Bash prompt (virtualenv + git status)

prompt.sh

RED="\033[0;31m"
YELLOW="\033[0;33m"
GREEN="\033[0;32m"
BLUE="\033[0;34m"
LIGHT_GRAY="\033[0;37m"
COLOR_NONE="\033[0;0m"

RE_GIT_BRANCH="^On branch ([^${IFS}]*)"
RE_GIT_REMOTE="Your branch is (.*) '"
RE_GIT_GAP="Your branch is .* ([0-9]+) commits?"
RE_GIT_DIVERGE="Your branch and (.*) have diverged"


function gen_prompt {
    # Handle last command's return value
    retval=$?
    if [ $retval -eq 0 ]; then
        last_ret="${GREEN}${retval}↩${COLOR_NONE}"
    else
        last_ret="${RED}${retval}↩${COLOR_NONE}"
    fi

    # Handle Git repository informations
    if [ ! -d "$(pwd)/.git" ]; then
        git_infos=""
    else
        git_status="$(LC_ALL=en_US.UTF-8 git status 2> /dev/null)"
        
        # Handle uncommited changes
        if [[ ! ${git_status} =~ "working directory clean" ]]; then
            state="${RED}⚡"
        else
            state="${GREEN}✓"
        fi

        # Handle commits gap with remote
        if [[ ${git_status} =~ ${RE_GIT_REMOTE} ]]; then
            if [[ ${BASH_REMATCH[1]} == "ahead of" ]]; then
                remote="${YELLOW}↑"
                remote_symbol="+"
            elif [[ ${BASH_REMATCH[1]} == "up-to-date with" ]]; then
                remote=""
                remote_symbol=""
            else
                remote="${YELLOW}↓"
                remote_symbol="-"
            fi
            if [[ ${git_status} =~ ${RE_GIT_GAP} ]]; then
                remote="${remote_symbol}${BASH_REMATCH[1]}${remote}"
            fi
        else
            remote=""
        fi

        # Handle diverged branches
        if [[ ${git_status} =~ ${RE_GIT_DIVERGE} ]]; then
            remote="${YELLOW}↕"
        fi

        # Generate git informations summary
        if [[ ${git_status} =~ ${RE_GIT_BRANCH} ]]; then
            branch=${BASH_REMATCH[1]}
            git_infos=" (${branch} ${remote}${state}${GREEN})"
        else
            git_infos=""
        fi
    fi

    # Handle virtualenvs
    if [ "$VIRTUAL_ENV" != "" ]; then
        venv="($(basename $VIRTUAL_ENV))"
    else
        venv=""
    fi

    # Build the prompt
    current_path=`pwd | sed "s|${HOME}|~|"`
    main_part="${YELLOW}$(whoami)${COLOR_NONE}@${YELLOW}$(hostname -s)${LIGHT_GRAY}:${BLUE}${current_path}"

    PS1L="$venv${LIGHT_GRAY}[${main_part}${GREEN}${git_infos}${LIGHT_GRAY}]${COLOR_NONE}"
    PS1L_NOCOLOR=$(echo "${PS1L}" | sed -r 's|\\033\[[0-9];[0-9]+m||g')

    # Go figure why there is always a 20 characters difference
    PS1=$(printf "%s%$((${COLUMNS}-${#PS1L_NOCOLOR}+20))s \n\$ " "${PS1L}" "${last_ret}")
}

PROMPT_COMMAND="gen_prompt