from __future__ import annotations

import uuid

from geoalchemy2 import Geometry
from sqlalchemy import (
    Boolean,
    DateTime,
    Float,
    ForeignKey,
    Integer,
    Numeric,
    String,
    Text,
    UniqueConstraint,
)
from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column
from sqlalchemy.sql import func


class Base(DeclarativeBase):
    """Base class for all SQLAlchemy models."""


class TimestampMixin:
    created_at: Mapped[DateTime] = mapped_column(
        DateTime(timezone=True), server_default=func.now(), nullable=False
    )
    updated_at: Mapped[DateTime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
        onupdate=func.now(),
        nullable=False,
    )


class User(Base, TimestampMixin):
    __tablename__ = "users"

    id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
    )
    username: Mapped[str] = mapped_column(String(64), unique=True, nullable=False)
    email: Mapped[str | None] = mapped_column(String(255), unique=True, nullable=True)
    full_name: Mapped[str | None] = mapped_column(String(128), nullable=True)
    password_hash: Mapped[str] = mapped_column(String(256), nullable=False)
    role: Mapped[str] = mapped_column(String(32), nullable=False, default="player")
    preferences: Mapped[str | None] = mapped_column(Text, nullable=True)


class Station(Base, TimestampMixin):
    __tablename__ = "stations"

    id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
    )
    osm_id: Mapped[str | None] = mapped_column(String(32), nullable=True)
    name: Mapped[str] = mapped_column(String(128), nullable=False)
    code: Mapped[str | None] = mapped_column(String(16), nullable=True)
    location: Mapped[str] = mapped_column(
        Geometry(geometry_type="POINT", srid=4326), nullable=False
    )
    elevation_m: Mapped[float | None] = mapped_column(Float, nullable=True)
    is_active: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True)


class Track(Base, TimestampMixin):
    __tablename__ = "tracks"

    id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
    )
    name: Mapped[str | None] = mapped_column(String(128), nullable=True)
    start_station_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("stations.id", ondelete="RESTRICT"),
        nullable=False,
    )
    end_station_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("stations.id", ondelete="RESTRICT"),
        nullable=False,
    )
    length_meters: Mapped[float | None] = mapped_column(Numeric(10, 2), nullable=True)
    max_speed_kph: Mapped[int | None] = mapped_column(Integer, nullable=True)
    is_bidirectional: Mapped[bool] = mapped_column(
        Boolean, nullable=False, default=True
    )
    status: Mapped[str] = mapped_column(String(32), nullable=False, default="planned")
    track_geometry: Mapped[str] = mapped_column(
        Geometry(geometry_type="LINESTRING", srid=4326), nullable=False
    )

    __table_args__ = (
        UniqueConstraint(
            "start_station_id", "end_station_id", name="uq_tracks_station_pair"
        ),
    )


class Train(Base, TimestampMixin):
    __tablename__ = "trains"

    id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
    )
    designation: Mapped[str] = mapped_column(String(64), nullable=False, unique=True)
    operator_id: Mapped[uuid.UUID | None] = mapped_column(
        UUID(as_uuid=True), ForeignKey("users.id", ondelete="SET NULL")
    )
    home_station_id: Mapped[uuid.UUID | None] = mapped_column(
        UUID(as_uuid=True), ForeignKey("stations.id", ondelete="SET NULL")
    )
    capacity: Mapped[int] = mapped_column(Integer, nullable=False)
    max_speed_kph: Mapped[int] = mapped_column(Integer, nullable=False)
    consist: Mapped[str | None] = mapped_column(Text, nullable=True)


class TrainSchedule(Base, TimestampMixin):
    __tablename__ = "train_schedules"

    id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
    )
    train_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True), ForeignKey("trains.id", ondelete="CASCADE"), nullable=False
    )
    sequence_index: Mapped[int] = mapped_column(Integer, nullable=False)
    station_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("stations.id", ondelete="CASCADE"),
        nullable=False,
    )
    scheduled_arrival: Mapped[DateTime | None] = mapped_column(
        DateTime(timezone=True), nullable=True
    )
    scheduled_departure: Mapped[DateTime | None] = mapped_column(
        DateTime(timezone=True), nullable=True
    )
    dwell_seconds: Mapped[int | None] = mapped_column(Integer, nullable=True)

    __table_args__ = (
        UniqueConstraint(
            "train_id", "sequence_index", name="uq_train_schedule_sequence"
        ),
    )