"""Category model. Self-referential (parent_id) for subcategories.

`field_schema` is admin-editable JSON describing category-specific listing
fields. Shape:
{
  "fields": [
    {"name":"condition","label":"Condition","type":"select",
     "required":true,"options":["new","like_new","good","fair"],"hot":true},
    {"name":"brand","label":"Brand","type":"text","required":false,"max":80},
    {"name":"salary_min","label":"Min salary","type":"number","required":false,"hot":true}
  ]
}
Supported types: text, number, select, bool. `hot:true` marks a field whose
value is denormalized onto an indexed Listing column for fast filtering.
"""
from datetime import datetime
from sqlalchemy import JSON
from app.extensions import db


class Category(db.Model):
    __tablename__ = "categories"

    id = db.Column(db.BigInteger().with_variant(db.Integer, "sqlite"),
                   primary_key=True, autoincrement=True)
    slug = db.Column(db.String(60), unique=True, nullable=False, index=True)
    name = db.Column(db.String(80), nullable=False)
    parent_id = db.Column(db.BigInteger().with_variant(db.Integer, "sqlite"),
                          db.ForeignKey("categories.id"), nullable=True, index=True)
    field_schema = db.Column(JSON, nullable=False, default=dict)
    icon = db.Column(db.String(40), nullable=True)
    sort_order = db.Column(db.Integer, nullable=False, default=0)
    sponsor_id = db.Column(db.BigInteger, nullable=True)  # FK wired in Phase 5
    is_active = db.Column(db.Boolean, nullable=False, default=True)

    created_at = db.Column(db.DateTime, default=datetime.utcnow, nullable=False)
    updated_at = db.Column(db.DateTime, default=datetime.utcnow,
                           onupdate=datetime.utcnow, nullable=False)

    children = db.relationship("Category", backref=db.backref("parent",
                               remote_side=[id]), lazy="selectin")
    listings = db.relationship("Listing", back_populates="category", lazy="dynamic")

    @property
    def is_subcategory(self):
        return self.parent_id is not None

    def fields(self):
        return (self.field_schema or {}).get("fields", [])

    def hot_fields(self):
        return [f for f in self.fields() if f.get("hot")]

    def __repr__(self):
        return f"<Category {self.slug}>"