# Copyright (C) 2015 Facebook, Inc
# Maintained by Ryan McElroy <[email protected]>
#
# Inspiration and derivation from git-completion.bash by Shawn O. Pearce.
#
# Distributed under the GNU General Public License, version 2.0.
#
# ========================================================================
#
# Quickly determines the and emits some useful information about the state
# of your current mercurial or git repository. Useful for PS1 prompts.
#
# Design goals:
#  * Useful for both git and mercurial
#  * Portable to both zsh and bash
#  * Portable to both Mac (BSD-based utils) and Linux (GNU-based utils)
#  * As fast as possible given the above constraints (few command invocations)
#  * Avoids invoking git or mercurial, which may be slow on large repositories
#
# To use from zsh:
#
#   NOTE! the single quotes are important; if you use double quotes
#   then the prompt won't change when you chdir or checkout different
#   branches!
#
#   setopt PROMPT_SUBST
#   source /path/to/scm-prompt
#   export PS1='$(_scm_prompt)$USER@%m:%~%% '
#
# To use from bash:
#
#   source /path/to/scm-prompt
#   export PS1="\$(_scm_prompt)\u@\h:\W\$ "
#
#   NOTE! You *EITHER* need to single-quote the whole thing *OR* back-slash
#   the $(...) (as above), but not both. Which one you use depends on if
#   you need the rest of your PS1 to interpolate variables.
#
# You may additionally pass a format-string to the scm_info command. This
# allows you to control the format of the prompt string without interfering
# with the prompt outside of a mercurial or git repository. For example:
#
#   $(_scm_prompt "%s")
#
# The default format string is " (%s)" (note the space)
#
# Options: you may want to set these environment variables
#  * HOME_IS_NOT_A_REPO : Stop walking up the filesystem looking for a git or
#    hg repo at (but not including) /home instead of /.  This helps when /home
#    is a remote or autofs mount point.
#  * WANT_OLD_SCM_PROMPT : Use '%s' as the formatting for the prompt instead
#    of ' (%s)'
#
# Notes to developers:
#
#  * Aliases can screw up the default commands. To prevent this issue, use
#    the 'builtin' prefix for built-in shell commands (eg, 'cd' and 'echo')
#    and use the 'command' prefix for external commands that you do not want
#    to invoke aliases for (eg, 'grep', 'cut').
#
# =========================================================================
#

_find_most_relevant() {
    # We don't want to output all remote bookmarks because there can be many
    # of them. This function finds the most relevant remote bookmark using this
    # algorithm:
    # 1. If 'master' or '@' bookmark is available then output it
    # 2. Sort remote bookmarks and output the first in reverse sorted order (
    # it's a heuristic that tries to find the newest bookmark. It will work well
    # with bookmarks like 'release20160926' and 'release20161010').
    relevantbook="$(command grep -m1 -E -o "^[^/] /(master|@)$" <<< "$1")"
    if [[ -n $relevantbook ]]; then
        builtin echo $relevantbook
        return 0
    fi

    builtin echo "$(command sort -r <<< "$1" | command head -n 1)"
}

_hg_prompt() {
  local hg br extra
  hg="$1"

  if [[ -f "$hg/bisect.state" ]]; then
    extra="|BISECT"
  elif [[ -f "$hg/histedit-state" ]]; then
    extra="|HISTEDIT"
  elif [[ -f "$hg/graftstate" ]]; then
    extra="|GRAFT"
  elif [[ -f "$hg/unshelverebasestate" ]]; then
    extra="|UNSHELVE"
  elif [[ -f "$hg/rebasestate" ]]; then
    extra="|REBASE"
  elif [[ -d "$hg/merge" ]]; then
    extra="|MERGE"
  elif [[ -L "$hg/store/lock" ]]; then
    extra="|STORE-LOCKED"
  elif [[ -L "$hg/wlock" ]]; then
    extra="|WDIR-LOCKED"
  fi
  local dirstate="$( \
    ( [[ -f "$hg/dirstate" ]]