"""Compilation of utility functions for working with ninja."""

from __future__ import absolute_import
import re

# Example: [123/9876]
NINJA_PROGRESS_PREFIX = r'^\[\d+/\d+\]'
NINJA_FAILED_PREFIX = '^FAILED: '
NINJA_BUILD_STOPPED = '^ninja: build stopped: '
# Example: 1 error generated.
# Example: 15 errors generated.
NINJA_ERRORS_GENERATED = r'^\d+ error(s?) generated\.$'
NINJA_FILE_INCLUDED_FROM = '^In file included from '
NINJA_CLANG = r'third_party/llvm-build/Release\+Asserts/bin/clang\+\+'
# Example: prebuilt/toolchain/mips32r1/bin/mipsel-buildroot-linux-uclibc-g++
# Example: prebuilt/toolchain/armv7a/bin/armv7a-cros-linux-gnueabi-g++
NINJA_GXX = r'prebuilt/toolchain/(\S+)(g\+\+)'

NINJA_TOO_MANY_ERRORS_MSG = 'Too many errors! See the logs for the rest.'


def ninja_failure_to_comments(ninja_output, max_errors=None):
  """Convert a ninja failure message to comments for a gerrit review.

  In general, a log is from ninja is expected to look somewhat like:

  [...snip...]
  [123/9876] CXX obj/path/to/foo.o
  [124/9876] CXX obj/path/to/bar.o
  FAILED: obj/path/to/bar.o
  path/to/compiler/clang++ -FLAG -FLAG ... ... ...
  path/to/foo:503:27: error: error was here
      More specific error stuff
                          ^~~~~
  1 error generated.
  [125/9876] STAMP obj/path/to/baz.o
  [126/9876] ACTION path/to/script
  ninja: build stopped: subcommand failed
  [...snip...]

  And this extracts out the FAILED block from the rest of the log.

  Args:
    ninja_output: output from a ninja build command.
                  (Note: this can also include output from other tools in
                   addition to the ninja output, in case ninja is a subcommand
                   of another tool, such as make.)
    max_errors: The maximum number of errors to include. If not None,
                then the returned list will contain at most N error messages.
                If more than N errors were generated, then the list will also
                contain an N+1'th message indicating errors were left out.

  Returns:
    A list of multi-line strings. Each string represents the text of a
    single "FAILED" message from ninja.
    An empty list is returned if no comments are found.
  """
  comments = set()

  comment, in_failed_block = '', False
  for line in ninja_output.splitlines(True):

    # Found the start of a failure block
    if re.search(NINJA_FAILED_PREFIX, line):
      in_failed_block = True
      continue

    # Haven't found the start of a failure block yet,
    # so this line is part of a success. Skip it.
    if not in_failed_block:
      continue

    # Found the end of a failure block.
    if (re.search(NINJA_BUILD_STOPPED, line) or
        re.search(NINJA_ERRORS_GENERATED, line) or
        re.search(NINJA_PROGRESS_PREFIX, line)):
      comments.add(comment.strip('\n'))
      comment, in_failed_block = '', False
      continue

    # Ignore these lines, as they are long and do not add enough
    # useful information compared to other lines
    if (re.search(NINJA_FILE_INCLUDED_FROM, line) or
        re.search(NINJA_CLANG, line) or
        re.search(NINJA_GXX, line)):
      continue

    # Found a line within a failure block.
    comment += line

  comments = list(comments)  # pylint: disable=redefined-variable-type
  if max_errors and isinstance(max_errors, int):
    max_errors = int(max_errors)
    if len(comments) > max_errors:
      comments = comments[0:max_errors] + [NINJA_TOO_MANY_ERRORS_MSG]

  return comments