port of https://gist.github.com/zwily/631fcef80c0e00a8b8ce to zsh

git_prompt.zsh

# in your ~/.zshrc add these lines:
#
# source path/to/this/file
# precmd() { zsh_prompt }
#



NONE="%{\e[0m%}"    # unsets color to term's fg color
K="%{\e[0;30m%}"    # black
R="%{\e[0;31m%}"    # red
G="%{\e[0;32m%}"    # green
Y="%{\e[0;33m%}"    # yellow
B="%{\e[0;34m%}"    # blue
M="%{\e[0;35m%}"    # magenta
C="%{\e[0;36m%}"    # cyan
W="%{\e[0;37m%}"    # white
EMK="%{\e[1;30m%}"
EMR="%{\e[1;31m%}"
EMG="%{\e[1;32m%}"
EMY="%{\e[1;33m%}"
EMB="%{\e[1;34m%}"
EMM="%{\e[1;35m%}"
EMC="%{\e[1;36m%}"
EMW="%{\e[1;37m%}"
BGK="%{\e[40m%}"
BGR="%{\e[41m%}"
BGG="%{\e[42m%}"
BGY="%{\e[43m%}"
BGB="%{\e[44m%}"
BGM="%{\e[45m%}"
BGC="%{\e[46m%}"
BGW="%{\e[47m%}"

# returns a truncated path (used in prompt)
truncated_pwd () {
  local maxlen=25
  if [[ $PWD == $HOME* ]]; then
    newPWD="~${PWD#$HOME}"
  else
    newPWD=${PWD}
  fi
  if [ ${#newPWD} -gt $maxlen ]; then
    local pwdoffset=$(( ${#newPWD} - $maxlen + 3 ))
    newPWD="…${newPWD:$pwdoffset:$maxlen}"
  fi
  echo $newPWD
}

__git_prompt ()
{
    local g="$(git rev-parse --git-dir 2>/dev/null)"
    if [ -n "$g" ]; then
        local r
        local b
        if [ -d "$g/../.dotest" ]
        then
            if test -f "$g/../.dotest/rebasing"
            then
                r="|REBASE"
            elif test -f "$g/../.dotest/applying"
            then
                r="|AM"
            else
                r="|AM/REBASE"
            fi
            b="$(git symbolic-ref HEAD 2>/dev/null)"
        elif [ -f "$g/.dotest-merge/interactive" ]
        then
            r="|REBASE-i"
            b="$(cat "$g/.dotest-merge/head-name")"
        elif [ -d "$g/.dotest-merge" ]
        then
            r="|REBASE-m"
            b="$(cat "$g/.dotest-merge/head-name")"
        elif [ -f "$g/MERGE_HEAD" ]
        then
            r="|MERGING"
            b="$(git symbolic-ref HEAD 2>/dev/null)"
        else
            if [ -f "$g/BISECT_LOG" ]
            then
                r="|BISECTING"
            fi
            if ! b="$(git symbolic-ref HEAD 2>/dev/null)"
            then
                if ! b="$(git describe --exact-match HEAD 2>/dev/null)"
                then
                    b="$(cut -c1-7 "$g/HEAD")..."
                fi
            fi
        fi

        local git_status="$(git status 2> /dev/null)"

        local remote
        local ahead_pattern="# Your branch is ahead of .* by ([0-9]+) commit"
        local behind_pattern="# Your branch is behind .* by ([0-9]+) commit"
        local diverge_pattern="and have ([0-9]+) and ([0-9]+) different"
        if [[ ${git_status} =~ ${ahead_pattern} ]]; then
            remote="${M}↑${BASH_REMATCH[1]}"
        elif [[ ${git_status} =~ ${behind_pattern} ]]; then
            remote="${B}↓${BASH_REMATCH[1]}"
        elif [[ ${git_status} =~ ${diverge_pattern} ]]; then
            remote="${M}↑${BASH_REMATCH[1]}${Y}↓${BASH_REMATCH[2]}"
        fi

        local state
        if [[ ! ${git_status} =~ "working directory clean" ]]; then
            state="${R}●"
        fi

        echo " [${b##refs/heads/}$r$remote$state${NONE}]"
    else
        #default RPROMPT
        echo "${EMK}[%* %D]${NONE}"
    fi
}
zsh_prompt() {
    RPROMPT="$(__git_prompt)"
}