#!/bin/bash
# Copyright 2021 Google LLC
#
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

export LD_LIBRARY_PATH="external/clang_linux_amd64/usr/lib/x86_64-linux-gnu:external/clang_linux_amd64/usr/lib/llvm-13/lib"

set -e

# We only want to run include-what-you-use if DSKIA_ENFORCE_IWYU is in the arguments
# passed in (i.e. the "skia_enforce_iwyu" feature is enabled) and we are not linking
# (as detected by the presence of -fuse-ld).
if [[ "$@" != *DSKIA_ENFORCE_IWYU* || "$@" == *use-ld* ]]; then
  external/clang_linux_amd64/bin/clang $@
  exit 0
fi

supported_files_or_dirs=(
  "experimental/bazel_test/"
  "modules/skunicode/"
  "src/sksl/"
  "src/svg/"
  "src/utils/"
  "tools/debugger/"
)

function opted_in_to_IWYU_checks() {
  # Need [@] for entire list: https://stackoverflow.com/a/46137325
  for path in ${supported_files_or_dirs[@]}; do
    if [[ $1 == *"-c $path"* ]]; then
      echo $path
      return 0
    fi
  done
  echo ""
  return 0
}

# We want to concatenate all args into a string so we can do some
# string matching in the opted_in_to_IWYU_checks function.
# https://unix.stackexchange.com/a/197794
opt_in=$(opted_in_to_IWYU_checks "'$*'")
if [[ -z $opt_in ]]; then
  external/clang_linux_amd64/bin/clang $@
  exit 0
else
  # Now try to compile with Clang, and then verify with IWYU
  external/clang_linux_amd64/bin/clang $@
  # IWYU always [1] returns a non-zero code because it doesn't produce the .o file (that's why
  # we ran Clang first). As such, we do not want bash to fail after running IWYU.
  # [1] Until v0.18 at least
  set +e
  # Get absolute path to the mapping file because resolving the relative path is tricky, given
  # how Bazel locates the toolchain files.
  MAPPING_FILE=$(realpath $(dirname ${BASH_SOURCE[0]}))"/IWYU_mapping.imp"
  # IWYU always outputs something to stderr, which can be noisy if everything is fixed.
  # Otherwise, we send the exact same arguments to include-what-you-use that we would for
  # regular compilation with clang.
  # We always allow SkTypes.h because it sets some defines that later #ifdefs use and IWYU is
  # not consistent with detecting that.
  external/clang_linux_amd64/usr/bin/include-what-you-use \
      -Xiwyu --keep="include/core/SkTypes.h" \
      -Xiwyu --no_default_mappings \
      -Xiwyu --mapping_file=$MAPPING_FILE $@ 2>/dev/null
  # IWYU returns 2 if everything looks good. It returns some other non-zero exit code otherwise.
  if [ $? -eq 2 ]; then
    exit 0 # keep the build going
  else
    # Run IWYU again, but this time display the output. Then return non-zero to fail the build.
    # These flags are a little different, but only in ways that affect what was displayed, not the
    # analysis. If we aren't sure why IWYU wants to include something, try changing verbose to 3.
    external/clang_linux_amd64/usr/bin/include-what-you-use \
        -Xiwyu --keep="include/core/SkTypes.h" \
        -Xiwyu --no_default_mappings \
        -Xiwyu --mapping_file=$MAPPING_FILE -Xiwyu --no_comments \
        -Xiwyu --quoted_includes_first -Xiwyu --verbose=3 $@
    exit 1 # fail the build
  fi
fi