#!/usr/bin/env bash
# SPDX-License-Identifier: Apache-2.0
# Copyright (C) 2021 Arm Limited or its affiliates and Contributors. All rights reserved.

[[ "$TRACE" ]] && set -x
set -euo pipefail

print_help() {
    echo 'Usage: manyclangs-run [ELFSHAKER] [COMITTISH] [COMMAND]...'
    echo ''
    echo 'Extracts the snapshot matching COMITTISH to the specified ELFSHAKER directory and runs COMMAND.'
    echo 'If the first token of COMMAND is a path to a file in the ELFSHAKER directory, that path will be resolved as an absolute path to that file.'
    echo ''
    echo 'The commit is matched to a snapshot by searching for a snapshot with a tag containing a part of the truncated commit SHA.'
    echo 'ELFSHAKER/build/bin is removed, and ELFSHAKER/build/link.sh is run after extraction and before COMMAND.'
    echo ''
    echo 'If any step of finding a matching snapshot, extraction, or ./link.sh fails, the script exists with code 125 (git bisect skip).'
    echo 'Otherwise, the exit code is the code returned by COMMAND.'
}

get_file_arch() {
    readelf -h "$1" | grep Machine | awk '{$1=""; print $0}' | tr -d ' '
}

has_docker_image() {
    docker image inspect "$1" &>/dev/null
}

run_docker_image() {
    docker run --rm --mount type=bind,source="$(realpath "$ELFSHAKER_DIR")",target=/elfshaker "$@"
}

link_and_run() {
    rm -r ./bin || true
    mkdir -p ./bin

    COMMAND_BASENAME="$(basename "$1")"
    LINK_AND_RUN_COMMAND="bash ./link.sh $COMMAND_BASENAME || exit 125; ./bin/$@"

    if [ "${USE_DOCKER_QEMU-,,}" = "aarch64" ]; then
        TEST_OBJECT=lib/Object/CMakeFiles/LLVMObject.dir/Object.cpp.o
        HOST_ARCH="$(get_file_arch /bin/cat)"
        TARGET_ARCH="$(get_file_arch "$TEST_OBJECT")"
        if [ "$HOST_ARCH" != "$TARGET_ARCH" ] && [ "$TARGET_ARCH" = "AArch64" ]; then
            if ! command -v docker &> /dev/null; then
                echo "The architecture of the executables you are attempting to run is '$TARGET_ARCH'."
                echo "We support running these on '$HOST_ARCH' through emulation, but require docker to do so."
                echo "Please install docker. https://www.docker.com/"
                exit 125
            elif ! has_docker_image manyclangs-qemu-aarch64 &>/dev/null; then
                echo 'You need the manyclangs-qemu-aarch64 docker image to run manyclangs with AArch64 emulation.'
                echo 'See https://github.com/elfshaker/manyclangs/blob/main/docker-qemu-aarch64/README.md for instructions.'
                exit 1
            else
                run_docker_image manyclangs-qemu-aarch64 bash -c "$LINK_AND_RUN_COMMAND"
            fi
        else
            echo "Running $TARGET_ARCH binaries on $HOST_ARCH via the manyclangs-qemu-aarch64 docker image is not supported!"
            exit 1
        fi
    else
        $LINK_AND_RUN_COMMAND
    fi
}

main() {
    ELFSHAKER_DIR="$1"
    COMITTISH="$2"
    COMMAND=(${@:3})

    SHA="$(git rev-parse --short=10 "$COMITTISH")"
    (cd "$ELFSHAKER_DIR" && elfshaker find "$SHA") | {
        read -r SNAPSHOT PACK || exit 125
        TIMEFORMAT="elfshaker extracted $SHA in %R seconds"
        COMMAND_BASENAME="$(basename "${COMMAND[0]}")"
        time (
            (cd "$ELFSHAKER_DIR" && elfshaker extract "$PACK:$SNAPSHOT" || exit 125)
        )

        link_and_run "${COMMAND[@]}"
    }
}

case "${1:--h}" in
    -h | --help)
        print_help
        [ $# -ne 0 ]
        exit $?
        ;;
    *)
        main "$@"
        ;;
esac