"""Persona: Lyra's identity and voice, loaded from an editable markdown prompt.

The prompt lives in `personas/<name>.md` so it can be tuned without touching code.
`LYRA_PERSONA` selects which file to load (default: "lyra").

The file is split on `## ` headers so the control plane can include only what a turn
needs: the **core** (identity + voice — the anti-generic essentials) is always sent;
the heavier situational sections (her origin, the self-model, the poker guardrails)
are pulled in by `mind` only when relevant. This keeps the per-turn prompt tight
without losing fidelity. `system_prompt()` still returns the whole thing (fallback).
"""
from __future__ import annotations

import os
import re
from functools import lru_cache
from pathlib import Path

_PERSONA_DIR = Path(__file__).parent / "personas"

# Sections always sent (besides the intro) — the voice + identity that keep her her.
_CORE = ("Who you are", "How you talk", "Right now")


def _name(name: str | None) -> str:
    return name or os.getenv("LYRA_PERSONA", "lyra")


@lru_cache(maxsize=None)
def _sections(name: str) -> dict[str, str]:
    """Parse the persona file into {header: text}; the pre-header preamble is 'intro'."""
    text = (_PERSONA_DIR / f"{name}.md").read_text(encoding="utf-8").strip()
    chunks = re.split(r"(?m)^## ", text)
    out = {"intro": chunks[0].strip()}
    for ch in chunks[1:]:
        header = ch.split("\n", 1)[0].strip()
        out[header] = ("## " + ch).strip()
    return out


@lru_cache(maxsize=None)
def system_prompt(name: str | None = None) -> str:
    """The full persona (every section). Fallback / back-compat."""
    return (_PERSONA_DIR / f"{_name(name)}.md").read_text(encoding="utf-8").strip()


def core_prompt(name: str | None = None) -> str:
    """Intro + the always-on core sections (identity + voice)."""
    s = _sections(_name(name))
    parts = [s["intro"]] + [section(h, name) for h in _CORE]
    return "\n\n".join(p for p in parts if p)


def section(header_prefix: str, name: str | None = None) -> str:
    """A situational section by header prefix (e.g. 'How you actually work'); '' if absent."""
    pref = header_prefix.lower()
    for header, body in _sections(_name(name)).items():
        if header.lower().startswith(pref):
            return body
    return ""