/*
 * Copyright 2011 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.gwt.dev.codeserver;

import com.google.gwt.core.ext.TreeLogger;
import com.google.gwt.core.ext.UnableToCompleteException;
import com.google.gwt.thirdparty.guava.common.base.Charsets;
import com.google.gwt.thirdparty.guava.common.collect.Lists;
import com.google.gwt.thirdparty.guava.common.io.Files;

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

/**
 * Defines a directory tree used for compiling a GWT app one time. Each time we recompile
 * the app, we will create a new, empty CompileDir. This way, a failed compile doesn't
 * modify the last good compile.
 *
 * <p>The CompileDir gets created within the appropriate {@link OutboxDir} for the app
 * being compiled.
 */
public class CompileDir {
  private final File dir;

  /**
   * @see #create
   */
  public CompileDir(File dir) {
    this.dir = dir;
  }

  /**
   * Top-level directory, containing the others.
   */
  public File getRoot() {
    return dir;
  }

  /**
   * The directory tree where the compiler saves output files that should be available
   * via HTTP. It will be in a subdirectory based on the module name, possibly after
   * renaming. Files will be accessible via HTTP until a new compile finishes successfully.
   */
  public File getWarDir() {
    return new File(dir, "war");
  }

  File getDeployDir() {
    return new File(getWarDir(), "WEB-INF/deploy");
  }

  /**
   * The directory where the compiler saves auxiliary files that shouldn't be available via HTTP.
   */
  public File getExtraDir() {
    return new File(dir, "extras");
  }

  /**
   * The directory tree where the compiler saves source code created by GWT generators.
   * The source is also accessible via HTTP, for use by browser debuggers.
   */
  public File getGenDir() {
    return new File(dir, "gen");
  }

  File getWorkDir() {
    return new File(dir, "work");
  }

  /**
   * The file where the GWT compiler writes compile errors and warnings.
   * Also accessible via HTTP.
   */
  public File getLogFile() {
    return new File(dir, "compile.log");
  }

  File findSymbolMapDir(String moduleName) {
    // The JUnit module moves the symbolMaps directory in a post linker.
    // TODO(skybrian) query this information from the compiler somehow?
    File[] candidates = {
        new File(getExtraDir(), moduleName + "/symbolMaps"),
        new File(getWarDir(), moduleName + "/.junit_symbolMaps")
    };

    for (File candidate : candidates) {
      if (candidate.isDirectory()) {
        return candidate;
      }
    }

    return null;
  }

  /**
   * Reads a GWT-RPC serialization policy manifest in this directory.
   * @return a PolicyFile record for each entry in the policy file. If the policy file isn't there,
   * returns the empty list.
   * @throws java.io.IOException if the file exists but we can't read it.
   */
  List<PolicyFile> readRpcPolicyManifest(String outputModuleName) throws IOException {
    File manifest = new File(getExtraDir(), outputModuleName + "/rpcPolicyManifest/manifest.txt");
    if (!manifest.isFile()) {
      return Lists.newArrayList();
    }
    String text = Files.toString(manifest, Charsets.UTF_8);

    List<PolicyFile> result = Lists.newArrayList();

    for (String line : text.split("\n")) {
      line = line.trim();
      if (line.isEmpty() || line.startsWith("#")) {
        continue;
      }
      String[] fields = line.split(", ");
      if (fields.length < 2) {
        continue;
      }

      String serviceName = fields[0];
      String policyFileName = fields[1];
      PolicyFile policy = new PolicyFile(policyFileName, serviceName, outputModuleName);
      result.add(policy);
    }

    return result;
  }

  /**
   * Creates a new compileDir directory structure. The directory must not already exist,
   * but its parent should exist.
   * @throws UnableToCompleteException if unable to create the directory
   */
  static CompileDir create(File dir, TreeLogger logger)
      throws UnableToCompleteException {

    CompileDir result = new CompileDir(dir);

    mkdir(dir, logger);
    mkdir(result.getWarDir(), logger);

    return result;
  }

  private static void mkdir(File dirToCreate, TreeLogger logger)
      throws UnableToCompleteException {
    if (!dirToCreate.mkdir()) {
      logger.log(TreeLogger.Type.ERROR, "unable to create directory: " + dirToCreate);
      throw new UnableToCompleteException();
    }
  }

  /**
   * A record describing one GWT-RPC serialization policy file.
   */
  static class PolicyFile {
    private final String name;
    private final String serviceName;
    private final String outputModuleName;

    /**
     * Creates a record.
     * @param name A filename in the format "{strong name}.gwt.rpc".
     * @param serviceName The name of a Java interface that extends RemoteService.
     * @param outputModuleName The module that contains the service.
     */
    PolicyFile(String name, String serviceName, String outputModuleName) {
      this.name = name;
      this.serviceName = serviceName;
      this.outputModuleName = outputModuleName;
    }

    /**
     * Returns the name of the policy file.
     * This looks like "{strong name}.gwt.rpc".
     */
    String getName() {
      return name;
    }

    /**
     * Returns the URL of the policy file itself.
     * (This is a site-relative URL like "/policies/{strong name}.gwt.rpc".)
     */
    String getUrl() {
      return "/policies/" + name;
    }

    /**
     * Returns the name of the Java interface that extends RemoteService.
     */
    String getServiceName() {
      return serviceName;
    }

    /**
     * Returns the URL to the Java source code for the Java interface.
     * (This is a site-relative URL like "/sourcemaps/{module name}/path/to/JavaFile.java".)
     */
    String getServiceSourceUrl() {
      return SourceHandler.SOURCEMAP_PATH + outputModuleName + "/" +
          serviceName.replace('.', '/') + ".java";
    }
  }
}