#!/usr/bin/env bash

# Copyright (c) 2016 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

set -e -o pipefail

MYPATH=$(dirname "${BASH_SOURCE[0]}")
CYGWIN=false

# Make sure this starts empty
ARCH=

UNAME=`uname -s | tr '[:upper:]' '[:lower:]'`
case "${UNAME}" in
  aix)
    OS="${UNAME}"
    ARCH="ppc64"  # apparently 'uname -m' returns something very different
    ;;
  linux)
    OS="${UNAME}"
    ;;
  cygwin*)
    OS=windows
    CYGWIN=true
    ;;
  msys*|mingw*)
    OS=windows
    ;;
  darwin)
    OS=mac
    ;;
  *)
    >&2 echo "CIPD not supported on ${UNAME}"
    exit 1
esac

if [ -z $ARCH ]; then
  UNAME=`uname -m | tr '[:upper:]' '[:lower:]'`
  case "${UNAME}" in
    x86_64|amd64)
      ARCH=amd64
      ;;
    s390x|ppc64|ppc64le)  # best-effort support
      ARCH="${UNAME}"
      ;;
    aarch64)
      ARCH=arm64
      ;;
    armv7l)
      ARCH=armv6l
      ;;
    arm*)
      ARCH="${UNAME}"
      ;;
    *86)
      ARCH=386
      ;;
    mips*)
      # detect mips64le vs mips64.
      ARCH="${UNAME}"
      if lscpu | grep -q "Little Endian"; then
        ARCH+=le
      fi
      ;;
    *)
      >&2 echo "UNKNOWN Machine architecture: ${UNAME}"
      exit 1
  esac
fi

# CIPD_BACKEND can be changed to ...-dev for manual testing.
CIPD_BACKEND="https://chrome-infra-packages.appspot.com"
VERSION_FILE="${MYPATH}/cipd_client_version"

CLIENT="${MYPATH}/.cipd_client"
VERSION=`cat "${VERSION_FILE}"`
PLATFORM="${OS}-${ARCH}"

URL="${CIPD_BACKEND}/client?platform=${PLATFORM}&version=${VERSION}"
USER_AGENT="depot_tools/$(git -C ${MYPATH} rev-parse HEAD 2>/dev/null || echo "???")"


# calc_sha256 is "portable" variant of sha256sum. It uses sha256sum when
# available (most Linuxes and cygwin) and 'shasum -a 256' otherwise (for OSX).
#
# Args:
#   Path to a file.
# Stdout:
#   Lowercase SHA256 hex digest of the file.
function calc_sha256() {
  if hash sha256sum 2> /dev/null ; then
    sha256sum "$1" | cut -d' ' -f1
  elif hash shasum 2> /dev/null ; then
    shasum -a 256 "$1" | cut -d' ' -f1
  else
    >&2 echo -n "[31;1m"
    >&2 echo -n "Don't know how to calculate SHA256 on your platform. "
    >&2 echo -n "Please use your package manager to install one before continuing:"
    >&2 echo
    >&2 echo "  sha256sum"
    >&2 echo -n "  shasum"
    >&2 echo "[0m"
    return 1
  fi
}


# expected_sha256 reads the expected SHA256 hex digest from *.digests file.
#
# Args:
#   Name of the platform to get client's digest for.
# Stdout:
#   Lowercase SHA256 hex digest.
function expected_sha256() {
  local line
  while read -r line; do
    if [[ "${line}" =~ ^([0-9a-z\-]+)[[:blank:]]+sha256[[:blank:]]+([0-9a-f]+)$ ]] ; then
      local plat="${BASH_REMATCH[1]}"
      local hash="${BASH_REMATCH[2]}"
      if [ "${plat}" ==  "$1" ]; then
        echo "${hash}"
        return 0
      fi
    fi
  done < "${VERSION_FILE}.digests"

  >&2 echo -n "[31;1m"
  >&2 echo -n "Platform $1 is not supported by the CIPD client bootstrap: "
  >&2 echo -n "there's no pinned SHA256 hash for it in the *.digests file."
  >&2 echo "[0m"

  return 1
}


# clean_bootstrap bootstraps the client from scratch using 'curl' or 'wget'.
#
# It checks that the SHA256 of the downloaded file is known. Exits the script
# if the client can't be downloaded or its hash doesn't match the expected one.
function clean_bootstrap() {
  local expected_hash=$(expected_sha256 "${PLATFORM}")
  if [ -z "${expected_hash}" ] ; then
    exit 1
  fi

  # Download the client into a temporary file, check its hash, then move it into
  # the final location.
  #
  # This wonky tempdir method works on Linux and Mac.
  local CIPD_CLIENT_TMP=$(\
    mktemp -p "${MYPATH}" 2>/dev/null || \
    mktemp "${MYPATH}/.cipd_client.XXXXXXX")

  if hash curl 2> /dev/null ; then
    curl "${URL}" -s --show-error -f -A "${USER_AGENT}" -L -o "${CIPD_CLIENT_TMP}"
  elif hash wget 2> /dev/null ; then
    wget "${URL}" -q -U "${USER_AGENT}" -O "${CIPD_CLIENT_TMP}"
  else
    >&2 echo -n "[31;1m"
    >&2 echo -n "Your platform is missing a supported fetch command. "
    >&2 echo "Please use your package manager to install one before continuing:"
    >&2 echo
    >&2 echo "  curl"
    >&2 echo "  wget"
    >&2 echo
    >&2 echo "Alternately, manually download:"
    >&2 echo "  ${URL}"
    >&2 echo -n "To ${CLIENT}, and then re-run this command."
    >&2 echo "[0m"
    rm "${CIPD_CLIENT_TMP}"
    exit 1
  fi

  local actual_hash=$(calc_sha256 "${CIPD_CLIENT_TMP}")
  if [ -z "${actual_hash}" ] ; then
    rm "${CIPD_CLIENT_TMP}"
    exit 1
  fi

  if [ "${actual_hash}" != "${expected_hash}" ]; then
    >&2 echo -n "[31;1m"
    >&2 echo "SHA256 digest of the downloaded CIPD client is incorrect:"
    >&2 echo "  Expecting ${expected_hash}"
    >&2 echo "  Got       ${actual_hash}"
    >&2 echo -n "Refusing to run it. Check that *.digests file is up-to-date."
    >&2 echo "[0m"
    rm "${CIPD_CLIENT_TMP}"
    exit 1
  fi

  set +e
  chmod +x "${CIPD_CLIENT_TMP}"
  mv "${CIPD_CLIENT_TMP}" "${CLIENT}"
  set -e
}


# self_update launches CIPD client's built-in selfupdate mechanism.
#
# It is more efficient that redownloading the binary all the time.
function self_update() {
  "${CLIENT}" selfupdate -version-file "${VERSION_FILE}" -service-url "${CIPD_BACKEND}"
}


if [ ! -x "${CLIENT}" ]; then
  clean_bootstrap
fi

export CIPD_HTTP_USER_AGENT_PREFIX="${USER_AGENT}"
if ! self_update 2> /dev/null ; then
  >&2 echo -n "[31;1m"
  >&2 echo -n "CIPD selfupdate failed. "
  >&2 echo -n "Trying to bootstrap the CIPD client from scratch..."
  >&2 echo "[0m"
  clean_bootstrap
  if ! self_update ; then  # need to run it again to setup .cipd_version file
    >&2 echo -n "[31;1m"
    >&2 echo -n "Bootstrap from scratch failed, something is seriously broken. "
    >&2 echo "Run the following commands to diagnose if this is repeating:"
    >&2 echo "  export CIPD_HTTP_USER_AGENT_PREFIX=${USER_AGENT}/manual"
    >&2 echo -n "  ${CLIENT} selfupdate -version-file ${VERSION_FILE}"
    >&2 echo "[0m"
    exit 1
  fi
fi

# CygWin requires changing absolute paths to Windows form. Relative paths
# are typically okay as Windows generally accepts both forward and back
# slashes. This could possibly be constrained to only /tmp/ and /cygdrive/.
if ${CYGWIN}; then
  args=("$@")
  for i in `seq 2 $#`; do
    arg="${@:$i:1}"
    if [ "${arg:0:1}" == "/" ]; then
      last=$((i-1))
      next=$((i+1))
      set -- "${@:1:$last}" `cygpath -w "$arg"` "${@:$next}"
    fi
  done
  echo "${CLIENT}" "${@}"
fi

exec "${CLIENT}" "${@}"