from datetime import datetime
from decimal import Decimal
from sqlalchemy import String, Boolean, Text, Numeric, ForeignKey, DateTime, func, ARRAY
from sqlalchemy.orm import Mapped, mapped_column, relationship
from app.database import Base


class OperationType(Base):
    __tablename__ = "operation_types"

    id: Mapped[int] = mapped_column(primary_key=True)
    name: Mapped[str] = mapped_column(String(50), unique=True, nullable=False)  # income | expense | transfer
    description: Mapped[str | None] = mapped_column(Text)

    operations: Mapped[list["Operation"]] = relationship("Operation", back_populates="operation_type")


class Operation(Base):
    __tablename__ = "operations"

    id: Mapped[int] = mapped_column(primary_key=True)
    user_id: Mapped[int] = mapped_column(ForeignKey("users.id"), nullable=False, index=True)
    account_id: Mapped[int] = mapped_column(ForeignKey("accounts.id"), nullable=False, index=True)
    category_id: Mapped[int | None] = mapped_column(ForeignKey("categories.id"), nullable=True)
    operation_type_id: Mapped[int] = mapped_column(ForeignKey("operation_types.id"), nullable=False)
    amount: Mapped[Decimal] = mapped_column(Numeric(20, 2), nullable=False)
    currency_id: Mapped[int] = mapped_column(ForeignKey("currencies.id"), nullable=False)
    amount_converted: Mapped[Decimal | None] = mapped_column(Numeric(20, 2))  # in account currency
    exchange_rate: Mapped[Decimal | None] = mapped_column(Numeric(20, 6))
    date: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, index=True)
    description: Mapped[str | None] = mapped_column(Text)
    location_id: Mapped[int | None] = mapped_column(ForeignKey("locations.id"), nullable=True)
    is_planned: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), server_default=func.now(), onupdate=func.now()
    )

    user: Mapped["User"] = relationship("User", back_populates="operations")
    account: Mapped["Account"] = relationship("Account", back_populates="operations")
    category: Mapped["Category | None"] = relationship("Category", back_populates="operations")
    operation_type: Mapped["OperationType"] = relationship("OperationType", back_populates="operations")
    currency: Mapped["Currency"] = relationship("Currency", back_populates="operations")
    location: Mapped["Location | None"] = relationship("Location", back_populates="operations")

    relations_from: Mapped[list["OperationRelation"]] = relationship(
        "OperationRelation", foreign_keys="OperationRelation.operation_from_id", back_populates="operation_from"
    )
    relations_to: Mapped[list["OperationRelation"]] = relationship(
        "OperationRelation", foreign_keys="OperationRelation.operation_to_id", back_populates="operation_to"
    )
    calendar_events: Mapped[list] = relationship("CalendarEvent", back_populates="related_operation")


class OperationRelation(Base):
    """Links two operations — e.g., the debit and credit legs of a transfer."""
    __tablename__ = "operation_relations"

    id: Mapped[int] = mapped_column(primary_key=True)
    operation_from_id: Mapped[int] = mapped_column(ForeignKey("operations.id"), nullable=False)
    operation_to_id: Mapped[int] = mapped_column(ForeignKey("operations.id"), nullable=False)
    relation_type: Mapped[str] = mapped_column(String(50), nullable=False)  # transfer | split | correction
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())

    operation_from: Mapped["Operation"] = relationship(
        "Operation", foreign_keys=[operation_from_id], back_populates="relations_from"
    )
    operation_to: Mapped["Operation"] = relationship(
        "Operation", foreign_keys=[operation_to_id], back_populates="relations_to"
    )