#!/bin/sh
#
# addlicense -- a script to insert license comments automatically
#
# This script is part of OSN Commons. Copyright (C) 2024 OSN Developers.
#
# OSN Commons is free software: you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# OSN Commons is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with OSN Commons. If not, see <https://www.gnu.org/licenses/>.
#

me=$0
canonical_name=$(echo $me | rev | cut -d'/' -f1 | rev)

if [ $(echo $me | cut -c1) = "/" ]; then
    me=$canonical_name
fi

version="1.0.0"

usage() {
    echo "Usage: $me [options...] [[directory...] | [-]]"
    echo "Automatically insert license comments to the project's "
    echo "source files."
    echo ""
    echo "Options:"
    echo "  -e, --exclude       Add an exclusion pattern"
    echo "  -i, --include       Add an inclusion pattern"
    echo "  -E, --exclude-file  Exclude a file path"
    echo "  -I, --include-file  Include a file path"
    echo "  -h, --help          Show this help and exit"
    echo "  -v, --version       Show version info and exit"
    echo "  -f, --file          Specify a file containing the license"
    echo "                      notice to insert"
    echo ""
    echo "Bug reports and general questions should be sent to "
    echo "<commons@onesoftnet.eu.org>."
    exit 0
}

show_version() {
    echo "$canonical_name (OSN Commons) v$version"
    echo ""
    echo "Copyright (C) 2024 OSN Developers."
    echo "License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>."
    echo "This is free software: you are free to change and redistribute it."
    echo "There is NO WARRANTY, to the extent permitted by law."
    echo ""
    echo "Written by Ar Rakin."
    exit 0
}

trim_string() {
    echo "$1" | sed -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//'
}

targets=""
exclpats=""
inclpats=""
exclfiles=""
inclfiles=""
license_notice_file=""
license_notice="/*
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */"
stdin_read=""

while [ $# -gt 0 ]; do
    case "$1" in
    -h | --help)
        usage
        ;;

    -v | --version)
        show_version
        ;;

    -e | --exclude)
        if [ -z "$2" ]; then
            echo "$me: option requires an argument -- '$1'" >&2
            echo "Try '$me --help' for more detailed information." >&2
            exit 2
        fi

        if [ "$2" != "$(echo "$2" | tr -d ':')" ]; then
            echo "$me: exclusion patterns must not contain colons (':')" >&2
            exit 2
        fi

        if [ -z "$exclpats" ]; then
            exclpats="$2"
        else
            exclpats="$exclpats:$2"
        fi

        shift
        ;;

    -i | --include)
        if [ -z "$2" ]; then
            echo "$me: option requires an argument -- '$1'" >&2
            echo "Try '$me --help' for more detailed information." >&2
            exit 2
        fi

        if [ "$2" != "$(echo "$2" | tr -d ':')" ]; then
            echo "$me: inclusion patterns must not contain colons (':')" >&2
            exit 2
        fi

        if [ -z "$inclpats" ]; then
            inclpats="$2"
        else
            inclpats="$inclpats:$2"
        fi

        shift
        ;;

    -E | --exclude-file)
        if [ -z "$2" ]; then
            echo "$me: option requires an argument -- '$1'" >&2
            echo "Try '$me --help' for more detailed information." >&2
            exit 2
        fi

        if [ "$2" != "$(echo "$2" | tr -d ':')" ]; then
            echo "$me: file paths must not contain colons (':')" >&2
            exit 2
        fi

        if [ ! -e "$2" ]; then
            echo "$me: $2: No such file or directory" >&2
            exit 2
        fi

        file=$(readlink -f "$2")

        if [ $? -ne 0 ]; then
            echo "$me: $2: Ignoring" >&2
        else
            if [ -z "$exclfiles" ]; then
                exclfiles="$file"
            else
                exclfiles="$exclfiles:$file"
            fi
        fi

        shift
        ;;

    -I | --include-file)
        if [ -z "$2" ]; then
            echo "$me: option requires an argument -- '$1'" >&2
            echo "Try '$me --help' for more detailed information." >&2
            exit 2
        fi

        if [ "$2" != "$(echo "$2" | tr -d ':')" ]; then
            echo "$me: file paths must not contain colons (':')" >&2
            exit 2
        fi

        if [ ! -e "$2" ]; then
            echo "$me: $2: No such file or directory" >&2
            exit 2
        fi

        file=$(readlink -f "$2")

        if [ $? -ne 0 ]; then
            echo "$me: $2: Ignoring" >&2
        else
            if [ -z "$inclfiles" ]; then
                inclfiles="$file"
            else
                inclfiles="$inclfiles:$file"
            fi
        fi

        shift
        ;;

    -f | --file)
        if [ -z "$2" ]; then
            echo "$me: option requires an argument -- '$1'" >&2
            echo "Try '$me --help' for more detailed information." >&2
            exit 2
        fi

        if [ "$2" = "-" ]; then
            if [ -t 0 ]; then
                echo "$me: nothing to read from standard input" >&2
                exit 2
            fi

            if [ ! -z "$stdin_read" ] && [ "$stdin_read" != "notice" ]; then
                echo "$me: multiple options are being directed to standard input" >&2
                exit 2
            fi

            license_notice="$(
                cat
                echo E
            )"
            stdin_read="notice"
        else
            if [ ! -f "$2" ]; then
                echo "$me: $2: No such file or directory" >&2
                exit 2
            fi

            license_notice_file="$2"
            license_notice="$(
                cat "$2"
                echo E
            )"
        fi

        license_notice=${license_notice%E}
        shift
        ;;

    -)
        if [ -t 0 ]; then
            echo "$me: nothing to read from standard input" >&2
            exit 2
        fi

        if [ ! -z "$stdin_read" ] && [ "$stdin_read" != "targets" ]; then
            echo "$me: multiple options are being directed to standard input" >&2
            exit 2
        fi

        while IFS='' read -r line; do
            if [ "$line" != "$(echo "$line" | tr -d ':')" ] || [ -z "$line" ]; then
                echo "$me: target paths must not contain colons (':')" >&2
                exit 2
            fi

            if [ -z "$targets" ]; then
                targets="$line"
            else
                targets="$targets:$line"
            fi
        done

        stdin_read="targets"
        ;;

    -*)
        echo "$me: Invalid option -- '$1'" >&2
        echo "Try '$me --help' for more detailed information." >&2
        exit 2
        ;;

    *)
        if [ "$1" != "$(echo "$1" | tr -d ':')" ] || [ -z "$1" ]; then
            echo "$me: target paths must not contain colons (':')" >&2
            exit 2
        fi

        if [ -z "$targets" ]; then
            targets="$1"
        else
            targets="$targets:$1"
        fi
        ;;
    esac

    shift
done

if [ -z "$targets" ]; then
    echo "$me: No target operands specified" >&2
    echo "Try '$me --help' for more detailed information" >&2
    exit 2
fi

success=0

insert_license() {
    set -e
    local file="$1"
    local tmpfile="$(mktemp)"

    echo "$license_notice" >$tmpfile
    cat $file >>$tmpfile
    mv $tmpfile $file
    set +e
}

process_files() {
    echo "$targets" | while IFS=':' read -r target; do
        local stat_out=$(stat "$target" 2>&1)

        if [ $? -ne 0 ]; then
            echo "$me: $(echo $stat_out | cut -c 7-)" >&2
            continue
        fi

        echo "$me: scanning: $target"
        local find_cmd="find '$target' -type f ! -path \"*/*~\" \
        ! -path \"*/.git/*\" ! -path \"*/.svn/*\" \
        ! -path \"*/.hg/*\" ! -path \"*/CVS/*\" \
        ! -path \"*/.bzr/*\" ! -path \"$me\""

        if [ ! -z "$exclpats" ]; then
            local ifs="$IFS"

            IFS=":"

            for exclpat in $exclpats; do
                find_cmd="$find_cmd ! -path \"$exclpat\""
            done

            IFS="$ifs"
        fi

        if [ ! -z "$inclpats" ]; then
            local ifs="$IFS"

            IFS=":"

            for inclpat in $inclpats; do
                find_cmd="$find_cmd -path \"$inclpat\""
            done

            IFS="$ifs"
        fi

        local files=$(eval $find_cmd)

        if [ -z "$files" ]; then
            echo "$me: no files found" >&2
            continue
        fi

        local r_license_notice_file

        if [ ! -z "$license_notice_file" ]; then
            r_license_notice_file=$(readlink -f "$license_notice_file")
        fi

        for file in $files; do
            local rpath=$(readlink -f "$file")

            if [ ! -z "$license_notice_file" ] && [ "$rpath" = "$r_license_notice_file" ]; then
                continue
            fi

            if [ ! -z "$exclfiles" ]; then
                local ifs="$IFS"

                IFS=":"

                for exclfile in $exclfiles; do
                    if [ "$rpath" = "$exclfile" ]; then
                        continue 2
                    fi
                done

                IFS="$ifs"
            fi

            if [ ! -z "$inclfiles" ]; then
                local ifs="$IFS"

                IFS=":"

                for inclfile in $inclfiles; do
                    if [ "$rpath" = "$inclfile" ]; then
                        break
                    fi
                done

                if [ "$rpath" != "$inclfile" ]; then
                    continue
                fi

                IFS="$ifs"
            fi

            if file "$file" -b | grep -Eq 'binary|ELF|executable|data'; then
                echo "$me: skipping binary/data file: $file"
                continue
            fi

            local license_notice_size=$(echo "$license_notice" | wc -c)
            local part=$(sed ':a; /^$/d; $!{N; ba}; s/^[[:space:]]*//' $file | head -c $license_notice_size)

            if [ "$license_notice" = "$part" ]; then
                echo "$me: license notice already present in: $file"
                success=1
                continue
            fi

            echo "$me: inserting license comment to: $file"
            insert_license "$file"
        done

        success=1
    done
}

process_files

if [ $success -ne 1 ]; then
    exit 1
fi