#!/usr/bin/env python
#
# Copyright (c) 2019, the Dart 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.

# Simple tool for verifying that sources from one layer do not reference
# sources from another layer.
#
# Currently it only checks that core runtime headers RUNTIME_LAYER_HEADERS
# are not included into any sources listed in SHOULD_NOT_DEPEND_ON_RUNTIME.

import glob
import os
import re
import sys

INCLUDE_DIRECTIVE_RE = re.compile(r'^#include "(.*)"')

RUNTIME_LAYER_HEADERS = [
  'runtime/vm/isolate.h',
  'runtime/vm/object.h',
  'runtime/vm/raw_object.h',
  'runtime/vm/thread.h',
]

SHOULD_NOT_DEPEND_ON_RUNTIME = [
  'runtime/vm/allocation.h',
  'runtime/vm/growable_array.h',
]

class LayeringChecker(object):
  def __init__(self, root):
    self.root = root
    self.worklist = set()
    # Mapping from header to a set of files it is included into.
    self.included_into = dict()
    # Set of files that were parsed to avoid double parsing.
    self.loaded = set()
    # Mapping from headers to their layer.
    self.file_layers = {file: 'runtime' for file in RUNTIME_LAYER_HEADERS}

  def Check(self):
    self.AddAllSourcesToWorklist(os.path.join(self.root, 'runtime/vm'))
    self.BuildIncludesGraph()
    errors = self.PropagateLayers()
    errors += self.CheckNotInRuntime(SHOULD_NOT_DEPEND_ON_RUNTIME)
    return errors

  def CheckNotInRuntime(self, files):
    """Check that given files do not depend on runtime layer."""
    errors = []
    for file in files:
      if not os.path.exists(os.path.join(self.root, file)):
        errors.append('File %s does not exist.' % (file))
      if self.file_layers.get(file) is not None:
        errors.append(
            'LAYERING ERROR: %s includes object.h or raw_object.h' % (file))
    return errors

  def BuildIncludesGraph(self):
    while self.worklist:
      file = self.worklist.pop()
      deps = self.ExtractIncludes(file)
      self.loaded.add(file)
      for d in deps:
        if d not in self.included_into:
          self.included_into[d] = set()
        self.included_into[d].add(file)
        if d not in self.loaded:
          self.worklist.add(d)

  def PropagateLayers(self):
    """Propagate layering information through include graph.

    If A is in layer L and A is included into B then B is in layer L.
    """
    errors = []
    self.worklist = set(self.file_layers.keys())
    while self.worklist:
      file = self.worklist.pop()
      if file not in self.included_into:
        continue
      file_layer = self.file_layers[file]
      for tgt in self.included_into[file]:
        if tgt in self.file_layers:
          if self.file_layers[tgt] != file_layer:
            errors.add('Layer mismatch: %s (%s) is included into %s (%s)' % (
                file, file_layer, tgt, self.file_layers[tgt]))
        self.file_layers[tgt] = file_layer
        self.worklist.add(tgt)
    return errors

  def AddAllSourcesToWorklist(self, dir):
    """Add all *.cc and *.h files from dir recursively into worklist."""
    for file in os.listdir(dir):
      path = os.path.join(dir, file)
      if os.path.isdir(path):
        self.AddAllSourcesToWorklist(path)
      elif path.endswith('.cc') or path.endswith('.h'):
        self.worklist.add(os.path.relpath(path, self.root))

  def ExtractIncludes(self, file):
    """Extract the list of includes from the given file."""
    deps = set()
    with open(os.path.join(self.root, file)) as file:
      for line in file:
        if line.startswith('namespace dart {'):
          break

        m = INCLUDE_DIRECTIVE_RE.match(line)
        if m is not None:
          header = os.path.join('runtime', m.group(1))
          if os.path.isfile(os.path.join(self.root,header)):
            deps.add(header)
    return deps

def DoCheck(sdk_root):
  """Run layering check at the given root folder."""
  return LayeringChecker(sdk_root).Check()

if __name__ == '__main__':
  errors = DoCheck('.')
  print '\n'.join(errors)
  if errors:
    sys.exit(-1)