#!/usr/bin/env bash

# Copyright 2017 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 sysroot 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 sysroot, install it in the
# prebuilt/downloads directory, and update prebuilt/config.mk with the sysroot
# path.

set -e

readonly FUCHSIA_GS_BUCKET="https://storage.googleapis.com/fuchsia"

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# Download the tools if they don't already exist, or if their versions are out of date.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

function downloadSysroot() {
  local host_platform="${1}"

  # These are files and paths we expect to already exist.
  local common_path="sysroot/${host_platform}"
  local version_file="${PREBUILTS_DIR}/versions/${common_path}/sysroot.sha1"
  if [[ ! -f "${version_file}" ]]; then
    echo "File ${version_file} does not exist."
    return 1
  fi
  local required_version="$(<"${version_file}")"
  local prebuilt_url="${FUCHSIA_GS_BUCKET}/sysroot/${host_platform}/${required_version}"

  # These are files and paths we control in this script.
  local stamp_path="${INSTALL_DIR}/${host_platform}.stamp"
  local tool_path="${INSTALL_DIR}/${host_platform}.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}" "${prebuilt_url}"
    rm -rf -- "${host_platform}"
    echo "Unpacking ${tool_path}"
    unzip -q -d "${INSTALL_DIR}/${host_platform}" "${tool_path}"
    echo "${required_version}" > "${stamp_path}"
  fi

  # Record the locations of the various sysroots.
  local sysroot_dir="${host_platform}"
  local relative_install_dir="\$(LKMAKEROOT)${INSTALL_DIR#${ZIRCON_ROOT}}"
  SYSROOT_MAKEVARS+=("SYSROOT_${host_platform}_PATH = ${relative_install_dir}/${sysroot_dir}")

  # Leave some breadcrumbs in the makefile so `make ...` can check if the sysroot is up-to-date.
  PREBUILT_NAMES+=" ${host_platform}"  # FYI: That's load-bearing leading whitespace.
  SYSROOT_MAKEVARS+=("SYSROOT_${host_platform}_STAMP = \$(LKMAKEROOT)${stamp_path#${ZIRCON_ROOT}}")
  SYSROOT_MAKEVARS+=("SYSROOT_${host_platform}_SHAFILE = \$(LKMAKEROOT)${version_file#${ZIRCON_ROOT}}")
}

# We want the sysroot for all hosts.
readonly TARGETS=("linux-arm64" "linux-amd64")
for target in "${TARGETS[@]}"; do
  downloadSysroot "${target}"
done

# 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 '/SYSROOT.*/d' "${ENV_MK}"
fi

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