from datetime import datetime, date
from typing import TYPE_CHECKING

from sqlalchemy import ForeignKey, Table, Column
from sqlalchemy.sql import expression
from sqlalchemy.orm import Mapped, mapped_column, relationship

from models.base import BaseModel

if TYPE_CHECKING:
    from models import User, Position


class WorkShift(BaseModel):
    __tablename__ = "work_shifts"

    id: Mapped[int] = mapped_column(primary_key=True)
    started_at: Mapped[datetime] = mapped_column(
        nullable=False,
    )
    finished_at: Mapped[datetime] = mapped_column(
        nullable=True,
    )
    is_paused: Mapped[bool] = mapped_column(
        default=False,
        server_default=expression.false(),
    )

    user_id: Mapped[int] = mapped_column(
        ForeignKey("users.id"),
    )
    user: Mapped["User"] = relationship(
        "User",
        back_populates="work_shifts",
        lazy="selectin",
    )

    pauses: Mapped[list["WorkShiftPause"]] = relationship(
        "WorkShiftPause",
        back_populates="work_shift",
        uselist=True,
        foreign_keys="[WorkShiftPause.work_shift_id]",
        cascade="all, delete",
    )


class WorkShiftPause(BaseModel):
    __tablename__ = "work_shifts_pauses"

    id: Mapped[int] = mapped_column(primary_key=True)
    started_at: Mapped[datetime] = mapped_column(
        nullable=False,
    )
    finished_at: Mapped[datetime] = mapped_column(
        nullable=True,
    )

    work_shift_id: Mapped[int] = mapped_column(
        ForeignKey("work_shifts.id"),
    )
    work_shift: Mapped[WorkShift] = relationship(
        "WorkShift",
        back_populates="pauses",
        lazy="selectin",
    )


work_shifts_positions = Table(
    'work_shifts_positions',
    BaseModel.metadata,
    Column('position_key', ForeignKey('positions.key'), primary_key=True),
    Column('work_shift_id', ForeignKey('planned_work_shifts.id'), primary_key=True),
)


class PlannedWorkShift(BaseModel):
    __tablename__ = "planned_work_shifts"

    id: Mapped[int] = mapped_column(primary_key=True)
    shift_date: Mapped[date] = mapped_column(nullable=False, index=True)
    created_at: Mapped[datetime] = mapped_column(nullable=False)

    user_id: Mapped[int] = mapped_column(ForeignKey('users.id'), nullable=False, index=True)
    user: Mapped["User"] = relationship(lazy="selectin", backref="planned_work_shifts")

    positions: Mapped[list["Position"]] = relationship(
        "Position",
        uselist=True,
        secondary=work_shifts_positions,
        lazy="selectin",
    )