"""
数据库 ORM 模型模块。

定义全局架构中的五个核心模型，以及邮箱验证码模型：
- User：用户（visitor / friend / blogger）
- Article：文章（public / friend 两种可见性）
- Comment：评论（支持回复，parent_id 指向父评论）
- Like：点赞
- Friend：好友申请
- EmailCode：邮箱验证码（一次性、带过期时间）
"""

from datetime import datetime, timezone

from sqlalchemy import Boolean, Column, DateTime, ForeignKey, Integer, String, Text, UniqueConstraint
from sqlalchemy.orm import relationship

from .database import Base

# ---------- 常量定义 ----------

# 用户角色（全局架构：visitor / friend / blogger）
ROLE_VISITOR = "visitor"
ROLE_FRIEND = "friend"
ROLE_BLOGGER = "blogger"

# 文章可见性（全局架构：public / friend）
VISIBILITY_PUBLIC = "public"
VISIBILITY_FRIEND = "friend"

# 文章分区（life 生活 / study 学习）
ARTICLE_CATEGORY_LIFE = "life"
ARTICLE_CATEGORY_STUDY = "study"

# 项目类型（L0 静态托管 / GitHub 外链）
PROJECT_TYPE_STATIC = "static"
PROJECT_TYPE_LINK = "link"

# 好友申请状态
FRIEND_STATUS_PENDING = "pending"
FRIEND_STATUS_ACCEPTED = "accepted"
FRIEND_STATUS_REJECTED = "rejected"

# 邮箱验证码用途
PURPOSE_REGISTER = "register"
PURPOSE_RESET = "reset"


def utcnow() -> datetime:
    """返回当前 UTC 时间（无时区），作为各模型时间字段的默认值。"""
    return datetime.now(timezone.utc).replace(tzinfo=None)


class User(Base):
    """用户模型：对应权限系统的 visitor / friend / blogger 三种角色。"""

    __tablename__ = "users"

    id = Column(Integer, primary_key=True, index=True, comment="用户 ID")
    email = Column(String(255), unique=True, index=True, nullable=False, comment="邮箱，唯一")
    username = Column(String(50), unique=True, index=True, nullable=False, comment="用户名，唯一")
    password_hash = Column(String(255), nullable=False, comment="bcrypt 密码哈希，禁止保存明文")
    role = Column(String(20), nullable=False, default=ROLE_VISITOR, comment="角色")
    avatar = Column(String(500), nullable=True, comment="头像图片路径（uploads/avatar/）")
    avatar_updated_time = Column(DateTime, nullable=True, comment="头像最近一次更换时间（配合更换频率限制）")
    bio = Column(Text, nullable=True, comment="个人简介（我的简介页面展示）")
    token_version = Column(Integer, nullable=False, default=0, comment="令牌版本号（重置密码时自增，使旧 JWT 立即失效）")
    created_time = Column(DateTime, nullable=False, default=utcnow, comment="创建时间")

    # 关联关系：删除用户时级联删除其文章、评论、点赞与好友记录
    articles = relationship("Article", back_populates="author", cascade="all, delete-orphan")
    comments = relationship("Comment", back_populates="user", cascade="all, delete-orphan")
    likes = relationship("Like", back_populates="user", cascade="all, delete-orphan")
    friends = relationship("Friend", back_populates="user", cascade="all, delete-orphan")


class Article(Base):
    """文章模型：Markdown 正文，支持 public / friend 两种可见性。"""

    __tablename__ = "articles"

    id = Column(Integer, primary_key=True, index=True, comment="文章 ID")
    title = Column(String(200), nullable=False, comment="文章标题")
    content = Column(Text, nullable=False, comment="Markdown 格式正文")
    cover = Column(String(500), nullable=True, comment="文章封面图片路径（uploads/article/）")
    visibility = Column(String(20), nullable=False, default=VISIBILITY_PUBLIC, comment="可见性")
    category = Column(String(30), nullable=False, default=ARTICLE_CATEGORY_LIFE, index=True, comment="分区：life 生活 / study 学习")
    author_id = Column(Integer, ForeignKey("users.id"), nullable=False, index=True, comment="作者 ID")
    created_time = Column(DateTime, nullable=False, default=utcnow, comment="创建时间")

    author = relationship("User", back_populates="articles")
    comments = relationship("Comment", back_populates="article", cascade="all, delete-orphan")
    likes = relationship("Like", back_populates="article", cascade="all, delete-orphan")


class Project(Base):
    """项目模型：L0 静态托管（static，自动在线演示）或 GitHub 外链（link）。"""

    __tablename__ = "projects"

    id = Column(Integer, primary_key=True, index=True, comment="项目 ID")
    name = Column(String(100), nullable=False, comment="项目名称")
    description = Column(Text, nullable=True, comment="项目简介")
    tech = Column(String(500), nullable=True, comment="技术标签（逗号分隔）")
    project_type = Column(String(20), nullable=False, default=PROJECT_TYPE_STATIC, comment="项目类型：static 静态托管 / link 外链")
    visibility = Column(String(20), nullable=False, default=VISIBILITY_PUBLIC, comment="可见性：public 公开 / friend 好友")
    demo_url = Column(String(500), nullable=True, comment="在线运行地址（static 为站内演示地址，link 为 GitHub 链接）")
    download_url = Column(String(500), nullable=True, comment="下载文件地址（uploads/project/）")
    github_url = Column(String(500), nullable=True, comment="GitHub 仓库链接（link 类型必填）")
    created_time = Column(DateTime, nullable=False, default=utcnow, comment="创建时间")
    updated_time = Column(DateTime, nullable=False, default=utcnow, onupdate=utcnow, comment="更新时间")


class Comment(Base):
    """评论模型：好友及博主可对文章发表评论，支持回复（parent_id）。"""

    __tablename__ = "comments"

    id = Column(Integer, primary_key=True, index=True, comment="评论 ID")
    article_id = Column(Integer, ForeignKey("articles.id"), nullable=False, index=True, comment="文章 ID")
    user_id = Column(Integer, ForeignKey("users.id"), nullable=False, index=True, comment="评论者 ID")
    parent_id = Column(Integer, ForeignKey("comments.id"), nullable=True, index=True, comment="父评论 ID（回复时填写，顶层评论为空）")
    content = Column(Text, nullable=False, comment="评论内容")
    created_time = Column(DateTime, nullable=False, default=utcnow, comment="创建时间")

    article = relationship("Article", back_populates="comments")
    user = relationship("User", back_populates="comments")
    parent = relationship("Comment", remote_side=[id], back_populates="replies")
    replies = relationship("Comment", back_populates="parent")


class Like(Base):
    """点赞模型：同一用户对同一文章只能点赞一次。"""

    __tablename__ = "likes"

    id = Column(Integer, primary_key=True, index=True, comment="点赞记录 ID")
    article_id = Column(Integer, ForeignKey("articles.id"), nullable=False, index=True, comment="文章 ID")
    user_id = Column(Integer, ForeignKey("users.id"), nullable=False, index=True, comment="点赞者 ID")

    # 唯一约束：防止同一用户重复点赞同一文章
    __table_args__ = (
        UniqueConstraint("article_id", "user_id", name="uq_like_article_user"),
    )

    article = relationship("Article", back_populates="likes")
    user = relationship("User", back_populates="likes")


class Friend(Base):
    """好友申请模型：按已确认架构字段（id / user_id / status）实现。"""

    __tablename__ = "friends"

    id = Column(Integer, primary_key=True, index=True, comment="好友记录 ID")
    user_id = Column(Integer, ForeignKey("users.id"), nullable=False, index=True, comment="申请人 ID")
    status = Column(String(20), nullable=False, default=FRIEND_STATUS_PENDING, comment="申请状态")
    created_time = Column(DateTime, nullable=False, default=utcnow, comment="申请创建时间")

    user = relationship("User", back_populates="friends")


class EmailCode(Base):
    """邮箱验证码模型：一次性验证码，带过期时间。"""

    __tablename__ = "email_codes"

    id = Column(Integer, primary_key=True, index=True, comment="验证码记录 ID")
    email = Column(String(255), index=True, nullable=False, comment="目标邮箱")
    code = Column(String(10), nullable=False, comment="验证码")
    purpose = Column(String(30), nullable=False, comment="用途：register / reset")
    expires_at = Column(DateTime, nullable=False, comment="过期时间")
    used = Column(Boolean, nullable=False, default=False, comment="是否已使用")
    created_time = Column(DateTime, nullable=False, default=utcnow, comment="创建时间")