"""Skills Scanner — Scan skills/ directory and generate SKILLS_SNAPSHOT.md."""

from hashlib import sha256
from pathlib import Path
import re

import yaml


MAX_SKILL_BYTES = 64 * 1024


def parse_skill(content: str) -> dict:
    """Validate the small, declarative SKILL.md format used by the workbench."""
    if not isinstance(content, str) or not content.startswith("---") or len(content.encode("utf-8")) > MAX_SKILL_BYTES:
        raise ValueError("SKILL.md 缺少 YAML 头或超过 64 KB")
    parts = content.split("---", 2)
    meta = yaml.safe_load(parts[1]) if len(parts) == 3 else None
    if not isinstance(meta, dict) or not isinstance(meta.get("name"), str) or not meta["name"].strip():
        raise ValueError("SKILL.md 必须声明 name")
    if not isinstance(meta.get("description"), str) or not meta["description"].strip():
        raise ValueError("SKILL.md 必须声明 description")
    details = meta.get("metadata", {})
    if not isinstance(details, dict):
        raise ValueError("SKILL.md 的 metadata 必须是对象")
    for field in ("inputs", "audience"):
        value = meta.get(field, details.get(field))
        if value is not None and (not isinstance(value, list) or not all(isinstance(item, str) for item in value)):
            raise ValueError(f"SKILL.md 的 {field} 必须是文本列表")
    return meta


def skill_attributes(meta: dict) -> dict:
    return {**meta, **meta.get("metadata", {})}


def skill_slug(meta: dict) -> str:
    slug = re.sub(r"[^a-z0-9-]+", "-", meta["name"].strip().lower().replace("_", "-")).strip("-")
    if not slug or len(slug) > 64:
        raise ValueError("Skill 名称需使用 1–64 位英文小写字母、数字或连字符")
    return slug


def install_skill(base_dir: Path, content: str) -> dict:
    """Install one uploaded SKILL.md under the managed imported-skills directory."""
    meta = parse_skill(content)
    slug = skill_slug(meta)
    root = (base_dir / "skills").resolve()
    target = (root / "imported" / slug / "SKILL.md").resolve()
    if not target.is_relative_to(root):
        raise ValueError("Skill 目录不在允许范围内")
    if target.exists():
        raise FileExistsError("同名 Skill 已存在，请先归档旧版本或修改 name")
    target.parent.mkdir(parents=True, exist_ok=False)
    temporary = target.with_suffix(".tmp")
    temporary.write_text(content, encoding="utf-8")
    temporary.replace(target)
    legacy_id = target.relative_to(root).as_posix()
    return {"id": legacy_id, "legacy_id": legacy_id, "name": meta["name"], "description": meta["description"], "meta": skill_attributes(meta)}


def discover_skills(base_dir: Path) -> list[dict]:
    """Read the native Skills catalog without changing its generated snapshot."""
    root = (base_dir / "skills").resolve()
    entries = []
    for file in sorted(root.rglob("SKILL.md")):
        resolved = file.resolve()
        if not resolved.is_relative_to(root):
            continue
        try:
            content = file.read_text(encoding="utf-8")
            meta = parse_skill(content)
            attributes = skill_attributes(meta)
            if str(attributes.get("status", "published")) == "archived":
                continue
            legacy_id = file.relative_to(root).as_posix()
            entries.append({
                "id": legacy_id,
                "component_id": str(attributes.get("id", legacy_id)),
                "legacy_id": legacy_id,
                "kind": str(attributes.get("kind", "skill")),
                "version": str(attributes.get("version", "legacy")),
                "schema_version": int(attributes.get("schema_version", 1)),
                "status": str(attributes.get("status", "published")),
                "name": str(meta.get("name", file.parent.name)),
                "description": str(meta.get("description", "")),
                "content_hash": sha256(content.encode("utf-8")).hexdigest(),
                "content": content,
            })
        except (OSError, ValueError, TypeError, yaml.YAMLError):
            continue
    return entries


def scan_skills(base_dir: Path) -> str:
    """Scan all SKILL.md files and generate SKILLS_SNAPSHOT.md."""
    skills_dir = base_dir / "skills"
    snapshot_path = base_dir / "SKILLS_SNAPSHOT.md"

    if not skills_dir.exists():
        skills_dir.mkdir(parents=True)

    skills = [{**s, "location":f"./backend/skills/{s['legacy_id']}"} for s in discover_skills(base_dir)]

    # Build XML-style snapshot
    lines = ["<available_skills>"]
    for s in skills:
        lines.append("  <skill>")
        lines.append(f"    <name>{s['name']}</name>")
        lines.append(f"    <description>{s['description']}</description>")
        lines.append(f"    <location>{s['location']}</location>")
        lines.append("  </skill>")
    lines.append("</available_skills>")

    snapshot = "\n".join(lines)
    snapshot_path.write_text(snapshot, encoding="utf-8")
    print(f"📋 Skills snapshot: {len(skills)} skills found")
    return snapshot