"""Load editable clipboard skills from data/skills/."""

from __future__ import annotations

from pathlib import Path

from util.paths import SKILLS_DIR

_ENGINE_MARKERS = {
    "rpgmaker": ("<!-- engine:rpgmaker -->", "<!-- /engine:rpgmaker -->"),
    "wolf": ("<!-- engine:wolf -->", "<!-- /engine:wolf -->"),
}


def _read_skill_file(name: str) -> str:
    path = SKILLS_DIR / name
    if not path.is_file():
        raise FileNotFoundError(f"Skill file missing: {path}")
    return path.read_text(encoding="utf-8")


def _extract_engine_section(text: str, engine: str) -> str:
    """Keep shared body + the requested engine block; drop other engine blocks."""
    start_tag, end_tag = _ENGINE_MARKERS.get(engine, (None, None))
    if not start_tag:
        return text

    result_parts: list[str] = []
    pos = 0
    while pos < len(text):
        next_starts = [
            (text.find(marker[0], pos), eng, marker)
            for eng, marker in _ENGINE_MARKERS.items()
            if text.find(marker[0], pos) != -1
        ]
        if not next_starts:
            result_parts.append(text[pos:])
            break
        next_starts.sort(key=lambda x: x[0])
        idx, eng, (s_tag, e_tag) = next_starts[0]
        result_parts.append(text[pos:idx])
        end_idx = text.find(e_tag, idx)
        if end_idx == -1:
            raise ValueError(f"Unclosed engine block {s_tag} in skill file")
        block_body = text[idx + len(s_tag) : end_idx]
        if eng == engine:
            result_parts.append(block_body.strip("\n") + "\n")
        pos = end_idx + len(e_tag)
    return "".join(result_parts).strip() + "\n"


def load_project_setup(engine: str = "rpgmaker", *, prepend: str = "") -> str:
    """Load the Project Setup clipboard skill for *engine*."""
    raw = _read_skill_file("project_setup.md")
    body = _extract_engine_section(raw, engine)
    if prepend:
        return prepend.rstrip() + "\n\n" + body
    return body


def load_clipboard_skill(name: str) -> str:
    """Load a static clipboard prompt from ``data/skills``.

    Read on every copy so edits made in the Skills tab take effect immediately.
    Only a plain Markdown filename is accepted to keep callers inside the shipped
    skills directory.
    """
    path_name = Path(name)
    if path_name.name != name or path_name.suffix.casefold() != ".md":
        raise ValueError(f"Invalid clipboard skill filename: {name!r}")
    return _read_skill_file(name).strip() + "\n"


def skills_dir() -> Path:
    return SKILLS_DIR