#!/bin/sh

# The MIT License (MIT)
#
# Copyright (c) 2026 pacman64
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.


# gsub [options...] [regexp-substitution pairs / regexps...]
#
# Global extended regex SUBstitute, using the AWK function of the same name:
# arguments are used as regex-replacement pairs, in that order. Input lines
# are always rid of ANSI-styles beforehand, if present.
#
# When run in erase/remove mode (see options below), arguments are all used
# as regexes (instead of regex-substitution pairs), and all replacements are
# empty strings.
#
# The options are, available both in single and double-dash versions
#
#   -e, -erase, -r, -remove    run in erase/remove mode
#   -h, -help                  show this help message
#   -i, -ins, -insensitive     match regexes case-insensitively


erase=0
case_insensitive=0

case "$1" in
    -h|--h|-help|--help)
        awk '/^# +gsub /, /^$/ { gsub(/^# ?/, ""); print }' "$0"
        exit 0
    ;;

    -e|--e|-erase|--erase|-r|--r|-remove|--remove)
        erase=1
        shift
    ;;

    -i|--i|-ins|--ins|-insensitive|--insensitive)
        case_insensitive=1
        shift
    ;;
esac

[ "$1" = '--' ] && shift

command='awk'
if { [ -p /dev/stdout ] || [ -t 1 ]; } && [ -e /usr/bin/stdbuf ]; then
    command='stdbuf -oL awk'
fi

${command} -v ci="${case_insensitive}" -v erase="${erase}" '
    BEGIN {
        if (ci && IGNORECASE == "") {
            m = "your `awk` command lacks case-insensitive regex-matching"
            print(m) > "/dev/stderr"
            exit 125
        }
        if (ci) IGNORECASE = 1

        for (i = 1; i < ARGC; i++) {
            args[++n] = ARGV[i]
            delete ARGV[i]
            if (erase) args[++n] = ""
        }
    }

    {
        # ignore cursor-movers and style-changers
        gsub(/\x1b\[[0-9;]*[A-Za-z]/, "")

        # ignore OSC sequences
        gsub(/\x1b\][^\x1b]+\x1b\\/, "")

        for (i = 1; i <= n; i += 2) gsub(args[i], args[i + 1])
        print
    }
' "$@"