better bash prompt for git repos

bash_prompt.sh

# Colors

RED="\[\033[0;31m\]"
YELLOW="\[\033[0;33m\]"
BLUE="\[\033[0;34m\]"
LIGHT_RED="\[\033[1;31m\]"
LIGHT_GREEN="\[\033[1;32m\]"
WHITE="\[\033[1;37m\]"
LIGHT_GRAY="\[\033[0;37m\]"
COLOR_NONE="\[\e[0m\]"


# Used by GIT and SVN for clean directories
GREEN="\[\033[0;32m\]"

# Used by SVN for modified files
# Used by GIT for files tracked, modified but not staged.
YELLOW="\[\033[0;33m\]"

# Used by GIT for staged, but modified. Shouldn't normally see this, the way I work.
CYAN="\[\033[0;36m\]"

# Used by GIT and SVN for unrevisioned / untracked files
RED="\[\033[0;31m\]"

function is_git_repo {
  git branch > /dev/null 2>&1
}

function set_git_branch {

  # Capture the output of the "git status" command.
  git_status="$(git status 2>&1)"

  # Set color based on clean/staged/dirty.
  if [[ ${git_status} =~ "working directory clean" ]]; then
    state="${GREEN}"
  elif [[ ${git_status} =~ "working tree clean" ]]; then
    state="${GREEN}"
  elif [[ ${git_status} =~ "Changes to be committed" ]]; then
    state="${YELLOW}"
  elif [[ ${git_status} =~ "fatal: this operation" ]]; then
    state="${BLUE}"
  else
    state="${RED}"
  fi

  # Set arrow icon based on status against remote.
  ahead_pattern="Your branch is ahead of"
  behind_pattern="Your branch is behind"
  diverge_pattern="Your branch and (.*) have diverged"

  if [[ ${git_status} =~ ${ahead_pattern} ]]; then
      compared_to_remote="↑"

  elif [[ ${git_status} =~ ${behind_pattern} ]]; then
      compared_to_remote="↓"

  elif [[ ${git_status} =~ ${diverge_pattern} ]]; then
      compared_to_remote="↕"

  else
      compared_to_remote=""
  fi


  # Get the name of the branch.
  branch_pattern="On branch ([^${IFS}]*)"
  if [[ ${git_status} =~ ${branch_pattern} ]]; then
    branch=${BASH_REMATCH[1]}
  else
    detached_pattern="HEAD detached at ([^${IFS}]*)"
    if [[ ${git_status} =~ ${detached_pattern} ]]; then
      branch=${BASH_REMATCH[1]}
    else
      branch="no branch"
    fi
  fi

  # Get Current branch. If no branch, warn about detached HEAD
  #cur_branch=$(git rev-parse --abbrev-ref HEAD)
  #[[ ${cur_branch} == "HEAD" ]] || branch=${cur_branch} &&\
  #  branch="DETACHED: $(git rev-parse --short HEAD)"

  # Are we in a submodule?
  dotgit="$(git rev-parse --show-toplevel)/.git"
  [[ -f "${dotgit}" ]] && sub="<sub>" || sub=""


  # Set the final branch string that gets used in the caller function
  GITPROMPT="${state}(${branch})${sub}${compared_to_remote}${COLOR_NONE} "
}


# Return the prompt symbol to use, colorized based on the return value of the
# previous command.
function set_prompt_symbol () {
  if test $1 -eq 0 ; then
      PROMPT_SYMBOL="\$"
  else
      PROMPT_SYMBOL="${RED}\$${COLOR_NONE}"
  fi
}

# Set the full bash prompt.
function set_bash_prompt () {
  #{{{
  # Set the PROMPT_SYMBOL variable. We do this first so we don't lose the
  # return value of the last command.
  set_prompt_symbol $?

  # Set the GITPROMPT variable.
  GITPROMPT=""
  PS1="[\u@${HH}][\w] ${GITPROMPT}${PROMPT_SYMBOL}\n$ "
  if is_git_repo ; then
    set_git_branch
  fi

  # Set the bash prompt variable.
  PS1="[\u@${HH}][\w] ${GITPROMPT}${PROMPT_SYMBOL}\n$ "
}
#}}}

PROMPT_COMMAND=set_bash_prompt