#!/bin/sh
set -e
# I'd love to use `jq` for parsing the JSON properly, but macOS is totally underequipped for this kind of work.
TARGET=$(rustc --print target-spec-json -Z unstable-options | grep llvm-target | cut -d '"' -f 4)
SYSROOT=$(rustc --print sysroot)
# We set the rpath so that Miri finds the private rustc libraries it needs.
# We enable debug-assertions to get tracing.
# We enable line-only debuginfo for backtraces.
export RUSTFLAGS="-C link-args=-Wl,-rpath,$SYSROOT/lib/rustlib/$TARGET/lib -C debug-assertions -C debuginfo=1"

## Helper functions

# Build a sysroot and set MIRI_SYSROOT to use it.  Arguments are passed to `cargo miri setup`.
build_sysroot() {
    # Build once, for the user to see.
    cargo run --release --bin cargo-miri -- miri setup "$@"
    # Call again, to just set env var.
    eval $(cargo run --release -q --bin cargo-miri -- miri setup --env "$@")
    export MIRI_SYSROOT
}

# Prepare and set MIRI_SYSROOT.  Respects `MIRI_TEST_TARGET` and takes into account
# locally built vs. distributed rustc.
find_sysroot() {
    # Get ourselves a sysroot
    if [ -n "$MIRI_SYSROOT" ]; then
        # Sysroot already set, use that.
        true
    elif echo "$SYSROOT" | egrep -q 'build/[^/]+/stage'; then
        # A local rustc build.
        if [ -n "$MIRI_TEST_TARGET" ]; then
            # Foreign targets still need a build.  Use the rustc sources.
            export XARGO_RUST_SRC="$SYSROOT/../../../src"
            build_sysroot --target "$MIRI_TEST_TARGET"
        else
            # Assume we have a proper host libstd in $SYSROOT.
            true
        fi
    else
        # A normal toolchain.  We have to build a sysroot either way.
        if [ -n "$MIRI_TEST_TARGET" ]; then
            build_sysroot --target "$MIRI_TEST_TARGET"
        else
            build_sysroot
        fi
    fi
}

## Main

COMMAND="$1"
shift

case "$COMMAND" in
install)
    # "--locked" to respect the Cargo.lock file if it exists,
    # "--offline" to avoid querying the registry (for yanked packages).
    exec cargo "$COMMAND" --path "$(dirname "$0")" --force --locked --offline "$@"
    ;;
build)
    # Build, and let caller control flags.
    exec cargo "$COMMAND" --release "$@"
    ;;
test|run)
    # In "run" mode, scan for "--target" to set the "MIRI_TEST_TARGET" env var so
    # that we set the MIRI_SYSROOT up the right way.
    if [ "$COMMAND" = "run" ] && [ -z "$MIRI_TEST_TARGET" ]; then
        for ARG in "$@"; do
            if [ "$LAST_ARG" = "--target" ]; then
                # Found it!
                export MIRI_TEST_TARGET="$ARG"
                break
            fi
            LAST_ARG="$ARG"
        done
    fi
    # First build and get a sysroot.
    cargo build --release
    find_sysroot
    # Then run the actual command.
    exec cargo "$COMMAND" --release "$@"
    ;;
esac