/*
 * Copyright 2013 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.template.soy;

import com.google.common.base.Function;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;
import com.google.inject.Injector;
import com.google.template.soy.SoyFileSet.Builder;
import com.google.template.soy.base.SoySyntaxException;
import com.google.template.soy.msgs.SoyMsgBundle;
import com.google.template.soy.msgs.SoyMsgBundleHandler;
import com.google.template.soy.msgs.SoyMsgBundleHandler.OutputFileOptions;
import com.google.template.soy.shared.internal.MainEntryPointUtils;

import org.kohsuke.args4j.Argument;
import org.kohsuke.args4j.CmdLineParser;
import org.kohsuke.args4j.Option;

import java.io.File;
import java.io.IOException;
import java.util.List;

/**
 * Executable for pruning messages from extracted msgs files, given a set of Soy files as reference
 * for which messages to keep.
 *
 */
public class SoyMsgPruner {


  /** The string to prepend to the usage message. */
  private static final String USAGE_PREFIX = "" +
      "Usage:\n" +
      "java com.google.template.soy.SoyMsgPruner  \\\n" +
      "             [<flag_1> <flag_2> ...]  \\\n" +
      "             --inputMsgFilePathFormat <formatString>  \\\n" +
      "             --outputMsgFilePathFormat <formatString>  \\\n" +
      "             --locales <locale>,... --srcs <soyFilePath>,...\n";


  @Option(
      name = "--inputPrefix",
      usage = "If provided, this path prefix will be prepended to each input file path. This is a" +
          " literal string prefix, so you'll need to include a trailing slash if necessary.")
  private String inputPrefix = "";

  @Option(
      name = "--srcs",
      usage = "[Required] The list of source Soy files.",
      handler = MainClassUtils.StringListOptionHandler.class)
  private List<String> srcs = Lists.newArrayList();

  @Option(
      name = "--allowExternalCalls",
      usage = "Whether to allow external calls. New projects should set this to false, and" +
          " existing projects should remove existing external calls and then set this to false." +
          " It will save you a lot of headaches. Currently defaults to true for backward" +
          " compatibility.",
      handler = MainClassUtils.BooleanOptionHandler.class)
  private boolean allowExternalCalls = true;

  @Option(
      name = "--locales",
      usage = "[Required] Comma-delimited list of locales.",
      handler = MainClassUtils.StringListOptionHandler.class)
  private List<String> locales = Lists.newArrayList();

  @Option(
      name = "--inputMsgFilePathFormat",
      usage = "[Required] A format string that specifies how to build the path to each translated" +
          " messages file. The format string can include literal characters as well as the" +
          " placeholders {INPUT_PREFIX}, {LOCALE}, and {LOCALE_LOWER_CASE}. Note" +
          " {LOCALE_LOWER_CASE} also turns dash into underscore, e.g. pt-BR becomes pt_br. The" +
          " format string must end with an extension matching the message file format" +
          " (case-insensitive).")
  private String inputMsgFilePathFormat = "";

  @Option(
      name = "--outputMsgFilePathFormat",
      usage = "[Required] A format string that specifies how to build the path to each pruned" +
          " output translated messages file. The format string can include literal characters as" +
          " well as the placeholders {INPUT_PREFIX}, {LOCALE}, and {LOCALE_LOWER_CASE}. Note" +
          " {LOCALE_LOWER_CASE} also turns dash into underscore, e.g. pt-BR becomes pt_br. The" +
          " format string must end with an extension matching the message file format" +
          " (case-insensitive).")
  private String outputMsgFilePathFormat = "";

  @Option(
      name = "--msgPluginModule",
      usage = "Specifies the full class name of a Guice module that binds a" +
          " BidirectionalSoyMsgPlugin.")
  private String msgPluginModule = "";

  /** The remaining arguments after parsing command-line flags. */
  @Argument
  private List<String> arguments = Lists.newArrayList();


  /**
   * Prunes messages from XTB files, given a set of Soy files as reference for which messages to
   * keep.
   *
   * @param args Should contain command-line flags and the list of paths to the Soy files.
   * @throws IOException If there are problems reading the input files or writing the output file.
   * @throws SoySyntaxException If a syntax error is detected.
   */
  public static void main(String[] args) throws IOException, SoySyntaxException {
    (new SoyMsgPruner()).execMain(args);
  }


  private SoyMsgPruner() {}


  private void execMain(String[] args) throws IOException, SoySyntaxException {

    final CmdLineParser cmdLineParser = MainClassUtils.parseFlags(this, args, USAGE_PREFIX);

    final Function<String, Void> exitWithErrorFn = new Function<String, Void>() {
      @Override public Void apply(String errorMsg) {
        MainClassUtils.exitWithError(errorMsg, cmdLineParser, USAGE_PREFIX);
        return null;
      }
    };

    if (arguments.size() > 1) {
      MainClassUtils.exitWithError(
          "Unrecognized args left on command line: \"" + arguments + "\".",
          cmdLineParser, USAGE_PREFIX);
    }

    Injector injector = MainClassUtils.createInjectorForMsgPlugin(msgPluginModule);

    // Create SoyFileSet.
    Builder sfsBuilder = injector.getInstance(Builder.class);
    MainClassUtils.addSoyFilesToBuilder(
        sfsBuilder, inputPrefix, srcs, ImmutableSet.<String>of(),
        ImmutableSet.<String>of(), ImmutableSet.<String>of(), exitWithErrorFn);
    sfsBuilder.setAllowExternalCalls(allowExternalCalls);
    SoyFileSet sfs = sfsBuilder.build();

    // Get msg bundle handler.
    SoyMsgBundleHandler msgBundleHandler = injector.getInstance(SoyMsgBundleHandler.class);

    // Main loop.
    for (String locale : locales) {

      // Get the input msg bundle.
      String inputMsgFilePath = MainEntryPointUtils.buildFilePath(
          inputMsgFilePathFormat, locale, null, inputPrefix);
      SoyMsgBundle origTransMsgBundle = msgBundleHandler.createFromFile(new File(inputMsgFilePath));
      if (origTransMsgBundle.getLocaleString() == null) {
        throw new IOException("Error opening or parsing message file " + inputMsgFilePath);
      }

      // Do the pruning.
      SoyMsgBundle prunedTransSoyMsgBundle = sfs.pruneTranslatedMsgs(origTransMsgBundle);

      // Write out the pruned msg bundle.
      String outputMsgFilePath = MainEntryPointUtils.buildFilePath(
          outputMsgFilePathFormat, locale, inputMsgFilePath, inputPrefix);
      msgBundleHandler.writeToTranslatedMsgsFile(
          prunedTransSoyMsgBundle, new OutputFileOptions(), new File(outputMsgFilePath));
    }
  }

}