"""Load map/reduce prompts: env wins, else file, else bundled k8s prompts.

Blank ``MAP_PROMPT`` / ``SUMMARY_PROMPT`` (compose ``${VAR:-}``) is treated as
unset so a host .env can swap text without rebuilding the image.
"""

from __future__ import annotations

import os
from pathlib import Path

_BUNDLED = Path(__file__).resolve().parent / "prompt_files"
_MAP_FILE = "map.txt"
_SUMMARY_FILE = "summary.txt"


def resolve_prompt(env_name: str, file_env: str, bundled_name: str) -> str:
    raw = (os.getenv(env_name) or "").strip()
    if raw:
        return raw
    path = (os.getenv(file_env) or "").strip() or str(_BUNDLED / bundled_name)
    try:
        text = Path(path).read_text(encoding="utf-8")
    except OSError as exc:
        raise RuntimeError(f"{env_name} unset and prompt file unreadable: {path}") from exc
    if not text.strip():
        raise RuntimeError(f"{env_name} unset and prompt file empty: {path}")
    return text


def map_prompt_template() -> str:
    return resolve_prompt("MAP_PROMPT", "MAP_PROMPT_FILE", _MAP_FILE)


def summary_prompt_template() -> str:
    return resolve_prompt("SUMMARY_PROMPT", "SUMMARY_PROMPT_FILE", _SUMMARY_FILE)