// Backfills products.productimages for everything imported before the column
// existed.
//
// The import used to keep `Images[0]` and discard the rest, so roughly six
// thousand products carry one photo where the global catalogue has up to ten.
// Re-importing would work but rewrites price, category and stock links; this
// only fills the gallery.
//
// The images are re-listed rather than reconstructed. Filenames are
// `image_000.jpeg`, `image_001.jpg` … — the extension varies within a single
// product, so the sibling URLs cannot be derived from the first one. The
// `image_id` is taken out of the stored URL and the same S3 listing the API
// uses is asked for the rest, which is why this boots the app's own
// connections instead of talking to Postgres alone.
//
// Dry by default; pass --apply to write.
//
//	go run ./scratch/productimages            # report only
//	go run ./scratch/productimages --apply    # write
//	go run ./scratch/productimages --apply --tenant 1087
package main

import (
	"encoding/json"
	"flag"
	"fmt"
	"log"
	"strings"

	"nearle/db"

	"github.com/joho/godotenv"
)

type row struct {
	Productid    int
	Tenantid     int
	Productbrand string
	Productimage string
}

func main() {
	apply := flag.Bool("apply", false, "write the changes; otherwise report only")
	tenant := flag.Int("tenant", 0, "restrict to one tenant")
	flag.Parse()

	_ = godotenv.Load()
	db.Connect()

	if db.ImageStore == nil {
		log.Fatal("the image store is not configured (USE_S3 / S3_*), so there is nothing to list images from")
	}

	q := `
		SELECT productid, tenantid,
		       COALESCE(productbrand,'') AS productbrand,
		       COALESCE(productimage,'') AS productimage
		FROM products
		WHERE COALESCE(productimage,'') <> ''
		  AND COALESCE(productimages::text,'') IN ('', 'null', '[]')`
	args := []interface{}{}
	if *tenant > 0 {
		q += ` AND tenantid = ?`
		args = append(args, *tenant)
	}
	q += ` ORDER BY productid`

	var rows []row
	if err := db.DB.Raw(q, args...).Scan(&rows).Error; err != nil {
		log.Fatal(err)
	}

	fmt.Printf("candidates: %d\n\n", len(rows))

	var filled, single, unparsed, nolist int
	for _, r := range rows {
		brand, imageID := parseImageRef(r.Productimage)
		if brand == "" || imageID == "" {
			unparsed++
			continue
		}
		// The stored brand is authoritative where it exists; the URL is only a
		// fallback, because a product renamed in the back office keeps its
		// original image path.
		if b := strings.ToLower(strings.TrimSpace(r.Productbrand)); b != "" {
			brand = b
		}

		images := db.GetImages(brand, imageID)
		if len(images) == 0 {
			nolist++
			continue
		}
		if len(images) == 1 {
			// Nothing gained — leave the column null rather than writing a
			// one-element array that says the same as productimage.
			single++
			continue
		}

		encoded, err := json.Marshal(images)
		if err != nil {
			log.Printf("product %d: encoding failed: %v", r.Productid, err)
			continue
		}

		if *apply {
			if err := db.DB.Exec(
				`UPDATE products SET productimages = ?::jsonb, updated = NOW() WHERE productid = ?`,
				string(encoded), r.Productid).Error; err != nil {
				log.Printf("product %d: update failed: %v", r.Productid, err)
				continue
			}
		}
		filled++
		if filled <= 10 {
			fmt.Printf("  product %-7d %-10s %-34s %d images\n", r.Productid, brand, imageID, len(images))
		}
	}

	fmt.Printf(`
would fill (>1 image) : %d
only one image        : %d
image_id unparseable  : %d
nothing listed in S3  : %d
`, filled, single, unparsed, nolist)

	if !*apply {
		fmt.Println("\ndry run — nothing written. Re-run with --apply.")
	}
}

// parseImageRef pulls the brand and image_id out of a stored image URL.
//
//	https://…/daily/brands/nestle/nestle_maggi_615a9fa9/image_000.jpeg
//	                        ^brand  ^image_id
//
// Returns empty strings for anything that does not match, so a hand-uploaded
// image URL is skipped rather than guessed at.
func parseImageRef(url string) (brand, imageID string) {
	const marker = "/daily/brands/"
	i := strings.Index(url, marker)
	if i < 0 {
		return "", ""
	}
	parts := strings.Split(strings.Trim(url[i+len(marker):], "/"), "/")
	if len(parts) < 3 {
		return "", ""
	}
	return strings.ToLower(parts[0]), parts[1]
}