/*
 * Copyright 2008 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package build.tools.spp;

import java.util.*;
import java.util.regex.*;

/*
 * Spp: A simple regex-based stream preprocessor based on Mark Reinhold's
 *      sed-based spp.sh
 *
 * Usage: java build.tools.spp.Spp [-be] [-Kkey] -Dvar=value ... <in >out
 *
 * Source-file constructs
 *
 *   Meaningful only at beginning of line, works with any number of keys:
 *
 *    #if[key]              Includes text between #if/#end if -Kkey specified,
 *    #else[key]            otherwise changes text to blank lines; key test
 *    #end[key]             may be negated by prefixing !, e.g., #if[!key]
 *
 *    #begin                If -be is specified then lines up to and including
 *    #end                  #begin, and from #end to EOF, are deleted
 *
 *    #warn                 Changed into warning that file is generated
 *
 *    // ##                 Changed into blank line
 *
 *  Meaningful anywhere in line
 *
 *    {#if[key]?yes}        Expands to yes if -Kkey specified
 *    {#if[key]?yes:no}     Expands to yes if -Kkey, otherwise no
 *    {#if[!key]?yes}       Expands to yes if -Kother
 *    {#if[!key]?yes:no}    Expands to yes if -Kother, otherwise no
 *    $var$                 Expands to value if -Dvar=value given
 *
 *    yes, no must not contain whitespace
 *
 * @author Xueming Shen
 */

public class Spp {
    public static void main(String args[]) throws Exception {
        Map<String, String> vars = new HashMap<String, String>();
        Set<String> keys = new HashSet<String>();
        boolean be = false;

        for (String arg:args) {
	    if (arg.startsWith("-D")) {
		int i = arg.indexOf('=');
		vars.put(arg.substring(2, i),arg.substring(i+1));
	    } else if (arg.startsWith("-K")) {
		keys.add(arg.substring(2));
	    } else if ("-be".equals(arg)) {
                be = true;
	    } else {
                System.err.println("Usage: java build.tools.spp.Spp [-be] [-Kkey] -Dvar=value ... <in >out");
		System.exit(-1);
	    }
	}

        StringBuffer out = new StringBuffer();
	new Spp().spp(new Scanner(System.in),
		      out, "",
		      keys, vars, be,
		      false);
        System.out.print(out.toString());
    }

    static final String LNSEP = System.getProperty("line.separator");
    static final String KEY = "([a-zA-Z0-9]+)";
    static final String VAR = "([a-zA-Z0-9_\\-]+)";
    static final String TEXT = "([a-zA-Z0-9&;,.<>/#() \\$]+)"; // $ -- hack embedded $var$

    static final int GN_NOT = 1;
    static final int GN_KEY = 2;
    static final int GN_YES = 3;
    static final int GN_NO  = 5;
    static final int GN_VAR = 6;

    Matcher ifkey = Pattern.compile("^#if\\[(!)?" + KEY + "\\]").matcher("");
    Matcher elsekey = Pattern.compile("^#else\\[(!)?" + KEY + "\\]").matcher("");
    Matcher endkey = Pattern.compile("^#end\\[(!)?" + KEY + "\\]").matcher("");
    Matcher  vardef = Pattern.compile("\\{#if\\[(!)?" + KEY + "\\]\\?" + TEXT + "(:"+ TEXT + ")?\\}|\\$" + VAR + "\\$").matcher("");
    Matcher  vardef2 = Pattern.compile("\\$" + VAR + "\\$").matcher("");

    void append(StringBuffer buf, String ln,
		Set<String> keys, Map<String, String> vars) {
	vardef.reset(ln);
	while (vardef.find()) {
            String repl = "";
	    if (vardef.group(GN_VAR) != null)
                repl = vars.get(vardef.group(GN_VAR));
	    else {
                boolean test = keys.contains(vardef.group(GN_KEY));
                if (vardef.group(GN_NOT) != null)
                    test = !test;
		repl = test?vardef.group(GN_YES):vardef.group(GN_NO);
		if (repl == null)
		    repl = "";
		else {  // embedded $var$
		    while (vardef2.reset(repl).find()) {
                        repl = vardef2.replaceFirst(vars.get(vardef2.group(1))); 
		    }
		}
	    }
	    vardef.appendReplacement(buf, repl);
	}
	vardef.appendTail(buf);
    }

    // return true if #end[key], #end or EOF reached
    boolean spp(Scanner in, StringBuffer buf, String key,
		Set<String> keys, Map<String, String> vars,
		boolean be, boolean skip) {
	while (in.hasNextLine()) {
	    String ln = in.nextLine();
	    if (be) {
	        if (ln.startsWith("#begin")) {
		    buf.setLength(0);      //clean up to this line
		    continue;
		}
	        if (ln.equals("#end")) {
                    while (in.hasNextLine())
                        in.nextLine();
		    return true;           //discard the rest to EOF
		}
	    }
	    if (ifkey.reset(ln).find()) {
                String k = ifkey.group(GN_KEY);
		boolean test = keys.contains(k);
		if (ifkey.group(GN_NOT) != null)
		    test = !test;
	        buf.append(LNSEP);
                if (!spp(in, buf, k, keys, vars, be, skip || !test)) {
		    spp(in, buf, k, keys, vars, be, skip || test);
		}
                continue;
	    }
            if (elsekey.reset(ln).find()) {
                if (!key.equals(elsekey.group(GN_KEY))) {
                    throw new Error("Mis-matched #if-else-end at line <" + ln + ">");
		}
	        buf.append(LNSEP);	      
                return false;
	    }
            if (endkey.reset(ln).find()) {
                if (!key.equals(endkey.group(GN_KEY))) {
                    throw new Error("Mis-matched #if-else-end at line <" + ln + ">");                
		}
	        buf.append(LNSEP);	      
		return true;
	    }
            if (ln.startsWith("#warn")) {
	        ln = "// -- This file was mechanically generated: Do not edit! -- //";
	    } else if (ln.trim().startsWith("// ##")) {
                ln = ""; 
	    }
            if (!skip) {
                append(buf, ln, keys, vars);
	    }
	    buf.append(LNSEP);
	}
	return true;
    }
}