"""Prompt loader + renderer.

Every prompt — system or user — lives as a `.txt` file in this directory.
Two ways to consume them:

- `load(name)` returns the file's text unchanged. Use for system prompts
  (and any user prompt that has no placeholders).
- `render(name, **vars)` loads then runs `str.format(**vars)` on it. Use
  for user prompts that interpolate question/SQL/rows/findings/etc.
  Placeholders are standard Python format syntax: `{name}`. Literal braces
  must be doubled: `{{` / `}}`.
"""

from __future__ import annotations

from functools import lru_cache
from pathlib import Path
from typing import Any

PROMPTS_DIR = Path(__file__).resolve().parent


@lru_cache(maxsize=None)
def load(name: str) -> str:
    """Read the named prompt file (no substitution)."""
    return (PROMPTS_DIR / f"{name}.txt").read_text(encoding="utf-8").strip()


def render(name: str, /, **vars: Any) -> str:
    """Load a prompt and substitute `{placeholder}` values from kwargs."""
    return load(name).format(**vars)