from __future__ import annotations

from datetime import datetime
from typing import Optional

from sqlalchemy import JSON, BigInteger, DateTime, Float, ForeignKey, Integer, String, Text, func
from sqlalchemy.dialects.mysql import LONGTEXT
from sqlalchemy.orm import Mapped, mapped_column, relationship

from ..db.base import Base

# 自定义列类型：兼容跨数据库环境
BIGINT_PK_TYPE = BigInteger().with_variant(Integer, "sqlite")
LONG_TEXT_TYPE = Text().with_variant(LONGTEXT, "mysql")


class _MetadataAccessor:
    """Descriptor 用于将 `metadata` 访问重定向到 `metadata_`，且保持 Base.metadata 可用。"""

    def __get__(self, instance, owner):
        if instance is None:
            return Base.metadata
        return instance.metadata_

    def __set__(self, instance, value):
        instance.metadata_ = value


class NovelProject(Base):
    """小说项目主表，仅存放轻量级元数据。"""

    __tablename__ = "novel_projects"

    id: Mapped[str] = mapped_column(String(36), primary_key=True)
    user_id: Mapped[int] = mapped_column(ForeignKey("users.id", ondelete="CASCADE"), nullable=False, index=True)
    title: Mapped[str] = mapped_column(String(255), nullable=False)
    initial_prompt: Mapped[Optional[str]] = mapped_column(Text)
    status: Mapped[str] = mapped_column(String(32), default="draft")
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
    updated_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now())

    owner: Mapped["User"] = relationship("User", back_populates="novel_projects")
    blueprint: Mapped[Optional["NovelBlueprint"]] = relationship(
        back_populates="project", cascade="all, delete-orphan", uselist=False
    )
    conversations: Mapped[list["NovelConversation"]] = relationship(
        back_populates="project", cascade="all, delete-orphan", order_by="NovelConversation.seq"
    )
    characters: Mapped[list["BlueprintCharacter"]] = relationship(
        back_populates="project", cascade="all, delete-orphan", order_by="BlueprintCharacter.position"
    )
    relationships_: Mapped[list["BlueprintRelationship"]] = relationship(
        back_populates="project", cascade="all, delete-orphan", order_by="BlueprintRelationship.position"
    )
    outlines: Mapped[list["ChapterOutline"]] = relationship(
        back_populates="project", cascade="all, delete-orphan", order_by="ChapterOutline.chapter_number"
    )
    chapters: Mapped[list["Chapter"]] = relationship(
        back_populates="project", cascade="all, delete-orphan", order_by="Chapter.chapter_number"
    )


class NovelConversation(Base):
    """对话记录表，存储概念阶段的连续对话。"""

    __tablename__ = "novel_conversations"

    id: Mapped[int] = mapped_column(BIGINT_PK_TYPE, primary_key=True, autoincrement=True)
    project_id: Mapped[str] = mapped_column(ForeignKey("novel_projects.id", ondelete="CASCADE"), nullable=False)
    seq: Mapped[int] = mapped_column(Integer, nullable=False)
    role: Mapped[str] = mapped_column(String(32), nullable=False)
    content: Mapped[str] = mapped_column(LONG_TEXT_TYPE, nullable=False)
    metadata_: Mapped[Optional[dict]] = mapped_column("metadata", JSON)
    metadata = _MetadataAccessor()
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())

    project: Mapped[NovelProject] = relationship(back_populates="conversations")


class NovelBlueprint(Base):
    """蓝图主体信息（标题、风格等）。"""

    __tablename__ = "novel_blueprints"

    project_id: Mapped[str] = mapped_column(
        ForeignKey("novel_projects.id", ondelete="CASCADE"), primary_key=True
    )
    title: Mapped[Optional[str]] = mapped_column(String(255))
    target_audience: Mapped[Optional[str]] = mapped_column(String(255))
    genre: Mapped[Optional[str]] = mapped_column(String(128))
    style: Mapped[Optional[str]] = mapped_column(String(128))
    tone: Mapped[Optional[str]] = mapped_column(String(128))
    one_sentence_summary: Mapped[Optional[str]] = mapped_column(Text)
    full_synopsis: Mapped[Optional[str]] = mapped_column(LONG_TEXT_TYPE)
    world_setting: Mapped[Optional[dict]] = mapped_column(JSON, default=dict)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
    updated_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now())

    project: Mapped[NovelProject] = relationship(back_populates="blueprint")


class BlueprintCharacter(Base):
    """蓝图角色信息。"""

    __tablename__ = "blueprint_characters"

    id: Mapped[int] = mapped_column(BIGINT_PK_TYPE, primary_key=True, autoincrement=True)
    project_id: Mapped[str] = mapped_column(ForeignKey("novel_projects.id", ondelete="CASCADE"), nullable=False)
    name: Mapped[str] = mapped_column(String(255), nullable=False)
    identity: Mapped[Optional[str]] = mapped_column(String(255))
    personality: Mapped[Optional[str]] = mapped_column(Text)
    goals: Mapped[Optional[str]] = mapped_column(Text)
    abilities: Mapped[Optional[str]] = mapped_column(Text)
    relationship_to_protagonist: Mapped[Optional[str]] = mapped_column(Text)
    extra: Mapped[Optional[dict]] = mapped_column(JSON)
    position: Mapped[int] = mapped_column(Integer, default=0)

    project: Mapped[NovelProject] = relationship(back_populates="characters")


class BlueprintRelationship(Base):
    """角色之间的关系。"""

    __tablename__ = "blueprint_relationships"

    id: Mapped[int] = mapped_column(BIGINT_PK_TYPE, primary_key=True, autoincrement=True)
    project_id: Mapped[str] = mapped_column(ForeignKey("novel_projects.id", ondelete="CASCADE"), nullable=False)
    character_from: Mapped[str] = mapped_column(String(255), nullable=False)
    character_to: Mapped[str] = mapped_column(String(255), nullable=False)
    description: Mapped[Optional[str]] = mapped_column(Text)
    position: Mapped[int] = mapped_column(Integer, default=0)

    project: Mapped[NovelProject] = relationship(back_populates="relationships_")


class ChapterOutline(Base):
    """章节纲要。"""

    __tablename__ = "chapter_outlines"

    id: Mapped[int] = mapped_column(BIGINT_PK_TYPE, primary_key=True, autoincrement=True)
    project_id: Mapped[str] = mapped_column(ForeignKey("novel_projects.id", ondelete="CASCADE"), nullable=False)
    chapter_number: Mapped[int] = mapped_column(Integer, nullable=False)
    title: Mapped[str] = mapped_column(String(255), nullable=False)
    summary: Mapped[Optional[str]] = mapped_column(Text)

    project: Mapped[NovelProject] = relationship(back_populates="outlines")


class Chapter(Base):
    """章节正文状态，指向选中的版本。"""

    __tablename__ = "chapters"

    id: Mapped[int] = mapped_column(BIGINT_PK_TYPE, primary_key=True, autoincrement=True)
    project_id: Mapped[str] = mapped_column(ForeignKey("novel_projects.id", ondelete="CASCADE"), nullable=False)
    chapter_number: Mapped[int] = mapped_column(Integer, nullable=False)
    real_summary: Mapped[Optional[str]] = mapped_column(Text)
    status: Mapped[str] = mapped_column(String(32), default="not_generated")
    word_count: Mapped[int] = mapped_column(Integer, default=0)
    selected_version_id: Mapped[Optional[int]] = mapped_column(
        ForeignKey("chapter_versions.id", ondelete="SET NULL"), nullable=True
    )
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
    updated_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now())

    project: Mapped[NovelProject] = relationship(back_populates="chapters")
    versions: Mapped[list["ChapterVersion"]] = relationship(
        "ChapterVersion",
        back_populates="chapter",
        cascade="all, delete-orphan",
        order_by="ChapterVersion.created_at",
        primaryjoin="Chapter.id == ChapterVersion.chapter_id",
        foreign_keys="[ChapterVersion.chapter_id]",
    )
    selected_version: Mapped[Optional["ChapterVersion"]] = relationship(
        "ChapterVersion",
        foreign_keys=[selected_version_id],
        primaryjoin="Chapter.selected_version_id == ChapterVersion.id",
        post_update=True,
    )
    evaluations: Mapped[list["ChapterEvaluation"]] = relationship(
        back_populates="chapter", cascade="all, delete-orphan", order_by="ChapterEvaluation.created_at"
    )


class ChapterVersion(Base):
    """章节生成的不同版本文本。"""

    __tablename__ = "chapter_versions"

    id: Mapped[int] = mapped_column(BIGINT_PK_TYPE, primary_key=True, autoincrement=True)
    chapter_id: Mapped[int] = mapped_column(ForeignKey("chapters.id", ondelete="CASCADE"), nullable=False)
    version_label: Mapped[Optional[str]] = mapped_column(String(64))
    provider: Mapped[Optional[str]] = mapped_column(String(64))
    content: Mapped[str] = mapped_column(LONG_TEXT_TYPE, nullable=False)
    metadata_: Mapped[Optional[dict]] = mapped_column("metadata", JSON)
    metadata = _MetadataAccessor()
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())

    chapter: Mapped[Chapter] = relationship(
        "Chapter",
        back_populates="versions",
        foreign_keys=[chapter_id],
    )
    evaluations: Mapped[list["ChapterEvaluation"]] = relationship(
        back_populates="version", cascade="all, delete-orphan"
    )


class ChapterEvaluation(Base):
    """章节评估记录。"""

    __tablename__ = "chapter_evaluations"

    id: Mapped[int] = mapped_column(BIGINT_PK_TYPE, primary_key=True, autoincrement=True)
    chapter_id: Mapped[int] = mapped_column(ForeignKey("chapters.id", ondelete="CASCADE"), nullable=False)
    version_id: Mapped[Optional[int]] = mapped_column(ForeignKey("chapter_versions.id", ondelete="CASCADE"))
    decision: Mapped[Optional[str]] = mapped_column(String(32))
    feedback: Mapped[Optional[str]] = mapped_column(Text)
    score: Mapped[Optional[float]] = mapped_column(Float)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())

    chapter: Mapped[Chapter] = relationship(back_populates="evaluations")
    version: Mapped[Optional[ChapterVersion]] = relationship(back_populates="evaluations")