from datetime import datetime

from sqlalchemy import (
    BigInteger,
    DateTime,
    ForeignKey,
    Index,
    String,
    Text,
    UniqueConstraint,
    func,
)
from sqlalchemy.dialects.postgresql import JSONB
from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column, relationship


class Base(DeclarativeBase):
    pass


class Section(Base):
    """A sub-section inside a vertical, e.g. ('real_estate', 'dubai').

    The pair (vertical, slug) is unique and identifies a section in URLs
    and API calls. A channel belongs to exactly one section, the section
    knows its vertical, and the LLM prompt store can hold a per-section
    override that falls back to the vertical-level prompt.
    """

    __tablename__ = "sections"
    __table_args__ = (
        UniqueConstraint(
            "vertical",
            "department_id",
            "slug",
            name="uq_section_vertical_department_slug",
        ),
        Index("ix_sections_vertical_department", "vertical", "department_id"),
    )

    id: Mapped[int] = mapped_column(primary_key=True)
    vertical: Mapped[str] = mapped_column(String(32))
    department_id: Mapped[str | None] = mapped_column(String(64), nullable=True)
    slug: Mapped[str] = mapped_column(String(64))
    title: Mapped[str] = mapped_column(String(255))
    emoji: Mapped[str | None] = mapped_column(String(8), nullable=True)
    description: Mapped[str | None] = mapped_column(Text, nullable=True)
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), server_default=func.now()
    )

    channels: Mapped[list["Channel"]] = relationship(back_populates="section")


class Channel(Base):
    __tablename__ = "channels"
    __table_args__ = (
        UniqueConstraint("section_id", "identifier", name="uq_channels_section_identifier"),
        Index("ix_channels_source_channel_id", "source_channel_id"),
    )

    id: Mapped[int] = mapped_column(primary_key=True)
    # Telegram numeric channel id (peer id), nullable until first resolve
    tg_id: Mapped[int | None] = mapped_column(BigInteger, unique=True, nullable=True)
    # Username or t.me/joinchat link supplied by user
    identifier: Mapped[str] = mapped_column(String(255))
    title: Mapped[str | None] = mapped_column(String(512), nullable=True)
    # 'real_estate' or 'hr' — picks which LLM prompt and lead schema is used
    vertical: Mapped[str] = mapped_column(
        String(32), default="real_estate", server_default="real_estate", index=True
    )
    section_id: Mapped[int] = mapped_column(
        ForeignKey("sections.id", ondelete="RESTRICT"), index=True
    )
    source_channel_id: Mapped[int | None] = mapped_column(
        ForeignKey("channels.id", ondelete="SET NULL"), nullable=True
    )
    is_active: Mapped[bool] = mapped_column(default=True, server_default="true")
    last_message_id: Mapped[int | None] = mapped_column(BigInteger, nullable=True)
    last_polled_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    last_poll_status: Mapped[str | None] = mapped_column(String(32), nullable=True)
    last_poll_error_code: Mapped[str | None] = mapped_column(String(64), nullable=True)
    last_poll_error: Mapped[str | None] = mapped_column(Text, nullable=True)
    last_poll_error_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), server_default=func.now()
    )

    section: Mapped[Section] = relationship(back_populates="channels")
    messages: Mapped[list["Message"]] = relationship(
        back_populates="channel",
        cascade="all, delete-orphan",
        passive_deletes=True,
    )


class Message(Base):
    __tablename__ = "messages"
    __table_args__ = (
        UniqueConstraint("channel_id", "tg_message_id", name="uq_channel_message"),
        Index("ix_messages_channel_date", "channel_id", "date"),
    )

    id: Mapped[int] = mapped_column(primary_key=True)
    channel_id: Mapped[int] = mapped_column(ForeignKey("channels.id", ondelete="CASCADE"))
    tg_message_id: Mapped[int] = mapped_column(BigInteger)
    date: Mapped[datetime] = mapped_column(DateTime(timezone=True))
    text: Mapped[str | None] = mapped_column(Text, nullable=True)
    sender_id: Mapped[int | None] = mapped_column(BigInteger, nullable=True)
    sender_username: Mapped[str | None] = mapped_column(String(64), nullable=True)
    sender_name: Mapped[str | None] = mapped_column(String(255), nullable=True)
    grouped_id: Mapped[int | None] = mapped_column(BigInteger, nullable=True)
    has_media: Mapped[bool] = mapped_column(default=False, server_default="false")
    views: Mapped[int | None] = mapped_column(nullable=True)
    forwards: Mapped[int | None] = mapped_column(nullable=True)
    raw: Mapped[dict | None] = mapped_column(JSONB, nullable=True)
    media_files: Mapped[list | None] = mapped_column(JSONB, nullable=True)
    extracted: Mapped[dict | None] = mapped_column(JSONB, nullable=True)
    fetched_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), server_default=func.now()
    )

    channel: Mapped[Channel] = relationship(back_populates="messages")


class MessageClassification(Base):
    __tablename__ = "message_classifications"
    __table_args__ = (
        UniqueConstraint("message_id", "section_id", name="uq_message_classification_section"),
        Index("ix_message_classifications_message", "message_id"),
        Index("ix_message_classifications_section", "section_id"),
    )

    id: Mapped[int] = mapped_column(primary_key=True)
    message_id: Mapped[int] = mapped_column(ForeignKey("messages.id", ondelete="CASCADE"))
    section_id: Mapped[int] = mapped_column(ForeignKey("sections.id", ondelete="CASCADE"))
    vertical: Mapped[str] = mapped_column(String(32))
    verdict: Mapped[dict] = mapped_column(JSONB)
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), server_default=func.now()
    )


class AppSetting(Base):
    """Runtime-editable settings, edited from the UI without a restart."""

    __tablename__ = "app_settings"

    key: Mapped[str] = mapped_column(String(255), primary_key=True)
    value: Mapped[dict | str | int | bool | None] = mapped_column(JSONB, nullable=False)
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), server_default=func.now()
    )