#!/bin/bash
# Copyright lowRISC contributors.
# Licensed under the Apache License, Version 2.0, see LICENSE for details.
# SPDX-License-Identifier: Apache-2.0

set -o errexit
set -o pipefail
set -o nounset
set -x

readonly BUILD_DIR_PREFIX="build"
readonly TARGET_VERILATOR="verilator"
readonly TARGET_FPGA="fpga"

function usage() {
  cat << USAGE
Configure Meson build targets.

Usage: $0 [-r|-f]

  -f: Remove build directories before running Meson.
  -r: Force reconfiguration of build directories.
  -K: Keep include search paths as generated by Meson.

USAGE
}

FLAGS_force=false
FLAGS_reconfigure=""
FLAGS_keep_includes=false
while getopts 'r?:f?:K?' flag; do
  case "${flag}" in
    f) FLAGS_force=true;;
    r) FLAGS_reconfigure="--reconfigure";;
    K) FLAGS_keep_includes=true;;
    ?) usage && exit 1;;
    *) usage
       error "Unexpected option ${flag}"
       ;;
  esac
done

if [[ "${FLAGS_force}" == true && -n "${FLAGS_reconfigure}" ]]; then
  usage >&2
  echo "Error: -r and -f cannont be used at the same time." >&2
  exit 1
fi

if [[ ! -n "$(command -v meson)" ]]; then
  echo "Unable to find meson. Please install meson before running this command." >&2
  exit 1
fi

if [[ ! -n "$(command -v ninja)" ]]; then
  echo "Unable to find ninja. Please install ninja before running this command." >&2
  exit 1
fi

if [[ "${FLAGS_force}" == true ]]; then
  for target_suffix in "${TARGET_VERILATOR}" "${TARGET_FPGA}"; do
    rm -rf "${BUILD_DIR_PREFIX}-${target_suffix}"
  done
fi

if [[ ! -n "${FLAGS_reconfigure}" ]] ; then
  for target_suffix in "${TARGET_VERILATOR}" "${TARGET_FPGA}"; do
    if [[ -d "${BUILD_DIR_PREFIX}-${target_suffix}" ]]; then
      usage >&2
      echo "Error: ${BUILD_DIR_PREFIX}-${target_suffix} already exists. " \
           "Remove directory, or rerun $0 with the -r option" >&2
      exit 1
    fi
  done
fi

readonly DEFAULT_RISCV_TOOLS=/tools/riscv
TOOLCHAIN_PATH="${TOOLCHAIN_PATH:-$DEFAULT_RISCV_TOOLS}"
CROSS_FILE=$(mktemp /tmp/toolchain.XXXXXX.txt)
cp toolchain.txt "$CROSS_FILE"
perl -pi -e "s#$DEFAULT_RISCV_TOOLS#$TOOLCHAIN_PATH#g" "$CROSS_FILE"
echo "Set up toolchain file at $CROSS_FILE." >&2

# purge_includes $build_dir deletes any -I command line arguments that are not
# - Absolute paths.
# - Ephemeral build directories.
#
# This function is necessary because Meson does not give adequate
# control over what directories are passed in as -I search directories
# to the C compiler. While Meson does provide |implicit_include_directories|,
# support for this option is poor: empirically, Meson ignores this option for
# some targerts. Doing it as a post-processing step ensures that Meson does
# not allow improper #includes to compile successfully.
function purge_includes() {
  if [[ "${FLAGS_keep_includes}" == "true" ]]; then
    return
  fi
  echo "Purging superfluous -I arguments from $1."
  local ninja_file="$1/build.ninja"
  perl -pi -e 's#-I[^/][^@ ]+ # #g' -- "$ninja_file"
}

# configure_meson $target generates a build directory at build-$target.
function configure_meson() {
  local target="$1"
  local build_dir="${BUILD_DIR_PREFIX}-$target"

  mkdir -p "$build_dir"
  meson ${FLAGS_reconfigure} \
    -Dtarget="$target" \
    --cross-file="$CROSS_FILE" \
    --buildtype=plain \
    "$build_dir"
  purge_includes "$build_dir"
}

configure_meson "${TARGET_VERILATOR}"
configure_meson "${TARGET_FPGA}"