#!/usr/bin/env python3
"""
Docs as Code — 构建入口

读取 project.yaml → 拼接 chapters/*.md → 渲染为自包含 HTML 报告。
纯 Python 实现，依赖 requirements.txt 中的 PyYAML, markdown, Jinja2。

用法:
    python doc_builder/build.py

输出:
    output/读出子系统编程控制模型.html  （自包含 HTML，可离线分发）
"""

import os
import sys
import base64
import re
from pathlib import Path

import yaml
import markdown
from jinja2 import Environment, FileSystemLoader


# ---------- 配置 ----------
ROOT = Path(__file__).resolve().parent.parent
CHAPTERS_DIR = ROOT / "chapters"
ASSETS_DIR = ROOT / "assets"
OUTPUT_DIR = ROOT / "output"
OUTPUT_NAME = "读出子系统编程控制模型.html"


# ---------- 工具函数 ----------

def load_project_config() -> dict:
    """读取 project.yaml 并校验。"""
    config_path = ROOT / "project.yaml"
    if not config_path.exists():
        sys.exit(f"错误: 找不到 {config_path}")
    with open(config_path, "r", encoding="utf-8") as f:
        config = yaml.safe_load(f)
    return config


def resolve_image_path(md_content: str, assets_dir: Path, inline_images: bool = True) -> tuple[str, dict]:
    """
    处理 Markdown 中的图片引用:
    - 如果 inline_images=True，将图片内嵌为 base64 data URI
    - 否则转换为相对路径引用

    返回: (处理后的内容, {原始路径: data_uri 字典})
    """
    image_map = {}

    def replace_img(match):
        alt_text = match.group(1)
        img_path = match.group(2)

        # 解析路径: ./assets/xxx.png 或 assets/xxx.png
        if img_path.startswith("./"):
            img_path = img_path[2:]
        if img_path.startswith("assets/"):
            img_path = img_path[7:]

        full_path = assets_dir / img_path
        if not full_path.exists():
            print(f"  警告: 找不到图片 {full_path}，保留原始引用")
            return match.group(0)

        if inline_images:
            # 内嵌为 base64
            with open(full_path, "rb") as img_file:
                img_data = base64.b64encode(img_file.read()).decode("ascii")
            ext = full_path.suffix.lower()
            mime_map = {".png": "image/png", ".svg": "image/svg+xml",
                        ".jpg": "image/jpeg", ".jpeg": "image/jpeg",
                        ".gif": "image/gif"}
            mime = mime_map.get(ext, "image/png")
            data_uri = f"data:{mime};base64,{img_data}"
            image_map[img_path] = data_uri
            return f"![{alt_text}]({data_uri})"
        else:
            return f"![{alt_text}](assets/{img_path})"

    return re.sub(r'!\[([^\]]*)\]\(\./assets/([^)]+)\)', replace_img, md_content), image_map


def read_and_assemble(config: dict) -> str:
    """按 project.yaml 的章节列表拼接所有 chapters/*.md 文件。"""
    chapters = config.get("chapters", [])
    if not chapters:
        sys.exit("错误: project.yaml 中未定义 chapters 列表")

    parts = []
    for ch_file in chapters:
        ch_path = CHAPTERS_DIR / ch_file
        if not ch_path.exists():
            print(f"  警告: 章节文件不存在，跳过: {ch_file}")
            continue
        with open(ch_path, "r", encoding="utf-8") as f:
            content = f.read()
        parts.append(content)

    return "\n\n".join(parts)


def extract_toc(md_content: str) -> list[dict]:
    """从 Markdown 内容中提取目录结构 (H1, H2)。"""
    toc = []
    for line in md_content.split("\n"):
        m = re.match(r'^(#{1,3})\s+(.+)$', line)
        if m:
            level = len(m.group(1))
            title = m.group(2).strip()
            # 生成锚点：去除特殊字符，空格转连字符
            anchor = re.sub(r'[^\w\s一-鿿-]', '', title)
            anchor = anchor.strip().replace(' ', '-').lower()
            toc.append({"level": level, "title": title, "anchor": anchor})
    return toc


# ---------- HTML 生成 ----------

def generate_html(md_content: str, config: dict) -> str:
    """将 Markdown 内容转换为完整的 HTML 页面。"""

    # 处理图片内嵌
    processed_md, _ = resolve_image_path(md_content, ASSETS_DIR, inline_images=True)

    # Markdown → HTML
    md_extensions = [
        "markdown.extensions.tables",
        "markdown.extensions.fenced_code",
        "markdown.extensions.codehilite",
        "markdown.extensions.toc",
        "markdown.extensions.nl2br",
    ]
    html_body = markdown.markdown(processed_md, extensions=md_extensions)

    # 提取目录
    toc = extract_toc(md_content)

    # 加载 Jinja2 模板
    templates_dir = ROOT / "doc_builder" / "templates"
    env = Environment(loader=FileSystemLoader(str(templates_dir)))
    template = env.get_template("report.html")

    # 读取主题 CSS
    themes_dir = ROOT / "doc_builder" / "themes"
    css_screen = ""
    css_print = ""
    screen_css_path = themes_dir / "report.css"
    print_css_path = themes_dir / "print.css"
    if screen_css_path.exists():
        css_screen = screen_css_path.read_text(encoding="utf-8")
    if print_css_path.exists():
        css_print = print_css_path.read_text(encoding="utf-8")

    return template.render(
        title=config.get("title", "文档"),
        subtitle=config.get("subtitle", ""),
        author=config.get("author", ""),
        version=config.get("version", ""),
        toc=toc,
        body=html_body,
        css_screen=css_screen,
        css_print=css_print,
    )


# ---------- 主入口 ----------

def main():
    print("=== ez-Q 2.5 读出子系统编程控制模型 构建 ===")
    print()

    # 1. 加载配置
    print("[1/3] 读取 project.yaml ...")
    config = load_project_config()
    print(f"  项目: {config.get('title', '未命名')}")
    print(f"  版本: {config.get('version', 'N/A')}")
    print(f"  章节数: {len(config.get('chapters', []))}")

    # 2. 拼接章节
    print("[2/3] 拼接章节 ...")
    assembled = read_and_assemble(config)
    print(f"  总字符数: {len(assembled)}")

    # 3. 生成 HTML
    print("[3/3] 生成 HTML ...")
    html = generate_html(assembled, config)

    # 4. 输出
    OUTPUT_DIR.mkdir(parents=True, exist_ok=True)
    output_path = OUTPUT_DIR / OUTPUT_NAME
    output_path.write_text(html, encoding="utf-8")
    print(f"  输出: {output_path}")
    print(f"  文件大小: {output_path.stat().st_size:,} 字节")

    print()
    print("Build completed successfully!")


if __name__ == "__main__":
    main()