#!/bin/sh
set -eu
base="${TMPDIR-/tmp}/mcpu-cpp-deps-$$"
mkdir -p "$base/user" "$base/sys" "$base/cfg-user" "$base/cfg-sys" "$base/after" "$base/cfg-after"
trap 'rm -rf "$base"' EXIT HUP INT TERM

cat > "$base/config.conf" <<EOT
MCPU_CPP_INCLUDE_PATH = $base/cfg-user;
MCPU_CPP_SYSTEM_INCLUDE_PATH = $base/cfg-sys;
MCPU_CPP_AFTER_INCLUDE_PATH = $base/cfg-after;
EOT

cat > "$base/main.c" <<'EOT'
#include "local.h"
#include "local-alias.h"
#include <user.h>
#include <cfg-user.h>
#include "sys-explicit.h"
#include <sys-config.h>
#include <after-explicit.h>
#include <after-config.h>
#include <same.h>
#include <shared.h>
SHOULD_NOT_APPEAR_IN_DEP_OUTPUT
EOT

cat > "$base/local.h" <<'EOT'
#pragma once
#line 100 "logical-local.h"
LOCAL_BODY
EOT
ln "$base/local.h" "$base/local-alias.h"

cat > "$base/user/user.h" <<'EOT'
USER_HEADER
EOT
cat > "$base/cfg-user/cfg-user.h" <<'EOT'
CONFIG_USER_HEADER
EOT
cat > "$base/user/shared.h" <<'EOT'
SHARED_USER_HEADER
EOT
cat > "$base/user/transitive-only.h" <<'EOT'
TRANSITIVE_USER_HEADER
EOT

cat > "$base/sys/sys-explicit.h" <<'EOT'
#include <transitive-only.h>
#include <shared.h>
#include "sys-child.h"
EOT
cat > "$base/sys/sys-child.h" <<'EOT'
SYSTEM_CHILD
EOT
cat > "$base/cfg-sys/sys-config.h" <<'EOT'
SYSTEM_CONFIG
EOT
cat > "$base/after/after-explicit.h" <<'EOT'
AFTER_EXPLICIT
EOT
cat > "$base/cfg-after/after-config.h" <<'EOT'
AFTER_CONFIG
EOT

cat > "$base/user/same.h" <<'EOT'
USER_WRAPPER
#include_next <same.h>
EOT
cat > "$base/sys/same.h" <<'EOT'
SYSTEM_WRAPPED
EOT

"$MCPU_CPP" --config-file "$base/config.conf" \
  -I "$base/user" -isystem "$base/sys" -idirafter "$base/after" \
  -M "$base/main.c" > "$base/M.out"

# -M emits only a make rule and includes every physical dependency.
grep "^main\\.o:" "$base/M.out" >/dev/null
! grep 'SHOULD_NOT_APPEAR_IN_DEP_OUTPUT' "$base/M.out" >/dev/null
for f in \
  "$base/main.c" "$base/local.h" "$base/user/user.h" \
  "$base/cfg-user/cfg-user.h" "$base/sys/sys-explicit.h" \
  "$base/user/transitive-only.h" "$base/user/shared.h" \
  "$base/sys/sys-child.h" "$base/cfg-sys/sys-config.h" \
  "$base/after/after-explicit.h" "$base/cfg-after/after-config.h" \
  "$base/user/same.h" "$base/sys/same.h"
do
  grep -F "$f" "$base/M.out" >/dev/null || {
    echo "-M omitted dependency: $f" >&2
    exit 1
  }
done

# local-alias.h is a hard link to local.h and must not create a duplicate
# physical dependency.  The logical #line name is not a dependency either.
! grep -F "$base/local-alias.h" "$base/M.out" >/dev/null
! grep -F 'logical-local.h' "$base/M.out" >/dev/null

"$MCPU_CPP" --config-file "$base/config.conf" \
  -I "$base/user" -isystem "$base/sys" -idirafter "$base/after" \
  -MM "$base/main.c" > "$base/MM.out"

grep "^main\\.o:" "$base/MM.out" >/dev/null
for f in "$base/main.c" "$base/local.h" "$base/user/user.h" \
         "$base/cfg-user/cfg-user.h" "$base/user/same.h" "$base/user/shared.h"
do
  grep -F "$f" "$base/MM.out" >/dev/null || {
    echo "-MM omitted user dependency: $f" >&2
    exit 1
  }
done

# Quoting style does not define system-ness.  sys-explicit.h was included
# with quotes but found in -isystem, and all descendants reachable only from
# that system header are excluded.  -idirafter/config AFTER are system class.
for f in "$base/sys/sys-explicit.h" "$base/user/transitive-only.h" \
         "$base/sys/sys-child.h" "$base/cfg-sys/sys-config.h" \
         "$base/after/after-explicit.h" "$base/cfg-after/after-config.h" \
         "$base/sys/same.h"
do
  if grep -F "$f" "$base/MM.out" >/dev/null; then
    echo "-MM kept system dependency: $f" >&2
    exit 1
  fi
done

# The same physical shared.h is first reached transitively from a system
# header, then directly from main.  The direct user inclusion makes it a user
# dependency, so -MM must retain it (checked above).

# Normal mcpu-cpp output-file syntax remains usable for dependency output.
"$MCPU_CPP" --config-file "$base/config.conf" -I "$base/user" \
  -isystem "$base/sys" -idirafter "$base/after" \
  -MM "$base/main.c" -o "$base/deps.mk"
test -s "$base/deps.mk"
grep '^main\.o:' "$base/deps.mk" >/dev/null

# stdin follows GNU cpp's useful default target convention.
printf 'int x;\n' | "$MCPU_CPP" --no-config -M > "$base/stdin.dep"
grep '^-: -$' "$base/stdin.dep" >/dev/null