#!/bin/bash
set +o posix

quiet_cd() {
  cd "$@" >/dev/null
}

symlink_target_directory() {
  local target="$(readlink "$1")"
  local target_dirname="$(dirname "$target")"
  local directory="$2"
  quiet_cd "$directory" && quiet_cd "$target_dirname" && pwd -P
}

BREW_FILE_DIRECTORY="$(quiet_cd "${0%/*}/" && pwd -P)"
HOMEBREW_BREW_FILE="${BREW_FILE_DIRECTORY%/}/${0##*/}"
HOMEBREW_PREFIX="${HOMEBREW_BREW_FILE%/*/*}"

# Default to / prefix if unset or the bin/brew file.
if [[ -z "$HOMEBREW_PREFIX" || "$HOMEBREW_PREFIX" = "$HOMEBREW_BREW_FILE" ]]
then
  HOMEBREW_PREFIX="/"
fi

HOMEBREW_REPOSITORY="$HOMEBREW_PREFIX"

# Resolve the bin/brew symlink to find Homebrew's repository
if [[ -L "$HOMEBREW_BREW_FILE" ]]
then
  BREW_FILE_DIRECTORY="$(symlink_target_directory "$HOMEBREW_BREW_FILE" "$BREW_FILE_DIRECTORY")"
  HOMEBREW_REPOSITORY="${BREW_FILE_DIRECTORY%/*}"
fi

# Try to find a /usr/local HOMEBREW_PREFIX where possible (for bottles)
if [[ -L "/usr/local/bin/brew" ]]
then
  USR_LOCAL_BREW_FILE_DIRECTORY="$(symlink_target_directory "/usr/local/bin/brew" "/usr/local/bin")"
  USR_LOCAL_HOMEBREW_REPOSITORY="${USR_LOCAL_BREW_FILE_DIRECTORY%/*}"
  if [[ "$HOMEBREW_REPOSITORY" = "$USR_LOCAL_HOMEBREW_REPOSITORY" ]]
  then
    HOMEBREW_PREFIX="/usr/local"
  fi
fi

HOMEBREW_LIBRARY="$HOMEBREW_REPOSITORY/Library"

# Whitelist and copy to HOMEBREW_* all variables previously mentioned in
# manpage or used elsewhere by Homebrew.
for VAR in AWS_ACCESS_KEY_ID AWS_SECRET_ACCESS_KEY BINTRAY_USER BINTRAY_KEY \
           BROWSER EDITOR GIT PATH VISUAL
do
  # Skip if variable value is empty.
  [[ -z "${!VAR}" ]] && continue

  VAR_NEW="HOMEBREW_${VAR}"
  # Skip if existing HOMEBREW_* variable is set.
  [[ -n "${!VAR_NEW}" ]] && continue
  export "$VAR_NEW"="${!VAR}"
done

if [[ -n "$HOMEBREW_ENV_FILTERING" ]]
then
  PATH="/usr/bin:/bin:/usr/sbin:/sbin"

  FILTERED_ENV=()
  for VAR in HOME SHELL PATH TERM LOGNAME USER "${!HOMEBREW_@}"
  do
    FILTERED_ENV+=( "${VAR}=${!VAR}" )
  done

  /usr/bin/env -i "${FILTERED_ENV[@]}" /bin/bash "$HOMEBREW_LIBRARY/Homebrew/brew.sh" "$@"
else
  source "$HOMEBREW_LIBRARY/Homebrew/brew.sh"
fi
