#!/bin/sh

# git pre-commit hook that runs an Uncrustify stylecheck.
# Features:
#  - abort commit when commit does not comply with the style guidelines
#  - create a patch of the proposed style changes
#
# More info on Uncrustify: http://uncrustify.sourceforge.net/

# This file is part of a set of unofficial pre-commit hooks available
# at github.
# Link:    https://github.com/ddddavidmartin/Pre-commit-hooks
# Contact: David Martin, ddddavidmartin@fastmail.com

##################################################################
# There should be no need to change anything below this line.
# For configuration see pre-commit-uncrustify.cfg and
# pre-commit-uncrustify.example.cfg.

# exit on error
set -e

# Absolute path to this script, e.g. /home/user/bin/foo.sh
SCRIPT="$(readlink -f "$0")"
# Absolute path this script is in, e.g. /home/user/bin/
SCRIPTPATH="$(dirname -- "$SCRIPT")"
CONFIG="$SCRIPTPATH/pre-commit-uncrustify.cfg"
REPO="$(git rev-parse --show-toplevel)"

if [ ! -f "$CONFIG" ] ; then
    echo "Missing config file $CONFIG."
    exit 1
else
    . "$CONFIG"
fi


# check whether the given file matches any of the set extensions
matches_extension() {
    local filename="$(basename -- "$1")"
    local extension=".${filename##*.}"
    local ext

    for ext in $FILE_EXTS; do [ "$ext" = "$extension" ] && return 0; done

    return 1
}

# necessary check for initial commit
if git rev-parse --verify HEAD >/dev/null 2>&1 ; then
    against=HEAD
else
    # Initial commit: diff against an empty tree object
    against=4b825dc642cb6eb9a060e54bf8d69288fbee4904
fi

# make sure the config file and executable are correctly set
if [ ! -f "$UNCRUST_CONFIG" ] ; then
    printf "Error: uncrustify config file not found.\n"
    printf "Set the correct path in $CONFIG.\n"
    exit 1
fi

if ! command -v "$UNCRUSTIFY" > /dev/null ; then
    printf "Error: uncrustify executable not found.\n"
    printf "Set the correct path in $CONFIG.\n"
    exit 1
fi

# create a filename to store our generated patch
prefix="pre-commit-uncrustify"
suffix="$(date +%C%y-%m-%d_%Hh%Mm%Ss)"
patch="/tmp/$prefix-$suffix.patch"

# clean up any older uncrustify patches
$DELETE_OLD_PATCHES && rm -f /tmp/$prefix*.patch

# create one patch containing all changes to the files
# sed to remove quotes around the filename, if inserted by the system
# (done sometimes, if the filename contains special characters, like the quote itself)
git diff-index --cached --diff-filter=ACMR --name-only $against -- | \
sed -e 's/^"\(.*\)"$/\1/' | \
while read file
do
    # ignore file if we do check for file extensions and the file
    # does not match any of the extensions specified in $FILE_EXTS
    if $PARSE_EXTS && ! matches_extension "$file"; then
        continue;
    fi

    # escape special characters in the source filename:
    # - '\': backslash needs to be escaped
    # - '*': used as matching string => '*' would mean expansion
    #        (curiously, '?' must not be escaped)
    # - '[': used as matching string => '[' would mean start of set
    # - '|': used as sed split char instead of '/', so it needs to be escaped
    #        in the filename
    # printf %s particularly important if the filename contains the % character
    file_escaped_source=$(printf "%s" "$file" | sed -e 's/[\*[|]/\\&/g')

    # escape special characters in the target filename:
    # phase 1 (characters escaped in the output diff):
    #     - '\': backslash needs to be escaped in the output diff
    #     - '"': quote needs to be escaped in the output diff if present inside
    #            of the filename, as it used to bracket the entire filename part
    # phase 2 (characters escaped in the match replacement):
    #     - '\': backslash needs to be escaped again for sed itself
    #            (i.e. double escaping after phase 1)
    #     - '&': would expand to matched string
    #     - '|': used as sed split char instead of '/'
    # printf %s particularly important if the filename contains the % character
    file_escaped_target=$(printf "%s" "$file" | sed -e 's/[\"]/\\&/g' -e 's/[\&|]/\\&/g')

    # Uncrustify detects the language automatically if it is not specified
    language_option=""
    if [ "$SOURCE_LANGUAGE" != "AUTO" ] ; then
        language_option="-l $SOURCE_LANGUAGE"
    fi

    # uncrustify our sourcefile, create a patch with diff and append it to our $patch
    # The sed call is necessary to transform the patch from
    #    --- $file timestamp
    #    +++ - timestamp
    # to both lines working on the same file and having a a/ and b/ prefix.
    # Else it can not be applied with 'git apply'.
    "$UNCRUSTIFY" -c "$UNCRUST_CONFIG" -f "$file" $language_option | \
        diff -u -- "$file" - | \
        sed -e "1s|--- $file_escaped_source|--- \"a/$file_escaped_target\"|" -e "2s|+++ -|+++ \"b/$file_escaped_target\"|" >> "$patch"
done

# if no patch has been generated all is ok, clean up the file stub and exit
if [ ! -s "$patch" ] ; then
    printf "Files in this commit comply with the uncrustify rules.\n"
    rm -f "$patch"
    exit 0
fi

# a patch has been created, notify the user and exit
printf "\nThe following differences were found between the code to commit "
printf "and the uncrustify rules:\n\n"
cat "$patch"

printf "\nYou can apply these changes with:\n git apply $patch\n"
printf "(may need to be called from the root directory of your repository)\n"
printf "Aborting commit. Apply changes and commit again or skip checking with"
printf " --no-verify (not recommended).\n"

exit 1