"""Custom hatchling build hook: build the React frontend if it is missing or stale.

This makes NVCurve installable with a single command, e.g.::

    uv tool install "git+https://gitea.zephyre.one/Pakobbix/nvcurve.git"

The hook runs inside the isolated build environment right before the wheel
(or sdist) is assembled. If ``frontend/dist`` does not exist yet — or is older
than the frontend sources — it compiles the frontend using the host's ``npm``
(PATH is inherited from the environment).
"""

from __future__ import annotations

import os
import shutil
import subprocess
import sys

from hatchling.builders.hooks.plugin.interface import BuildHookInterface

# Frontend inputs that must be newer than dist/index.html to trigger a rebuild.
_FRONTEND_INPUTS = (
    "src",
    "index.html",
    "vite.config.ts",
    "package.json",
    "tsconfig.json",
)


class FrontendBuildHook(BuildHookInterface):
    """Build ``frontend/dist`` with npm when it is missing or stale."""

    PLUGIN_NAME = "custom"

    def initialize(self, version: str, build_data: dict) -> None:
        frontend = os.path.join(self.root, "frontend")
        dist_index = os.path.join(frontend, "dist", "index.html")

        if not self._needs_build(frontend, dist_index):
            return

        npm = shutil.which("npm")
        if npm is None:
            raise RuntimeError(
                "npm not found on PATH. Node.js 18+ and npm are required to build "
                "the NVCurve frontend. Install them and retry, or use install.sh "
                "which checks prerequisites for you."
            )

        print(
            "[nvcurve] frontend/dist missing or stale — building frontend with npm ...",
            file=sys.stderr,
        )
        subprocess.run([npm, "ci", "--no-audit", "--no-fund"], cwd=frontend, check=True)
        subprocess.run([npm, "run", "build"], cwd=frontend, check=True)

    @staticmethod
    def _needs_build(frontend: str, dist_index: str) -> bool:
        if not os.path.isfile(dist_index):
            return True
        dist_mtime = os.path.getmtime(dist_index)
        for name in _FRONTEND_INPUTS:
            path = os.path.join(frontend, name)
            if os.path.isfile(path):
                if os.path.getmtime(path) > dist_mtime:
                    return True
            elif os.path.isdir(path):
                for root, _dirs, files in os.walk(path):
                    for file in files:
                        if os.path.getmtime(os.path.join(root, file)) > dist_mtime:
                            return True
        return False