.bash_prompt

prompt_function() {
  local previous_return_value=$?;

  local         BLACK="\[\033[0;30m\]"
  local           RED="\[\033[0;31m\]"
  local         GREEN="\[\033[0;32m\]"
  local        YELLOW="\[\033[0;33m\]"
  local          BLUE="\[\033[0;34m\]"
  local       MAGENTA="\[\033[0;35m\]"
  local          CYAN="\[\033[0;36m\]"
  local    LIGHT_GRAY="\[\033[0;37m\]"
  local     LIGHT_RED="\[\033[1;31m\]"
  local   LIGHT_GREEN="\[\033[1;32m\]"
  local  LIGHT_YELLOW="\[\033[1;33m\]"
  local    LIGHT_BLUE="\[\033[1;34m\]"
  local LIGHT_MAGENTA="\[\033[1;35m\]"
  local    LIGHT_CYAN="\[\033[1;36m\]"
  local         WHITE="\[\033[1;37m\]"
  local    COLOR_NONE="\[\e[0m\]"

  local unclean_state="${LIGHT_YELLOW}⚡"
  local changes_to_push="${LIGHT_YELLOW}↑"
  local changes_to_pull="${LIGHT_YELLOW}↓"
  local changes_to_push_and_pull="${LIGHT_YELLOW}↕"

  local git_status="$(git status 2> /dev/null)"
  local branch_pattern="#? ?On branch ([^${IFS}]*)"
  local remote_pattern="#? ?Your branch is (.*) of"
  local diverge_pattern="#? ?Your branch and (.*) have diverged"

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

  # add an else if or two here if you want to get more specific
  if [[ ${git_status} =~ ${remote_pattern} ]]; then
    if [[ ${BASH_REMATCH[1]} == "ahead" ]]; then
      local remote="$changes_to_push"
    else
      local remote="$changes_to_pull"
    fi
  fi
  if [[ ${git_status} =~ ${diverge_pattern} ]]; then
    local remote="$changes_to_push_and_pull"
  fi
  if [[ ${git_status} =~ ${branch_pattern} ]]; then
    local branch=${BASH_REMATCH[1]}
    local git_branch=" (${branch})${remote}${state}"
  fi

  [[ $(who am i) =~ \([0-9\.]+\)$ ]] && local host=" \\u@\h "

  local path="${LIGHT_BLUE}\w"
  local branch="${LIGHT_MAGENTA}$git_branch"

  local prompt="$path$branch$host${COLOR_NONE}"
  if test $previous_return_value -eq 0; then
    PS1="${prompt}\\\$ "
  else
    PS1="${prompt}${RED}\\\$${COLOR_NONE} "
  fi
}