#!/usr/bin/env bash
#=============================================================================
# Copyright 2010-2011 Kitware, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#=============================================================================

die() {
	echo 'pre-commit hook failure' 1>&2
	echo '-----------------------' 1>&2
	echo '' 1>&2
	echo "$@" 1>&2
	exit 1
}

zero='0000000000000000000000000000000000000000'

#-----------------------------------------------------------------------------
# Check for committer identity.
advice='
Use the commands

	git config --global user.name '\''Your Name'\''
	git config --global user.email '\''you@yourdomain.com'\''

to introduce yourself to Git before committing.'

# Ensure name and email are available.
git config --get user.name > /dev/null &&
git config --get user.email > /dev/null ||
die 'Identity not configured!' "$advice"

# Validate the name and email.
git config --get user.name | grep ' ' > /dev/null ||
die 'Set user.name to your Real Name (with a space), not a userid.' "$advice"
git config --get user.email | grep '^[^@]*@[^@]*$' > /dev/null ||
die 'Set user.email to an email address (userid@validdomain.com).' "$advice"

#-----------------------------------------------------------------------------
# Check content that will be added by this commit.

if git rev-parse --verify -q HEAD > /dev/null; then
	against=HEAD
else
	# Initial commit: diff against an empty tree object
	against=4b825dc642cb6eb9a060e54bf8d69288fbee4904
fi

# Merge ("git commit" after "git merge" with conflicts or --no-commit)
merge_head=$(git rev-parse -q --verify MERGE_HEAD) || merge_head=''

# Disallow non-ascii file names.  The printable range starts at the
# space character and ends with tilde.
if test "$(git diff --cached --name-only --diff-filter=A -z $against |
	   LC_ALL=C tr -d '[ -~]\0')"; then
	die 'Non-ascii file names may not be added:
'"$(git diff --cached --name-only --diff-filter=A $against)"
fi

#-----------------------------------------------------------------------------
# Builtin whitespace checks.
bad=$(git diff-index --check --cached $against --) || die "$bad"

# Approximate whitespace=tab-in-indent check with Git < 1.7.2.
git --version | grep -q " \(1\.[0-6]\|1\.7\.[01]\)" &&
approx_tab_in_indent=true || approx_tab_in_indent=false
check_tab() {
	lines=$(git diff-index -p --cached $against -- "$1" |
	        grep '^+	') &&
	echo "$lines" |
	while read line; do
		echo "$1: tab in indent." &&
		echo "$line"
	done
}

# Reject addition of a line without a newline at end-of-file.
check_no_lf_at_eof() {
	lines=$(git diff-index -p --cached $against -- "$1" | tail -2)
	if echo "$lines" | head -1 | grep -q '^+' &&
	   echo "$lines" | tail -1 | grep -q '^\\ No newline'; then
		echo "$1: No newline at end of file"
	fi
}

# Custom whitespace checks.
check_whitespace() {
	ws=$(git check-attr whitespace -- "$file" |
	     sed 's/^[^:]*: whitespace: //')
	if $approx_tab_in_indent; then
		case ",$ws," in
			*,tab-in-indent,*) check_tab "$1" ;;
		esac
	fi
	case ",$ws," in
		*,no-lf-at-eof,*) check_no_lf_at_eof "$1" ;;
	esac
}
bad=$(git diff-index --name-only --cached $against -- |
while read file; do
	check_whitespace "$file"
done)
test -z "$bad" || die "$bad"

#-----------------------------------------------------------------------------
# Check file modes and sizes.
mode_looks_exe() {
	case "$1" in
		*.bat) return 0 ;;
		*.cmd) return 0 ;;
		*.exe) return 0 ;;
		*.com) return 0 ;;
	esac
	git cat-file blob "$2" | head -1 | grep "^#!/" > /dev/null
}
mode_not_exe () {
	echo "The file '$file' has looks executable but does not have an executable mode."
}
mode_bad_exe () {
	echo "The file '$file' has executable mode but does not look executable."
}
mode_non_file () {
	echo "The path '$file' has a non-file mode."
}
check_mode() {
	case "$dst_mode" in
		100755) mode_looks_exe "$file" "$dst_obj" || mode_bad_exe ;;
		100644) mode_looks_exe "$file" "$dst_obj" && mode_not_exe ;;
		160000) ;;
		*)	mode_non_file ;;
	esac
}

size_max_KiB=$(git config hooks.MaxObjectKiB)
test -n "$size_max_KiB" || size_max_KiB=1024
size_too_large_once=""
size_too_large_once() {
	test -z "$size_too_large_once" || return ; size_too_large_once=done
	echo 'At least one file is staged for commit with size larger than its limit.
We prefer to keep large files out of the main source tree, especially
binary files that do not compress well.  This hook disallows large files
by default but can be configured.  A limit for specific files or patterns
may be set in ".gitattributes" with the "hooks.MaxObjectKiB" attribute.
For example, the line

  *.c              hooks.MaxObjectKiB=2048

sets a limit of 2048 KiB for C source files.  See "git help attributes"
for details on the .gitattributes format.  If no attribute has been set
for a given file then its size is limited by the local default.  Run

  git config hooks.MaxObjectKiB $KiB

to set the local default limit (0 to disable).
'
}
size_too_large() {
	size_too_large_once
	echo "The path '$file' has size $file_KiB KiB, greater than allowed $max_KiB KiB."
}
size_validate_max_KiB() {
	test "$max_KiB" -ge "0" 2>/dev/null && return 0
	echo "The path '$file' has invalid attribute \"hooks-MaxObjectKiB=$max_KiB\"."
	return 1
}
check_size() {
	test "$dst_obj" != "$zero" || return
	max_KiB=$(git check-attr hooks.MaxObjectKiB -- "$file" |
		  sed 's/^[^:]*: hooks.MaxObjectKiB: //')
	case "$max_KiB" in
		'unset')       return ;; # No maximum for this object.
		'set')         max_KiB="$size_max_KiB" ;; # Use local default.
		'unspecified') max_KiB="$size_max_KiB" ;; # Use local default.
		*) size_validate_max_KiB || return ;;
	esac
	if test "$max_KiB" -gt "0"; then
		file_KiB=$(expr '(' $(git cat-file -s "$dst_obj") + 1023 ')' / 1024)
		test "$file_KiB" -le "$max_KiB" || size_too_large
	fi
}

short_commit() {
	git rev-parse --short "$1" 2>/dev/null || echo "$1"
}

lookup_config_module_update() {
	update=$(git config "hooks.$1.update")

	# Special-case "true" to accept any update.
	test "{$update}" = "{true}" && echo '.' && return

	# Format is "aaaaaa..bbbbbb" for update aaaaaa => bbbbbb.
	# Convert to regex "^aaaaaa[a-z0-9]* bbbbbb[a-z0-9]*$".
	sha1ex='[a-z0-9][a-z0-9][a-z0-9][a-z0-9][a-z0-9][a-z0-9][a-z0-9]*'
	regex='^\('"$sha1ex"'\)\.\.\('"$sha1ex"'\)$'
	echo "$update" |
	sed -n "/$regex/ {s/$regex/"'^\1[a-z0-9]* \2[a-z0-9]*$/;p;}' |
	grep '.' # Return false if result is empty.
}

check_module() {
	enabled=$(git config --get --bool hooks.submodule) || enabled=true
	test "$enabled" = "false" && return

	# Allow merged submodule updates.
	test -n "$merge_head" &&
	merge_obj=$(git rev-parse -q --verify "$merge_head:$file") &&
	test "$merge_obj" = "$dst_obj" && return

	# Allow module-only commits without extra work.
	test -z "$diffs_normal" && return

	# Check if module update is allowed with other changes.
	allow=$(lookup_config_module_update "$file") || allow='none'
	if echo "$src_obj $dst_obj" | grep "$allow" > /dev/null; then
		return
	fi
	src_short=$(short_commit "$src_obj")
	dst_short=$(short_commit "$dst_obj")
	echo 'A submodule link is staged for commit (among other changes):

  "'"$file"'"  '"$src_short => $dst_short"'

This may occur by accident so we require an extra step to commit.
If you intend to include this change in your commit, run

  git config "hooks.'"$file"'.update" '"$src_short..$dst_short"'

to explicitly allow the change and try the commit again.  Otherwise run

  git reset HEAD -- "'"$file"'"

to unstage the change.  Furthermore, if you did not intend to modify
the submodule at all, also run

  git submodule update -- "'"$file"'"

to checkout the current version of the submodule in your work tree.
Test your changes again to see if they still work with the module.
Finally, try the commit again.
'
}

diffs=$(git diff-index --cached $against -- |
        sed -n '/^:[^:]/ {s/^://;p;}')
diffs_normal=$(echo "$diffs" | grep -v '^...... 160000')
diffs_module=$(echo "$diffs" | grep    '^...... 160000')
bad=$(
test -n "$diffs_normal" && echo "$diffs_normal" |
while read src_mode dst_mode src_obj dst_obj status file; do
	if test "$src_mode" != "$dst_mode" -a "$dst_mode" != "000000"; then
		check_mode
	fi
	if test "$dst_mode" != "160000" -a "$dst_mode" != '000000'; then
		check_size
	fi
done
test -n "$diffs_module" && echo "$diffs_module" |
while read src_mode dst_mode src_obj dst_obj status file; do
	check_module
done
)
test -z "$bad" || die "$bad"

#-----------------------------------------------------------------------------
# Style hooks.
. "$GIT_DIR/hooks/pre-commit-style"

#-----------------------------------------------------------------------------
# Chain to project-specific hook.
. "$GIT_DIR/hooks/hooks-chain.bash"
hooks_chain pre-commit "$@"

# vim: set filetype=sh tabstop=8 softtabstop=8 shiftwidth=8 noexpandtab :