#!/usr/bin/env python3
"""Run C++/MSVC Harness validation commands."""

from __future__ import annotations

import json
import os
import shutil
import subprocess
import sys
from pathlib import Path


DEFAULT_GENERATOR = "Visual Studio 17 2022"
DEFAULT_PLATFORM = "x64"
DEFAULT_CONFIG = "Debug"
DEFAULT_BUILD_DIR = "build/msvc-debug"
PRESET_NAME = "msvc-debug"
COMMON_CMAKE_BIN = Path(r"C:\Program Files\CMake\bin")


def load_env_commands() -> list[str]:
    raw = os.environ.get("HARNESS_VALIDATION_COMMANDS", "")
    return [line.strip() for line in raw.splitlines() if line.strip()]


def _cmake_config() -> tuple[str, str, str, Path]:
    generator = os.environ.get("HARNESS_CMAKE_GENERATOR", DEFAULT_GENERATOR)
    platform = os.environ.get("HARNESS_CMAKE_PLATFORM", DEFAULT_PLATFORM)
    config = os.environ.get("HARNESS_CMAKE_CONFIG", DEFAULT_CONFIG)
    build_dir = Path(os.environ.get("HARNESS_BUILD_DIR", DEFAULT_BUILD_DIR))
    return generator, platform, config, build_dir


def _read_presets(root: Path) -> dict:
    presets_file = root / "CMakePresets.json"
    if not presets_file.exists():
        return {}
    try:
        return json.loads(presets_file.read_text(encoding="utf-8"))
    except json.JSONDecodeError:
        return {}


def _preset_binary_dir(root: Path, preset: dict) -> Path:
    binary_dir = str(preset.get("binaryDir") or DEFAULT_BUILD_DIR)
    binary_dir = binary_dir.replace("${sourceDir}", str(root))
    binary_dir = binary_dir.replace("$sourceDir", str(root))
    path = Path(binary_dir)
    return path if path.is_absolute() else root / path


def load_preset_commands(root: Path) -> list[str]:
    payload = _read_presets(root)
    config = os.environ.get("HARNESS_CMAKE_CONFIG", DEFAULT_CONFIG)
    for preset in payload.get("configurePresets", []):
        if isinstance(preset, dict) and preset.get("name") == PRESET_NAME:
            build_dir = _preset_binary_dir(root, preset)
            return [
                f"cmake --preset {PRESET_NAME}",
                f'cmake --build "{build_dir}" --config {config}',
                f'ctest --test-dir "{build_dir}" --output-on-failure -C {config}',
            ]
    return []


def load_cmake_commands(root: Path) -> list[str]:
    if not (root / "CMakeLists.txt").exists():
        return []

    generator, platform, config, build_dir = _cmake_config()
    if not build_dir.is_absolute():
        build_dir = root / build_dir
    return [
        f'cmake -S "{root}" -B "{build_dir}" -G "{generator}" -A {platform}',
        f'cmake --build "{build_dir}" --config {config}',
        f'ctest --test-dir "{build_dir}" --output-on-failure -C {config}',
    ]


def discover_commands(root: Path) -> list[str]:
    env_commands = load_env_commands()
    if env_commands:
        return env_commands
    preset_commands = load_preset_commands(root)
    if preset_commands:
        return preset_commands
    return load_cmake_commands(root)


def run_command(command: str, root: Path) -> subprocess.CompletedProcess:
    return subprocess.run(
        command,
        cwd=root,
        shell=True,
        capture_output=True,
        text=True,
        encoding="utf-8",
        errors="replace",
        env=validation_environment(os.environ),
    )


def validation_environment(base_env: os._Environ | dict[str, str]) -> dict[str, str]:
    env = dict(base_env)
    if shutil.which("cmake") is not None:
        return env
    cmake_exe = COMMON_CMAKE_BIN / "cmake.exe"
    if not cmake_exe.exists():
        return env

    current_path = env.get("PATH", "")
    paths = [part for part in current_path.split(os.pathsep) if part]
    common_bin_text = str(COMMON_CMAKE_BIN)
    if not any(part.lower() == common_bin_text.lower() for part in paths):
        env["PATH"] = common_bin_text + (os.pathsep + current_path if current_path else "")
    return env


def emit_stream(prefix: str, content: str, *, stream) -> None:
    text = (content or "").strip()
    if not text:
        return
    print(prefix, file=stream)
    print(text, file=stream)


def main() -> int:
    root = Path(__file__).resolve().parent.parent
    commands = discover_commands(root)

    if not commands:
        print("No C++ validation commands configured.")
        print("Add CMakeLists.txt or set HARNESS_VALIDATION_COMMANDS.")
        return 0

    for command in commands:
        print(f"$ {command}")
        result = run_command(command, root)
        emit_stream("[stdout]", result.stdout, stream=sys.stdout)
        emit_stream("[stderr]", result.stderr, stream=sys.stderr)
        if result.returncode != 0:
            print(f"Validation failed: {command}", file=sys.stderr)
            return result.returncode

    print("Validation succeeded.")
    return 0


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