git-mix

#!/bin/bash
#
# git-mix - syntactic sugar for configuring "git mixdown"
#
# Wrapper around git-config(1) which makes it convenient to configure
# mix branches for use with git-mixdown.
#
# Copyright (C) 2014 Adam Spiers <git@adamspiers.org>
#
# The software in this repository 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 software 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 <http://www.gnu.org/licenses/>.

default_mix_branch=working

usage () {
    # Call as: usage [EXITCODE] [USAGE MESSAGE]
    exit_code=1
    if [[ "$1" == [0-9] ]]; then
        exit_code="$1"
        shift
    fi
    if [ -n "$1" ]; then
        echo >&2 "$*"
        echo
    fi

    me='git mix'

    cat <<EOF >&2
usage: $me [options] [--] [arguments]

Arguments:
  <no arguments>           Show all available mixes
  <target>                 Show mix for target branch
  <target> A B [C ...]     Set mix for target branch to branches A, B, ...
  [<target>] +D [-B ...]   Add/remove branches to/from mix for target
                           branch (defaults to 'working')

Options:
  -h, --help               Show this help and exit
  -d <target>              Remove mix for target branch

You can also change the mix via git config, e.g. edit the mix order
via git config --edit.
EOF
    exit "$exit_code"
}

parse_opts () {
    checkout=

    while [ $# != 0 ]; do
        case "$1" in
            -h|--help)
                usage 0
                ;;
            -d)
                if [ $# != 2 ]; then
                    usage
                fi
                delete_mix "$2"
                exit 0
                ;;
            --)
                shift
                break
                ;;
            *)
                break
                ;;
        esac
    done

    ARGV=( "$@" )
}

fatal () {
    echo "$*" >&2
    exit 1
}

show_mixes () {
  # git config --list | grep "^mixdown\." | sed 's/^mixdown\.//' | \
  #     sort -t= -k1,1 --stable
  mixes=( $(
      git config --list | grep "^mixdown\." | \
          sed -e 's/^mixdown\.//' -e 's/=.*//' | sort -u
  ) )
  for mix in "${mixes[@]}"; do
      unescape_mix
      echo -n "$mix: "
      echo `list_mix "$mix"` # evil hack to convert new lines to spaces
  done
}

list_mix () {
    mix="$1"
    escape_mix
    if git config --get "mixdown.$mix" >/dev/null 2>&1; then
        git config --list | grep "^mixdown\.$mix=" | sed "s/^mixdown\.$mix=//"
    else
        fatal "ERROR: No such mix configured for '$mix'"
    fi
}

delete_mix () {
    mix="$1"
    escape_mix
    git config --unset-all "mixdown.$mix"
}

set_mix () {
    mix="$1"
    escape_mix
    shift

    delete_mix "$mix"

    for branch in "$@"; do
        git config --add "mixdown.$mix" "$branch"
    done
}

SLASH="-x2f-"

escape_mix () {
    mix="${mix//\//$SLASH}"
}

unescape_mix () {
    mix="${mix//$SLASH/\/}"
}

change_mix () {
    mix="$1"
    escape_mix
    shift

    key="mixdown.${mix//\//_}"

    for change in "$@"; do
        case "$change" in
            -*)
                branch="${change#-}"
                regexp="^$branch\$"
                if git config --get "$key" "$regexp" >/dev/null; then
                    git config --unset "$key" "$regexp"
                else
                    echo "WARNING: $branch was not in the mix for $mix" >&2
                fi
                ;;
            +?*)
                git config --add "$key" "${change#+}"
                ;;
            *)
                usage "Invalid change '$change'."
                ;;
        esac
    done
}

main () {
    parse_opts "$@"
    set -- "${ARGV[@]}"

    if [ $# = 0 ]; then
        show_mixes
    elif [[ $1 == [-+]* ]]; then
        change_mix "$default_mix_branch" "$@"
    elif [ $# = 1 ]; then
        list_mix "${1,,}"
    else
        mix="${1,,}"
        shift
        if [[ $1 == [-+]* ]]; then
            change_mix "$mix" "$@"
        else
            set_mix "$mix" "$@"
        fi
    fi
}

main "$@"