package main

import (
	"context"
	"log"
	"time"

	"git.k6n.net/mats/go-redis-inventory/pkg/inventory"
	contract "git.k6n.net/mats/platform/order"
	"git.k6n.net/mats/platform/rabbit"
	"github.com/redis/go-redis/v9"
)

// commitOrder applies an order.created event to inventory. The sale already
// happened, so this is an unconditional permanent decrement (it may drive stock
// negative — visible oversell, reconciled downstream as backorder), NOT a
// check-and-reserve that could refuse. It then releases the cart's TTL hold and
// emits the resulting level crossing. Idempotent per order via a Redis marker,
// since the bus is at-least-once.
func commitOrder(ctx context.Context, rdb *redis.Client, svc *inventory.RedisInventoryService, resv *inventory.RedisCartReservationService, conn *rabbit.Conn, country string, low int64, c contract.Created) {
	if c.OrderID == "" {
		return
	}
	// Idempotency: first writer wins; redelivery is a no-op.
	fresh, err := rdb.SetNX(ctx, "invcommit:"+c.OrderID, "1", 30*24*time.Hour).Result()
	if err != nil {
		log.Printf("inventory: commit idempotency order=%s: %v", c.OrderID, err)
		return
	}
	if !fresh {
		return // already committed
	}
	// Default location for lines that don't carry their own: the order country
	// (central stock), falling back to the service's configured country.
	defaultLoc := c.Country
	if defaultLoc == "" {
		defaultLoc = country
	}
	for _, line := range c.Lines {
		if line.SKU == "" || line.Quantity <= 0 {
			continue
		}
		// Drop-ship items are fulfilled by the supplier — never decrement
		// local stock for them.
		if line.DropShip {
			continue
		}
		loc := inventory.LocationID(defaultLoc)
		if line.Location != "" {
			loc = inventory.LocationID(line.Location)
		}
		sku := inventory.SKU(line.SKU)
		pipe := rdb.Pipeline()
		if err := svc.DecrementInventory(ctx, pipe, sku, loc, int64(line.Quantity)); err != nil {
			log.Printf("inventory: commit decrement sku=%s order=%s: %v", sku, c.OrderID, err)
			continue
		}
		if _, err := pipe.Exec(ctx); err != nil {
			log.Printf("inventory: commit exec sku=%s order=%s: %v", sku, c.OrderID, err)
			continue
		}
		// Release the cart's TTL hold now the sale is committed (best-effort —
		// it would expire on its own anyway).
		if c.CartID != "" && resv != nil {
			if err := resv.ReleaseForCart(ctx, sku, loc, inventory.CartID(c.CartID)); err != nil {
				log.Printf("inventory: commit release sku=%s cart=%s: %v", sku, c.CartID, err)
			}
		}
		// Emit the level crossing from the new on-hand.
		if newQty, err := svc.GetInventory(ctx, sku, loc); err == nil {
			emitLevelIfChanged(ctx, rdb, conn, country, low, string(sku), string(loc), newQty)
		}
	}
}