package main

import (
	"context"
	"log"
	"sync"

	"git.k6n.net/mats/go-redis-inventory/pkg/inventory"
	"git.k6n.net/mats/platform/rabbit"
	"git.k6n.net/mats/slask-finder/pkg/types"
	"github.com/redis/go-redis/v9"
)

type StockHandler struct {
	rdb                 *redis.Client
	ctx                 context.Context
	svc                 inventory.RedisInventoryService
	MainStockLocationID inventory.LocationID

	// Bus producer config. conn is nil when RABBIT_HOST is unset (no bus); the
	// handler still updates Redis and just skips emitting.
	conn    *rabbit.Conn
	country string
	low     int64
}

func (s *StockHandler) HandleItem(item types.Item, wg *sync.WaitGroup) {
	wg.Go(func() {
		ctx := s.ctx
		centralStock, ok := item.GetNumberFieldValue("inStock")
		if !ok {
			centralStock = 0
		}
		sku, ok := item.GetStringFieldValue("sku")
		if !ok {
			log.Printf("unable to parse central stock for item: sku missing")
			return
		}
		// One linear pass: write the authoritative quantity, then derive and
		// emit the level crossing from the same value. No Redis pub/sub
		// round-trip — Redis stays the internal store, the bus carries levels.
		pipe := s.rdb.Pipeline()
		s.svc.UpdateInventory(ctx, pipe, inventory.SKU(sku), s.MainStockLocationID, int64(centralStock))
		if _, err := pipe.Exec(ctx); err != nil {
			log.Printf("unable to update stock: %v", err)
			return
		}
		emitLevelIfChanged(ctx, s.rdb, s.conn, s.country, s.low, sku, string(s.MainStockLocationID), int64(centralStock))
	})
}