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package io.vertx.codegen;

import javax.annotation.processing.Processor;
import javax.tools.DiagnosticCollector;
import javax.tools.DiagnosticListener;
import javax.tools.JavaCompiler;
import javax.tools.JavaFileObject;
import javax.tools.StandardJavaFileManager;
import javax.tools.StandardLocation;
import javax.tools.ToolProvider;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;
import java.io.Writer;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

/**
 * @author Julien Viet
 */
public class Compiler {

  private Processor processor;
  private DiagnosticListener diagnosticListener;
  private List options = new ArrayList<>();

  public Compiler(Processor processor) {
    this(processor, new DiagnosticCollector<>());
  }

  public Compiler(Processor processor, DiagnosticListener diagnosticListener) {
    this.processor = processor;
    this.diagnosticListener = diagnosticListener;
  }

  public Compiler() {
    this(null);
  }

  public Processor getProcessor() {
    return processor;
  }

  public Compiler addOption(String option) {
    options.add(option);
    return this;
  }

  public boolean compile(Class... types) throws Exception {
    return compile(Arrays.asList(types));
  }

  public boolean compile(List types) throws Exception {
    ArrayList tmpFiles = new ArrayList<>();
    for (Class type : types) {
      String className = type.getCanonicalName();
      String fileName = className.replace(".", "/") + ".java";
      ClassLoader loader = type.getClassLoader();
      InputStream is = loader.getResourceAsStream(fileName);
      if (is == null) {
        throw new IllegalStateException("Can't find source on classpath: " + fileName);
      }
      // Load the source
      String source;
      try (Scanner scanner = new Scanner(is, "UTF-8").useDelimiter("\\A")) {
        source = scanner.next();
      }
      // Now copy it to a file (this is clunky but not sure how to get around it)
      String tmpFileName = System.getProperty("java.io.tmpdir") + "/" + fileName;
      File f = new File(tmpFileName);
      File parent = f.getParentFile();
      parent.mkdirs();
      try (PrintStream out = new PrintStream(new FileOutputStream(tmpFileName))) {
        out.print(source);
      }
      tmpFiles.add(f);
    }
    return compile(tmpFiles.toArray(new File[tmpFiles.size()]));
  }

  public boolean compile(File... sourceFiles) throws Exception {
    JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
    StandardJavaFileManager fm = compiler.getStandardFileManager(diagnosticListener, null, null);
    File tmp = Files.createTempDirectory("codegen").toFile();
    tmp.deleteOnExit();
    fm.setLocation(StandardLocation.CLASS_OUTPUT, Arrays.asList(tmp));
    Iterable fileObjects = fm.getJavaFileObjects(sourceFiles);
    Writer out = new NullWriter();
    JavaCompiler.CompilationTask task = compiler.getTask(out, fm, diagnosticListener, options, null, fileObjects);
    List processors = Collections.singletonList(processor);
    task.setProcessors(processors);
    try {
      return task.call();
    } catch (RuntimeException e) {
      if (e.getCause() != null && e.getCause() instanceof RuntimeException) {
        throw (RuntimeException)e.getCause();
      } else {
        throw e;
      }
    }
  }

  private static class NullWriter extends Writer {
    @Override
    public void write(char[] cbuf, int off, int len) throws IOException {
    }

    @Override
    public void flush() throws IOException {
    }

    @Override
    public void close() throws IOException {
    }
  }

}