from datetime import datetime
from decimal import Decimal

from sqlalchemy import (
    Boolean,
    DateTime,
    ForeignKey,
    Index,
    Integer,
    Numeric,
    String,
    Text,
    UniqueConstraint,
)
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.models.base import Base, utcnow
from app.models.user import User


class NcrSequence(Base):
    """Per-year NCR number allocator. Incremented atomically inside the
    NCR-creation transaction (row lock held until commit) so concurrent
    submissions can never produce the same number."""

    __tablename__ = "ncr_sequences"

    year: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=False)
    last_seq: Mapped[int] = mapped_column(Integer, nullable=False, default=0)


class Ncr(Base):
    __tablename__ = "ncrs"
    __table_args__ = (
        UniqueConstraint("ncr_number", name="uq_ncrs_ncr_number"),
        Index("ix_ncrs_stage", "stage"),
        Index("ix_ncrs_job_number", "job_number"),
        Index("ix_ncrs_created_at", "created_at"),
    )

    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
    ncr_number: Mapped[str] = mapped_column(String(20))
    ncr_year: Mapped[int] = mapped_column(Integer)
    ncr_seq: Mapped[int] = mapped_column(Integer)

    # ── Request (stage 1) ────────────────────────────────────────────────────
    job_number: Mapped[str] = mapped_column(String(100))
    department_id: Mapped[int] = mapped_column(ForeignKey("departments.id"))
    deviation_category_id: Mapped[int] = mapped_column(ForeignKey("deviation_categories.id"))
    disposition_authority_id: Mapped[int] = mapped_column(ForeignKey("users.id"))
    deviation_detail: Mapped[str] = mapped_column(Text)
    requester_id: Mapped[int] = mapped_column(ForeignKey("users.id"))

    # ── Workflow state ───────────────────────────────────────────────────────
    stage: Mapped[str] = mapped_column(String(30))
    stage_entered_at: Mapped[datetime] = mapped_column(DateTime, default=utcnow)
    created_at: Mapped[datetime] = mapped_column(DateTime, default=utcnow)
    updated_at: Mapped[datetime] = mapped_column(DateTime, default=utcnow, onupdate=utcnow)

    # ── Disposition (initial + secondary) ────────────────────────────────────
    qc_authority: Mapped[str | None] = mapped_column(String(255), nullable=True)
    work_order: Mapped[str | None] = mapped_column(String(100), nullable=True)
    disposition_notes: Mapped[str | None] = mapped_column(Text, nullable=True)  # sanitized HTML
    secondary_review_needed: Mapped[bool | None] = mapped_column(Boolean, nullable=True)

    # ── Operations ───────────────────────────────────────────────────────────
    operations_complete: Mapped[bool] = mapped_column(Boolean, default=False)
    operations_completed_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
    operations_completed_by_id: Mapped[int | None] = mapped_column(
        ForeignKey("users.id"), nullable=True
    )

    # ── QC Inspection ────────────────────────────────────────────────────────
    qc_approval: Mapped[str | None] = mapped_column(String(10), nullable=True)  # yes | no
    inspection_notes: Mapped[str | None] = mapped_column(Text, nullable=True)
    qc_closed: Mapped[bool] = mapped_column(Boolean, default=False)
    qc_closed_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
    qc_closed_by_id: Mapped[int | None] = mapped_column(ForeignKey("users.id"), nullable=True)

    # ── Costing ──────────────────────────────────────────────────────────────
    labor_cost: Mapped[Decimal | None] = mapped_column(Numeric(12, 2), nullable=True)
    material_cost: Mapped[Decimal | None] = mapped_column(Numeric(12, 2), nullable=True)
    service_cost: Mapped[Decimal | None] = mapped_column(Numeric(12, 2), nullable=True)
    other_cost: Mapped[Decimal | None] = mapped_column(Numeric(12, 2), nullable=True)
    costing_completed_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
    costing_completed_by_id: Mapped[int | None] = mapped_column(
        ForeignKey("users.id"), nullable=True
    )

    # ── Closure ──────────────────────────────────────────────────────────────
    closed_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
    closed_by_id: Mapped[int | None] = mapped_column(ForeignKey("users.id"), nullable=True)

    # ── Relationships ────────────────────────────────────────────────────────
    department = relationship("Department", lazy="selectin")
    deviation_category = relationship("DeviationCategory", lazy="selectin")
    requester: Mapped[User] = relationship(foreign_keys=[requester_id], lazy="selectin")
    disposition_authority: Mapped[User] = relationship(
        foreign_keys=[disposition_authority_id], lazy="selectin"
    )
    operations_completed_by: Mapped[User | None] = relationship(
        foreign_keys=[operations_completed_by_id], lazy="selectin"
    )
    qc_closed_by: Mapped[User | None] = relationship(
        foreign_keys=[qc_closed_by_id], lazy="selectin"
    )
    costing_completed_by: Mapped[User | None] = relationship(
        foreign_keys=[costing_completed_by_id], lazy="selectin"
    )
    closed_by: Mapped[User | None] = relationship(foreign_keys=[closed_by_id], lazy="selectin")

    secondary_assignee_rows: Mapped[list["NcrSecondaryAssignee"]] = relationship(
        back_populates="ncr", cascade="all, delete-orphan", lazy="selectin"
    )
    transitions: Mapped[list["StageTransition"]] = relationship(
        back_populates="ncr",
        cascade="all, delete-orphan",
        lazy="selectin",
        order_by="StageTransition.acted_at",
    )
    attachments: Mapped[list["Attachment"]] = relationship(  # noqa: F821
        back_populates="ncr", cascade="all, delete-orphan", lazy="selectin"
    )
    job_info: Mapped["JobInfo | None"] = relationship(
        back_populates="ncr", cascade="all, delete-orphan", lazy="selectin", uselist=False
    )

    @property
    def secondary_authorities(self) -> list[User]:
        return [row.user for row in self.secondary_assignee_rows]

    @property
    def total_cost(self) -> Decimal | None:
        costs = [self.labor_cost, self.material_cost, self.service_cost, self.other_cost]
        present = [c for c in costs if c is not None]
        if not present:
            return None
        return sum(present, Decimal("0"))


class NcrSecondaryAssignee(Base):
    """Users selected as 'Notify These People' for secondary disposition."""

    __tablename__ = "ncr_secondary_assignees"

    ncr_id: Mapped[int] = mapped_column(
        ForeignKey("ncrs.id", ondelete="CASCADE"), primary_key=True
    )
    user_id: Mapped[int] = mapped_column(ForeignKey("users.id"), primary_key=True)

    ncr: Mapped[Ncr] = relationship(back_populates="secondary_assignee_rows")
    user: Mapped[User] = relationship(lazy="selectin")


class StageTransition(Base):
    """One row per lifecycle event (create, stage change, reopen) — the basis
    for aging and cycle-time reporting."""

    __tablename__ = "stage_transitions"
    __table_args__ = (Index("ix_stage_transitions_ncr", "ncr_id", "acted_at"),)

    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
    ncr_id: Mapped[int] = mapped_column(ForeignKey("ncrs.id", ondelete="CASCADE"))
    from_stage: Mapped[str | None] = mapped_column(String(30), nullable=True)
    to_stage: Mapped[str] = mapped_column(String(30))
    action: Mapped[str] = mapped_column(String(40))
    acted_by_id: Mapped[int] = mapped_column(ForeignKey("users.id"))
    acted_at: Mapped[datetime] = mapped_column(DateTime, default=utcnow)
    note: Mapped[str | None] = mapped_column(Text, nullable=True)  # e.g. reopen reason

    ncr: Mapped[Ncr] = relationship(back_populates="transitions")
    acted_by: Mapped[User] = relationship(lazy="selectin")


class JobInfo(Base):
    """Read-only enrichment for a job number, populated by a JobLookupService.

    Stays empty under NullJobLookupService; the future VisualJobLookupService
    will fill it from Infor VISUAL (WORK_ORDER + customer order linkage).
    """

    __tablename__ = "job_info"

    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
    ncr_id: Mapped[int] = mapped_column(
        ForeignKey("ncrs.id", ondelete="CASCADE"), unique=True
    )
    part_id: Mapped[str | None] = mapped_column(String(30), nullable=True)
    part_description: Mapped[str | None] = mapped_column(String(255), nullable=True)
    customer_name: Mapped[str | None] = mapped_column(String(100), nullable=True)
    work_order_status: Mapped[str | None] = mapped_column(String(20), nullable=True)
    source: Mapped[str] = mapped_column(String(20), default="null")
    fetched_at: Mapped[datetime] = mapped_column(DateTime, default=utcnow)

    ncr: Mapped[Ncr] = relationship(back_populates="job_info")