"""自研 skill 发现与解析。"""

from __future__ import annotations

import re
from pathlib import Path

from skiff.paths import SKILLS_DIR, TEMPLATE_DIR, ensure_skills_home
from skiff.registry import external_skill_path, load_registry


def list_owned_skills() -> list[str]:
    ensure_skills_home()
    if not SKILLS_DIR.is_dir():
        return []
    names: list[str] = []
    for entry in sorted(SKILLS_DIR.iterdir()):
        if not entry.is_dir():
            continue
        if entry.name.startswith("_"):
            continue
        if (entry / "SKILL.md").is_file():
            names.append(entry.name)
    return names


def owned_skill_path(name: str) -> Path:
    path = SKILLS_DIR / name
    if not (path / "SKILL.md").is_file():
        raise SystemExit(f"自研 skill 不存在: {name}")
    return path


def resolve_skill_source(name: str, *, source: str | None = None) -> tuple[Path, str]:
    """返回 (skill_path, kind)，kind 为 owned 或 external。"""
    ensure_skills_home()

    owned = SKILLS_DIR / name
    if source in (None, "owned") and (owned / "SKILL.md").is_file():
        return owned, "owned"

    registry = load_registry()
    if source in (None, "registry") and name in registry:
        path = external_skill_path(name, registry[name])
        if not path.exists():
            raise SystemExit(
                f"外部 skill {name!r} 尚未 fetch。请先运行: skiff fetch {name}"
            )
        return path, "external"

    if (owned / "SKILL.md").is_file():
        return owned, "owned"

    raise SystemExit(f"找不到 skill: {name}")


def read_skill_meta(skill_dir: Path) -> dict[str, str]:
    skill_md = skill_dir / "SKILL.md"
    if not skill_md.is_file():
        return {}
    text = skill_md.read_text(encoding="utf-8")
    if not text.startswith("---"):
        return {}
    end = text.find("\n---", 3)
    if end == -1:
        return {}
    frontmatter = text[3:end]
    meta: dict[str, str] = {}

    name_match = re.search(r"^name:\s*(.+)$", frontmatter, re.MULTILINE)
    if name_match:
        meta["name"] = name_match.group(1).strip().strip("\"'")

    desc_match = re.search(
        r"^description:\s*(?:>-|>\||>|-)?\s*\n((?:[ \t].+\n?)+)",
        frontmatter,
        re.MULTILINE,
    )
    if desc_match:
        lines = [line.strip() for line in desc_match.group(1).splitlines() if line.strip()]
        meta["description"] = " ".join(lines)
    else:
        inline = re.search(r"^description:\s*(.+)$", frontmatter, re.MULTILINE)
        if inline:
            meta["description"] = inline.group(1).strip().strip("\"'")

    return meta


def skill_description(name: str) -> str | None:
    meta = read_skill_meta(SKILLS_DIR / name)
    desc = meta.get("description")
    return desc.strip() if desc else None


def validate_skill_name(name: str) -> None:
    import re

    if not re.fullmatch(r"[a-z0-9]+(?:-[a-z0-9]+)*", name):
        raise SystemExit(
            f"skill 名称无效: {name!r}（小写 + 连字符，如 security-review）"
        )
    if name == "_template":
        raise SystemExit("不能使用保留名 _template")