"""Internal ticket model.

Fallback ticket table for L1 intake when the account has no PSA integration.
Tracks the customer-facing problem, resolution lifecycle, and optional links
to a flow, flow proposal, AI session, and assigned engineer.
"""
import uuid
from datetime import datetime, timezone
from typing import Optional, TYPE_CHECKING

from sqlalchemy import String, Text, DateTime, ForeignKey, CheckConstraint
from sqlalchemy import text as sa_text
from sqlalchemy.orm import Mapped, mapped_column, relationship
from sqlalchemy.dialects.postgresql import UUID

from app.core.database import Base

if TYPE_CHECKING:
    from app.models.account import Account
    from app.models.user import User
    from app.models.tree import Tree
    from app.models.flow_proposal import FlowProposal
    from app.models.ai_session import AISession


class InternalTicket(Base):
    """A fallback support ticket for accounts without a PSA integration.

    status lifecycle:
    - open: Submitted, not yet picked up.
    - walking: L1 technician is actively walking the flow.
    - resolved: Issue resolved; resolution_notes captured.
    - escalated: Could not resolve; requires higher-tier intervention.
    """
    __tablename__ = "internal_tickets"
    __table_args__ = (
        CheckConstraint(
            "status IN ('open', 'walking', 'resolved', 'escalated')",
            name="ck_internal_tickets_status",
        ),
    )

    id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
    )
    account_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("accounts.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )
    created_by_user_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("users.id", ondelete="RESTRICT"),
        nullable=False,
    )

    # ── Customer info ──
    customer_name: Mapped[Optional[str]] = mapped_column(String(120), nullable=True)
    customer_contact: Mapped[Optional[str]] = mapped_column(String(200), nullable=True)
    problem_statement: Mapped[str] = mapped_column(Text(), nullable=False)

    # ── Lifecycle ──
    status: Mapped[str] = mapped_column(
        String(30), nullable=False, server_default=sa_text("'open'"), index=True,
    )

    # ── Optional links ──
    flow_id: Mapped[Optional[uuid.UUID]] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("trees.id", ondelete="SET NULL"),
        nullable=True,
    )
    flow_proposal_id: Mapped[Optional[uuid.UUID]] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("flow_proposals.id", ondelete="SET NULL"),
        nullable=True,
    )
    ai_session_id: Mapped[Optional[uuid.UUID]] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("ai_sessions.id", ondelete="SET NULL"),
        nullable=True,
    )
    assigned_user_id: Mapped[Optional[uuid.UUID]] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("users.id", ondelete="SET NULL"),
        nullable=True,
        index=True,
    )

    # ── Resolution ──
    resolution_notes: Mapped[Optional[str]] = mapped_column(Text(), nullable=True)
    psa_promoted_ticket_id: Mapped[Optional[str]] = mapped_column(
        String(64), nullable=True,
        comment="External PSA ticket ID when this ticket is promoted to a PSA system",
    )

    # ── Timestamps ──
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), default=lambda: datetime.now(timezone.utc)
    )
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        default=lambda: datetime.now(timezone.utc),
        onupdate=lambda: datetime.now(timezone.utc),
    )
    resolved_at: Mapped[Optional[datetime]] = mapped_column(
        DateTime(timezone=True), nullable=True,
    )

    # ── Relationships ──
    account: Mapped["Account"] = relationship("Account")
    created_by: Mapped["User"] = relationship("User", foreign_keys=[created_by_user_id])
    assigned_user: Mapped[Optional["User"]] = relationship("User", foreign_keys=[assigned_user_id])
    flow: Mapped[Optional["Tree"]] = relationship("Tree")
    flow_proposal: Mapped[Optional["FlowProposal"]] = relationship("FlowProposal")
    ai_session: Mapped[Optional["AISession"]] = relationship("AISession")