package catalog

import (
	"context"
	"fmt"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
)

const maxResetProductIDs = 5000

// ResetProductsToUnprocessed resets selected products so they reappear as unprocessed raw items.
// kind "raw" updates raw_products by id; kind "processed" (default) deletes processed rows and
// resets linked raw rows (by raw_product_id and shared product_id/gtin), matching legacy behavior.
func (s *Service) ResetProductsToUnprocessed(ctx context.Context, companyID uuid.UUID, productIDs []uuid.UUID, kind string) (map[string]any, error) {
	if len(productIDs) == 0 {
		return nil, ClientMsg("product_ids is required")
	}
	if len(productIDs) > maxResetProductIDs {
		return nil, ClientMsg(fmt.Sprintf("at most %d product_ids allowed", maxResetProductIDs))
	}

	tx, err := s.Pool.Begin(ctx)
	if err != nil {
		return nil, err
	}
	defer tx.Rollback(ctx)

	var resetCount int64
	switch kind {
	case "raw":
		resetCount, err = resetRawProducts(ctx, tx, companyID, productIDs)
	default:
		resetCount, err = resetProcessedProducts(ctx, tx, companyID, productIDs)
	}
	if err != nil {
		return nil, err
	}
	if err := tx.Commit(ctx); err != nil {
		return nil, err
	}
	return map[string]any{
		"success":      true,
		"reset_count":  resetCount,
		"message":      fmt.Sprintf("%d product(s) returned to unprocessed state", resetCount),
	}, nil
}

func resetRawProducts(ctx context.Context, tx pgx.Tx, companyID uuid.UUID, ids []uuid.UUID) (int64, error) {
	ct, err := tx.Exec(ctx, `
		UPDATE raw_products
		SET is_processed = false,
			processing_status = 'unprocessed',
			updated_at = now()
		WHERE company_id = $1 AND id = ANY($2::uuid[])`, companyID, ids)
	if err != nil {
		return 0, err
	}
	_, err = tx.Exec(ctx, `
		DELETE FROM processed_products
		WHERE company_id = $1 AND raw_product_id = ANY($2::uuid[])`, companyID, ids)
	if err != nil {
		return 0, err
	}
	return ct.RowsAffected(), nil
}

func resetProcessedProducts(ctx context.Context, tx pgx.Tx, companyID uuid.UUID, ids []uuid.UUID) (int64, error) {
	rows, err := tx.Query(ctx, `
		SELECT id, raw_product_id, product_id
		FROM processed_products
		WHERE company_id = $1 AND id = ANY($2::uuid[])`, companyID, ids)
	if err != nil {
		return 0, err
	}
	defer rows.Close()

	processedIDs := make([]uuid.UUID, 0, len(ids))
	rawIDs := make([]uuid.UUID, 0)
	gtins := make([]string, 0)
	seenGTIN := map[string]struct{}{}
	for rows.Next() {
		var id uuid.UUID
		var rawID *uuid.UUID
		var productID *string
		if err := rows.Scan(&id, &rawID, &productID); err != nil {
			return 0, err
		}
		processedIDs = append(processedIDs, id)
		if rawID != nil {
			rawIDs = append(rawIDs, *rawID)
		}
		if productID != nil {
			g := *productID
			if g != "" {
				if _, ok := seenGTIN[g]; !ok {
					seenGTIN[g] = struct{}{}
					gtins = append(gtins, g)
				}
			}
		}
	}
	if err := rows.Err(); err != nil {
		return 0, err
	}
	if len(processedIDs) == 0 {
		return 0, ClientMsg("no products found to return to unprocessed state")
	}

	if len(gtins) > 0 {
		_, err = tx.Exec(ctx, `
			UPDATE raw_products
			SET is_processed = false,
				processing_status = 'unprocessed',
				updated_at = now()
			WHERE company_id = $1 AND gtin = ANY($2::text[])`, companyID, gtins)
		if err != nil {
			return 0, err
		}
	}
	if len(rawIDs) > 0 {
		_, err = tx.Exec(ctx, `
			UPDATE raw_products
			SET is_processed = false,
				processing_status = 'unprocessed',
				updated_at = now()
			WHERE company_id = $1 AND id = ANY($2::uuid[])`, companyID, rawIDs)
		if err != nil {
			return 0, err
		}
	}

	ct, err := tx.Exec(ctx, `
		DELETE FROM processed_products
		WHERE company_id = $1 AND id = ANY($2::uuid[])`, companyID, processedIDs)
	if err != nil {
		return 0, err
	}
	return ct.RowsAffected(), nil
}