"""Visualization layer: consume EvalReport artifacts, render views.

Strictly a CONSUMER of the eval layer (reads saved report json, never scores).
Renderers are registered plugins: text table, markdown, and ascii bar/radar
charts today; a web renderer can register the same way later.

    from evalharness.viz import render
    render('report.json', style='text')          # console table
    render([r1, r2], style='md_compare')         # benchmark comparison table
"""

import importlib
import pkgutil
from pathlib import Path
from typing import Callable, Dict, List, Union

from ..eval.record import EvalReport

RendererFn = Callable[[Union['EvalReport', List['EvalReport'], str, Path], Dict], str]

RENDERERS: Dict[str, RendererFn] = {}


def register_renderer(name: str):
    def decorator(fn: RendererFn) -> RendererFn:
        if name in RENDERERS:
            raise ValueError(f'renderer {name!r} already registered')
        RENDERERS[name] = fn
        return fn

    return decorator


def get_renderer(name: str) -> RendererFn:
    if name not in RENDERERS:
        raise KeyError(f"unknown renderer {name!r}. Available: {', '.join(sorted(RENDERERS))}")
    return RENDERERS[name]


def render(target, style: str = 'text', **opts) -> str:
    """Render one report path/object or a list of them (comparison styles)."""
    return get_renderer(style)(_load(target), opts)


def _load(target) -> Union[EvalReport, List[EvalReport]]:
    if isinstance(target, (str, Path)):
        return EvalReport.load(target)
    if isinstance(target, EvalReport):
        return target
    if isinstance(target, (list, tuple)):
        return [_load(t) for t in target]
    raise TypeError(f'cannot load report from {type(target)}')


def _discover_builtin_renderers() -> None:
    pkg_dir = Path(__file__).parent / 'renderers'
    if not pkg_dir.exists():
        return
    for info in pkgutil.iter_modules([str(pkg_dir)]):
        importlib.import_module(f'{__name__}.renderers.{info.name}')


_discover_builtin_renderers()