#! /bin/sh
# Copyright 2017 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may not
# use this file except in compliance with the License.  You may obtain a copy
# of the License at:
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
# License for the specific language governing permissions and limitations
# under the License.

set -e

readonly PROGNAME="${0##*/}"
readonly SRCDIR="$(cd "$(dirname "${0}")" && pwd -P)"

# Settings that end up in the Makefile.
CARGO=cargo
CLEANFILES=target
FEATURES=
GOPATH="$(pwd)/.gopath"
GOROOT=
IS_BMAKE=
IS_GNUMAKE=
PREFIX=
DISTCLEANFILES="Makefile go.sum ${GOPATH}"

# List of variables exposed to the Makefile.
MK_VARS="CARGO CLEANFILES DISTCLEANFILES FEATURES GOPATH GOROOT PREFIX"

# List of variables replaced in the Makefile.
MK_SUBSTS="IS_BMAKE IS_GNUMAKE"

err() {
  echo "${PROGNAME}: E: ${@}" 1>&2
  exit 1
}

info() {
  echo "${PROGNAME}: I: ${@}" 1>&2
}

find_prog() {
    local prog="${1}"; shift

    local oldifs="${IFS}"
    IFS=:
    set -- ${PATH}
    IFS="${oldifs}"

    while [ ${#} -gt 0 ]; do
        if [ -x "${1}/${prog}" ]; then
            echo "${1}/${prog}"
            return 0
        else
            shift
        fi
    done
    return 1
}

find_progs() {
    while [ ${#} -gt 0 ]; do
        if find_prog "${1}"; then
            return 0
        else
            shift
        fi
    done
    return 1
}

setup_cargo() {
    local user_override="${1}"; shift

    if [ -n "${user_override}" ]; then
        [ -e "${user_override}" ] || err "cargo not found in" \
            "${user_override}; bogus argument to --cargo?"
        CARGO="${user_override}"
    else
        local cargo="$(find_progs cargo)"
        [ -n "${cargo}" ] || err "Cannot find cargo in path; pass" \
            "--cargo=/path/to/cargo to configure"
        CARGO="${cargo}"
    fi

    info "Using Cargo from: ${CARGO}"
}

# Installs git hooks into the git directory provided in git_dir.
setup_git() {
  local git_dir="${1}"; shift

  cd "${git_dir}/hooks"
  for hook in ../../admin/pre-commit; do
    info "Installing git hook ${hook##*/}"
    ln -s -f "${hook}" .
  done
  cd - >/dev/null 2>&1
}

setup_go() {
  local user_override="${1}"; shift

  if [ -n "${user_override}" ]; then
    [ "${user_override}" = none ] || GOROOT="${user_override}"
  else
    local go="$(find_progs go)"
    [ -n "${go}" ] && GOROOT="$(dirname "$(dirname "${go}")")"
  fi

  if [ -z "${GOROOT}" ]; then
    info "Go not found; cannot run integration tests"
  else
    info "Using Go with GOROOT: ${GOROOT}"
    GOPATH="${GOPATH}" "${GOROOT}/bin/go" mod download
    GOPATH="${GOPATH}" "${GOROOT}/bin/go" install golang.org/x/lint/golint
  fi
}

setup_make() {
  IS_BMAKE=#
  IS_GNUMAKE=#
  if make --version >/dev/null 2>&1; then
    info "make is GNU Make"
    IS_GNUMAKE=
  else
    info "make is bmake"
    IS_BMAKE=
  fi
}

setup_prefix() {
  local prefix="${1:-/usr/local}"; shift

  info "Installation prefix is ${prefix}"
  PREFIX="${prefix}"
}

setup_vscode() {
  {
    echo '// AUTOMATICALLY GENERATED!!!'
    echo '// EDIT settings.json.in INSTEAD'
    sed \
        -e "s,__GOPATH__,${GOPATH},g" \
        -e "s,__GOROOT__,${GOROOT},g" \
        -e "s,__TOOLS_GOPATH__,$(pwd)/.gopath-tools,g" \
        .vscode/settings.json.in
  } >.vscode/settings.json
}

generate_makefile() {
    local src="${1}"; shift
    local dest="${1}"; shift

    info "Generating ${dest}"
    echo "# AUTOMATICALLY GENERATED; DO NOT EDIT!" >"${dest}.tmp"
    for var in ${MK_VARS}; do
        local value
        eval "value=\"\$${var}\""
        echo "${var} = ${value}" >>"${dest}.tmp"
    done
    local substs=
    for var in ${MK_SUBSTS}; do
        local value
        eval "value=\"\$${var}\""
        substs="${substs} -e s,@${var}@,${value},g"
    done
    sed ${substs} "${src}" >>"${dest}.tmp"
    mv "${dest}.tmp" "${dest}"
}

main() {
  cd "${SRCDIR}"

  local cargo=
  local goroot=
  local prefix=
  for arg in "${@}"; do
    case "${arg}" in
      --cargo=*) cargo="${arg#*=}" ;;
      --features=*) FEATURES="${arg#*=}" ;;
      --goroot=*) goroot="${arg#*=}" ;;
      --prefix=*) prefix="${arg#*=}" ;;
      *) err "Unknown argument ${arg}" ;;
    esac
  done

  setup_cargo "${cargo}"
  [ -d .git ] && setup_git .git
  setup_go "${goroot}"
  setup_make
  setup_prefix "${prefix}"
  setup_vscode

  generate_makefile Makefile.in Makefile
}

main "${@}"