from datetime import datetime, timezone

from sqlalchemy import BigInteger, Boolean, Column, DateTime, ForeignKey, Index, Integer, Table, Text, text
from sqlalchemy.orm import Mapped, mapped_column

from scribe.models import Base
from scribe.models.base import SoftDeleteMixin, TimestampMixin, iso


class Rulebook(Base, TimestampMixin, SoftDeleteMixin):
    __tablename__ = "rulebooks"

    id: Mapped[int] = mapped_column(BigInteger, primary_key=True)
    owner_user_id: Mapped[int] = mapped_column(
        BigInteger, ForeignKey("users.id", ondelete="CASCADE")
    )
    title: Mapped[str] = mapped_column(Text)
    description: Mapped[str | None] = mapped_column(Text, nullable=True)
    always_on: Mapped[bool] = mapped_column(
        Boolean, default=False, nullable=False, server_default="false"
    )

    def to_dict(self) -> dict:
        return {
            "id": self.id,
            "owner_user_id": self.owner_user_id,
            "title": self.title,
            "description": self.description or "",
            "always_on": self.always_on,
            "created_at": iso(self.created_at),
            "updated_at": iso(self.updated_at),
        }


class RulebookTopic(Base, TimestampMixin, SoftDeleteMixin):
    __tablename__ = "rulebook_topics"
    # Partial unique: a title is unique among LIVE topics in a rulebook, so a
    # trashed topic doesn't block recreating/restoring the same title.
    __table_args__ = (
        Index(
            "uq_topic_per_rulebook", "rulebook_id", "title",
            unique=True, postgresql_where=text("deleted_at IS NULL"),
        ),
    )

    id: Mapped[int] = mapped_column(BigInteger, primary_key=True)
    rulebook_id: Mapped[int] = mapped_column(
        BigInteger, ForeignKey("rulebooks.id", ondelete="CASCADE")
    )
    title: Mapped[str] = mapped_column(Text)
    description: Mapped[str | None] = mapped_column(Text, nullable=True)
    order_index: Mapped[int] = mapped_column(Integer, default=0)

    def to_dict(self) -> dict:
        return {
            "id": self.id,
            "rulebook_id": self.rulebook_id,
            "title": self.title,
            "description": self.description or "",
            "order_index": self.order_index,
            "created_at": iso(self.created_at),
            "updated_at": iso(self.updated_at),
        }


class Rule(Base, TimestampMixin, SoftDeleteMixin):
    __tablename__ = "rules"
    # Partial unique: title unique among LIVE rules in a topic (soft-deleted
    # rules don't block recreating/restoring the same title).
    __table_args__ = (
        Index(
            "uq_rule_per_topic", "topic_id", "title",
            unique=True, postgresql_where=text("deleted_at IS NULL"),
        ),
    )

    id: Mapped[int] = mapped_column(BigInteger, primary_key=True)
    # Exactly one of topic_id / project_id is set — enforced by CHECK
    # constraint ck_rule_topic_xor_project (migration 0059).
    topic_id: Mapped[int | None] = mapped_column(
        BigInteger,
        ForeignKey("rulebook_topics.id", ondelete="CASCADE"),
        nullable=True,
    )
    project_id: Mapped[int | None] = mapped_column(
        BigInteger,
        ForeignKey("projects.id", ondelete="CASCADE"),
        nullable=True,
        index=True,
    )
    title: Mapped[str] = mapped_column(Text)
    statement: Mapped[str] = mapped_column(Text)
    why: Mapped[str | None] = mapped_column(Text, nullable=True)
    how_to_apply: Mapped[str | None] = mapped_column(Text, nullable=True)
    order_index: Mapped[int] = mapped_column(Integer, default=0)

    def to_dict(self) -> dict:
        return {
            "id": self.id,
            "topic_id": self.topic_id,
            "project_id": self.project_id,
            "title": self.title,
            "statement": self.statement,
            "why": self.why or "",
            "how_to_apply": self.how_to_apply or "",
            "order_index": self.order_index,
            "created_at": iso(self.created_at),
            "updated_at": iso(self.updated_at),
        }


# Pure many-to-many — no model class, just the join table.
project_rulebook_subscriptions = Table(
    "project_rulebook_subscriptions",
    Base.metadata,
    Column("project_id", BigInteger, ForeignKey("projects.id", ondelete="CASCADE"), primary_key=True),
    Column("rulebook_id", BigInteger, ForeignKey("rulebooks.id", ondelete="CASCADE"), primary_key=True),
    Column("created_at", DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)),
)

# Suppressions — let a project mute individual rules or whole topics from
# rulebooks it subscribes to, without unsubscribing the rulebook itself.
# FKs CASCADE so the row vanishes when its parent is removed.
project_rule_suppressions = Table(
    "project_rule_suppressions",
    Base.metadata,
    Column("project_id", BigInteger, ForeignKey("projects.id", ondelete="CASCADE"), primary_key=True),
    Column("rule_id", BigInteger, ForeignKey("rules.id", ondelete="CASCADE"), primary_key=True),
    Column("created_at", DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)),
)

# A project's opt-out of a whole ALWAYS-ON rulebook (milestone 297): the
# sibling of the two suppression tables below, one level up. Always-on
# rulebooks bind every project implicitly; an inception decision can exclude
# specific ones for this project, and get_applicable_rules /
# list_always_on_rules(project_id) skip them. FKs CASCADE like the others.
project_rulebook_exclusions = Table(
    "project_rulebook_exclusions",
    Base.metadata,
    Column("project_id", BigInteger, ForeignKey("projects.id", ondelete="CASCADE"), primary_key=True),
    Column("rulebook_id", BigInteger, ForeignKey("rulebooks.id", ondelete="CASCADE"), primary_key=True),
    Column("created_at", DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)),
)

project_topic_suppressions = Table(
    "project_topic_suppressions",
    Base.metadata,
    Column("project_id", BigInteger, ForeignKey("projects.id", ondelete="CASCADE"), primary_key=True),
    Column("topic_id", BigInteger, ForeignKey("rulebook_topics.id", ondelete="CASCADE"), primary_key=True),
    Column("created_at", DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)),
)
