"""Build the SETCore shared library without imposing one host toolchain.

CMake remains the primary build.  On a Windows workstation where CMake is
absent, the script locates Visual Studio and invokes MSVC directly.  Unix-like
hosts fall back to the system C compiler.
"""

from __future__ import annotations

import argparse
import os
import platform
import shutil
import subprocess
from pathlib import Path


ROOT = Path(__file__).resolve().parent.parent
INCLUDE = ROOT / "include"
SOURCES = [
    ROOT / "src" / name for name in (
        "gui_frame.c", "pcan_abi.c", "pcan_crc.c", "pcan_frame.c", "pcan_id.c",
        "pcan_link.c", "pcan_ring.c", "pcan_gas.c",
    )
]


def _visual_studio_vcvars() -> Path | None:
    installer = Path(os.environ.get("ProgramFiles(x86)", r"C:\Program Files (x86)"))
    vswhere = installer / "Microsoft Visual Studio" / "Installer" / "vswhere.exe"
    if vswhere.exists():
        result = subprocess.run(
            [str(vswhere), "-latest", "-products", "*",
             "-requires", "Microsoft.VisualStudio.Component.VC.Tools.x86.x64",
             "-property", "installationPath"],
            text=True, capture_output=True, check=False,
        )
        if result.returncode == 0 and result.stdout.strip():
            candidate = (Path(result.stdout.strip()) / "VC" / "Auxiliary" /
                         "Build" / "vcvars64.bat")
            if candidate.exists():
                return candidate
    return None


def _build_msvc(output: Path, build_dir: Path) -> None:
    vcvars = _visual_studio_vcvars()
    if vcvars is None:
        raise SystemExit("Visual Studio C++ tools were not found")
    quoted_sources = " ".join(f'"{source}"' for source in SOURCES)
    import_library = build_dir / "setcore.lib"
    command = (
        f'call "{vcvars}" && cl /nologo /W4 /std:c11 '
        f'/DPCAN_ABI_BUILD_DLL /I"{INCLUDE}" /LD {quoted_sources} '
        f'/Fe"{output}" /link /IMPLIB:"{import_library}"'
    )
    # shell=True is intentional on Windows: ``call`` must run the batch file
    # in the same cmd.exe process that subsequently launches cl.exe.
    subprocess.run(command, cwd=build_dir, check=True, shell=True)


def _build_cc(output: Path, build_dir: Path) -> None:
    compiler = shutil.which("cc") or shutil.which("clang") or shutil.which("gcc")
    if compiler is None:
        raise SystemExit("C compiler was not found")
    command = [compiler, "-std=c99", "-Wall", "-Wextra", "-Wpedantic",
               "-fPIC", "-shared", f"-I{INCLUDE}", *map(str, SOURCES),
               "-o", str(output)]
    subprocess.run(command, cwd=build_dir, check=True)


def main() -> int:
    parser = argparse.ArgumentParser()
    parser.add_argument("--output", type=Path, required=True)
    args = parser.parse_args()
    output = args.output.resolve()
    output.parent.mkdir(parents=True, exist_ok=True)
    build_dir = output.parent / ".setcore-build"
    build_dir.mkdir(parents=True, exist_ok=True)
    if platform.system() == "Windows":
        _build_msvc(output, build_dir)
    else:
        _build_cc(output, build_dir)
    print(output)
    return 0


if __name__ == "__main__":
    raise SystemExit(main())