from __future__ import annotations

import inspect
from functools import update_wrapper
from pathlib import Path
from typing import Callable, Generic, ParamSpec

from .registry import PageDefinition, registry

P = ParamSpec("P")


def _normalise_page_number(number: str | int | float) -> str:
    value = str(number).strip().strip(".")
    parts = [part.strip() for part in value.split(".")]
    if not value or any(not part for part in parts):
        raise ValueError("Page number must contain non-empty dot-separated parts")
    return ".".join(parts)


class Component(Generic[P]):
    """Turn a function returning HTML into a reusable documentation component."""

    def __init__(self, function: Callable[P, str]) -> None:
        if not callable(function):
            raise TypeError("@Component must decorate a callable")
        self.function = function
        update_wrapper(self, function)

    def __call__(self, *args: P.args, **kwargs: P.kwargs) -> str:
        result = self.function(*args, **kwargs)
        if not isinstance(result, str):
            raise TypeError(f"Component {self.__name__} must return str, got {type(result).__name__}")
        return result


class Page:
    """Register a zero-argument function as a numbered documentation page."""

    def __init__(self, number: str | int | float, title: str) -> None:
        self.number = _normalise_page_number(number)
        self.title = str(title).strip()
        if not self.title:
            raise ValueError("Page title cannot be empty")

    def __call__(self, function: Callable[[], object]) -> Callable[[], object]:
        signature = inspect.signature(function)
        if signature.parameters:
            raise TypeError(f"Page function {function.__name__} must not accept arguments")
        source = inspect.getsourcefile(function)
        source_file = str(Path(source).resolve()) if source else None
        registry.register(
            PageDefinition(
                number=self.number,
                title=self.title,
                render=function,
                module=function.__module__,
                source_file=source_file,
            )
        )
        return function


__all__ = ["Component", "Page"]