git-xlog

#!/usr/bin/env bash

app_name="$(basename "${BASH_SOURCE[0]}")"

print_help() {
	expand -t 4 << EOF
Usage:
	$app_name
		Search history for string only in added or removed lines.

Options:
	-t, --diff-type=<A|R|Added|Removed>
		Whether to search in added or removed lines.

	-l, --log-opt=<LOG_OPTIONS>
		Options to pass on to git log commands.

	-d, --diff-opt=<DIFF_OPTIONS>
		Options to pass on to git diff commands.

	-?, --help
		Show this help information and exit.
EOF
}

getopt -q -T
if [[ $? -ne 4 ]]; then
	echo "$app_name: [Error] This script requires an enhanced getopt version." >&2
	exit 1
fi

for ((i=1; i <= $#; i++)); do
	opt="${!i}"
	case "$opt" in
		-\?|--help)
			print_help
			exit 0
			;;
		--)
			break
			;;
	esac
done

opts=$(getopt -o 't:l:d:' -l 'diff-type:,log-opt:,diff-opt:' -n "$app_name" -- "$@") || exit $?

eval "opts=($opts)"

for ((i=0; i < ${#opts[@]}; i++)); do
	opt="${opts[$i]}"
	case "$opt" in
		-t|--diff-type)
			diff_type="${opts[++i]}"
			;;
		-l|--log-opt)
			log_opt="${opts[++i]}"
			;;
		-d|--diff-opt)
			diff_opt="${opts[++i]}"
			;;
		--)
			break
			;;
	esac
done

if [[ ! -v diff_type ]]; then
	echo "$app_name: [Error] Missing '--diff-type' argument." >&2
	exit 1
elif [[ -z $diff_type ]]; then
	echo "$app_name: [Error] Missing value for argument '--diff-type'." >&2
	exit 1
elif [[ ${diff_type@U} == 'A' || ${diff_type@U} == "ADDED" ]]; then
	diff_mark='>'
elif [[ ${diff_type@U} == 'R' || ${diff_type@U} == "REMOVED" ]]; then
	diff_mark='<'
else
	echo "$app_name: [Error] Unrecognized diff-type: '$diff_type'. Accepted values: 'A', 'Added', 'R', 'Removed'." >&2
	exit 1
fi

if [[ ! -v log_opt ]]; then
	echo "$app_name: [Error] Missing '--log-opt' argument." >&2
	exit 1
elif [[ -z $log_opt ]]; then
	echo "$app_name: [Error] Missing value for argument '--log-opt'." >&2
	exit 1
fi

opts=$(eval getopt -q -o 'S:G:' -n "$app_name" -- "$log_opt")

eval "opts=($opts)"

for ((i=0; i < ${#opts[@]}; i++)); do
	opt="${opts[$i]}"
	case "$opt" in
		-S)
			search_text="${opts[++i]}"
			;;
		-G)
			search_regex="${opts[++i]}"
			;;
		--)
			break
			;;
		*)
			echo 'Internal error!' >&2
			exit 1
			;;
	esac
done

if [[ ! -v search_text && ! -v search_regex ]]; then
	echo "$app_name: [Error] No '-S' or '-G' found in log options." >&2
	exit 1
elif [[ -z $search_text && -z $search_regex ]]; then
	echo "$app_name: [Error] Missing value for argument '-S' or '-G' in log options." >&2
	exit 1
fi

interrupt () {
	echo "$app_name: [Error] Interrupted." >&2
	exit 1
}

trap interrupt INT

if [[ -t 1 ]]; then 
	git_color="--color"
	less_color="-r"
fi

if [[ -n $search_regex ]]; then
	grep_opt='-E "$search_regex"'
elif [[ -n $search_text ]]; then
	grep_opt='"$search_text"'
fi

set -e

eval git --no-pager log "$log_opt" --no-patch --format=%H |
while read -r sha; do
	eval git --no-pager diff -U0 "$sha~" "$sha" --output-indicator-new='\>' --output-indicator-old='\<' |
	grep -E "^$diff_mark" |
	eval grep -q "$grep_opt" &&
	eval git --no-pager log "$git_color" --no-walk "$sha" "$log_opt" "$diff_opt"
done | less -deFX $less_color