home/files/bin/pcat

#!/bin/sh

set -eu

# variables
#
FROM=
UNTIL=

SED_ARGS=
GREP_ARGS=
GREPV_ARGS=

# bin helpers
#
if STDBUF=$(which stdbuf); then
	STDBUF="$STDBUF -i0 -o0"
fi

PERL=$(which perl || true)
if [ -n "$(sed 2>&1 | grep -- -u,)" ]; then
	SED="sed -u"
else
	SED="${STDBUF:+$STDBUF }sed"
fi
GREP="${STDBUF:+$STDBUF }grep"

# Colours
#
NORMAL="$(printf '\x1b[39;49m')"
COLOUR="$NORMAL"

RED="$(printf '\x1b[31m')"
GREEN="$(printf '\x1b[32m')"
YELLOW="$(printf '\x1b[33m')"
BLUE="$(printf '\x1b[34m')"
MAGENTA="$(printf '\x1b[35m')"
CYAN="$(printf '\x1b[36m')"

# shell helpers
#
die() {
	local arg0="$(basename "$0")"

	if [ $# -eq 0 ]; then
		sed -e "s!^!$arg0 :"
	else
		echo "$arg0: $@"
	fi >&2
	exit 1
}

cat <<EOT >&2
# $PWD
# $0 $*
EOT

# arguments
#
while [ $# -gt 0 ]; do

	case "${1:-}" in
	-f)
		# prefilter from
		FROM="$2"
		shift
		;;
	-u)
		# prefilter until
		UNTIL="$2"
		shift
		;;

	-e)
		# highlight pattern
		#
		if [ "$COLOUR" = "$RED" ]; then
			COLOUR="$GREEN"
		elif [ "$COLOUR" = "$GREEN" ]; then
			COLOUR="$MAGENTA"
		elif [ "$COLOUR" = "$MAGENTA" ]; then
			COLOUR="$YELLOW"
		elif [ "$COLOUR" = "$YELLOW" ]; then
			COLOUR="$CYAN"
		elif [ "$COLOUR" = "$CYAN" ]; then
			COLOUR="$BLUE"
		else
			COLOUR="$RED"
		fi

		case "$2" in
		"^"*"$") PATTERN="$2" ;;
		"^"*)    PATTERN="$2.*" ;;
		*"$")    PATTERN=".*$2" ;;
		*)       PATTERN=".*$2.*"
		esac

		SED_ARGS="${SED_ARGS:+$SED_ARGS }-e 's!$PATTERN!$COLOUR\0$NORMAL!g'"
		shift
		;;

	# simple grep options with arguments
	-C|-A|-B)
		GREP_ARGS="${GREP_ARGS:+$GREP_ARGS }$1 $2"
		shift
		;;
	# grep options with merged arguments
	-C*|-A*|-B*)
		GREP_ARGS="${GREP_ARGS:+$GREP_ARGS }'$1'"
		;;
	# complex grep options with arguments
	-E)
		GREP_ARGS="${GREP_ARGS:+$GREP_ARGS }$1 '$2'"
		shift
		;;
	# -g is `grep -e`
	-g)
		GREP_ARGS="${GREP_ARGS:+$GREP_ARGS }-e '$2'"
		shift
		;;
	# -v is `grep -v e`
	-v)
		GREPV_ARGS="${GREPV_ARGS:+$GREPV_ARGS }-e '$2'"
		shift
		;;
	# simple grep options without arguments
	-i)
		GREP_ARGS="${GREP_ARGS:+$GREP_ARGS }$1"
		;;

	--)	shift
		break
		;;
	# any other option
	-*)
		die "$1 unsupported"
		;;

	# straight arguments
	*)
		break
		;;
	esac
	shift
done

export LC_ALL=C

#
# compose pipeline
#

PIPELINE=

# GREP -v FILTER
if [ -n "${GREPV_ARGS:-}" ]; then
	PIPELINE="${PIPELINE:+$PIPELINE | }$GREP -a -v $GREPV_ARGS"
fi

# FROM/UNTIL FILTER
if [ -z "${FROM:-}${UNTIL:-}" ]; then
	:
elif [ -x "$PERL" ]; then
	prg=

	if [ -n "$FROM" ]; then
		prg="print if \$print; \$print ||= /$FROM/;"
	else
		prg="print;"
	fi

	[ -z "$UNTIL" ] || prg="last if /$UNTIL/; $prg"

	PIPELINE="${PIPELINE:+$PIPELINE | }$PERL -lne '$prg'"
else
	PIPELINE="${PIPELINE:+$PIPELINE | }$SED"

	[ -z "${FROM:-}" ]  || PIPELINE="$PIPELINE -e '0,/$FROM/d'"
	[ -z "${UNTIL:-}" ] || PIPELINE="$PIPELINE -e '/$UNTIL/,\$d'"

	# no grep? combine both sed calls
	if [ -z "${GREP_ARGS:-}" -a -n "${SED_ARGS:-}" ]; then
		PIPELINE="$PIPELINE $SED_ARGS"
		SED_ARGS=
	fi
fi

# GREP FILTER
if [ -n "${GREP_ARGS:-}" ]; then
	PIPELINE="${PIPELINE:+$PIPELINE | }$GREP -a $GREP_ARGS"
fi

# HIGHLIGHT
if [ -n "${SED_ARGS:-}" ]; then
	PIPELINE="${PIPELINE:+$PIPELINE | }$SED $SED_ARGS"
fi

#and run
if [ $# -eq 0 ]; then
	eval "${PIPELINE:-cat}"
elif [ -n "$PIPELINE" ]; then
	"$@" | $PIPELINE
else
	"$@"
fi