#!/bin/bash
set +o posix

# Fail fast with concise message when cwd does not exist
if ! [[ -d "$PWD" ]]; then
  echo "Error: The current working directory doesn't exist, cannot proceed." >&2
  exit 1
fi

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

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

# Enable and use default Bash builtins rather than user-defined functions
builtin enable compgen unset
for cmd in $(builtin compgen -A builtin)
do
  builtin unset -f $cmd
  builtin enable $cmd
done
unset cmd

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" && ! -L "$HOMEBREW_PREFIX/Cellar" ]]
then
  USR_LOCAL_BREW_FILE_DIRECTORY="$(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 BROWSER DISPLAY EDITOR NO_COLOR PATH
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

# Use VISUAL if HOMEBREW_EDITOR and EDITOR are unset.
if [[ -z "$HOMEBREW_EDITOR" && -n "$VISUAL" ]]
then
  export HOMEBREW_EDITOR="$VISUAL"
fi

# Set CI variable for GitHub Actions, Azure Pipelines, Jenkins
# (Set by default on Circle and Travis CI)
if [[ -n "$GITHUB_ACTIONS" || -n "$TF_BUILD" || -n "$JENKINS_HOME" ]]
then
  export CI="1"
fi

# test-bot does environment filtering itself
if [[ -z "$HOMEBREW_NO_ENV_FILTERING" && "$1" != "test-bot" ]]
then
  PATH="/usr/bin:/bin:/usr/sbin:/sbin"

  FILTERED_ENV=()
  # Filter all but the specific variables.
  for VAR in HOME SHELL PATH TERM TERMINFO COLUMNS DISPLAY LOGNAME USER CI SSH_AUTH_SOCK SUDO_ASKPASS \
             http_proxy https_proxy ftp_proxy no_proxy all_proxy HTTPS_PROXY FTP_PROXY ALL_PROXY \
             "${!HOMEBREW_@}"
  do
    # Skip if variable value is empty.
    [[ -z "${!VAR}" ]] && continue

    FILTERED_ENV+=( "${VAR}=${!VAR}" )
  done

  exec /usr/bin/env -i "${FILTERED_ENV[@]}" /bin/bash "$HOMEBREW_LIBRARY/Homebrew/brew.sh" "$@"
else
  # Don't need shellcheck to follow this `source`.
  # shellcheck disable=SC1090
  source "$HOMEBREW_LIBRARY/Homebrew/brew.sh"
fi
