#!/usr/bin/env python3
"""Print a human-facing builtin skill list: one-liner + copy-paste example.

Reads each skill's README.md. Do not substitute SKILL.md descriptions.
"""

from __future__ import annotations

import argparse
import re
import sys
from pathlib import Path

_HEADING_RE = re.compile(r"^#{1,6}\s+")
_FENCE_RE = re.compile(r"^```(\w+)?\s*$")


def skills_dir() -> Path:
    here = Path(__file__).resolve()
    repo_skills = here.parents[2]
    if (repo_skills / "pouch" / "SKILL.md").is_file():
        return repo_skills
    return Path.home() / ".pouch" / "skills"


def _strip_md(text: str) -> str:
    text = re.sub(r"\[([^\]]+)\]\([^)]+\)", r"\1", text)
    text = re.sub(r"`([^`]+)`", r"\1", text)
    return " ".join(text.split())


def _first_sentence(text: str) -> str:
    text = _strip_md(text).strip()
    for sep in ("。", "！", "？"):
        idx = text.find(sep)
        if idx != -1:
            return text[: idx + 1]
    return text.rstrip("：:") + ("。" if text else "")


def _lede(readme: str) -> str:
    lines = readme.splitlines()
    i = 0
    while i < len(lines) and (
        not lines[i].strip() or _HEADING_RE.match(lines[i])
    ):
        i += 1
    chunk: list[str] = []
    while i < len(lines):
        raw = lines[i]
        stripped = raw.strip()
        if not stripped:
            break
        if _HEADING_RE.match(raw) or stripped.startswith(("- ", "* ", "> ")):
            break
        chunk.append(stripped)
        i += 1
    return _first_sentence(" ".join(chunk))


def _section_body(readme: str, titles: tuple[str, ...]) -> str | None:
    lines = readme.splitlines()
    start = None
    for i, line in enumerate(lines):
        if line.startswith("## ") and line[3:].strip() in titles:
            start = i + 1
            break
    if start is None:
        return None
    end = len(lines)
    for j in range(start, len(lines)):
        if lines[j].startswith("## "):
            end = j
            break
    return "\n".join(lines[start:end])


def _first_example(readme: str) -> str:
    body = _section_body(readme, ("使用示例", "常见用法"))
    search = body if body is not None else readme
    lines = search.splitlines()
    i = 0
    while i < len(lines):
        fence = _FENCE_RE.match(lines[i].strip())
        if not fence:
            i += 1
            continue
        i += 1
        block: list[str] = []
        while i < len(lines) and not lines[i].strip().startswith("```"):
            block.append(lines[i])
            i += 1
        for raw in block:
            stripped = raw.strip()
            if not stripped or stripped.startswith("#"):
                continue
            return stripped
        i += 1
    return ""


def iter_skills(root: Path) -> list[Path]:
    skills: list[Path] = []
    if not root.is_dir():
        return skills
    for entry in sorted(root.iterdir()):
        if not entry.is_dir() or entry.name.startswith("_"):
            continue
        if (entry / "SKILL.md").is_file():
            skills.append(entry)
    return skills


def catalog_rows(root: Path) -> list[tuple[str, str, str]]:
    rows: list[tuple[str, str, str]] = []
    errors: list[str] = []
    for skill in iter_skills(root):
        readme_path = skill / "README.md"
        if not readme_path.is_file():
            errors.append(f"{skill.name}: 缺少 README.md")
            continue
        text = readme_path.read_text(encoding="utf-8")
        lede = _lede(text)
        example = _first_example(text)
        if not lede:
            errors.append(f"{skill.name}: README 缺少一句话说明")
        if not example:
            errors.append(f"{skill.name}: README 缺少可复制的使用示例")
        if lede and example:
            rows.append((skill.name, lede, example))
    if errors:
        raise SystemExit("catalog 失败:\n  " + "\n  ".join(errors))
    return rows


def format_table(rows: list[tuple[str, str, str]]) -> str:
    lines = [
        "| Skill | 做什么 | 可以这么说 |",
        "| --- | --- | --- |",
    ]
    for name, lede, example in rows:
        example = example.replace("|", "\\|")
        lede = lede.replace("|", "\\|")
        lines.append(f"| {name} | {lede} | `{example}` |")
    return "\n".join(lines) + "\n"


def main() -> int:
    parser = argparse.ArgumentParser(
        description="列出 builtin skill 的一句话说明和可复制示例"
    )
    parser.add_argument(
        "--skills-dir",
        type=Path,
        default=None,
        help="skill 根目录（默认本仓库 skills/ 或 ~/.pouch/skills）",
    )
    args = parser.parse_args()
    root = args.skills_dir.resolve() if args.skills_dir else skills_dir()
    if not root.is_dir():
        print(f"找不到 skills 目录: {root}", file=sys.stderr)
        return 2
    sys.stdout.write(format_table(catalog_rows(root)))
    return 0


if __name__ == "__main__":
    raise SystemExit(main())