/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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 org.apache.maven.toolchain.building;
  
  import javax.inject.Inject;
  import javax.inject.Named;
  import javax.inject.Singleton;
  
  import java.io.IOException;
  import java.io.StringReader;
  import java.io.StringWriter;
  import java.util.Collections;
  import java.util.List;
  import java.util.Map;
  
  import org.apache.maven.building.Problem;
  import org.apache.maven.building.ProblemCollector;
  import org.apache.maven.building.ProblemCollectorFactory;
  import org.apache.maven.building.Source;
  import org.apache.maven.toolchain.io.ToolchainsParseException;
  import org.apache.maven.toolchain.io.ToolchainsReader;
  import org.apache.maven.toolchain.io.ToolchainsWriter;
  import org.apache.maven.toolchain.merge.MavenToolchainMerger;
  import org.apache.maven.toolchain.model.PersistedToolchains;
  import org.apache.maven.toolchain.model.TrackableBase;
  import org.codehaus.plexus.interpolation.EnvarBasedValueSource;
  import org.codehaus.plexus.interpolation.InterpolationException;
  import org.codehaus.plexus.interpolation.RegexBasedInterpolator;
  
  /**
   *
   * @author Robert Scholte
   * @since 3.3.0
   */
  @Named
  @Singleton
  public class DefaultToolchainsBuilder implements ToolchainsBuilder {
      private final MavenToolchainMerger toolchainsMerger = new MavenToolchainMerger();
      private final ToolchainsWriter toolchainsWriter;
      private final ToolchainsReader toolchainsReader;
  
      @Inject
      public DefaultToolchainsBuilder(ToolchainsWriter toolchainsWriter, ToolchainsReader toolchainsReader) {
          this.toolchainsWriter = toolchainsWriter;
          this.toolchainsReader = toolchainsReader;
      }
  
      @Override
      public ToolchainsBuildingResult build(ToolchainsBuildingRequest request) throws ToolchainsBuildingException {
          ProblemCollector problems = ProblemCollectorFactory.newInstance(null);
  
          PersistedToolchains globalToolchains = readToolchains(request.getGlobalToolchainsSource(), request, problems);
  
          PersistedToolchains userToolchains = readToolchains(request.getUserToolchainsSource(), request, problems);
  
          toolchainsMerger.merge(userToolchains, globalToolchains, TrackableBase.GLOBAL_LEVEL);
  
          problems.setSource("");
  
          userToolchains = interpolate(userToolchains, problems);
  
          if (hasErrors(problems.getProblems())) {
              throw new ToolchainsBuildingException(problems.getProblems());
          }
  
          return new DefaultToolchainsBuildingResult(userToolchains, problems.getProblems());
      }
  
      private PersistedToolchains interpolate(PersistedToolchains toolchains, ProblemCollector problems) {
  
          StringWriter stringWriter = new StringWriter(1024 * 4);
          try {
              toolchainsWriter.write(stringWriter, null, toolchains);
          } catch (IOException e) {
              throw new IllegalStateException("Failed to serialize toolchains to memory", e);
          }
  
          String serializedToolchains = stringWriter.toString();
  
          RegexBasedInterpolator interpolator = new RegexBasedInterpolator();
  
          try {
              interpolator.addValueSource(new EnvarBasedValueSource());
         } catch (IOException e) {
             problems.add(
                     Problem.Severity.WARNING,
                     "Failed to use environment variables for interpolation: " + e.getMessage(),
                     -1,
                     -1,
                     e);
         }
 
         interpolator.addPostProcessor((expression, value) -> {
             if (value != null) {
                 // we're going to parse this back in as XML so we need to escape XML markup
                 value = value.toString()
                         .replace("&", "&")
                         .replace("<", "&lt;")
                         .replace(">", "&gt;");
                 return value;
             }
             return null;
         });
 
         try {
             serializedToolchains = interpolator.interpolate(serializedToolchains);
         } catch (InterpolationException e) {
             problems.add(Problem.Severity.ERROR, "Failed to interpolate toolchains: " + e.getMessage(), -1, -1, e);
             return toolchains;
         }
 
         PersistedToolchains result;
         try {
             Map<String, ?> options = Collections.singletonMap(ToolchainsReader.IS_STRICT, Boolean.FALSE);
 
             result = toolchainsReader.read(new StringReader(serializedToolchains), options);
         } catch (IOException e) {
             problems.add(Problem.Severity.ERROR, "Failed to interpolate toolchains: " + e.getMessage(), -1, -1, e);
             return toolchains;
         }
 
         return result;
     }
 
     private PersistedToolchains readToolchains(
             Source toolchainsSource, ToolchainsBuildingRequest request, ProblemCollector problems) {
         if (toolchainsSource == null) {
             return new PersistedToolchains();
         }
 
         PersistedToolchains toolchains;
 
         try {
             Map<String, ?> options = Collections.singletonMap(ToolchainsReader.IS_STRICT, Boolean.TRUE);
 
             try {
                 toolchains = toolchainsReader.read(toolchainsSource.getInputStream(), options);
             } catch (ToolchainsParseException e) {
                 options = Collections.singletonMap(ToolchainsReader.IS_STRICT, Boolean.FALSE);
 
                 toolchains = toolchainsReader.read(toolchainsSource.getInputStream(), options);
 
                 problems.add(Problem.Severity.WARNING, e.getMessage(), e.getLineNumber(), e.getColumnNumber(), e);
             }
         } catch (ToolchainsParseException e) {
             problems.add(
                     Problem.Severity.FATAL,
                     "Non-parseable toolchains " + toolchainsSource.getLocation() + ": " + e.getMessage(),
                     e.getLineNumber(),
                     e.getColumnNumber(),
                     e);
             return new PersistedToolchains();
         } catch (IOException e) {
             problems.add(
                     Problem.Severity.FATAL,
                     "Non-readable toolchains " + toolchainsSource.getLocation() + ": " + e.getMessage(),
                     -1,
                     -1,
                     e);
             return new PersistedToolchains();
         }
 
         return toolchains;
     }
 
     private boolean hasErrors(List<Problem> problems) {
         if (problems != null) {
             for (Problem problem : problems) {
                 if (Problem.Severity.ERROR.compareTo(problem.getSeverity()) >= 0) {
                     return true;
                 }
             }
         }
 
         return false;
     }
 }