#!/bin/bash
# Copyright (C) 2016 Ian Kelling

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at

#     http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

teeu() {
    local help="Usage: teeu [-h|--help] FILE [LINE]
Append LINE if it's not already in FILE

If no LINE is specified, process each line from STDIN.
teeu is short for tee unique.

-h|--help  display this message"

    if [[ $1 == --help || $1 == -h ]]; then
        echo "$help"
        return
    fi

    if (( ${#@} == 0 )) ; then
        echo "teeu error: need 1 or more arguments"
        echo "$help"
        return 1
    fi
    local MAPFILE
    (( ${#@} >= 2 )) && MAPFILE="${@:2}" || mapfile -t
    for line in "${MAPFILE[@]}"; do
        grep -xFq "$line" "$1" &>/dev/null || tee -a "$1" <<<"$line"
    done
    return 0
}
teeu "$@"