#!/usr/bin/env bash
set -e -x

# Abort the script with an error message
abort() {
  echo $1 >&2
  exit 1
}

# Extract some info from rustc
rustc_info() {
  rustc -Vv | grep $1 | awk '{print $2}'
}

is_lib() {
  grep -q '\[lib\]' Cargo.toml || [ -e src/lib.rs ]
}

# Check that the rustc command exists
command -v rustc > /dev/null || abort "rustc cannot be found on path"

# Ensure that $ARCH has been specified
[ -z $ARCH ] && abort 'no $ARCH specified'

SOURCE_HOST=$(rustc_info "host")
SOURCE_ARCH=$(echo $SOURCE_HOST | cut -d - -f 1)
SOURCE_OS=$(echo $SOURCE_HOST | cut -d - -f 2-)
TARGET_HOST=$ARCH-$SOURCE_OS
RUSTC_ROOT=$(rustc --print sysroot)
RUSTC_LIB="$RUSTC_ROOT/lib/rustlib"
RUSTC_DATE=$(rustc_info "commit-date")
BCK_FILE="Cargo.toml.cross-compile-bck"

[ $ARCH != $SOURCE_ARCH ] && {
  # Ensure supported arch
  [[ "i686 x86_64" =~ $ARCH ]] || abort "unsuported ARCH $ARCH"

  # Make sure that the target arch's lib is present
  [ -d "$RUSTC_LIB/$TARGET_HOST" ] || {
    RELEASE=$(rustc_info "release")

    if echo $RELEASE | grep -q beta; then
      VERSION="beta"
    elif echo $RELEASE | grep -q nightly; then
      VERSION="nightly"
    else
      VERSION=$RELEASE
    fi

    DIST_URL=https://static.rust-lang.org/dist/rust-$VERSION-$TARGET_HOST.tar.gz
    RUST_STD=rust-std-$TARGET_HOST
    LIB_SUBDIR=lib/rustlib/$TARGET_HOST

    echo "Installing alternate rust for arch=$ARCH"

    # Download
    curl $DIST_URL | tar -zxf -
    pushd rust-$VERSION-$TARGET_HOST

    # If the new stdlib directory exists, copy files out of there, otherwise
    # fallback to the old location
    if [ -d "$RUST_STD" ]; then
      # rust-std-i686-unknown-linux-gnu/lib/rustlib/i686-unknown-linux-gnu/lib
      mv $RUST_STD/$LIB_SUBDIR $RUSTC_LIB/
    else
      mv rustc/$LIB_SUBDIR $RUSTC_LIB/
    fi

    popd
  }

  # Cargo does not currently support doc tests when cross compiling nor a way
  # to disable doc tests via the CLI, so doc tests must be disabled in the
  # manifest.
  #
  # The strategy is pretty hacky. If there is already a lib section, then just
  # add doctest=false to the section. If there is no lib section, then the
  # package name needs to be determined and a lib section created.
  #
  # See: rust-lang/cargo#1789
  is_lib && {
    mv Cargo.toml $BCK_FILE

    if grep -q '\[lib\]' $BCK_FILE; then
      cat $BCK_FILE |
        grep -vE 'doctest *=' | # Remove the current doctest value
        awk '/\[lib\]/ { print; print "doctest=false"; next }1' > Cargo.toml
    else
      # First, extract the name of the lib, assume it is the first value
      LIB_NAME=$(cat $BCK_FILE | grep 'name *=' | head -n 1 | awk -F '"' '{print $2}')
      # Second, normalize the name by converting dashes to underscores.
      # This is required by the [lib] directive (see issue #4)
      LIB_NAME="$(echo "$LIB_NAME" | tr - _)"

      cp $BCK_FILE Cargo.toml
      echo "[lib]" >> Cargo.toml
      echo "name=\"$LIB_NAME\"" >> Cargo.toml
      echo "doctest=false" >> Cargo.toml
    fi
  }
}

reset_manifest() {
  if [ -e "$BCK_FILE" ]; then
    rm -f Cargo.toml
    mv $BCK_FILE Cargo.toml
  fi
}

# Finally run the tests
cargo test $CARGOOPTS --target $TARGET_HOST || {
  reset_manifest
  exit 1
}

reset_manifest