import uuid
from datetime import date, datetime
from typing import Any

from sqlalchemy import (
    JSON,
    BigInteger,
    CheckConstraint,
    Date,
    ForeignKey,
    ForeignKeyConstraint,
    Integer,
    String,
    UniqueConstraint,
    Uuid,
)
from sqlalchemy.orm import Mapped, mapped_column

from app.db.base import Base, PkMixin, TimestampMixin, UTCDateTime

PERIOD_STATUSES = ("open", "closed")
FUNDING_KINDS = ("fund", "unfund")


class BudgetPeriod(Base, PkMixin, TimestampMixin):
    """Calendar month budget period in the space timezone (month granularity)."""

    __tablename__ = "budget_periods"
    __table_args__ = (
        CheckConstraint("status IN ('open', 'closed')", name="status_valid"),
        CheckConstraint("month BETWEEN 1 AND 12", name="month_valid"),
        UniqueConstraint("space_id", "year", "month", name="uq_budget_periods_space_ym"),
        UniqueConstraint("space_id", "id", name="uq_budget_periods_space_id"),
    )

    space_id: Mapped[uuid.UUID] = mapped_column(
        Uuid, ForeignKey("financial_spaces.id", ondelete="CASCADE"), nullable=False, index=True
    )
    year: Mapped[int] = mapped_column(nullable=False)
    month: Mapped[int] = mapped_column(nullable=False)
    status: Mapped[str] = mapped_column(String(8), nullable=False, default="open")
    version: Mapped[int] = mapped_column(Integer, nullable=False, default=1)

    __mapper_args__ = {"version_id_col": version}


class PlanAssignment(Base, PkMixin, TimestampMixin):
    __tablename__ = "plan_assignments"
    __table_args__ = (
        CheckConstraint("planned_kopecks >= 0", name="planned_nonnegative"),
        ForeignKeyConstraint(
            ["space_id", "period_id"],
            ["budget_periods.space_id", "budget_periods.id"],
            ondelete="CASCADE",
            name="fk_plan_assignments_period_tenant",
        ),
        ForeignKeyConstraint(
            ["space_id", "category_id"],
            ["categories.space_id", "categories.id"],
            name="fk_plan_assignments_category_tenant",
        ),
        UniqueConstraint("period_id", "category_id", name="uq_plan_assignments_period_category"),
        UniqueConstraint("space_id", "id", name="uq_plan_assignments_space_id"),
    )

    space_id: Mapped[uuid.UUID] = mapped_column(
        Uuid, ForeignKey("financial_spaces.id", ondelete="CASCADE"), nullable=False, index=True
    )
    period_id: Mapped[uuid.UUID] = mapped_column(Uuid, nullable=False, index=True)
    category_id: Mapped[uuid.UUID] = mapped_column(Uuid, nullable=False)
    planned_kopecks: Mapped[int] = mapped_column(BigInteger, nullable=False, default=0)
    version: Mapped[int] = mapped_column(Integer, nullable=False, default=1)

    __mapper_args__ = {"version_id_col": version}


class ExpectedIncome(Base, PkMixin, TimestampMixin):
    __tablename__ = "expected_incomes"
    __table_args__ = (
        CheckConstraint("amount_kopecks > 0", name="amount_positive"),
        ForeignKeyConstraint(
            ["space_id", "period_id"],
            ["budget_periods.space_id", "budget_periods.id"],
            ondelete="CASCADE",
            name="fk_expected_incomes_period_tenant",
        ),
        UniqueConstraint("space_id", "id", name="uq_expected_incomes_space_id"),
    )

    space_id: Mapped[uuid.UUID] = mapped_column(
        Uuid, ForeignKey("financial_spaces.id", ondelete="CASCADE"), nullable=False, index=True
    )
    period_id: Mapped[uuid.UUID] = mapped_column(Uuid, nullable=False, index=True)
    expected_on: Mapped[date] = mapped_column(Date, nullable=False)
    amount_kopecks: Mapped[int] = mapped_column(BigInteger, nullable=False)
    source_name: Mapped[str | None] = mapped_column(String(200), nullable=True)
    note: Mapped[str | None] = mapped_column(String(500), nullable=True)
    version: Mapped[int] = mapped_column(Integer, nullable=False, default=1)

    __mapper_args__ = {"version_id_col": version}


class ExpectedIncomeMatch(Base, PkMixin, TimestampMixin):
    """Links one actual income operation to one expected income (1:1 per operation)."""

    __tablename__ = "expected_income_matches"
    __table_args__ = (
        CheckConstraint("amount_kopecks > 0", name="amount_positive"),
        ForeignKeyConstraint(
            ["space_id", "expected_income_id"],
            ["expected_incomes.space_id", "expected_incomes.id"],
            ondelete="CASCADE",
            name="fk_income_matches_expected_tenant",
        ),
        ForeignKeyConstraint(
            ["space_id", "operation_id"],
            ["operations.space_id", "operations.id"],
            name="fk_income_matches_operation_tenant",
        ),
        UniqueConstraint("operation_id", name="uq_income_matches_operation"),
        UniqueConstraint("space_id", "id", name="uq_income_matches_space_id"),
    )

    space_id: Mapped[uuid.UUID] = mapped_column(
        Uuid, ForeignKey("financial_spaces.id", ondelete="CASCADE"), nullable=False, index=True
    )
    expected_income_id: Mapped[uuid.UUID] = mapped_column(Uuid, nullable=False, index=True)
    operation_id: Mapped[uuid.UUID] = mapped_column(Uuid, nullable=False)
    amount_kopecks: Mapped[int] = mapped_column(BigInteger, nullable=False)


class FundingMovement(Base, PkMixin, TimestampMixin):
    """Manual money movement between the general pool and a category/reserve."""

    __tablename__ = "funding_movements"
    __table_args__ = (
        CheckConstraint("kind IN ('fund', 'unfund')", name="kind_valid"),
        CheckConstraint("amount_kopecks > 0", name="amount_positive"),
        ForeignKeyConstraint(
            ["space_id", "period_id"],
            ["budget_periods.space_id", "budget_periods.id"],
            ondelete="CASCADE",
            name="fk_funding_movements_period_tenant",
        ),
        ForeignKeyConstraint(
            ["space_id", "category_id"],
            ["categories.space_id", "categories.id"],
            name="fk_funding_movements_category_tenant",
        ),
        UniqueConstraint("space_id", "id", name="uq_funding_movements_space_id"),
    )

    space_id: Mapped[uuid.UUID] = mapped_column(
        Uuid, ForeignKey("financial_spaces.id", ondelete="CASCADE"), nullable=False, index=True
    )
    period_id: Mapped[uuid.UUID] = mapped_column(Uuid, nullable=False, index=True)
    category_id: Mapped[uuid.UUID] = mapped_column(Uuid, nullable=False)
    kind: Mapped[str] = mapped_column(String(8), nullable=False)
    amount_kopecks: Mapped[int] = mapped_column(BigInteger, nullable=False)
    note: Mapped[str | None] = mapped_column(String(500), nullable=True)
    created_by_user_id: Mapped[uuid.UUID | None] = mapped_column(
        Uuid, ForeignKey("users.id", ondelete="SET NULL"), nullable=True
    )


class PeriodClosure(Base, PkMixin, TimestampMixin):
    """Immutable-at-rest snapshot written when a period closes."""

    __tablename__ = "period_closures"
    __table_args__ = (
        ForeignKeyConstraint(
            ["space_id", "period_id"],
            ["budget_periods.space_id", "budget_periods.id"],
            ondelete="CASCADE",
            name="fk_period_closures_period_tenant",
        ),
        UniqueConstraint("space_id", "id", name="uq_period_closures_space_id"),
    )

    space_id: Mapped[uuid.UUID] = mapped_column(
        Uuid, ForeignKey("financial_spaces.id", ondelete="CASCADE"), nullable=False, index=True
    )
    period_id: Mapped[uuid.UUID] = mapped_column(Uuid, nullable=False)
    snapshot: Mapped[dict[str, Any]] = mapped_column(JSON, nullable=False)
    closed_at: Mapped[datetime] = mapped_column(UTCDateTime(), nullable=False)
    closed_by_user_id: Mapped[uuid.UUID | None] = mapped_column(
        Uuid, ForeignKey("users.id", ondelete="SET NULL"), nullable=True
    )