#!/bin/bash
# Copyright (C) 2009 Bart Trojanowski <bart@jukie.net>
#
# 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 version 2 of the License.
#
# 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, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

needs_escape=true

shrink_host=2tu.us
test -f ~/.bti && source ~/.bti || test -f ~/.config/bti && source ~/.config/bti

while test -n "$1" ; do
        word="$1"
        shift
        case "$word" in
            --escaped)
                needs_escape=
                ;;
            --help|-h)
                cat <<END
bti-shrink-urls - convert URLs to a shorter form using a web service

    $0 [--escaped] [<url>]

Currently supported: 2tu.us (default), bit.ly, j.mp.
END
                exit 0
                ;;
            *)
                URL=$word
                ;;
        esac
done

function convert_url() {
        local url=$1
        test -n "$url" || return 1
        test "${url%%:*}" = 'http' || return 1

        local urllen="${#url}"

        # http://en.wikipedia.org/wiki/Percent-encoding
        if test -n "$needs_escape" ; then
                url=$(echo "$url" | sed -e 's/\%/%25/g' \
                                        -e 's/!/%21/g' \
                                        -e 's/*/%2A/g' \
                                        -e "s/'/%27/g" \
                                        -e 's/(/%28/g' \
                                        -e 's/)/%29/g' \
                                        -e 's/;/%3B/g' \
                                        -e 's/:/%3A/g' \
                                        -e 's/@/%40/g' \
                                        -e 's/&/%26/g' \
                                        -e 's/=/%3D/g' \
                                        -e 's/+/%2B/g' \
                                        -e 's/\$/%24/g' \
                                        -e 's/,/%2C/g' \
                                        -e 's,/,%2F,g' \
                                        -e 's/?/%3F/g' \
                                        -e 's/#/%23/g' \
                                        -e 's/\[/%5B/g' \
                                        -e 's/]/%5D/g')
        fi

        case $shrink_host in
        2tu.us)
            local submit="http://2tu.us/?save=y&url=$url"
            local res=$(wget -q -O - "$submit" | awk -F"'" '/Your tight URL is:/ { print $2 }')
            ;;
        bit.ly|j.mp)
            if [ -z "$shrink_bitly_login" -o -z "$shrink_bitly_key" ]; then
                echo "To use $shrink_host you must set 'shrink_bitly_login' and 'shrink_bitly_key' in ~/.bti" >&2
                exit 1
            fi
            local submit="http://api.bit.ly/v3/shorten?format=txt&login=$shrink_bitly_login&apiKey=$shrink_bitly_key&domain=$shrink_host&longUrl=$url"
            local res=$(wget -q -O - "$submit")
            ;;
        *)
            echo "Shrinking with $shrink_host is not supported." >&2
            exit 1
            ;;
        esac

        if test "${res%%:*}" = 'http' -a "${#res}" -lt "$urllen" ; then
                echo $res
                return 0
        fi
        return 1
}

function die() {
        echo >&2 $@
        exit 1
}

if test -n "$URL" ; then
        convert_url "$URL" || die "Failed to shrink '$URL'"
        exit $?
fi

test -t 0 && echo >&2 "Type in some urls and I'll try to shrink them for you..."
while read line ; do
        convert_url "$line" || echo $line
done