BUILD.bazel

load("@bazel_skylib//lib:selects.bzl", "selects")
load("@bazel_skylib//rules:common_settings.bzl", "string_flag")
load("@rules_cc//cc:cc_library.bzl", "cc_library")

# Bazel build for clickhouse-cpp. The canonical build is CMake
# (top-level CMakeLists.txt); this file mirrors the same library as
# a bzlmod target so downstream Bazel projects can depend on it via
# the Bazel Central Registry without standing up CMake.
#
# Differences from the CMake build that callers should be aware of:
#   * TLS links against BoringSSL (`@boringssl`) by default; pass
#     `--@clickhouse_cpp//:tls=openssl` to use the BCR OpenSSL module
#     instead, or `--@clickhouse_cpp//:tls=no` to disable TLS
#     entirely. `USE_BORINGSSL` ifdef-guards the two OpenSSL-only
#     surfaces (`SSL_CONF_*` command API and `SSL_read_ex`) that
#     BoringSSL doesn't provide; see clickhouse/base/sslsocket.cpp.
#   * cityhash / lz4 / zstd / abseil come from BCR modules instead of
#     contrib/; the contrib/ trees are only used by the CMake build.

# Selects the TLS implementation: `--@clickhouse_cpp//:tls=boringssl`
# (default), `--@clickhouse_cpp//:tls=openssl`, or
# `--@clickhouse_cpp//:tls=no` to disable TLS entirely (matching
# CMake's `WITH_OPENSSL=OFF` default). The two TLS libraries come from
# BCR modules and are linked statically, keeping the build hermetic.
string_flag(
    name = "tls",
    build_setting_default = "boringssl",
    values = [
        "boringssl",
        "openssl",
        "no",
    ],
)

config_setting(
    name = "tls_boringssl",
    flag_values = {":tls": "boringssl"},
)

config_setting(
    name = "tls_openssl",
    flag_values = {":tls": "openssl"},
)

config_setting(
    name = "tls_no",
    flag_values = {":tls": "no"},
)

# OpenSSL on Windows pulls in Win32 system libraries (the cert store via
# crypt32, plus user32) that BoringSSL bundles itself. Used to gate the
# extra linkopts below.
selects.config_setting_group(
    name = "tls_openssl_on_windows",
    match_all = [
        ":tls_openssl",
        "@platforms//os:windows",
    ],
)

# The main clickhouse-cpp library. Downstream callers use
# `#include <clickhouse/client.h>` and link `@clickhouse_cpp//:clickhouse`.
cc_library(
    name = "clickhouse",
    srcs = glob(
        [
            "clickhouse/*.cpp",
            "clickhouse/base/*.cpp",
            "clickhouse/columns/*.cpp",
            "clickhouse/types/*.cpp",
        ],
        # Only compiled when TLS is enabled, mirroring CMake's
        # `IF (WITH_OPENSSL)` source-list append.
        exclude = ["clickhouse/base/sslsocket.cpp"],
    ) + select({
        ":tls_no": [],
        "//conditions:default": ["clickhouse/base/sslsocket.cpp"],
    }),
    hdrs = glob([
        "clickhouse/*.h",
        "clickhouse/base/*.h",
        "clickhouse/columns/*.h",
        "clickhouse/types/*.h",
    ]),
    defines = select({
        # `WITH_OPENSSL` enables the TLS code paths in client.cpp /
        # sslsocket.cpp (same macro as the CMake option). `USE_BORINGSSL`
        # takes the BoringSSL-compatible branches in sslsocket.cpp.
        ":tls_boringssl": [
            "WITH_OPENSSL",
            "USE_BORINGSSL",
        ],
        ":tls_openssl": ["WITH_OPENSSL"],
        ":tls_no": [],
    }),
    # Winsock, required by base/socket.cpp et al. Mirrors CMake's
    # `IF (WIN32 OR MINGW)` link block. (The BoringSSL backend already
    # propagates ws2_32 itself; declare it explicitly so the openssl
    # and no-TLS configurations link too.)
    linkopts = select({
        "@platforms//os:windows": [
            "-DEFAULTLIB:ws2_32.lib",
        ],
        "//conditions:default": [],
    }) + select({
        # OpenSSL references the Win32 cert store and user32; declare
        # them so downstream executables link without each consumer
        # having to repeat it. Mirrors CMake's MSVC `Crypt32` link.
        ":tls_openssl_on_windows": [
            "-DEFAULTLIB:crypt32.lib",
            "-DEFAULTLIB:user32.lib",
        ],
        "//conditions:default": [],
    }),
    # Expose headers at their workspace path so both internal
    # (`#include "client.h"` from clickhouse/*.cpp via quote-form
    # source-dir search) and external (`#include <clickhouse/client.h>`)
    # include forms resolve.
    strip_include_prefix = "/",
    visibility = ["//visibility:public"],
    deps = [
        "@abseil-cpp//absl/numeric:int128",
        "@cityhash//:cityhash",
        "@lz4//:lz4",
        "@zstd//:zstd",
    ] + select({
        ":tls_boringssl": [
            "@boringssl//:crypto",
            "@boringssl//:ssl",
        ],
        ":tls_openssl": [
            "@openssl//:crypto",
            "@openssl//:ssl",
        ],
        ":tls_no": [],
    }),
)