"""Versioned prompt files: `prompts/<task>/v<N>.md` (spec §125 — prompts live in code, versions are recorded on every event/job).

A prompt file is Markdown; everything after the optional front-matter comment is the *system* prompt. The user message is always a
compact JSON context built by the caller, so prompts never interpolate untrusted text into instructions.
"""
from __future__ import annotations

import re
from dataclasses import dataclass
from functools import lru_cache
from pathlib import Path

from companyatlas.config import settings

_REPO_ROOT = Path(__file__).resolve().parents[4]
_VERSION_RE = re.compile(r"^v(\d+)\.md$")


def prompts_dir() -> Path:
    return Path(settings.prompts_dir) if settings.prompts_dir else _REPO_ROOT / "prompts"


@dataclass(frozen=True, slots=True)
class Prompt:
    task: str
    version: str
    system: str

    @property
    def ref(self) -> str:
        return f"{self.task}/{self.version}"


@lru_cache(maxsize=64)
def load_prompt(task: str, version: str | None = None) -> Prompt:
    """Load `prompts/<task>/<version>.md` (latest `vN` when version is None). Raises FileNotFoundError when missing."""
    folder = prompts_dir() / task
    if version is None:
        candidates = sorted(((int(m.group(1)), p) for p in folder.glob("v*.md") if (m := _VERSION_RE.match(p.name))), reverse=True)
        if not candidates:
            raise FileNotFoundError(f"no prompt versions in {folder}")
        path = candidates[0][1]
        version = path.stem
    else:
        path = folder / f"{version}.md"
    text = path.read_text(encoding="utf-8")
    text = re.sub(r"\A<!--.*?-->\s*", "", text, flags=re.DOTALL)          # optional front-matter comment
    return Prompt(task=task, version=version, system=text.strip())


def available_prompts() -> dict[str, list[str]]:
    root = prompts_dir()
    if not root.exists():
        return {}
    return {d.name: sorted(p.stem for p in d.glob("v*.md")) for d in root.iterdir() if d.is_dir()}


__all__ = ["Prompt", "available_prompts", "load_prompt", "prompts_dir"]