Inserts copyright text into files if needed

copyright.sh

#!/usr/bin/env bash -eu
################################################################################
#
#   Copyright (c) 2014 Anthony Trinh.
#
#   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.
#
################################################################################
copyright="copyright.txt"
dir="."
includes=(-name "*.sh")
excludes=(-not -path "*test/.util/*")
comment="#"
verbose=false

#----------------------------------------------------------------------
# Prints this program's help text
#----------------------------------------------------------------------
usage() {
    name=$(basename "$0")
    echo "Inserts copyright text into files if needed

Usage: ./$name [OPTIONS]

OPTIONS:

  -c <FILE>     Copyright template to insert into files that are missing
                the copyright notice. This file is copied verbatim into files
                after the shebang line.
                (default: ./$copyright)

  -d <DIR>      Directory to recursively scan for files.
                (default: $dir)

  -i <PATT>     Pattern of filenames to include in scan.
                (default: ${includes[1]})

  -x <PATT>     Pattern of filenames to exclude from scan.
                (default: ${excludes[2]})

  -m <CHAR>     Line-prefix character(s), used to find existing copyright.
                (default: $comment)

  -v|--verbose  Show debug messages

EXAMPLES:

  ./$name
  ./$name -d my_files
  ./$name -c copyleft.txt
  ./$name -c copyleft.txt -d my_files -n \"*.txt\"
  ./$name -i \"*.sh\" -x \"foo/sh/*\" -x \"bar/txt/*\""
}

#----------------------------------------------------------------------
# Loads command-line arguments
#----------------------------------------------------------------------
args_load() {
    while [[ $# > 0 ]]; do
        key="$1"
        shift

        case "$key" in
            -c)
                copyright="$1"
                shift;;

            -d)
                dir="$1"
                shift;;

            -i)
                includes=(-name "$1")
                shift;;

            -m)
                comment="$1"
                shift;;

            -x)
                excludes+=(-not -path "$1")
                shift;;

            -h|--help)
                usage
                exit 0
                ;;

            -v|--verbose)
                verbose=true
                ;;

            *)
                fail unknown argument: "$key"
                ;;
        esac
    done
}

#----------------------------------------------------------------------
# Validates the loaded command-line arguments
#----------------------------------------------------------------------
args_validate() {
    [[ ! -d "$dir" ]] && fail "directory not found: $dir"
    [[ ! -f "$copyright" ]] && fail "file not found: $copyright"
    :
}

#----------------------------------------------------------------------
# Adds copyright text to a file, while preserving the shebang line
#----------------------------------------------------------------------
copyright_file() {
    file=${1?}

    _echo scanning $file
    has_copyright=$(grep "$comment\s*Copyright" "$file" || :)
    if [ ! -z "$has_copyright" ]; then
        _echo already copyrighted
    else
        echo adding copyright to "$file"

        buf=
        first_line=$(head -1 "$file")
        has_shebang=$(echo "$first_line" | grep "#\!" || :)
        if [ ! -z "$has_shebang" ]; then
            buf="$first_line"
            buf+="$(cat "$copyright")"
            buf+=$'\n'
            buf+="$(tail -n +2 "$file")"
        else
            buf="$(cat "$copyright")"
            buf+=$'\n'
            buf+="$(cat "$file")"
        fi

        echo -e "$buf" >"$file"
    fi
}

#----------------------------------------------------------------------
# Adds copyright text to all shell files in a directory
#----------------------------------------------------------------------
copyright_all_files() {
    while read -r file
    do
        [ -z "$file" ] && continue
        copyright_file "$file"
    done < <(find "$dir" -type f "${includes[@]}" "${excludes[@]}")
}

#----------------------------------------------------------------------
# Prints a message only if $verbose is true
#----------------------------------------------------------------------
_echo() {
    if [[ "$verbose" == true ]]; then
        echo "$@"
    fi
}

#----------------------------------------------------------------------
# Prints an error message and then exits with code 1
#----------------------------------------------------------------------
fail() {
    echo error: "$@" >&2
    exit 1
}

#----------------------------------------------------------------------
# Main
#----------------------------------------------------------------------
args_load "$@"
args_validate
copyright_all_files