"""Activity timeline ORM model and schemas."""

from __future__ import annotations

from datetime import datetime
from enum import StrEnum
from typing import Any

from pydantic import BaseModel, ConfigDict, Field
from sqlalchemy import DateTime, ForeignKey, Integer, func, text
from sqlalchemy import Enum as SqlEnum
from sqlalchemy.dialects.postgresql import JSONB
from sqlalchemy.orm import Mapped, mapped_column, relationship
from sqlalchemy.types import JSON as SA_JSON
from sqlalchemy.types import TypeDecorator

from app.models.base import Base, enum_values


class ActivityType(StrEnum):
    COMMENT = "comment"
    STATUS_CHANGED = "status_changed"
    STAGE_CHANGED = "stage_changed"
    TASK_CREATED = "task_created"
    SYSTEM = "system"


class JSONBCompat(TypeDecorator):
    """Uses JSONB on Postgres and plain JSON elsewhere for testability."""

    impl = JSONB
    cache_ok = True

    def load_dialect_impl(self, dialect):  # type: ignore[override]
        if dialect.name == "sqlite":
            from sqlalchemy.dialects.sqlite import JSON as SQLITE_JSON  # local import

            return dialect.type_descriptor(SQLITE_JSON())
        return dialect.type_descriptor(JSONB())


class Activity(Base):
    """Represents a timeline event for a deal."""

    __tablename__ = "activities"

    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    deal_id: Mapped[int] = mapped_column(ForeignKey("deals.id", ondelete="CASCADE"))
    author_id: Mapped[int | None] = mapped_column(
        ForeignKey("users.id", ondelete="SET NULL"),
        nullable=True,
    )
    type: Mapped[ActivityType] = mapped_column(
        SqlEnum(ActivityType, name="activity_type", values_callable=enum_values),
        nullable=False,
    )
    payload: Mapped[dict[str, Any]] = mapped_column(
        JSONBCompat().with_variant(SA_JSON(), "sqlite"),
        nullable=False,
        server_default=text("'{}'"),
    )
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
        nullable=False,
    )

    deal = relationship("Deal", back_populates="activities")
    author = relationship("User", back_populates="activities")


class ActivityBase(BaseModel):
    deal_id: int
    author_id: int | None = None
    type: ActivityType
    payload: dict[str, Any] = Field(default_factory=dict)


class ActivityCreate(ActivityBase):
    pass


class ActivityRead(ActivityBase):
    id: int
    created_at: datetime

    model_config = ConfigDict(from_attributes=True)