"""Resolve template text roles once for reuse within a component render."""
from __future__ import annotations

from dataclasses import dataclass
import math

import template_ref as ref


@dataclass(frozen=True)
class TextRole:
    family: str
    size: float
    weight: int
    line_height: float

    @property
    def svg_weight(self):
        return "normal" if self.weight == 400 else "bold" if self.weight == 700 else str(self.weight)

    @property
    def bold(self):
        return self.weight >= 600

    @property
    def line_size(self):
        return self.size * self.line_height


def resolve_role(style: dict, name: str) -> TextRole:
    typography = style["typography"]
    ref.require(name in typography["roles"], f"unknown typography role: {name}")
    role = typography["roles"][name]
    family = typography["families"][role["family_role"]]
    face = family["family"]
    ref.require(isinstance(face, str) and bool(face.strip()), f"{name}: font family required")
    ratio, points = style["canvas"]["pt_to_px"], role["size_pt"]
    line_height = role.get("line_height", 1.25)
    for value, label in ((ratio, "pt_to_px"), (points, "size_pt"), (line_height, "line_height")):
        ref.require(type(value) in (int, float) and math.isfinite(value) and value > 0,
                    f"{name}: positive finite {label} required")
    # A role can refine its family weight without losing the family's defaults.
    raw = role.get("weight_number", role.get("weight", family.get("weight_number", family.get("weight", "Regular"))))
    if isinstance(raw, str):
        weights = {"thin": 100, "extralight": 200, "light": 300, "regular": 400,
                   "normal": 400, "medium": 500, "semibold": 600, "bold": 700,
                   "extrabold": 800, "black": 900}
        raw = weights.get(raw.lower().replace(" ", "").replace("-", ""), raw)
        if isinstance(raw, str) and raw.isdigit():
            raw = int(raw)
    ref.require(type(raw) is int and 1 <= raw <= 1000, f"{name}: invalid font weight")
    return TextRole(face, points * ratio, raw, line_height)