#评论系统与交互：让道满博客的社区温度落地

# app/models/comment.py
from datetime import datetime
from app.extensions import db

class Comment(db.Model):
    __tablename__ = "comments"

    id = db.Column(db.Integer, primary_key=True)
    content = db.Column(db.Text, nullable=False, comment="评论内容")
    likes = db.Column(db.Integer, default=0, comment="点赞数")
    dislikes = db.Column(db.Integer, default=0, comment="踩数")
    is_deleted = db.Column(db.Boolean, default=False, comment="软删除标记")
    created_at = db.Column(db.DateTime, default=datetime.utcnow, comment="发布时间")

    # 外键关联
    post_id = db.Column(
        db.Integer,
        db.ForeignKey("posts.id", ondelete="CASCADE"),
        nullable=False,
        comment="关联文章ID"
    )
    author_id = db.Column(
        db.Integer,
        db.ForeignKey("users.id", ondelete="CASCADE"),
        nullable=False,
        comment="发布者ID"
    )
    parent_id = db.Column(
        db.Integer,
        db.ForeignKey("comments.id", ondelete="CASCADE"),
        nullable=True,
        comment="父评论ID（根评论时为空）"
    )

    # SQLAlchemy 关系映射
    post = db.relationship("Post", back_populates="comments")
    author = db.relationship("User", backref="comments")

    # 自引用关系：remote_side=[id] 指明“当前模型的 id 是被引用的一方（即父级）”
    parent = db.relationship(
        "Comment",
        remote_side=[id],
        backref=db.backref("replies", lazy="dynamic")
    )

    def __repr__(self):
        return f"<Comment {self.id} by User {self.author_id} on Post {self.post_id}>"

# app/comments/routes.py
from flask import Blueprint, request, redirect, url_for, flash, jsonify
from flask_login import login_required, current_user
from app.extensions import db
from app.models import Comment, Post

comments_bp = Blueprint("comments", __name__, url_prefix="/comments")

# 发布根评论 / 子回复
@comments_bp.route("/add", methods=["POST"])
@login_required
def add_comment():
    post_id = request.form.get("post_id", type=int)
    content = request.form.get("content", "").strip()
    parent_id = request.form.get("parent_id", type=int) or None

    # 基础校验
    if not post_id:
        flash("请选择关联文章", "danger")
        return redirect(request.referrer or url_for("home.index"))
    if not content:
        flash("评论内容不能为空哦", "warning")
        return redirect(url_for("articles.detail", post_id=post_id))
    if len(content) > 500:
        flash("评论内容不能超过500字", "warning")
        return redirect(url_for("articles.detail", post_id=post_id))

    # 验证文章存在
    post = Post.query.get_or_404(post_id)

    # 新增评论
    comment = Comment(
        content=content,
        post_id=post_id,
        author_id=current_user.id,
        parent_id=parent_id,
    )
    db.session.add(comment)
    db.session.commit()
    flash("评论发布成功！", "success")
    return redirect(url_for("articles.detail", post_id=post_id))

# 软删除评论
@comments_bp.route("/<int:comment_id>/delete", methods=["POST"])
@login_required
def delete_comment(comment_id):
    comment = Comment.query.get_or_404(comment_id)

    # 权限校验：只有作者本人或管理员可以删除
    if comment.author_id != current_user.id and not current_user.is_admin:
        flash("无权删除此评论", "danger")
        return redirect(url_for("articles.detail", post_id=comment.post_id))

    comment.is_deleted = True
    db.session.commit()
    flash("评论已隐藏（可联系管理员恢复）", "info")
    return redirect(url_for("articles.detail", post_id=comment.post_id))

# 点赞
@comments_bp.route("/<int:comment_id>/like", methods=["POST"])
@login_required
def like_comment(comment_id):
    comment = Comment.query.get_or_404(comment_id)
    if not comment.is_deleted:
        comment.likes += 1
        db.session.commit()
    return jsonify({
        "status": "ok",
        "likes": comment.likes,
        "dislikes": comment.dislikes
    })

# 踩
@comments_bp.route("/<int:comment_id>/dislike", methods=["POST"])
@login_required
def dislike_comment(comment_id):
    comment = Comment.query.get_or_404(comment_id)
    if not comment.is_deleted:
        comment.dislikes += 1
        db.session.commit()
    return jsonify({
        "status": "ok",
        "likes": comment.likes,
        "dislikes": comment.dislikes
    })

# app/utils/comments.py
def build_comment_tree(comments):
    """
    将数据库返回的扁平 Comment 列表转为树状结构
    输入: [Comment1(根), Comment2(根), Comment3(Comment1的子), ...]
    输出: [
        {"comment": Comment1, "replies": [{"comment": Comment3, "replies": []}]},
        {"comment": Comment2, "replies": []},
        ...
    ]
    """
    comment_nodes = {}
    root_comments = []

    for comment in comments:
        comment_nodes[comment.id] = {"comment": comment, "replies": []}

    for node in comment_nodes.values():
        parent_id = node["comment"].parent_id
        if parent_id and parent_id in comment_nodes:
            comment_nodes[parent_id]["replies"].append(node)
        elif not parent_id:
            root_comments.append(node)

    return root_comments