#搜索功能实现：模糊查询与全文检索

# app/articles/routes.py
from flask import request, render_template
from sqlalchemy import or_  # 用于多字段「或」匹配
from app import db
from app.articles.models import Post
from app.articles import articles_bp  # 假设已注册好蓝图

@articles_bp.route("/search")
def search():
    # 获取参数：关键词、页码（默认1）、可选参数先留空
    query = request.args.get("q", "").strip()
    page = request.args.get("page", 1, type=int)

    # 空关键词直接返回空结果页
    if not query:
        return render_template("articles/search.html", results=[], query="")

    # 构建搜索规则：%xxx% 匹配任意位置的关键词
    search_pattern = f"%{query}%"
    # 构建查询链：先过滤已发布 → 多字段或匹配 → 按发布时间倒序 → 分页
    pagination = (
        Post.query
        .filter(Post.is_published.is_(True))  # SQLAlchemy 推荐用 is_(True) 代替 == True
        .filter(
            or_(
                Post.title.ilike(search_pattern),
                Post.summary.ilike(search_pattern),
                Post.content.ilike(search_pattern),
            )
        )
        .order_by(Post.created_at.desc())
        .paginate(page=page, per_page=20, error_out=False)  # error_out=False：页码超范围不报错
    )

    return render_template(
        "articles/search.html",
        results=pagination.items,
        query=query,
        pagination=pagination,
        total=pagination.total,
    )

# app/utils/search.py
import re

def highlight_excerpt(text: str, query: str, max_length: int = 300) -> str:
    """
    从文本中截取包含搜索词的片段并高亮
    :param text: 原始文本（支持Markdown但这里只处理纯文本片段）
    :param query: 搜索关键词
    :param max_length: 无匹配时的最大截断长度
    :return: 处理好的HTML片段
    """
    if not text or not query:
        return text[:max_length] if text else ""

    # 构建不区分大小写的正则
    pattern = re.compile(re.escape(query), re.IGNORECASE)
    match = pattern.search(text)

    # 优先截取关键词前后的内容
    if match:
        # 关键词前留50字符，后留max_length//2左右，避免溢出
        context_length = max_length // 2
        start = max(0, match.start() - context_length)
        end = min(len(text), match.end() + context_length)
        excerpt = text[start:end]

        # 加省略号表示截断
        if start > 0:
            excerpt = "..." + excerpt
        if end < len(text):
            excerpt += "..."
    else:
        # 无匹配时直接截断前max_length
        excerpt = text[:max_length]
        if len(text) > max_length:
            excerpt += "..."

    # 动态保留原大小写高亮：sub第二个参数传函数，每次匹配返回原内容套mark标签
    highlighted = pattern.sub(lambda m: f'<mark class="search-highlight">{m.group()}</mark>', excerpt)
    return highlighted

# app/articles/routes.py（替换原search函数，保留其他导入）
from datetime import datetime, timedelta
from app.articles.models import Category  # 假设已有Category模型

@articles_bp.route("/search")
def search():
    query = request.args.get("q", "").strip()
    category_id = request.args.get("category", type=int)
    date_from = request.args.get("from", type=str)
    recent_days = request.args.get("recent", type=int)  # 新增：近N天
    page = request.args.get("page", 1, type=int)

    # 先获取所有已发布文章的分类（用于下拉框）
    categories = Category.query.join(Category.posts).filter(Post.is_published.is_(True)).distinct().all()

    base_query = Post.query.filter(Post.is_published.is_(True))

    # 关键词过滤
    if query:
        search_pattern = f"%{query}%"
        base_query = base_query.filter(
            or_(
                Post.title.ilike(search_pattern),
                Post.summary.ilike(search_pattern),
                Post.content.ilike(search_pattern),
            )
        )

    # 分类过滤
    if category_id:
        base_query = base_query.filter_by(category_id=category_id)

    # 时间过滤：优先用指定日期，再用近N天
    if date_from:
        try:
            start_date = datetime.fromisoformat(date_from)
            base_query = base_query.filter(Post.created_at >= start_date)
        except ValueError:
            pass  # 无效日期直接忽略
    elif recent_days:
        start_date = datetime.utcnow() - timedelta(days=recent_days)
        base_query = base_query.filter(Post.created_at >= start_date)

    pagination = (
        base_query
        .order_by(Post.created_at.desc())
        .paginate(page=page, per_page=20, error_out=False)
    )

    return render_template(
        "articles/search.html",
        results=pagination.items,
        query=query,
        categories=categories,
        selected_category=category_id,
        selected_from=date_from,
        selected_recent=recent_days,
        pagination=pagination,
        total=pagination.total,
    )

# app/articles/routes.py（仅替换关键词过滤部分的代码）
from sqlalchemy import func

@articles_bp.route("/search")
def search():
    # ... 前面的参数获取、分类时间过滤、分页逻辑保留 ...

    if query:
        # 1. 构建搜索向量：把标题和正文合并成一个中文向量（| 是向量合并操作符）
        search_vector = (
            func.to_tsvector("chinese", Post.title)
            .op("||")(func.to_tsvector("chinese", Post.content))
        )
        # 2. 构建搜索查询：plainto_tsquery 会自动把空格转成「且」匹配
        ts_query = func.plainto_tsquery("chinese", query)
        # 3. 过滤+按相关性排序（ts_rank 给标题更高的权重会更好，后面讲）
        base_query = (
            base_query
            .filter(search_vector.op("@@")(ts_query))  # @@ 是向量匹配操作符
            .order_by(func.ts_rank(search_vector, ts_query).desc())
        )

    # ... 后面的分页、渲染逻辑保留 ...