"""source_to_md.py: 把素材转成干净 Markdown,作为后续策略阶段的输入。

用法:
    python source_to_md.py <input>           # 自动按扩展名识别
    python source_to_md.py <url>             # http/https 走 web 抓
    python source_to_md.py file.pdf -o source.md

支持:
    .pdf  → pypdf 提取文本
    .docx → python-docx 段落
    .pptx → python-pptx 提取每页文字
    .txt/.md → 直读
    URL   → requests + 简易 HTML 剥离

设计原则:模型在策略阶段只看 Markdown,不读二进制 / 不爬复杂排版。
"""
from __future__ import annotations

import argparse
import re
import sys
from pathlib import Path
from urllib.parse import urlparse


def from_pdf(path: Path) -> str:
    try:
        from pypdf import PdfReader
    except ImportError:
        return "[error] pip install pypdf"
    reader = PdfReader(str(path))
    parts = [f"# {path.stem}\n"]
    for i, page in enumerate(reader.pages, 1):
        text = (page.extract_text() or "").strip()
        if text:
            parts.append(f"\n## Page {i}\n\n{text}\n")
    return "\n".join(parts)


def from_docx(path: Path) -> str:
    try:
        from docx import Document
    except ImportError:
        return "[error] pip install python-docx"
    doc = Document(str(path))
    parts = [f"# {path.stem}\n"]
    for para in doc.paragraphs:
        text = para.text.strip()
        if not text:
            continue
        style = (para.style.name or "").lower() if para.style else ""
        if "heading 1" in style:
            parts.append(f"\n## {text}\n")
        elif "heading 2" in style:
            parts.append(f"\n### {text}\n")
        elif "heading 3" in style:
            parts.append(f"\n#### {text}\n")
        else:
            parts.append(f"\n{text}\n")
    return "".join(parts)


def from_pptx(path: Path) -> str:
    try:
        from pptx import Presentation
    except ImportError:
        return "[error] pip install python-pptx"
    prs = Presentation(str(path))
    parts = [f"# {path.stem}\n"]
    for i, slide in enumerate(prs.slides, 1):
        parts.append(f"\n## Slide {i}\n")
        for shape in slide.shapes:
            if shape.has_text_frame:
                txt = shape.text_frame.text.strip()
                if txt:
                    parts.append(f"\n{txt}\n")
    return "".join(parts)


def from_text(path: Path) -> str:
    return path.read_text(encoding="utf-8", errors="replace")


_TAG_RE = re.compile(r"<[^>]+>")
_WS_RE = re.compile(r"\n{3,}")


def from_url(url: str) -> str:
    try:
        import requests
    except ImportError:
        return "[error] pip install requests"
    r = requests.get(url, timeout=30, headers={
        "User-Agent": "Mozilla/5.0 (compatible; ppt-source-to-md/1.0)"
    })
    r.raise_for_status()
    html = r.text

    # 极简剥离:script/style 删,标签去除
    html = re.sub(r"<script[\s\S]*?</script>", "", html, flags=re.I)
    html = re.sub(r"<style[\s\S]*?</style>", "", html, flags=re.I)

    title_m = re.search(r"<title[^>]*>([^<]+)</title>", html, re.I)
    title = title_m.group(1).strip() if title_m else url

    # 块级标签转换行
    html = re.sub(r"</?(p|div|br|li|h[1-6]|tr)[^>]*>", "\n", html, flags=re.I)
    text = _TAG_RE.sub("", html)
    text = re.sub(r"&nbsp;", " ", text)
    text = re.sub(r"&amp;", "&", text)
    text = re.sub(r"&lt;", "<", text)
    text = re.sub(r"&gt;", ">", text)
    text = re.sub(r"&quot;", '"', text)
    text = "\n".join(line.strip() for line in text.splitlines())
    text = _WS_RE.sub("\n\n", text).strip()

    return f"# {title}\n\nSource: {url}\n\n{text}\n"


def dispatch(src: str) -> str:
    parsed = urlparse(src)
    if parsed.scheme in ("http", "https"):
        return from_url(src)

    path = Path(src)
    if not path.exists():
        return f"[error] not found: {src}"

    ext = path.suffix.lower()
    if ext == ".pdf":
        return from_pdf(path)
    if ext == ".docx":
        return from_docx(path)
    if ext == ".pptx":
        return from_pptx(path)
    if ext in (".txt", ".md"):
        return from_text(path)
    return f"[error] unsupported extension: {ext}"


def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("src", help="文件路径或 http(s) URL")
    ap.add_argument("-o", "--output", type=Path, default=None,
                    help="写到文件;默认打印到 stdout")
    args = ap.parse_args()

    md = dispatch(args.src)
    if args.output:
        args.output.write_text(md, encoding="utf-8")
        print(f"[ok] {args.output}  ({len(md)} chars)")
    else:
        sys.stdout.write(md)


if __name__ == "__main__":
    main()