"""Essential model — actionable items under a Proposal.

Each Essential represents one deliverable scope item (feature, improvement,
or refactor).  When a Proposal is accepted, every Essential is converted into
a corresponding ``story/*`` task under the chosen Milestone.

See: NEXT_WAVE_DEV_DIRECTION.md §8.5
"""

from sqlalchemy import Column, Integer, String, Text, DateTime, ForeignKey, Enum
from sqlalchemy.sql import func
from app.core.config import Base
import enum


class EssentialType(str, enum.Enum):
    FEATURE = "feature"
    IMPROVEMENT = "improvement"
    REFACTOR = "refactor"


class Essential(Base):
    __tablename__ = "essentials"

    id = Column(Integer, primary_key=True, index=True)

    essential_code = Column(
        String(64),
        nullable=False,
        unique=True,
        index=True,
        comment="Unique human-readable code, e.g. PROJ:E00001",
    )

    proposal_id = Column(
        Integer,
        ForeignKey("proposes.id"),  # FK targets the actual DB table name
        nullable=False,
        comment="Owning Proposal",
    )

    type = Column(
        Enum(EssentialType, values_callable=lambda x: [e.value for e in x]),
        nullable=False,
        comment="Essential type: feature | improvement | refactor",
    )

    title = Column(String(255), nullable=False, comment="Short title")
    description = Column(Text, nullable=True, comment="Detailed description")

    created_by_id = Column(
        Integer,
        ForeignKey("users.id"),
        nullable=True,
        comment="Author of the essential",
    )

    created_at = Column(DateTime(timezone=True), server_default=func.now())
    updated_at = Column(DateTime(timezone=True), onupdate=func.now())