from __future__ import annotations

import hashlib
import re
from pathlib import Path

from docx import Document
from docx.oxml.ns import qn
from docx.table import Table
from docx.text.paragraph import Paragraph


ROOT = Path(__file__).resolve().parents[1]
DOC_DIR = ROOT / "docs" / "admin_reference_prd"
SOURCE = DOC_DIR / "后台管理系统需求文档.docx"
TARGET = DOC_DIR / "后台管理系统需求文档.md"
ASSET_DIR = DOC_DIR / "assets"

IMAGE_ALTS = {
    "prototype_01_dashboard.png": "后台首页看板脱敏原型",
    "prototype_02_member_list.png": "会员列表脱敏原型",
    "prototype_03_member_modal.png": "会员编辑弹窗原型",
    "prototype_04_withdrawal.png": "提现审核脱敏原型",
    "prototype_05_rbac.png": "RBAC 角色权限原型",
    "prototype_06_flow.png": "C 端与后台业务闭环原型",
}


def iter_blocks(document: Document):
    for child in document.element.body.iterchildren():
        if child.tag == qn("w:p"):
            yield Paragraph(child, document)
        elif child.tag == qn("w:tbl"):
            yield Table(child, document)


def media_map(document: Document) -> dict[str, str]:
    assets_by_hash = {
        hashlib.sha256(path.read_bytes()).hexdigest(): path.name
        for path in ASSET_DIR.glob("*.png")
    }
    mapping: dict[str, str] = {}
    for rel_id, rel in document.part.rels.items():
        if "image" not in rel.reltype:
            continue
        digest = hashlib.sha256(rel.target_part.blob).hexdigest()
        name = assets_by_hash.get(digest)
        if name:
            mapping[rel_id] = f"assets/{name}"
    return mapping


def paragraph_images(paragraph: Paragraph, images: dict[str, str]) -> list[str]:
    result: list[str] = []
    for blip in paragraph._p.xpath(".//a:blip"):
        rel_id = blip.get(qn("r:embed"))
        if rel_id in images:
            result.append(images[rel_id])
    return result


def escape_cell(value: str) -> str:
    return value.strip().replace("|", "\\|").replace("\n", "<br>") or "—"


def table_markdown(table: Table) -> list[str]:
    rows = [[escape_cell(cell.text) for cell in row.cells] for row in table.rows]
    if not rows:
        return []
    width = max(len(row) for row in rows)
    rows = [row + ["—"] * (width - len(row)) for row in rows]
    lines = [
        "| " + " | ".join(rows[0]) + " |",
        "| " + " | ".join(["---"] * width) + " |",
    ]
    lines.extend("| " + " | ".join(row) + " |" for row in rows[1:])
    return lines


def github_slug(title: str) -> str:
    slug = title.strip().lower()
    slug = re.sub(r"[^\w\-\u4e00-\u9fff ]", "", slug)
    return re.sub(r"\s+", "-", slug)


def convert() -> None:
    document = Document(SOURCE)
    images = media_map(document)
    body: list[str] = []
    top_level: list[str] = []
    image_number = 0

    for block in iter_blocks(document):
        if isinstance(block, Table):
            body.extend(table_markdown(block))
            body.append("")
            continue

        text = block.text.strip()
        style = block.style.name if block.style else "Normal"
        embedded = paragraph_images(block, images)

        if style == "Title" and text:
            body.extend([f"# {text}", ""])
        elif style == "Heading 1" and text:
            top_level.append(text)
            body.extend([f"## {text}", ""])
        elif style == "Heading 2" and text:
            body.extend([f"### {text}", ""])
        elif style == "List Bullet" and text:
            body.extend([f"- {text}", ""])
        elif style == "List Number" and text:
            body.extend([f"1. {text}", ""])
        elif text:
            if text.startswith("结论："):
                body.extend([f"> **{text[:3]}** {text[3:]}", ""])
            elif text.startswith("P0："):
                body.extend([f"> **P0 风险：** {text[3:]}", ""])
            else:
                body.extend([text, ""])

        for path in embedded:
            image_number += 1
            alt = IMAGE_ALTS.get(Path(path).name, f"需求原型图 {image_number}")
            body.extend([f"![{alt}]({path})", ""])

    # Word 封面之后放置 Markdown 可点击目录，去掉 Word 中无意义的空段落。
    first_section = next(i for i, line in enumerate(body) if line.startswith("## 1 "))
    toc = ["## 目录", ""]
    toc.extend(f"- [{title}](#{github_slug(title)})" for title in top_level)
    toc.extend(["", "---", ""])
    output = body[:first_section] + toc + body[first_section:]

    compact: list[str] = []
    for line in output:
        if line == "" and compact and compact[-1] == "":
            continue
        compact.append(line)
    rendered = "\n".join(compact).rstrip() + "\n"
    rendered = re.sub(r"(^- .+)\n\n(?=- )", r"\1\n", rendered, flags=re.MULTILINE)
    rendered = re.sub(r"(^1\. .+)\n\n(?=1\. )", r"\1\n", rendered, flags=re.MULTILINE)
    TARGET.write_text(rendered, encoding="utf-8")


if __name__ == "__main__":
    convert()