import uuid
from datetime import datetime
from decimal import Decimal

from sqlalchemy import (
    DateTime,
    ForeignKey,
    Numeric,
    Text,
    func,
    text,
)
from sqlalchemy.dialects.postgresql import JSONB
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.db.base import Base
from app.models.catalog import _timestamptz, _uuid_pk


class ProjectTransfer(Base):
    """project_transfers — Inter-project (inter-site) material transfer ledger.

    Records the movement of materials from a source project warehouse to a
    destination project. Stock is deducted from the source warehouse immediately
    upon creation (status = 'in_transit') via out_transaction_id.
    When the destination project PM confirms receipt in 'Arrivals', stock is
    added to the destination warehouse (status = 'received').
    While 'in_transit', the transfer can be edited or cancelled (restoring source stock).
    Once 'received', the transfer is permanently locked from edit or cancellation.
    """

    __tablename__ = "project_transfers"
    __mapper_args__ = {"eager_defaults": True}

    id: Mapped[uuid.UUID] = _uuid_pk()
    from_project_id: Mapped[uuid.UUID] = mapped_column(
        ForeignKey("projects.id", ondelete="RESTRICT"), nullable=False
    )
    from_warehouse_id: Mapped[uuid.UUID] = mapped_column(
        ForeignKey("warehouses.id", ondelete="RESTRICT"), nullable=False
    )
    to_project_id: Mapped[uuid.UUID] = mapped_column(
        ForeignKey("projects.id", ondelete="RESTRICT"), nullable=False
    )
    material_id: Mapped[uuid.UUID] = mapped_column(
        ForeignKey("materials.id", ondelete="RESTRICT"), nullable=False
    )
    brand_id: Mapped[uuid.UUID | None] = mapped_column(
        ForeignKey("brands.id", ondelete="SET NULL")
    )
    unit_id: Mapped[int] = mapped_column(
        ForeignKey("units.id", ondelete="RESTRICT"), nullable=False
    )
    quantity: Mapped[Decimal] = mapped_column(Numeric(18, 6), nullable=False)
    specs: Mapped[dict] = mapped_column(JSONB, nullable=False, server_default=text("'{}'::jsonb"))
    specs_hash: Mapped[str] = mapped_column(Text, nullable=False, server_default=text("'default'"))
    note: Mapped[str | None] = mapped_column(Text)
    status: Mapped[str] = mapped_column(Text, nullable=False, server_default=text("'in_transit'"))

    out_transaction_id: Mapped[uuid.UUID | None] = mapped_column(
        ForeignKey("inventory_transactions.id", ondelete="SET NULL")
    )
    transfer_date: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now()
    )
    transferred_by: Mapped[str | None] = mapped_column(Text)
    received_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
    received_by: Mapped[str | None] = mapped_column(Text)
    to_warehouse_id: Mapped[uuid.UUID | None] = mapped_column(
        ForeignKey("warehouses.id", ondelete="SET NULL")
    )
    receipt_allocations: Mapped[list | None] = mapped_column(JSONB)
    created_at: Mapped[datetime] = _timestamptz()
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now(), onupdate=func.now()
    )

    from_project: Mapped["Project"] = relationship("Project", foreign_keys=[from_project_id], lazy="raise")
    to_project: Mapped["Project"] = relationship("Project", foreign_keys=[to_project_id], lazy="raise")
    from_warehouse: Mapped["Warehouse"] = relationship("Warehouse", foreign_keys=[from_warehouse_id], lazy="raise")
    to_warehouse: Mapped["Warehouse | None"] = relationship("Warehouse", foreign_keys=[to_warehouse_id], lazy="raise")
    material: Mapped["Material"] = relationship("Material", foreign_keys=[material_id], lazy="raise")
    brand: Mapped["Brand | None"] = relationship("Brand", foreign_keys=[brand_id], lazy="raise")
    unit: Mapped["Unit"] = relationship("Unit", foreign_keys=[unit_id], lazy="raise")
    out_transaction: Mapped["InventoryTransaction | None"] = relationship(
        "InventoryTransaction", foreign_keys=[out_transaction_id], lazy="raise"
    )