#!/usr/bin/python
# Copyright 2014 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Runs Closure compiler on JavaScript files to check for errors and produce
minified output."""

import argparse
import os
import re
import subprocess
import sys
import tempfile

import build.inputs
import processor
import error_filter


_CURRENT_DIR = os.path.join(os.path.dirname(__file__))


class Checker(object):
  """Runs the Closure compiler on given source files to typecheck them
  and produce minified output."""

  _JAR_COMMAND = [
    "java",
    "-jar",
    "-Xms1024m",
    "-client",
    "-XX:+TieredCompilation"
  ]

  _MAP_FILE_FORMAT = "%s.map"

  def __init__(self, verbose=False, strict=False):
    """
    Args:
      verbose: Whether this class should output diagnostic messages.
      strict: Whether the Closure Compiler should be invoked more strictly.
    """
    self._runner_jar = os.path.join(_CURRENT_DIR, "runner", "runner.jar")
    self._temp_files = []
    self._verbose = verbose
    self._strict = strict
    self._error_filter = error_filter.PromiseErrorFilter()

  def _nuke_temp_files(self):
    """Deletes any temp files this class knows about."""
    if not self._temp_files:
      return

    self._log_debug("Deleting temp files: %s" % ", ".join(self._temp_files))
    for f in self._temp_files:
      os.remove(f)
    self._temp_files = []

  def _log_debug(self, msg, error=False):
    """Logs |msg| to stdout if --verbose/-v is passed when invoking this script.

    Args:
      msg: A debug message to log.
    """
    if self._verbose:
      print "(INFO) %s" % msg

  def _log_error(self, msg):
    """Logs |msg| to stderr regardless of --flags.

    Args:
      msg: An error message to log.
    """
    print >> sys.stderr, "(ERROR) %s" % msg

  def _run_jar(self, jar, args):
    """Runs a .jar from the command line with arguments.

    Args:
      jar: A file path to a .jar file
      args: A list of command line arguments to be passed when running the .jar.

    Return:
      (exit_code, stderr) The exit code of the command (e.g. 0 for success) and
          the stderr collected while running |jar| (as a string).
    """
    shell_command = " ".join(self._JAR_COMMAND + [jar] + args)
    self._log_debug("Running jar: %s" % shell_command)

    devnull = open(os.devnull, "w")
    kwargs = {"stdout": devnull, "stderr": subprocess.PIPE, "shell": True}
    process = subprocess.Popen(shell_command, **kwargs)
    _, stderr = process.communicate()
    return process.returncode, stderr

  def _get_line_number(self, match):
    """When chrome is built, it preprocesses its JavaScript from:

      <include src="blah.js">
      alert(1);

    to:

      /* contents of blah.js inlined */
      alert(1);

    Because Closure Compiler requires this inlining already be done (as
    <include> isn't valid JavaScript), this script creates temporary files to
    expand all the <include>s.

    When type errors are hit in temporary files, a developer doesn't know the
    original source location to fix. This method maps from /tmp/file:300 back to
    /original/source/file:100 so fixing errors is faster for developers.

    Args:
      match: A re.MatchObject from matching against a line number regex.

    Returns:
      The fixed up /file and :line number.
    """
    real_file = self._processor.get_file_from_line(match.group(1))
    return "%s:%d" % (os.path.abspath(real_file.file), real_file.line_number)

  def _filter_errors(self, errors):
    """Removes some extraneous errors. For example, we ignore:

      Variable x first declared in /tmp/expanded/file

    Because it's just a duplicated error (it'll only ever show up 2+ times).
    We also ignore Promose-based errors:

      found   : function (VolumeInfo): (Promise<(DirectoryEntry|null)>|null)
      required: (function (Promise<VolumeInfo>): ?|null|undefined)

    as templates don't work with Promises in all cases yet. See
    https://github.com/google/closure-compiler/issues/715 for details.

    Args:
      errors: A list of string errors extracted from Closure Compiler output.

    Return:
      A slimmer, sleeker list of relevant errors (strings).
    """
    first_declared_in = lambda e: " first declared in " not in e
    return self._error_filter.filter(filter(first_declared_in, errors))

  def _clean_up_error(self, error):
    """Reverse the effects that funky <include> preprocessing steps have on
    errors messages.

    Args:
      error: A Closure compiler error (2 line string with error and source).

    Return:
      The fixed up error string.
    """
    expanded_file = self._expanded_file
    fixed = re.sub("%s:(\d+)" % expanded_file, self._get_line_number, error)
    return fixed.replace(expanded_file, os.path.abspath(self._file_arg))

  def _format_errors(self, errors):
    """Formats Closure compiler errors to easily spot compiler output.

    Args:
      errors: A list of strings extracted from the Closure compiler's output.

    Returns:
      A formatted output string.
    """
    contents = "\n## ".join("\n\n".join(errors).splitlines())
    return "## %s" % contents if contents else ""

  def _create_temp_file(self, contents):
    """Creates an owned temporary file with |contents|.

    Args:
      content: A string of the file contens to write to a temporary file.

    Return:
      The filepath of the newly created, written, and closed temporary file.
    """
    with tempfile.NamedTemporaryFile(mode="wt", delete=False) as tmp_file:
      self._temp_files.append(tmp_file.name)
      tmp_file.write(contents)
    return tmp_file.name

  def _run_js_check(self, sources, out_file=None, externs=None,
                    closure_args=None):
    """Check |sources| for type errors.

    Args:
      sources: Files to check.
      out_file: A file where the compiled output is written to.
      externs: @extern files that inform the compiler about custom globals.
      closure_args: Arguments passed directly to the Closure compiler.

    Returns:
      (errors, stderr) A parsed list of errors (strings) found by the compiler
          and the raw stderr (as a string).
    """
    args = ["--js=%s" % s for s in sources]

    if out_file:
      out_dir = os.path.dirname(out_file)
      if not os.path.exists(out_dir):
        os.makedirs(out_dir)
      args += ["--js_output_file=%s" % out_file]
      args += ["--create_source_map=%s" % (self._MAP_FILE_FORMAT % out_file)]

    if externs:
      args += ["--externs=%s" % e for e in externs]

    if closure_args:
      args += ["--%s" % arg for arg in closure_args]

    args_file_content = " %s" % " ".join(args)
    self._log_debug("Args: %s" % args_file_content.strip())

    args_file = self._create_temp_file(args_file_content)
    self._log_debug("Args file: %s" % args_file)

    runner_args = ["--compiler-args-file=%s" % args_file]
    _, stderr = self._run_jar(self._runner_jar, runner_args)

    errors = stderr.strip().split("\n\n")
    maybe_summary = errors.pop()

    if re.search(".*error.*warning.*typed", maybe_summary):
      self._log_debug("Summary: %s" % maybe_summary)
    else:
      # Not a summary. Running the jar failed. Bail.
      self._log_error(stderr)
      self._nuke_temp_files()
      sys.exit(1)

    if errors and out_file:
      if os.path.exists(out_file):
        os.remove(out_file)
      if os.path.exists(self._MAP_FILE_FORMAT % out_file):
        os.remove(self._MAP_FILE_FORMAT % out_file)

    return errors, stderr

  def check(self, source_file, out_file=None, depends=None, externs=None,
            closure_args=None):
    """Closure compiler |source_file| while checking for errors.

    Args:
      source_file: A file to check.
      out_file: A file where the compiled output is written to.
      depends: Files that |source_file| requires to run (e.g. earlier <script>).
      externs: @extern files that inform the compiler about custom globals.
      closure_args: Arguments passed directly to the Closure compiler.

    Returns:
      (found_errors, stderr) A boolean indicating whether errors were found and
          the raw Closure compiler stderr (as a string).
    """
    self._log_debug("FILE: %s" % source_file)

    if source_file.endswith("_externs.js"):
      self._log_debug("Skipping externs: %s" % source_file)
      return

    self._file_arg = source_file

    cwd, tmp_dir = os.getcwd(), tempfile.gettempdir()
    rel_path = lambda f: os.path.join(os.path.relpath(cwd, tmp_dir), f)

    depends = depends or []
    includes = [rel_path(f) for f in depends + [source_file]]
    contents = ['<include src="%s">' % i for i in includes]
    meta_file = self._create_temp_file("\n".join(contents))
    self._log_debug("Meta file: %s" % meta_file)

    self._processor = processor.Processor(meta_file)
    self._expanded_file = self._create_temp_file(self._processor.contents)
    self._log_debug("Expanded file: %s" % self._expanded_file)

    errors, stderr = self._run_js_check([self._expanded_file],
                                        out_file=out_file, externs=externs,
                                        closure_args=closure_args)
    filtered_errors = self._filter_errors(errors)
    cleaned_errors = map(self._clean_up_error, filtered_errors)
    output = self._format_errors(cleaned_errors)

    if cleaned_errors:
      prefix = "\n" if output else ""
      self._log_error("Error in: %s%s%s" % (source_file, prefix, output))
    elif output:
      self._log_debug("Output: %s" % output)

    self._nuke_temp_files()
    return bool(cleaned_errors), stderr

  def check_multiple(self, sources, out_file=None, externs=None,
                     closure_args=None):
    """Closure compile a set of files and check for errors.

    Args:
      sources: An array of files to check.
      out_file: A file where the compiled output is written to.
      externs: @extern files that inform the compiler about custom globals.
      closure_args: Arguments passed directly to the Closure compiler.

    Returns:
      (found_errors, stderr) A boolean indicating whether errors were found and
          the raw Closure Compiler stderr (as a string).
    """
    errors, stderr = self._run_js_check(sources, out_file=out_file,
                                        externs=externs,
                                        closure_args=closure_args)
    self._nuke_temp_files()
    return bool(errors), stderr


if __name__ == "__main__":
  parser = argparse.ArgumentParser(
      description="Typecheck JavaScript using Closure compiler")
  parser.add_argument("sources", nargs=argparse.ONE_OR_MORE,
                      help="Path to a source file to typecheck")
  single_file_group = parser.add_mutually_exclusive_group()
  single_file_group.add_argument("--single-file", dest="single_file",
                                 action="store_true",
                                 help="Process each source file individually")
  # TODO(twellington): remove --no-single-file and use len(opts.sources).
  single_file_group.add_argument("--no-single-file", dest="single_file",
                                 action="store_false",
                                 help="Process all source files as a group")
  parser.add_argument("-d", "--depends", nargs=argparse.ZERO_OR_MORE)
  parser.add_argument("-e", "--externs", nargs=argparse.ZERO_OR_MORE)
  parser.add_argument("-o", "--out-file", dest="out_file",
                      help="A file where the compiled output is written to")
  parser.add_argument("-c", "--closure-args", dest="closure_args",
                      nargs=argparse.ZERO_OR_MORE,
                      help="Arguments passed directly to the Closure compiler")
  parser.add_argument("-v", "--verbose", action="store_true",
                      help="Show more information as this script runs")

  parser.set_defaults(single_file=True, strict=False)
  opts = parser.parse_args()

  depends = opts.depends or []
  # TODO(devlin): should we run normpath() on this first and/or do this for
  # depends as well?
  externs = set(opts.externs or [])
  sources = set(opts.sources)

  polymer_externs = os.path.join(os.path.dirname(_CURRENT_DIR), 'polymer',
                                 'v1_0', 'components-chromium',
                                 'polymer-externs', 'polymer.externs.js')
  externs.add(polymer_externs)

  checker = Checker(verbose=opts.verbose, strict=opts.strict)
  if opts.single_file:
    for source in sources:
      # Normalize source to the current directory.
      source = os.path.normpath(os.path.join(os.getcwd(), source))
      depends, externs = build.inputs.resolve_recursive_dependencies(
          source, depends, externs)

      found_errors, _ = checker.check(source, out_file=opts.out_file,
                                      depends=depends, externs=externs,
                                      closure_args=opts.closure_args)
      if found_errors:
        sys.exit(1)
  else:
    found_errors, stderr = checker.check_multiple(
        sources,
        out_file=opts.out_file,
        externs=externs,
        closure_args=opts.closure_args)
    if found_errors:
      print stderr
      sys.exit(1)