// Copyright (c) 2019, the R8 project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

package com.android.tools.r8.retrace;

import static com.android.tools.r8.retrace.RetraceUtils.methodDescriptionFromMethodReference;
import static com.google.common.base.Predicates.not;

import com.android.tools.r8.DiagnosticsHandler;
import com.android.tools.r8.references.ClassReference;
import com.android.tools.r8.references.MethodReference;
import com.android.tools.r8.references.Reference;
import com.android.tools.r8.utils.DescriptorUtils;
import com.android.tools.r8.utils.StringUtils;
import com.google.common.collect.ImmutableList;
import java.util.ArrayList;
import java.util.List;
import java.util.function.Predicate;

public final class RetraceStackTrace {

  public static class StackTraceNode {

    private final List<StackTraceLine> lines;

    StackTraceNode(List<StackTraceLine> lines) {
      this.lines = lines;
      assert !lines.isEmpty();
      assert lines.size() == 1 || lines.stream().allMatch(StackTraceLine::isAtLine);
    }

    public void append(List<String> strings) {
      assert !lines.isEmpty();
      if (lines.size() == 1) {
        strings.add(lines.get(0).toString());
        return;
      }
      // We must have an inlining or ambiguous match here, thus all lines are at-lines.
      assert lines.stream().allMatch(StackTraceLine::isAtLine);
      assert lines.stream()
          .allMatch(line -> line.asAtLine().isAmbiguous == lines.get(0).asAtLine().isAmbiguous);
      if (lines.get(0).asAtLine().isAmbiguous) {
        lines.sort(new AtStackTraceLineComparator());
      }
      boolean shouldPrintOr = false;
      for (StackTraceLine line : lines) {
        assert line.isAtLine();
        AtLine atLine = line.asAtLine();
        if (atLine.isAmbiguous && shouldPrintOr) {
          String atLineString = atLine.toString();
          int firstNonWhitespaceCharacter = StringUtils.firstNonWhitespaceCharacter(atLineString);
          strings.add(
              atLineString.substring(0, firstNonWhitespaceCharacter)
                  + "<OR> "
                  + atLineString.substring(firstNonWhitespaceCharacter));
        } else {
          strings.add(atLine.toString());
        }
        shouldPrintOr = true;
      }
    }
  }

  static class AtStackTraceLineComparator extends AmbiguousComparator<StackTraceLine> {

    AtStackTraceLineComparator() {
      super(
          (line, t) -> {
            assert line.isAtLine();
            AtLine atLine = line.asAtLine();
            switch (t) {
              case CLASS:
                return atLine.clazz;
              case METHOD:
                return atLine.method;
              case SOURCE:
                return atLine.fileName;
              case LINE:
                return atLine.linePosition + "";
              default:
                assert false;
            }
            throw new RuntimeException("Comparator key is unknown");
          });
    }
  }

  private final RetraceApi retracer;
  private final List<String> stackTrace;
  private final DiagnosticsHandler diagnosticsHandler;
  private final boolean verbose;

  RetraceStackTrace(
      RetraceApi retracer,
      List<String> stackTrace,
      DiagnosticsHandler diagnosticsHandler,
      boolean verbose) {
    this.retracer = retracer;
    this.stackTrace = stackTrace;
    this.diagnosticsHandler = diagnosticsHandler;
    this.verbose = verbose;
  }

  public RetraceCommandLineResult retrace() {
    ArrayList<StackTraceNode> result = new ArrayList<>();
    retraceLine(stackTrace, 0, result);
    List<String> retracedStrings = new ArrayList<>();
    for (StackTraceNode node : result) {
      node.append(retracedStrings);
    }
    return new RetraceCommandLineResult(retracedStrings);
  }

  private void retraceLine(List<String> stackTrace, int index, List<StackTraceNode> result) {
    if (stackTrace.size() <= index) {
      return;
    }
    StackTraceLine stackTraceLine = parseLine(index + 1, stackTrace.get(index));
    List<StackTraceLine> retraced = stackTraceLine.retrace(retracer, verbose);
    StackTraceNode node = new StackTraceNode(retraced);
    result.add(node);
    retraceLine(stackTrace, index + 1, result);
  }

  abstract static class StackTraceLine {

    abstract List<StackTraceLine> retrace(RetraceApi retracer, boolean verbose);

    static int firstNonWhiteSpaceCharacterFromIndex(String line, int index) {
      return firstFromIndex(line, index, not(Character::isWhitespace));
    }

    static int firstCharFromIndex(String line, int index, char ch) {
      return firstFromIndex(line, index, c -> c == ch);
    }

    static int firstFromIndex(String line, int index, Predicate<Character> predicate) {
      for (int i = index; i < line.length(); i++) {
        if (predicate.test(line.charAt(i))) {
          return i;
        }
      }
      return line.length();
    }

    boolean isAtLine() {
      return false;
    }

    AtLine asAtLine() {
      return null;
    }

    boolean isExceptionLine() {
      return false;
    }

    ExceptionLine asExceptionLine() {
      return null;
    }
  }

  /**
   * Captures a stack trace line of the following formats:
   *
   * <ul>
   *   <li>com.android.r8.R8Exception
   *   <li>com.android.r8.R8Exception: Problem when compiling program
   *   <li>Caused by: com.android.r8.R8InnerException: You have to write the program first
   *   <li>com.android.r8.R8InnerException: You have to write the program first
   * </ul>
   *
   * <p>This will also contains false positives, such as
   *
   * <pre>
   *   W( 8207) VFY: unable to resolve static method 11: Lprivateinterfacemethods/I$-CC;....
   * </pre>
   *
   * <p>The only invalid chars for type-identifiers for a java type-name is ';', '[' and '/', so we
   * cannot really disregard the above line.
   *
   * <p>Caused by and Suppressed seems to not change based on locale, so we use these as markers.
   */
  static class ExceptionLine extends StackTraceLine {

    private static final String CAUSED_BY = "Caused by: ";
    private static final String SUPPRESSED = "Suppressed: ";

    private final String initialWhiteSpace;
    private final String description;
    private final String exceptionClass;
    private final String message;

    ExceptionLine(
        String initialWhiteSpace, String description, String exceptionClass, String message) {
      this.initialWhiteSpace = initialWhiteSpace;
      this.description = description;
      this.exceptionClass = exceptionClass;
      this.message = message;
    }

    static ExceptionLine tryParse(String line) {
      if (line.isEmpty()) {
        return null;
      }
      int firstNonWhiteSpaceChar = firstNonWhiteSpaceCharacterFromIndex(line, 0);
      String description = "";
      if (line.startsWith(CAUSED_BY, firstNonWhiteSpaceChar)) {
        description = CAUSED_BY;
      } else if (line.startsWith(SUPPRESSED, firstNonWhiteSpaceChar)) {
        description = SUPPRESSED;
      }
      int exceptionStartIndex = firstNonWhiteSpaceChar + description.length();
      int messageStartIndex = firstCharFromIndex(line, exceptionStartIndex, ':');
      String className = line.substring(exceptionStartIndex, messageStartIndex);
      if (!DescriptorUtils.isValidJavaType(className)) {
        return null;
      }
      return new ExceptionLine(
          line.substring(0, firstNonWhiteSpaceChar),
          description,
          className,
          line.substring(messageStartIndex));
    }

    @Override
    List<StackTraceLine> retrace(RetraceApi retracer, boolean verbose) {
      List<StackTraceLine> exceptionLines = new ArrayList<>();
      retracer
          .retrace(Reference.classFromTypeName(exceptionClass))
          .forEach(
              element ->
                  exceptionLines.add(
                      new ExceptionLine(
                          initialWhiteSpace,
                          description,
                          element.getClassReference().getTypeName(),
                          message)));
      return exceptionLines;
    }

    @Override
    public String toString() {
      return initialWhiteSpace + description + exceptionClass + message;
    }

    @Override
    boolean isExceptionLine() {
      return true;
    }

    @Override
    ExceptionLine asExceptionLine() {
      return this;
    }
  }

  /**
   * Captures a stack trace line on the following form
   *
   * <ul>
   *   <li>at dalvik.system.NativeStart.main(NativeStart.java:99)
   *   <li>at dalvik.system.NativeStart.main(:99)
   *   <li>at dalvik.system.NativeStart.main(Foo.java:)
   *   <li>at dalvik.system.NativeStart.main(Native Method)
   *   <li>at classloader/named_module@version/foo.bar.baz(:20)
   *   <li>at classloader//foo.bar.baz(:20)
   * </ul>
   *
   * <p>Empirical evidence suggests that the "at" string is never localized.
   */
  static class AtLine extends StackTraceLine {

    private static final int NO_POSITION = -2;
    private static final int INVALID_POSITION = -1;

    private final String startingWhitespace;
    private final String at;
    private final String classLoaderName;
    private final String moduleName;
    private final String clazz;
    private final String method;
    private final String methodAsString;
    private final String fileName;
    private final int linePosition;
    private final boolean isAmbiguous;

    private AtLine(
        String startingWhitespace,
        String at,
        String classLoaderName,
        String moduleName,
        String clazz,
        String method,
        String methodAsString,
        String fileName,
        int linePosition,
        boolean isAmbiguous) {
      this.startingWhitespace = startingWhitespace;
      this.at = at;
      this.classLoaderName = classLoaderName;
      this.moduleName = moduleName;
      this.clazz = clazz;
      this.method = method;
      this.methodAsString = methodAsString;
      this.fileName = fileName;
      this.linePosition = linePosition;
      this.isAmbiguous = isAmbiguous;
    }

    static AtLine tryParse(String line) {
      // Check that the line is indented with some amount of white space.
      if (line.length() == 0 || !Character.isWhitespace(line.charAt(0))) {
        return null;
      }
      // Find the first non-white space character and check that we have the sequence 'a', 't', ' '.
      int firstNonWhiteSpace = firstNonWhiteSpaceCharacterFromIndex(line, 0);
      if (firstNonWhiteSpace + 2 >= line.length()
          || line.charAt(firstNonWhiteSpace) != 'a'
          || line.charAt(firstNonWhiteSpace + 1) != 't'
          || line.charAt(firstNonWhiteSpace + 2) != ' ') {
        return null;
      }
      int classClassLoaderOrModuleStartIndex =
          firstNonWhiteSpaceCharacterFromIndex(line, firstNonWhiteSpace + 2);
      if (classClassLoaderOrModuleStartIndex >= line.length()
          || classClassLoaderOrModuleStartIndex != firstNonWhiteSpace + 3) {
        return null;
      }
      int parensStart = firstCharFromIndex(line, classClassLoaderOrModuleStartIndex, '(');
      if (parensStart >= line.length()) {
        return null;
      }
      int parensEnd = firstCharFromIndex(line, parensStart, ')');
      if (parensEnd >= line.length()) {
        return null;
      }
      if (firstNonWhiteSpaceCharacterFromIndex(line, parensEnd) == line.length()) {
        return null;
      }
      int methodSeparator = line.lastIndexOf('.', parensStart);
      if (methodSeparator <= classClassLoaderOrModuleStartIndex) {
        return null;
      }
      // Check if we have a filename and position.
      String fileName = "";
      int position = NO_POSITION;
      int separatorIndex = firstCharFromIndex(line, parensStart, ':');
      if (separatorIndex < parensEnd) {
        fileName = line.substring(parensStart + 1, separatorIndex);
        try {
          String positionAsString = line.substring(separatorIndex + 1, parensEnd);
          position = Integer.parseInt(positionAsString);
        } catch (NumberFormatException e) {
          position = INVALID_POSITION;
        }
      } else {
        fileName = line.substring(parensStart + 1, parensEnd);
      }
      String classLoaderName = null;
      String moduleName = null;
      int classStartIndex = classClassLoaderOrModuleStartIndex;
      int classLoaderOrModuleEndIndex =
          firstCharFromIndex(line, classClassLoaderOrModuleStartIndex, '/');
      if (classLoaderOrModuleEndIndex < methodSeparator) {
        int moduleEndIndex = firstCharFromIndex(line, classLoaderOrModuleEndIndex + 1, '/');
        if (moduleEndIndex < methodSeparator) {
          // The stack trace contains both a class loader and module
          classLoaderName =
              line.substring(classClassLoaderOrModuleStartIndex, classLoaderOrModuleEndIndex);
          moduleName = line.substring(classLoaderOrModuleEndIndex + 1, moduleEndIndex);
          classStartIndex = moduleEndIndex + 1;
        } else {
          moduleName =
              line.substring(classClassLoaderOrModuleStartIndex, classLoaderOrModuleEndIndex);
          classStartIndex = classLoaderOrModuleEndIndex + 1;
        }
      }
      String className = line.substring(classStartIndex, methodSeparator);
      String methodName = line.substring(methodSeparator + 1, parensStart);
      return new AtLine(
          line.substring(0, firstNonWhiteSpace),
          line.substring(firstNonWhiteSpace, classClassLoaderOrModuleStartIndex),
          classLoaderName,
          moduleName,
          className,
          methodName,
          className + "." + methodName,
          fileName,
          position,
          false);
    }

    private boolean hasLinePosition() {
      return linePosition > -1;
    }

    @Override
    List<StackTraceLine> retrace(RetraceApi retracer, boolean verbose) {
      List<StackTraceLine> lines = new ArrayList<>();
      String retraceClassLoaderName = classLoaderName;
      if (retraceClassLoaderName != null) {
        ClassReference classLoaderReference = Reference.classFromTypeName(retraceClassLoaderName);
        retracer
            .retrace(classLoaderReference)
            .forEach(
                classElement -> {
                  retraceClassAndMethods(
                      retracer, verbose, lines, classElement.getClassReference().getTypeName());
                });
      } else {
        retraceClassAndMethods(retracer, verbose, lines, retraceClassLoaderName);
      }
      return lines;
    }

    private void retraceClassAndMethods(
        RetraceApi retracer, boolean verbose, List<StackTraceLine> lines, String classLoaderName) {
      ClassReference classReference = Reference.classFromTypeName(clazz);
      RetraceClassResult classResult = retracer.retrace(classReference);
      RetraceMethodResult retraceResult = classResult.lookupMethod(method);
      if (linePosition != NO_POSITION && linePosition != INVALID_POSITION) {
        retraceResult = retraceResult.narrowByLine(linePosition);
      }
      retraceResult.forEach(
          methodElement -> {
            MethodReference methodReference = methodElement.getMethodReference();
            lines.add(
                new AtLine(
                    startingWhitespace,
                    at,
                    classLoaderName,
                    moduleName,
                    methodReference.getHolderClass().getTypeName(),
                    methodReference.getMethodName(),
                    methodDescriptionFromMethodReference(methodReference, true, verbose),
                    methodElement.retraceSourceFile(fileName).getFilename(),
                    hasLinePosition()
                        ? methodElement.getOriginalLineNumber(linePosition)
                        : linePosition,
                    methodElement.getRetraceMethodResult().isAmbiguous()));
          });
    }

    @Override
    public String toString() {
      StringBuilder sb = new StringBuilder(startingWhitespace);
      sb.append(at);
      if (classLoaderName != null) {
        sb.append(classLoaderName);
        sb.append("/");
      }
      if (moduleName != null) {
        sb.append(moduleName);
        sb.append("/");
      }
      sb.append(methodAsString);
      sb.append("(");
      sb.append(fileName);
      if (linePosition != NO_POSITION) {
        sb.append(":");
      }
      if (linePosition > INVALID_POSITION) {
        sb.append(linePosition);
      }
      sb.append(")");
      return sb.toString();
    }

    @Override
    boolean isAtLine() {
      return true;
    }

    @Override
    AtLine asAtLine() {
      return this;
    }
  }

  static class MoreLine extends StackTraceLine {
    private final String line;

    MoreLine(String line) {
      this.line = line;
    }

    static StackTraceLine tryParse(String line) {
      int dotsSeen = 0;
      boolean isWhiteSpaceAllowed = true;
      for (int i = 0; i < line.length(); i++) {
        char ch = line.charAt(i);
        if (Character.isWhitespace(ch) && isWhiteSpaceAllowed) {
          continue;
        }
        isWhiteSpaceAllowed = false;
        if (ch != '.') {
          return null;
        }
        if (++dotsSeen == 3) {
          return new MoreLine(line);
        }
      }
      return null;
    }

    @Override
    List<StackTraceLine> retrace(RetraceApi retracer, boolean verbose) {
      return ImmutableList.of(new MoreLine(line));
    }

    @Override
    public String toString() {
      return line;
    }
  }

  static class CircularReferenceLine extends StackTraceLine {

    private final String startWhitespace;
    private final String exceptionClass;
    private final String endBracketAndWhitespace;

    private static final String CIRCULAR_REFERENCE = "[CIRCULAR REFERENCE:";

    public CircularReferenceLine(
        String startWhitespace, String exceptionClass, String endBracketAndWhitespace) {
      this.startWhitespace = startWhitespace;
      this.exceptionClass = exceptionClass;
      this.endBracketAndWhitespace = endBracketAndWhitespace;
    }

    static StackTraceLine tryParse(String line) {
      // Check that the line is indented with some amount of white space.
      if (line.length() == 0 || !Character.isWhitespace(line.charAt(0))) {
        return null;
      }
      // Find the first non-white space character and check that we have the sequence
      // '[CIRCULAR REFERENCE:Exception]'.
      int firstNonWhiteSpace = firstNonWhiteSpaceCharacterFromIndex(line, 0);
      if (!line.startsWith(CIRCULAR_REFERENCE, firstNonWhiteSpace)) {
        return null;
      }
      int exceptionStartIndex = firstNonWhiteSpace + CIRCULAR_REFERENCE.length();
      int lastBracketPosition = firstCharFromIndex(line, exceptionStartIndex, ']');
      if (lastBracketPosition == line.length()) {
        return null;
      }
      int onlyWhitespaceFromLastBracket =
          firstNonWhiteSpaceCharacterFromIndex(line, lastBracketPosition + 1);
      if (onlyWhitespaceFromLastBracket != line.length()) {
        return null;
      }
      return new CircularReferenceLine(
          line.substring(0, firstNonWhiteSpace),
          line.substring(exceptionStartIndex, lastBracketPosition),
          line.substring(lastBracketPosition));
    }

    @Override
    List<StackTraceLine> retrace(RetraceApi retracer, boolean verbose) {
      List<StackTraceLine> exceptionLines = new ArrayList<>();
      retracer
          .retrace(Reference.classFromTypeName(exceptionClass))
          .forEach(
              element ->
                  exceptionLines.add(
                      new CircularReferenceLine(
                          startWhitespace,
                          element.getClassReference().getTypeName(),
                          endBracketAndWhitespace)));
      return exceptionLines;
    }

    @Override
    public String toString() {
      return startWhitespace + CIRCULAR_REFERENCE + exceptionClass + endBracketAndWhitespace;
    }
  }

  static class UnknownLine extends StackTraceLine {
    private final String line;

    UnknownLine(String line) {
      this.line = line;
    }

    @Override
    List<StackTraceLine> retrace(RetraceApi retracer, boolean verbose) {
      return ImmutableList.of(new UnknownLine(line));
    }

    @Override
    public String toString() {
      return line;
    }
  }

  private StackTraceLine parseLine(int lineNumber, String line) {
    if (line == null) {
      diagnosticsHandler.error(RetraceInvalidStackTraceLineDiagnostics.createNull(lineNumber));
      throw new Retrace.RetraceAbortException();
    }
    // Most lines are 'at lines' so attempt to parse it first.
    StackTraceLine parsedLine = AtLine.tryParse(line);
    if (parsedLine != null) {
      return parsedLine;
    }
    parsedLine = ExceptionLine.tryParse(line);
    if (parsedLine != null) {
      return parsedLine;
    }
    parsedLine = CircularReferenceLine.tryParse(line);
    if (parsedLine != null) {
      return parsedLine;
    }
    parsedLine = MoreLine.tryParse(line);
    if (parsedLine == null) {
      diagnosticsHandler.warning(
          RetraceInvalidStackTraceLineDiagnostics.createParse(lineNumber, line));
    }
    parsedLine = new UnknownLine(line);
    return parsedLine;
  }
}