package com.lincfusion.udyamlinc.master;

import jakarta.persistence.*;
import lombok.*;

/**
 * What a district actually trades — the basket ingestion pulls for it.
 *
 * <p>Without this table ingestion is a cross product: every active district
 * against every active commodity. That is affordable at four cereals and four
 * districts and stops being affordable the moment fruit and vegetables are
 * tracked across six states, because most of the pairs it generates cannot
 * exist. Kolar has no soyabean arrivals, Kamrup no grapes, Nashik no chana.
 *
 * <p>The cost is not really the wasted calls, it is what they do to the
 * freshness screen. Agmarknet answers a filter that matches nothing with
 * HTTP 200 and an empty record list, so a structurally impossible pair and a
 * genuinely broken filter produce byte-identical responses. Under a cross
 * product the majority of pairs return empty on a healthy night, and a
 * commodity whose {@code sourceCode} is misspelt disappears into that crowd.
 * Pulling only what a district trades makes an empty result mean something
 * again: either arrivals genuinely stopped, or something is wrong.
 *
 * <p>Zone is deliberately not the grain. Kolar and Belagavi are both SOUTH and
 * trade almost disjoint baskets — tomato and mango against onion and maize.
 */
@Entity
@Table(name = "district_commodity", indexes = {
        @Index(name = "ix_dc_district", columnList = "districtId"),
        @Index(name = "ix_dc_pair", columnList = "districtId,commodityId", unique = true),
})
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@Builder
public class DistrictCommodity {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(nullable = false)
    private Long districtId;

    @Column(nullable = false)
    private Long commodityId;

    /**
     * True where this district is a reference market for the commodity — Nashik
     * for onion, Kolar for tomato. Not used to decide what to pull; it marks the
     * rows whose absence is worth a louder complaint, because a national onion
     * signal that has lost Nashik has lost the market that sets the price.
     */
    private Boolean benchmark;

    private Boolean active;

    @PrePersist
    void onCreate() {
        if (active == null) active = Boolean.TRUE;
        if (benchmark == null) benchmark = Boolean.FALSE;
    }
}