"""The widget templates a Prometheus widget can draw with.

Bundled templates ship in plugins/prometheus/widgets/*.yaml, read once and
read-only; their key is "bundled:<file name>". Templates an admin copies in
join them with the template library (#5692). Steward fetches none from
anywhere (System 181's ruling).
"""
from __future__ import annotations

from dataclasses import dataclass, field
from functools import lru_cache
from pathlib import Path

from sqlalchemy import select

from .models import PrometheusTarget
from .template_format import Problem, Template, TemplateError, check

BUNDLED = Path(__file__).parent / "widgets"


@dataclass
class Entry:
    key: str
    name: str
    bundled: bool
    text: str
    template: Template | None = None
    problems: list[Problem] = field(default_factory=list)


def _entry(key: str, fallback_name: str, text: str, bundled: bool) -> Entry:
    try:
        template = check(text)
    except TemplateError as exc:
        return Entry(key, fallback_name, bundled, text, None, exc.problems)
    return Entry(key, template.name, bundled, text, template)


@lru_cache(maxsize=1)
def bundled() -> tuple[Entry, ...]:
    return tuple(_entry(f"bundled:{p.stem}", p.stem, p.read_text(encoding="utf-8"), True)
                 for p in sorted(BUNDLED.glob("*.yaml")))


async def entries(db) -> list[Entry]:
    """Every template, by name."""
    return sorted(bundled(), key=lambda e: e.name.lower())


async def find(db, key: str) -> Entry | None:
    return next((e for e in await entries(db) if e.key == key), None)


# ── The widget's settings ────────────────────────────────────────────────────

async def target_options(db) -> list[dict]:
    rows = (await db.execute(select(PrometheusTarget.id, PrometheusTarget.name)
                             .order_by(PrometheusTarget.name))).all()
    return [{"value": tid, "label": name} for tid, name in rows]


async def template_options(db) -> list[dict]:
    return [{"value": e.key, "label": f"{e.name} (built in)" if e.bundled else e.name}
            for e in await entries(db) if e.template is not None]


async def default_title(db, config: dict) -> str | None:
    """A new widget is named after its template: "Fabled Archives"."""
    entry = await find(db, str(config.get("template") or ""))
    return entry.name if entry and entry.template else None