Git prompt for ZSH

# don't forget chmod +x ~/.zsh/git-prompt.zsh

suppress_errors() {
  # Syntactic sugar to ignore any errors. I created it because I can never
  # remember that 2> represents stderr.
  eval "$1" 2>/dev/null
}

git_prompt() {
  # Colors lifted from https://www.nordtheme.com/docs/colors-and-palettes
  local BRANCH_STYLE="%F{172}"          # Aurora Yellow (nord13)
  local BEHIND_STYLE="%F{196}"          # Aurora Red (nord11)
  local AHEAD_STYLE="%F{84}"            # Aurora Green (nord14)
  local UNSTAGED_STYLE="%F{196}"        # Aurora Red (nord11)
  local STAGED_STYLE="%F{38}"           # Aurora Blue (nord9)
  local UNTRACKED_STYLE="%F{141}"       # Aurora Purple (nord15)

  BRANCH=$(suppress_errors "git symbolic-ref --short HEAD")

  # if the length of $BRANCH is not (!) zero (-z) then...
  if [ ! -z $BRANCH ]; then
    # Exclude any untracked files from status
    BEHIND=$(git status --untracked-files=no | grep 'Your branch is behind')
    AHEAD=$(git status --untracked-files=no | grep 'Your branch is ahead')

    # See https://git-scm.com/docs/git-status#_short_format for more details.
    # I think, big question mark on whether or not I am rignt, the following is
    # true.
    #
    # - A leading space indicates that a change has been made, but not yet staged
    # - A trailing space indicates that changes has been staged
    #
    # There is some weirdness with merge conflicts i'm not accounting for, but in
    # general we can expect the following from tracked files.
    #
    #   - M (Modified)
    #   - D (Deleted)
    #   - R (Renamed)
    #   - C (Copied)
    #   - ?? (Untracked)

    # Find unstaged changes - note the leading space
    UNSTAGED_CHANGES=$(git status --short | grep '^\( M\| D\| R\| C\)')

    # Find staged changes - note the trailing space
    STAGED_CHANGES=$(git status --short | grep '^\(M \|D \|R \|C \)')

    # Find untracked files
    UNTRACKED_CHANGES=$(git status --short | grep '^??')

    echo -n "${BRANCH_STYLE} [$BRANCH]"

    if [ ! -z "$BEHIND" ]; then
        echo -n " ${BEHIND_STYLE}↓"
    fi

    if [ ! -z "$AHEAD" ]; then
        echo -n " ${AHEAD_STYLE}↑"
    fi

    if [ ! -z "$UNSTAGED_CHANGES" ]; then
        echo -n " ${UNSTAGED_STYLE}✖"
    fi

    if [ ! -z "$STAGED_CHANGES" ]; then
        echo -n " ${STAGED_STYLE}●"
    fi

    if [ ! -z "$UNTRACKED_CHANGES" ]; then
        echo -n " ${UNTRACKED_STYLE}?"
    fi
  fi
}