#!/usr/bin/env bash

# Copyright 2016 The Fuchsia Authors
#
# Use of this source code is governed by a MIT-style
# license that can be found in the LICENSE file or at
# https://opensource.org/licenses/MIT

# This script downloads the Zircon toolchain as prebuilts from Google Storage.

# This script is expected to be executed by Jiri as a runhook, or by individual
# developers who want to grab the latest prebuilts.  It takes no arguments, will
# download the latest version of the Zircon toolchain, install it in the
# prebuilt/downloads directory, and update prebuilt/config.mk with the toolchain
# prefix (so you shouldn't have to set PATH or anything yourself).

set -e

readonly FUCHSIA_GS_BUCKET="https://storage.googleapis.com/fuchsia"
readonly ZIRCON_GS_BUCKET="https://fuchsia-build.storage.googleapis.com/magenta"
readonly OS="$(uname)"
readonly HOSTOS=$(uname | tr '[:upper:]' '[:lower:]')
readonly HOSTARCH="$(uname -m)"

# We assume the following directory structure:
# ./zircon/scripts
# ./zircon/prebuilt
readonly SCRIPT_DIR="$(cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd)"
readonly ZIRCON_ROOT="$(cd "${SCRIPT_DIR}/.." && pwd)"
readonly PREBUILTS_DIR="$(cd "${ZIRCON_ROOT}/prebuilt" && pwd)"

# Install prebuilts into a .gitignore'd directory to keep things clean
mkdir -p "${PREBUILTS_DIR}/downloads"
readonly INSTALL_DIR="$(cd "${PREBUILTS_DIR}/downloads" && pwd)"

# Download the tools if they don't already exist, or if their versions are out of date.
TOOLCHAIN_MAKEVARS=()
PREBUILT_NAMES=()

function downloadToolchain() {
  local toolchain="${1}"

  case "${OS}-${HOSTARCH}" in
    "Darwin-x86_64") local host_platform="mac-amd64" ;;
    "Linux-x86_64") local host_platform="linux-amd64" ;;
    "Linux-aarch64") local host_platform="linux-aarch64" ;;
    "*") echo "Unknown operating system." 1>&2 && exit 1 ;;
  esac

  # These are files and paths we expect to already exist.
  local common_path="toolchain/${toolchain}/${host_platform}"
  local version_file="${PREBUILTS_DIR}/versions/${common_path}/${toolchain}.sha1"
  if [[ ! -f "${version_file}" ]]; then
    echo "File ${version_file} does not exist."
    echo "Your operating system is probably not supported, aborting ${toolchain} download."
    return
  fi
  local required_version="$(cat "${version_file}" )"
  local prebuilt_url="${FUCHSIA_GS_BUCKET}/${toolchain}/${host_platform}/${required_version}"

  # These are files and paths we control in this script.
  local stamp_path="${INSTALL_DIR}/${toolchain}.stamp"
  local tool_path="${INSTALL_DIR}/${toolchain}.zip"

  # The stamp file contains the SHA of the last version we downloaded.  If it doesn't
  # match the SHA found in the version file, download and unpack the new one.
  cd ${INSTALL_DIR}
  if [[ ! -f "${stamp_path}" || "${required_version}" != "$(cat ${stamp_path})" ]]; then
    rm -f -- "${tool_path}"
    echo "Downloading ${prebuilt_url}"
    curl --progress-bar -continue-at=- --location --output "${tool_path}" "${prebuilt_url}"
    rm -rf -- "${toolchain}"
    echo "Unpacking ${tool_path}"
    unzip -q -d "${INSTALL_DIR}/${toolchain}" "${tool_path}"
    echo "${required_version}" > "${stamp_path}"
  fi

  # Record the locations of the various toolchains.
  local relative_install_dir="\$(LKMAKEROOT)${INSTALL_DIR#${ZIRCON_ROOT}}"
  if [[ $# -gt 1 ]]; then
    shift
    for target in "$@"; do
      case "${target}" in
      "aarch64-elf")
        TOOLCHAIN_MAKEVARS+=("ARCH_arm64_TOOLCHAIN_PREFIX = ${relative_install_dir}/${toolchain}/bin/${target}-")
        ;;
      "x86_64-elf")
        TOOLCHAIN_MAKEVARS+=("ARCH_x86_64_TOOLCHAIN_PREFIX = ${relative_install_dir}/${toolchain}/bin/${target}-")
        ;;
      esac
    done
  else
    local toolchain_uppercase="$(echo ${toolchain} | tr '[:lower:]' '[:upper:]')"
    TOOLCHAIN_MAKEVARS+=("${toolchain_uppercase}_TOOLCHAIN_PREFIX = ${relative_install_dir}/${toolchain}/bin/")
  fi

  # Leave some breadcrumbs in the makefile so `make ...` can check if the toolchain is up-to-date.
  PREBUILT_NAMES+=" ${toolchain}"  # FYI: That's load-bearing leading whitespace.
  TOOLCHAIN_MAKEVARS+=("PREBUILT_${toolchain}_TOOLCHAIN_STAMP = \$(LKMAKEROOT)${stamp_path#${ZIRCON_ROOT}}")
  TOOLCHAIN_MAKEVARS+=("PREBUILT_${toolchain}_TOOLCHAIN_SHAFILE = \$(LKMAKEROOT)${version_file#${ZIRCON_ROOT}}")
}

downloadToolchain gcc x86_64-elf aarch64-elf
downloadToolchain clang

# Clear old config lines from prebuilt/config.mk.
readonly ENV_MK="${PREBUILTS_DIR}/config.mk"
echo "generating ${ENV_MK}"
if [[ -f "${ENV_MK}" ]]; then
  sed -i.bak '/.*_TOOLCHAIN_PREFIX/d' "${ENV_MK}"
  sed -i.bak '/PREBUILT_.*/d' "${ENV_MK}"
fi

# Update prebuilt/config.mk to point at the toolchains we just installed.
TOOLCHAIN_MAKEVARS+=("PREBUILT_TOOLCHAINS :=${PREBUILT_NAMES[@]}")
for line in "${TOOLCHAIN_MAKEVARS[@]}"; do
  echo $line >> "${ENV_MK}"
done