processing template");
                e.printStackTrace(System.err);
            }

            // and append them as appropriate to the string buffers
            if (ii > 0) {
                fsection.append("\n");
                msection.append("\n");
            }
            fsection.append(fwriter.toString());
            msection.append(mwriter.toString());
        }

        // now bolt everything back together into a class declaration
        try {
            BufferedWriter bout = new BufferedWriter(new FileWriter(source));
            for (int ii = 0; ii < nstart; ii++) {
                writeln(bout, lines[ii]);
            }
            if (fsection.length() > 0) {
                String prev = get(lines, nstart-1);
                if (!StringUtil.blank(prev) && !prev.equals("{")) {
                    bout.newLine();
                }
                writeln(bout, "    " + FIELDS_START);
                bout.write(fsection.toString());
                writeln(bout, "    " + FIELDS_END);
                if (!StringUtil.blank(get(lines, nend))) {
                    bout.newLine();
                }
            }
            for (int ii = nend; ii < mstart; ii++) {
                writeln(bout, lines[ii]);
            }

            if (msection.length() > 0) {
                if (!StringUtil.blank(get(lines, mstart-1))) {
                    bout.newLine();
                }
                writeln(bout, "    " + METHODS_START);
                bout.write(msection.toString());
                writeln(bout, "    " + METHODS_END);
                String next = get(lines, mend);
                if (!StringUtil.blank(next) && !next.equals("}")) {
                    bout.newLine();
                }
            }
            for (int ii = mend; ii < lines.length; ii++) {
                writeln(bout, lines[ii]);
            }
            bout.close();
        } catch (IOException ioe) {
            System.err.println("Error writing to '" + source + "': " + ioe);
        }
    }

    /** Safely gets the <code>index</code>th line, returning the empty
     * string if we exceed the length of the array. */
    protected String get (String[] lines, int index)
    {
        return (index < lines.length) ? lines[index] : "";
    }

    /** Helper function for sanity checking marker existence. */
    protected boolean check (File source, String mname, int mline,
                             String fname, int fline)
    {
        if (mline == -1 && fline != -1) {
            System.err.println("Found " + fname + " marker (at line " +
                               (fline+1) + ") but no " + mname +
                               " marker in '" + source + "'.");
            return true;
        }
        return false;
    }

    /** Helper function for writing a string and a newline to a writer. */
    protected void writeln (BufferedWriter bout, String line)
        throws IOException
    {
        bout.write(line);
        bout.newLine();
    }

    /** A list of filesets that contain tile images. */
    protected ArrayList _filesets = new ArrayList();

    /** Used to do our own classpath business. */
    protected ClassLoader _cloader;

    /** Used to generate source files from templates. */
    protected VelocityEngine _velocity;

    /** {@link DObject} resolved with the proper classloader so that we
     * can compare it to loaded derived classes. */
    protected Class _doclass;

    /** {@link DSet} resolved with the proper classloader so that we can
     * compare it to loaded derived classes. */
    protected Class _dsclass;

    /** {@link OidList} resolved with the proper classloader so that we
     * can compare it to loaded derived classes. */
    protected Class _olclass;

    /** Specifies the start of the path to our various templates. */
    protected static final String BASE_TMPL =
        "com/threerings/presents/tools/dobject_";

    /** Specifies the path to the name code template. */
    protected static final String NAME_TMPL = BASE_TMPL + "name.tmpl";

    // markers
    protected static final String MARKER = "// AUTO-GENERATED: ";
    protected static final String FIELDS_START = MARKER + "FIELDS START";
    protected static final String FIELDS_END = MARKER + "FIELDS END";
    protected static final String METHODS_START = MARKER + "METHODS START";
    protected static final String METHODS_END = MARKER + "METHODS END";
}