#Article publishing and Markdown support: rich text editor and paging

# app/utils.py
import markdown
import bleach

def render_markdown(content):
    """将 Markdown 渲染为符合规范的安全 HTML
    
    Args:
        content (str): 原始 Markdown 文本
    Returns:
        str: 清理后的 HTML 文本
    """
    # 1. 开启常用 Markdown 扩展
    html = markdown.markdown(
        content,
        extensions=[
            "extra",       # 支持表格、定义列表、删除线等基础语法增强
            "codehilite",  # 代码高亮（需要配合 Pygments 使用）
            "toc",         # 自动生成目录（可通过 [TOC] 标记插入正文）
        ],
        # 可选：配置代码高亮的 Pygments 参数
        extension_configs={
            "codehilite": {
                "css_class": "codehilite",  # 给代码块加 class 方便自定义样式
                "linenums": True,           # 开启行号显示
            }
        }
    )

    # 2. 用 Bleach 清理危险标签和属性
    # 只允许博客内容常用的标签
    allowed_tags = [
        "h1", "h2", "h3", "h4", "h5", "h6",
        "p", "br", "strong", "em", "u", "s", "blockquote", "pre", "code",
        "ul", "ol", "li",
        "a", "img",
        "table", "thead", "tbody", "tr", "th", "td",
        "div", "span",  # 给自定义样式/结构留空间
    ]
    # 只允许标签必需的属性
    allowed_attributes = {
        "a": ["href", "title", "target"],  # 加 target="_blank" 方便用户打开外部链接
        "img": ["src", "alt", "title"],
        "code": ["class"],  # 留 codehilite 的 class
        "span": ["class"],  # 留自定义 span 的 class
    }
    # 额外加个协议白名单，防止 a/img 用 javascript: 等恶意协议
    allowed_protocols = ["http", "https", "mailto"]

    return bleach.clean(
        html,
        tags=allowed_tags,
        attributes=allowed_attributes,
        protocols=allowed_protocols
    )

# app/articles/routes.py
from flask import render_template
from app import db
from app.models import Post
from app.utils import render_markdown
from . import articles_bp

@articles_bp.route("/<int:post_id>")
def detail(post_id):
    # 用 get_or_404 防止访问不存在的文章时报 500
    post = Post.query.get_or_404(post_id)
    # 简单增加阅读量
    post.views += 1
    db.session.commit()
    # 渲染 Markdown 正文
    rendered_content = render_markdown(post.content)
    return render_template(
        "articles/detail.html",
        post=post,
        rendered_content=rendered_content
    )

# app/forms/article.py
from flask_wtf import FlaskForm
from wtforms import (
    StringField, TextAreaField, SelectField, BooleanField, SubmitField
)
from wtforms.validators import DataRequired, Length, Optional

class ArticleForm(FlaskForm):
    title = StringField(
        "标题",
        validators=[
            DataRequired(message="标题是必填项哦😯"),
            Length(min=5, max=200, message="标题长度需要在 5-200 个字符之间")
        ],
        render_kw={"placeholder": "请输入一个清晰的标题"}
    )
    summary = StringField(
        "摘要",
        validators=[
            Optional(),
            Length(max=300, message="摘要太长啦，控制在 300 字符以内吧")
        ],
        render_kw={"placeholder": "可选，会显示在文章列表和搜索引擎预览中"}
    )
    content = TextAreaField(
        "正文（支持 Markdown）",
        validators=[
            DataRequired(message="正文不能是空的哦"),
            Length(min=10, message="正文至少需要 10 个字符")
        ],
        render_kw={"rows": 20, "placeholder": "在这里写你的文章内容～"}
    )
    category_id = SelectField(
        "分类",
        coerce=int,  # 把表单提交的字符串转成 int
        validators=[Optional()]
    )
    tags = StringField(
        "标签",
        render_kw={"placeholder": "多个标签用英文逗号分隔，比如 Python, Flask, 博客"}
    )
    is_published = BooleanField(
        "立即发布",
        default=True  # 默认勾选立即发布
    )
    submit = SubmitField("保存")

    # 动态加载分类下拉选项
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        from app.models import Category
        # 第一个选项是“无分类”
        self.category_id.choices = [(0, "无")] + [
            (c.id, c.name) for c in Category.query.order_by(Category.name).all()
        ]

# app/articles/routes.py
from flask import request

@articles_bp.route("/")
def index():
    # 从 URL 参数中获取当前页码，默认是第 1 页
    page = request.args.get("page", 1, type=int)
    # 每页显示的文章数量
    per_page = 10

    # 查询已发布的文章，按创建时间倒序排列，然后分页
    pagination = Post.query\
        .filter_by(is_published=True)\
        .order_by(Post.created_at.desc())\
        .paginate(
            page=page,
            per_page=per_page,
            error_out=False  # 页码不存在时返回空列表，而不是 404
        )

    # pagination.items 是当前页的文章列表
    return render_template(
        "articles/index.html",
        pagination=pagination,
        posts=pagination.items
    )

# app/utils.py（可以放在之前的 render_markdown 下面）
from app import db
from app.models import Tag

def process_article_tags(post, tags_string):
    """解析表单输入的标签字符串，更新文章的标签关联
    
    Args:
        post (Post): 要更新的文章对象
        tags_string (str): 用户输入的标签字符串，用英文逗号分隔
    """
    if not tags_string or not tags_string.strip():
        # 如果标签字符串为空，清空文章的所有标签
        post.tags = []
        return

    # 1. 解析标签字符串，去重并去除空白
    tag_names = list({
        t.strip() for t in tags_string.split(",") if t.strip()
    })

    # 2. 获取或创建标签对象
    tags = []
    for name in tag_names:
        tag = Tag.query.filter_by(name=name).first()
        if not tag:
            tag = Tag(name=name)
            db.session.add(tag)
        tags.append(tag)

    # 3. 更新文章的标签关联
    post.tags = tags