"""Shared Jinja2 environment with custom filters for the dashboard.
Imported by both routers/pages.py and routers/api.py so the filters are
registered exactly once."""
from __future__ import annotations

from pathlib import Path

from fastapi.templating import Jinja2Templates


TEMPLATE_DIR = Path(__file__).resolve().parent / "templates"


def _fmt_price(v: float | None) -> str:
    """Format a price in a way that's readable in dense terminal tables.
    Avoids scientific notation for large round numbers (FTSE 25,962, not 2.596e+04)
    and keeps enough precision for FX rates like 0.8725 EUR/GBP."""
    if v is None:
        return "—"
    av = abs(v)
    if av >= 1000:
        return f"{v:,.2f}"
    if av >= 10:
        return f"{v:.2f}"
    if av >= 1:
        return f"{v:.4f}"
    return f"{v:.4f}"


def _fmt_signed(v: float | None, decimals: int = 2) -> str:
    if v is None:
        return "—"
    return f"{v:+,.{decimals}f}"


def _fmt_money(v: float | None) -> str:
    if v is None:
        return "—"
    return f"{v:,.2f}"


templates = Jinja2Templates(directory=str(TEMPLATE_DIR))
templates.env.filters["price"] = _fmt_price
templates.env.filters["signed"] = _fmt_signed
templates.env.filters["money"] = _fmt_money