#!/usr/bin/env bash
# shellcheck source=/dev/null
. generate-layer.sh
set -eo pipefail

echo "---> Rust Buildpack"

# 1. GET ARGS
layers_dir=$1
plan_path=$3

# 2. DOWNLOAD Rust
rust_layer_dir="${layers_dir}/rust"
mkdir -p "${rust_layer_dir}"

export RUSTUP_HOME="${rust_layer_dir}/multirust"
# Our cargo installation.  We implicitly trust Rustup and Cargo
# to do the right thing when new versions are released.
export CARGO_HOME="${rust_layer_dir}"

# Default build flags to pass to `cargo build`.
RUST_CARGO_BUILD_FLAGS="--release"

# determine rust version provided during detection
rust_version=$(yj <"${plan_path}" -t | jq -r '.entries[] | select(.name == "rust") | .version')
remote_rust_version="not found"
if [[ -f "${rust_layer_dir}.toml" ]]; then
  remote_rust_version=$(yj <"${rust_layer_dir}.toml" -t | jq -r .metadata 2>/dev/null || echo 'not found')
fi

if [[ "${rust_version}" == "${remote_rust_version}" ]]; then
  echo "---> Reusing rustup, checking for new releases of Rust $rust_version channel"
  "${rust_layer_dir}"/bin/rustup self update
  "${rust_layer_dir}"/bin/rustup update "$rust_version"
  "${rust_layer_dir}"/bin/rustup default "$rust_version"
else
  # Standard paranoia.
  set -eu
  echo "---> Downloading rustup"
  curl https://sh.rustup.rs -sSf >rustup.sh
  chmod u+x rustup.sh
  echo "---> Using rustup to install Rust channel ${rust_version}"
  ./rustup.sh -y --default-toolchain "${rust_version}"
  rm rustup.sh
  mv "${CARGO_HOME}/env" "${CARGO_HOME}/bin"
  if [ ! -x "${CARGO_HOME}/bin/rustc" ]; then
    echo "failed: Cannot find Rust binaries at ${rust_layer_dir}"
    exit 1
  fi
  cat >"${rust_layer_dir}.toml" <<EOL
cache = true
build = true
launch = true
metadata = "${rust_version}"
EOL
fi

# 3. MAKE RUST AVAILABLE TO THIS SCRIPT
export PATH="${CARGO_HOME}/bin:${PATH}"
export CARGO_TARGET_DIR="${CARGO_HOME}/target"

echo "-----> Building application using Cargo"
if [ -s .cargo/config ]; then
  cp -f .cargo/config "${CARGO_HOME}/config"
fi
rm -rf target/
cargo build $RUST_CARGO_BUILD_FLAGS
mkdir -p target/release
find "$CARGO_TARGET_DIR/release" -maxdepth 1 -type f -executable -exec cp -a -t target/release {} \;

generate-launch.sh "${layers_dir}"