"""Bewegungsdaten: Recurrences, Preishistorie, Occurrences, Buchungen, Budgets, Ziele."""

from datetime import date
from decimal import Decimal

from sqlalchemy import (
    Boolean,
    CheckConstraint,
    Date,
    ForeignKey,
    Index,
    Integer,
    String,
    Text,
    UniqueConstraint,
)
from sqlalchemy.dialects.postgresql import ARRAY
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.db.base import Base, CreatedAtMixin, Money, TimestampMixin
from app.models.core import Account, Category, Merchant
from app.models.enums import BusinessDayShift, EntryKind, OccurrenceStatus, pg_enum


class Recurrence(Base, TimestampMixin):
    """Wiederkehrende Zahlung oder Einkunft, beschrieben durch eine RFC-5545-RRULE."""

    __tablename__ = "recurrence"

    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    kind: Mapped[EntryKind] = mapped_column(pg_enum(EntryKind, "entry_kind"), nullable=False)
    title: Mapped[str] = mapped_column(String(160), nullable=False)
    merchant_id: Mapped[int | None] = mapped_column(
        ForeignKey("merchant.id", ondelete="SET NULL"), nullable=True
    )
    category_id: Mapped[int] = mapped_column(
        ForeignKey("category.id", ondelete="RESTRICT"), nullable=False
    )
    account_id: Mapped[int] = mapped_column(
        ForeignKey("account.id", ondelete="RESTRICT"), nullable=False
    )

    amount: Mapped[Decimal] = mapped_column(Money, nullable=False)
    is_variable: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
    currency: Mapped[str] = mapped_column(String(3), nullable=False, default="EUR")

    # RRULE ohne DTSTART – der Startzeitpunkt steht separat in `dtstart`.
    rrule: Mapped[str] = mapped_column(Text, nullable=False)
    dtstart: Mapped[date] = mapped_column(Date, nullable=False)
    until: Mapped[date | None] = mapped_column(Date, nullable=True)

    business_day_shift: Mapped[BusinessDayShift] = mapped_column(
        pg_enum(BusinessDayShift, "business_day_shift"),
        nullable=False,
        default=BusinessDayShift.NEXT,
        server_default="next",
    )
    holiday_region: Mapped[str] = mapped_column(
        String(8), nullable=False, default="DE-NW", server_default="DE-NW"
    )

    # Ratenzahlung / Kredit
    installments_total: Mapped[int | None] = mapped_column(Integer, nullable=True)
    principal_amount: Mapped[Decimal | None] = mapped_column(Money, nullable=True)

    # Vertragsdaten
    contract_start: Mapped[date | None] = mapped_column(Date, nullable=True)
    contract_min_term_months: Mapped[int | None] = mapped_column(Integer, nullable=True)
    contract_notice_period_days: Mapped[int | None] = mapped_column(Integer, nullable=True)
    contract_auto_renew_months: Mapped[int | None] = mapped_column(Integer, nullable=True)
    contract_cancelled_at: Mapped[date | None] = mapped_column(Date, nullable=True)

    reserve_enabled: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
    notes: Mapped[str | None] = mapped_column(Text, nullable=True)
    tags: Mapped[list[str]] = mapped_column(
        ARRAY(Text), nullable=False, default=list, server_default="{}"
    )
    is_active: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True)

    merchant: Mapped[Merchant | None] = relationship(lazy="selectin")
    category: Mapped[Category] = relationship(lazy="selectin")
    account: Mapped[Account] = relationship(lazy="selectin")
    amount_versions: Mapped[list["AmountVersion"]] = relationship(
        back_populates="recurrence",
        cascade="all, delete-orphan",
        order_by="AmountVersion.valid_from",
        lazy="selectin",
    )
    occurrences: Mapped[list["Occurrence"]] = relationship(
        back_populates="recurrence",
        cascade="all, delete-orphan",
        order_by="Occurrence.occurrence_date",
    )

    __table_args__ = (
        CheckConstraint(
            "installments_total IS NULL OR installments_total > 0", name="installments"
        ),
        Index("ix_recurrence_kind_active", "kind", "is_active"),
        Index("ix_recurrence_category_id", "category_id"),
        Index("ix_recurrence_merchant_id", "merchant_id"),
    )


class AmountVersion(Base, CreatedAtMixin):
    """Preishistorie: gültig ist die Version mit dem größten `valid_from <= Fälligkeitsdatum`."""

    __tablename__ = "amount_version"

    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    recurrence_id: Mapped[int] = mapped_column(
        ForeignKey("recurrence.id", ondelete="CASCADE"), nullable=False
    )
    amount: Mapped[Decimal] = mapped_column(Money, nullable=False)
    valid_from: Mapped[date] = mapped_column(Date, nullable=False)
    note: Mapped[str | None] = mapped_column(Text, nullable=True)

    recurrence: Mapped[Recurrence] = relationship(back_populates="amount_versions")

    __table_args__ = (
        UniqueConstraint("recurrence_id", "valid_from", name="uq_amount_version_recurrence_id"),
    )


class Occurrence(Base, TimestampMixin):
    """Materialisierte Einzelfälligkeit – nur bei Abweichung, Bestätigung oder Auslassung."""

    __tablename__ = "occurrence"

    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    recurrence_id: Mapped[int] = mapped_column(
        ForeignKey("recurrence.id", ondelete="CASCADE"), nullable=False
    )
    # Immer das nominale (unverschobene) Datum – dadurch bleibt die Zuordnung stabil.
    occurrence_date: Mapped[date] = mapped_column(Date, nullable=False)
    status: Mapped[OccurrenceStatus] = mapped_column(
        pg_enum(OccurrenceStatus, "occurrence_status"),
        nullable=False,
        default=OccurrenceStatus.PLANNED,
    )
    planned_amount: Mapped[Decimal] = mapped_column(Money, nullable=False)
    actual_amount: Mapped[Decimal | None] = mapped_column(Money, nullable=True)
    actual_date: Mapped[date | None] = mapped_column(Date, nullable=True)
    account_id: Mapped[int | None] = mapped_column(
        ForeignKey("account.id", ondelete="RESTRICT"), nullable=True
    )
    note: Mapped[str | None] = mapped_column(Text, nullable=True)

    recurrence: Mapped[Recurrence] = relationship(back_populates="occurrences")

    __table_args__ = (
        UniqueConstraint("recurrence_id", "occurrence_date", name="uq_occurrence_recurrence_id"),
        Index("ix_occurrence_date", "occurrence_date"),
    )


class Transaction(Base, CreatedAtMixin):
    """Einmalige Buchung ohne Wiederholung."""

    __tablename__ = "transaction"

    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    kind: Mapped[EntryKind] = mapped_column(pg_enum(EntryKind, "entry_kind"), nullable=False)
    title: Mapped[str] = mapped_column(String(160), nullable=False)
    merchant_id: Mapped[int | None] = mapped_column(
        ForeignKey("merchant.id", ondelete="SET NULL"), nullable=True
    )
    category_id: Mapped[int] = mapped_column(
        ForeignKey("category.id", ondelete="RESTRICT"), nullable=False
    )
    account_id: Mapped[int] = mapped_column(
        ForeignKey("account.id", ondelete="RESTRICT"), nullable=False
    )
    amount: Mapped[Decimal] = mapped_column(Money, nullable=False)
    booking_date: Mapped[date] = mapped_column(Date, nullable=False)
    note: Mapped[str | None] = mapped_column(Text, nullable=True)
    tags: Mapped[list[str]] = mapped_column(
        ARRAY(Text), nullable=False, default=list, server_default="{}"
    )

    merchant: Mapped[Merchant | None] = relationship(lazy="selectin")
    category: Mapped[Category] = relationship(lazy="selectin")
    account: Mapped[Account] = relationship(lazy="selectin")

    __table_args__ = (
        Index("ix_transaction_booking_date", "booking_date"),
        Index("ix_transaction_category_id", "category_id"),
    )


class Budget(Base, CreatedAtMixin):
    """Monatsbudget je Kategorie. `period_month` ist immer der Monatserste."""

    __tablename__ = "budget"

    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    category_id: Mapped[int] = mapped_column(
        ForeignKey("category.id", ondelete="CASCADE"), nullable=False
    )
    period_month: Mapped[date] = mapped_column(Date, nullable=False)
    limit_amount: Mapped[Decimal] = mapped_column(Money, nullable=False)
    rollover: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)

    category: Mapped[Category] = relationship(lazy="selectin")

    __table_args__ = (
        UniqueConstraint("category_id", "period_month", name="uq_budget_category_id"),
        CheckConstraint("date_trunc('month', period_month) = period_month", name="month_start"),
    )


class BudgetTemplate(Base, TimestampMixin):
    """Dauerhaftes Budget ab einem Monat – erspart die Pflege jedes einzelnen Monats."""

    __tablename__ = "budget_template"

    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    category_id: Mapped[int] = mapped_column(
        ForeignKey("category.id", ondelete="CASCADE"), nullable=False
    )
    valid_from: Mapped[date] = mapped_column(Date, nullable=False)
    valid_until: Mapped[date | None] = mapped_column(Date, nullable=True)
    limit_amount: Mapped[Decimal] = mapped_column(Money, nullable=False)
    rollover: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)

    category: Mapped[Category] = relationship(lazy="selectin")

    __table_args__ = (
        UniqueConstraint("category_id", "valid_from", name="uq_budget_template_category_id"),
        CheckConstraint("date_trunc('month', valid_from) = valid_from", name="month_start"),
    )


class SavingsGoal(Base, TimestampMixin):
    """Sparziel mit Fortschritt und optionaler Zielrate."""

    __tablename__ = "savings_goal"

    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    name: Mapped[str] = mapped_column(String(160), nullable=False)
    target_amount: Mapped[Decimal] = mapped_column(Money, nullable=False)
    target_date: Mapped[date | None] = mapped_column(Date, nullable=True)
    current_amount: Mapped[Decimal] = mapped_column(Money, nullable=False, default=Decimal("0.00"))
    account_id: Mapped[int | None] = mapped_column(
        ForeignKey("account.id", ondelete="SET NULL"), nullable=True
    )
    monthly_contribution: Mapped[Decimal | None] = mapped_column(Money, nullable=True)
    color: Mapped[str] = mapped_column(String(9), nullable=False, default="#10b981")
    icon: Mapped[str] = mapped_column(String(64), nullable=False, default="piggy-bank")
    is_archived: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)

    __table_args__ = (UniqueConstraint("name", name="uq_savings_goal_name"),)


class ReserveLedger(Base, CreatedAtMixin):
    """Monatliche Rücklagenbildung für nicht-monatliche Posten."""

    __tablename__ = "reserve_ledger"

    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    recurrence_id: Mapped[int] = mapped_column(
        ForeignKey("recurrence.id", ondelete="CASCADE"), nullable=False
    )
    period_month: Mapped[date] = mapped_column(Date, nullable=False)
    amount: Mapped[Decimal] = mapped_column(Money, nullable=False)
    is_released: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)

    __table_args__ = (
        UniqueConstraint("recurrence_id", "period_month", name="uq_reserve_ledger_recurrence_id"),
        CheckConstraint("date_trunc('month', period_month) = period_month", name="month_start"),
    )