# Copyright 2020 The IREE Authors
#
# Licensed under the Apache License v2.0 with LLVM Exceptions.
# See https://llvm.org/LICENSE.txt for license information.
# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

import platform
import os
import subprocess
import sys


def detect_unix_platform_config(bazelrc):
    # This is hoaky. Ideally, bazel had any kind of rational way of selecting
    # options from within its environment (key word: "rational"), but sadly, it
    # is unintelligible to mere mortals. Why should a build system have a way for
    # people to condition their build options on what compiler they are using
    # (without descending down the hole of deciphering what a Bazel toolchain is)?
    # All I want to do is set a couple of project specific warning options!

    if platform.system() == "Darwin":
        print(f"build --config=macos_clang", file=bazelrc)
        print(f"build:release --config=macos_clang_release", file=bazelrc)
    else:
        # If the user specified a CXX environment var, bazel will later respect that,
        # so we just see if it says "clang".
        cxx = os.environ.get("CXX")
        cc = os.environ.get("CC")
        if (cxx is not None and cc is None) or (cxx is None and cc is not None):
            print(
                "WARNING: Only one of CXX or CC is set, which can confuse bazel. "
                "Recommend: set both appropriately (or none)"
            )
        if cc is not None and cxx is not None:
            # Persist the variables.
            print(f'build --action_env CC="{cc}"', file=bazelrc)
            print(f'build --action_env CXX="{cxx}"', file=bazelrc)
        else:
            print(
                "WARNING: CC and CXX are not set, which can cause mismatches between "
                "flag configurations and compiler. Recommend setting them explicitly."
            )

        if cxx is not None and "clang" in cxx:
            print(f"Choosing generic_clang config because CXX is set to clang ({cxx})")
            print(f"build --config=generic_clang", file=bazelrc)
            print(f"build:release --config=generic_clang_release", file=bazelrc)
        else:
            print(
                f"Choosing generic_gcc config by default because no CXX set or "
                f"not recognized as clang ({cxx})"
            )
            print(f"build --config=generic_gcc", file=bazelrc)
            print(f"build:release --config=generic_gcc_release", file=bazelrc)


def write_platform(bazelrc):
    if platform.system() == "Windows":
        print(f"build --config=msvc", file=bazelrc)
        print(f"build:release --config=msvc_release", file=bazelrc)
    else:
        detect_unix_platform_config(bazelrc)


def cmake_bool_is_true(value):
    """Check if a CMake-style bool value is true."""
    if not value:
        return False
    return value.upper() in ("ON", "YES", "TRUE", "Y", "1")


def get_hal_driver_defaults():
    """Get HAL driver defaults matching CMake option(IREE_HAL_DRIVER_*) definitions."""
    defaults_enabled = True  # Matches IREE_HAL_DRIVER_DEFAULTS in CMakeLists.txt

    return {
        "AMDGPU": False,
        "CUDA": False,
        "HIP": False,
        "LOCAL_SYNC": defaults_enabled,
        "LOCAL_TASK": defaults_enabled,
        "METAL": platform.system() == "Darwin" and defaults_enabled,
        "NULL": False,  # Special: OFF in tests, ON otherwise
        "VULKAN": defaults_enabled and platform.system() not in ("Android", "iOS"),
    }


def env_var_to_bazel_tag(name):
    """Convert env var name to Bazel tag format.

    Bazel tags use hyphens: local-task, vulkan-spirv
    Env vars use underscores: IREE_HAL_DRIVER_LOCAL_TASK
    """
    if name.startswith("IREE_HAL_DRIVER_"):
        tag_name = name[len("IREE_HAL_DRIVER_") :]
    else:
        tag_name = name
    return tag_name.lower().replace("_", "-")


def write_iree_hal_driver_options(bazelrc):
    """Write HAL driver configuration to bazelrc."""

    # Get defaults matching CMake
    hal_drivers = get_hal_driver_defaults()

    # Apply environment overrides
    enabled_drivers = []
    for driver, default in hal_drivers.items():
        env_var = f"IREE_HAL_DRIVER_{driver}"
        env_value = os.environ.get(env_var)
        enabled = cmake_bool_is_true(env_value) if env_value is not None else default

        if enabled:
            enabled_drivers.append(env_var_to_bazel_tag(env_var))

    # Write --iree_drivers flag (controls what gets built and linked)
    if enabled_drivers:
        print(f'build --iree_drivers={",".join(enabled_drivers)}', file=bazelrc)
        print(f'test --iree_drivers={",".join(enabled_drivers)}', file=bazelrc)


if len(sys.argv) > 1:
    local_bazelrc = sys.argv[1]
else:
    local_bazelrc = os.path.join(os.path.dirname(__file__), "configured.bazelrc")
with open(local_bazelrc, "wt") as bazelrc:
    write_platform(bazelrc)
    write_iree_hal_driver_options(bazelrc)

print("Wrote", local_bazelrc)