#!/usr/bin/env bash
set -euo pipefail

usage() {
    cat <<'EOF'
Usage: script/build_msquic.sh [options]

Build the pinned MsQuic source into:
  dependency/<arch>/third_party/msquic/v<version>

Options:
  --arch x86|arm       Dependency architecture (default: native host)
  --version VERSION    Supported pinned version without leading v (default: 2.5.9)
  --jobs N             Parallel build jobs (default: nproc)
  --clean              Recreate the MsQuic build and staging directories
  -h, --help           Show this help

Environment:
  CMVR_CMAKE                    Absolute CMake executable override
  CMVR_MSQUIC_TOOLCHAIN_FILE    CMake toolchain file for cross-compilation
  CC, CXX                       Native compiler overrides

The first run needs network access to clone the official MsQuic tag and its
QuicTLS submodule. No sudo or system MsQuic installation is used.
EOF
}

script_dir="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd -P)"
repo_root="$(cd -- "${script_dir}/.." && pwd -P)"
version="2.5.9"
arch=""
jobs=""
clean_build=false

while (($# > 0)); do
    case "$1" in
        --arch)
            [[ $# -ge 2 ]] || { echo "missing value for --arch" >&2; exit 2; }
            arch="$2"
            shift 2
            ;;
        --version)
            [[ $# -ge 2 ]] || { echo "missing value for --version" >&2; exit 2; }
            version="${2#v}"
            shift 2
            ;;
        --jobs)
            [[ $# -ge 2 ]] || { echo "missing value for --jobs" >&2; exit 2; }
            jobs="$2"
            shift 2
            ;;
        --clean)
            clean_build=true
            shift
            ;;
        -h|--help)
            usage
            exit 0
            ;;
        *)
            echo "unknown option: $1" >&2
            usage >&2
            exit 2
            ;;
    esac
done

host_machine="$(uname -m)"
case "${host_machine}" in
    x86_64|amd64)
        native_arch="x86"
        ;;
    aarch64|arm64|armv8*)
        native_arch="arm"
        ;;
    *)
        echo "unsupported host architecture: ${host_machine}" >&2
        exit 2
        ;;
esac

arch="${arch:-${native_arch}}"
if [[ "${arch}" != "x86" && "${arch}" != "arm" ]]; then
    echo "--arch must be x86 or arm" >&2
    exit 2
fi
if [[ ! "${version}" =~ ^[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
    echo "--version must use the form MAJOR.MINOR.PATCH" >&2
    exit 2
fi
case "${version}" in
    2.5.9)
        expected_source_commit="87b53085d76bd7920d490a6f226c9999b6614d14"
        ;;
    *)
        echo "unsupported MsQuic version: ${version}" >&2
        echo "add its reviewed tag and commit to script/build_msquic.sh first" >&2
        exit 2
        ;;
esac

if [[ -z "${jobs}" ]]; then
    jobs="$(nproc 2>/dev/null || getconf _NPROCESSORS_ONLN || echo 2)"
fi
if [[ ! "${jobs}" =~ ^[1-9][0-9]*$ ]]; then
    echo "--jobs must be a positive integer" >&2
    exit 2
fi

toolchain_args=()
if [[ "${arch}" != "${native_arch}" ]]; then
    if [[ -z "${CMVR_MSQUIC_TOOLCHAIN_FILE:-}" ]]; then
        echo "cross-building ${arch} on ${host_machine} requires" >&2
        echo "CMVR_MSQUIC_TOOLCHAIN_FILE=/absolute/path/to/toolchain.cmake" >&2
        exit 2
    fi
    if [[ ! -f "${CMVR_MSQUIC_TOOLCHAIN_FILE}" ]]; then
        echo "toolchain file does not exist: ${CMVR_MSQUIC_TOOLCHAIN_FILE}" >&2
        exit 2
    fi
    toolchain_file="$(realpath "${CMVR_MSQUIC_TOOLCHAIN_FILE}")"
    toolchain_args+=("-DCMAKE_TOOLCHAIN_FILE=${toolchain_file}")
fi

tag="v${version}"
source_dir="${repo_root}/build/third_party/msquic-src/${tag}"
build_dir="${repo_root}/build/third_party/msquic-build/${arch}-${tag}"
stage_dir="${repo_root}/build/third_party/msquic-stage/${arch}-${tag}"
stage_prefix="${stage_dir}/prefix"
install_root="${repo_root}/dependency/${arch}/third_party/msquic/${tag}"
backup_root="${install_root}.previous"

for guarded_path in \
    "${source_dir}" "${build_dir}" "${stage_dir}" \
    "${install_root}" "${backup_root}"; do
    case "${guarded_path}" in
        "${repo_root}"/build/third_party/*|\
        "${repo_root}"/dependency/"${arch}"/third_party/msquic/"${tag}"|\
        "${repo_root}"/dependency/"${arch}"/third_party/msquic/"${tag}".previous)
            ;;
        *)
            echo "refusing unsafe path: ${guarded_path}" >&2
            exit 2
            ;;
    esac
done

if [[ -n "${CMVR_CMAKE:-}" ]]; then
    cmake_bin="$(realpath "${CMVR_CMAKE}")"
else
    bundled_cmake="${repo_root}/dependency/${arch}/third_party/cmake/v3.30.3/cmake-3.30.3-linux-$(
        [[ "${arch}" == "x86" ]] && echo x86_64 || echo aarch64
    )/bin/cmake"
    if [[ "${arch}" == "${native_arch}" && -x "${bundled_cmake}" ]]; then
        cmake_bin="${bundled_cmake}"
    else
        cmake_bin="$(command -v cmake)"
    fi
fi
[[ -x "${cmake_bin}" ]] || {
    echo "CMake executable is unavailable: ${cmake_bin}" >&2
    exit 2
}

git_bin="/usr/bin/git"
[[ -x "${git_bin}" ]] || git_bin="$(command -v git)"
[[ -x "${git_bin}" ]] || { echo "git is required" >&2; exit 2; }

clean_path="$(dirname "${cmake_bin}"):/usr/local/bin:/usr/bin:/bin"
export PATH="${clean_path}"
unset CONDA_PREFIX CONDA_DEFAULT_ENV CMAKE_PREFIX_PATH PKG_CONFIG_PATH \
      OPENSSL_ROOT_DIR OPENSSL_DIR LD_LIBRARY_PATH LIBRARY_PATH CPATH \
      C_INCLUDE_PATH CPLUS_INCLUDE_PATH CFLAGS CXXFLAGS CPPFLAGS LDFLAGS \
      PERL5LIB PERL5OPT

if [[ "${arch}" == "${native_arch}" ]]; then
    export CC="${CC:-/usr/bin/cc}"
    export CXX="${CXX:-/usr/bin/c++}"
fi

mkdir -p "$(dirname "${source_dir}")" "$(dirname "${install_root}")"
if [[ ! -d "${source_dir}/.git" ]]; then
    "${git_bin}" clone \
        --branch "${tag}" \
        --depth 1 \
        https://github.com/microsoft/msquic.git \
        "${source_dir}"
fi

source_commit="$("${git_bin}" -C "${source_dir}" rev-parse HEAD)"
tag_commit="$("${git_bin}" -C "${source_dir}" rev-list -n 1 "${tag}")"
if [[ "${source_commit}" != "${tag_commit}" ]]; then
    echo "${source_dir} is not checked out at ${tag}" >&2
    echo "remove that cache directory and rerun the script" >&2
    exit 2
fi
if [[ "${source_commit}" != "${expected_source_commit}" ]]; then
    echo "${tag} resolved to an unexpected source commit" >&2
    echo "expected: ${expected_source_commit}" >&2
    echo "actual:   ${source_commit}" >&2
    exit 2
fi

unexpected_initialized_submodules="$(
    "${git_bin}" -C "${source_dir}" submodule status |
        awk '$2 != "submodules/quictls" && substr($1, 1, 1) != "-" {
            print $2 " (" $1 ")"
        }'
)"
if [[ -n "${unexpected_initialized_submodules}" ]]; then
    echo "MsQuic source cache contains initialized non-QuicTLS submodules:" >&2
    echo "${unexpected_initialized_submodules}" >&2
    echo "deinitialize those submodules or use a clean source cache before building" >&2
    exit 2
fi

"${git_bin}" -C "${source_dir}" submodule sync -- submodules/quictls
"${git_bin}" -C "${source_dir}" submodule update \
    --init --depth 1 -- submodules/quictls

source_changes="$("${git_bin}" -C "${source_dir}" status \
    --porcelain --untracked-files=all --ignore-submodules=all)"
if [[ -n "${source_changes}" ]]; then
    echo "MsQuic source cache contains local changes:" >&2
    echo "${source_changes}" >&2
    echo "use a clean source cache before building" >&2
    exit 2
fi
quictls_dir="${source_dir}/submodules/quictls"
expected_quictls_commit="$("${git_bin}" -C "${source_dir}" \
    rev-parse HEAD:submodules/quictls)"
actual_quictls_commit="$("${git_bin}" -C "${quictls_dir}" rev-parse HEAD)"
quictls_changes="$("${git_bin}" -C "${quictls_dir}" status \
    --porcelain --untracked-files=all)"
if [[ "${actual_quictls_commit}" != "${expected_quictls_commit}" ||
      -n "${quictls_changes}" ]]; then
    echo "QuicTLS source cache is not at the clean pinned commit" >&2
    echo "expected: ${expected_quictls_commit}" >&2
    echo "actual:   ${actual_quictls_commit}" >&2
    [[ -z "${quictls_changes}" ]] || echo "${quictls_changes}" >&2
    exit 2
fi

if [[ "${clean_build}" == true ]]; then
    "${cmake_bin}" -E remove_directory "${build_dir}"
fi
"${cmake_bin}" -E remove_directory "${stage_dir}"
"${cmake_bin}" -E make_directory "${build_dir}" "${stage_prefix}"

toolchain_fingerprint="native"
if [[ ${#toolchain_args[@]} -ne 0 ]]; then
    toolchain_fingerprint="$(
        sha256sum "${toolchain_file}" | awk '{print $1}'
    )"
fi
build_recipe_version="5"
build_fingerprint="$(
    printf '%s' \
        "${source_commit}|${build_recipe_version}|${arch}|" \
        "${CC:-toolchain}|${CXX:-toolchain}|" \
        "${toolchain_fingerprint}|${cmake_bin}"
)"
fingerprint_file="${build_dir}/cmvr-msquic-build.fingerprint"
if [[ -f "${build_dir}/CMakeCache.txt" ]]; then
    if [[ ! -f "${fingerprint_file}" ]]; then
        echo "existing MsQuic build cache predates compiler fingerprinting" >&2
        echo "rerun with --clean" >&2
        exit 2
    fi
    existing_fingerprint="$(<"${fingerprint_file}")"
    if [[ "${existing_fingerprint}" != "${build_fingerprint}" ]]; then
        echo "MsQuic compiler/toolchain fingerprint changed" >&2
        echo "rerun with --clean" >&2
        exit 2
    fi
fi
printf '%s\n' "${build_fingerprint}" >"${fingerprint_file}"

prefix_map_flags="\
-ffile-prefix-map=${repo_root}=. -fmacro-prefix-map=${repo_root}=."
"${cmake_bin}" \
    -S "${source_dir}" \
    -B "${build_dir}" \
    -G "Unix Makefiles" \
    -DCMAKE_BUILD_TYPE=Release \
    "-DCMAKE_INSTALL_PREFIX=${stage_prefix}" \
    "-DCMAKE_MODULE_PATH=${repo_root}/cmake/msquic" \
    "-DCMVR_MSQUIC_PROCESSOR_COUNT=${jobs}" \
    "-DCMAKE_C_FLAGS=${prefix_map_flags}" \
    "-DCMAKE_CXX_FLAGS=${prefix_map_flags}" \
    -DQUIC_BUILD_SHARED=ON \
    -DQUIC_BUILD_TEST=OFF \
    -DQUIC_BUILD_TOOLS=OFF \
    -DQUIC_BUILD_PERF=OFF \
    -DQUIC_ENABLE_LOGGING=OFF \
    -DQUIC_TLS_LIB=quictls \
    -DQUIC_USE_SYSTEM_LIBCRYPTO=OFF \
    -DNUMA:STRING=FALSE \
    "${toolchain_args[@]}"

# QuicTLS derives MODULESDIR from its temporary --prefix and compiles that
# absolute path into libcrypto. Dynamic providers are disabled above
# (no-shared, no-legacy and no-fips), so keep the unused fallback path stable
# instead of leaking the build workspace into the shipped MsQuic runtime.
openssl_makefile_target="_deps/opensslquic-build/submodules/quictls/Makefile"
openssl_build_rules="_deps/opensslquic-build/CMakeFiles/OpenSSL_Target.dir/build.make"
make_bin="$(command -v make)"
[[ -x "${make_bin}" ]] || {
    echo "GNU Make is required to configure the bundled QuicTLS source" >&2
    exit 2
}
"${make_bin}" -C "${build_dir}" -f "${openssl_build_rules}" \
    "${openssl_makefile_target}"
openssl_makefile="${build_dir}/${openssl_makefile_target}"
test -f "${openssl_makefile}"
if ! grep -Fx 'MODULESDIR=/usr/lib/ssl/ossl-modules' \
        "${openssl_makefile}" >/dev/null; then
    sed -i -E \
        's|^MODULESDIR=.*$|MODULESDIR=/usr/lib/ssl/ossl-modules|' \
        "${openssl_makefile}"
fi
grep -Fx 'MODULESDIR=/usr/lib/ssl/ossl-modules' \
    "${openssl_makefile}" >/dev/null

"${cmake_bin}" --build "${build_dir}" --parallel "${jobs}"
"${cmake_bin}" --install "${build_dir}"

# Keep only the public Linux API and shared runtime that cmvr-es consumes.
find "${stage_prefix}/include" -maxdepth 1 -type f \
    ! -name msquic.h \
    ! -name msquic_posix.h \
    ! -name quic_sal_stub.h \
    -delete
"${cmake_bin}" -E rm -f "${stage_prefix}/lib/libmsquic_platform.a"
"${cmake_bin}" -E remove_directory "${stage_prefix}/share"
"${cmake_bin}" -E make_directory "${stage_prefix}/share/licenses/msquic"
"${cmake_bin}" -E copy "${source_dir}/LICENSE" \
    "${stage_prefix}/share/licenses/msquic/LICENSE"
"${cmake_bin}" -E copy "${source_dir}/THIRD-PARTY-NOTICES" \
    "${stage_prefix}/share/licenses/msquic/THIRD-PARTY-NOTICES"

cat >"${stage_prefix}/BUILD-INFO.txt" <<EOF
msquic_version=${version}
source_tag=${tag}
source_commit=${source_commit}
dependency_arch=${arch}
tls_backend=quictls-static
dynamic_tls_providers=false
system_libcrypto=false
numa=false
EOF

test -f "${stage_prefix}/include/msquic.h"
test -f "${stage_prefix}/include/msquic_posix.h"
test -f "${stage_prefix}/include/quic_sal_stub.h"
test -f "${stage_prefix}/lib/libmsquic.so.${version}"
test -L "${stage_prefix}/lib/libmsquic.so"

if command -v readelf >/dev/null 2>&1; then
    if readelf -d "${stage_prefix}/lib/libmsquic.so.${version}" |
       grep -E 'NEEDED.*lib(ssl|crypto|numa)' >/dev/null; then
        echo "MsQuic unexpectedly depends on system TLS or NUMA libraries" >&2
        exit 1
    fi
fi
if grep -R -F --exclude='libmsquic.so*' \
       "${repo_root}" "${stage_prefix}" >/dev/null 2>&1; then
    echo "staged MsQuic metadata contains a non-relocatable workspace path" >&2
    exit 1
fi
if command -v strings >/dev/null 2>&1 &&
   strings "${stage_prefix}/lib/libmsquic.so.${version}" |
       grep -F "${repo_root}" >/dev/null; then
    echo "staged MsQuic runtime contains a non-relocatable workspace path" >&2
    exit 1
fi

swap_in_progress=false
restore_install_on_exit() {
    if [[ "${swap_in_progress}" != true ]]; then
        return
    fi
    if [[ -e "${install_root}" ]]; then
        "${cmake_bin}" -E remove_directory "${backup_root}" || true
    elif [[ -e "${backup_root}" ]]; then
        mv "${backup_root}" "${install_root}" || true
    fi
}
trap restore_install_on_exit EXIT

if [[ -e "${backup_root}" ]]; then
    if [[ ! -e "${install_root}" ]]; then
        mv "${backup_root}" "${install_root}"
    else
        echo "stale MsQuic backup requires manual inspection:" >&2
        echo "  ${backup_root}" >&2
        exit 2
    fi
fi
if [[ -e "${install_root}" ]]; then
    swap_in_progress=true
    mv "${install_root}" "${backup_root}"
fi
mv "${stage_prefix}" "${install_root}"
swap_in_progress=false
"${cmake_bin}" -E remove_directory "${backup_root}"
trap - EXIT

echo "MsQuic ${tag} installed to:"
echo "  ${install_root}"
echo "Configure cmvr-es with:"
echo "  -DCMVR_ENABLE_MSQUIC_BACKEND=ON -DCMVR_REQUIRE_MSQUIC=ON"