package queries

import (
	"bssapp-backend/db"
	"context"
	"database/sql"
	"fmt"
	"strings"
)

// GetProductPricingFilterOptions returns distinct option values for ProductPricing filters.
// This is used to render filter dropdowns without loading the full dataset.
func GetProductPricingFilterOptions(ctx context.Context, field string, q string, limit int, scopeUrunIlkGrubu []string) ([]string, error) {
	mssql := db.MssqlDB
	if mssql == nil {
		return nil, fmt.Errorf("mssql db is nil")
	}
	field = strings.TrimSpace(field)
	q = strings.TrimSpace(q)
	if limit <= 0 || limit > 200 {
		limit = 120
	}
	if len(scopeUrunIlkGrubu) > 3 {
		scopeUrunIlkGrubu = scopeUrunIlkGrubu[:3]
	}

	// Map UI filter fields -> MSSQL expression in ProductFilterWithDescription('TR')
	var expr string
	switch field {
	case "productCode":
		expr = "LTRIM(RTRIM(ProductCode))"
	case "brandGroupSelection":
		expr = `CASE ABS(CHECKSUM(LTRIM(RTRIM(ProductCode)))) % 3 
			WHEN 0 THEN 'MARKA GRUBU A' 
			WHEN 1 THEN 'MARKA GRUBU B' 
			ELSE 'MARKA GRUBU C' 
		END`
	case "marka":
		expr = "COALESCE(LTRIM(RTRIM(ProductAtt10Desc)), '')"
	case "askiliYan":
		expr = "COALESCE(LTRIM(RTRIM(ProductAtt45Desc)), '')"
	case "kategori":
		expr = "COALESCE(LTRIM(RTRIM(ProductAtt44Desc)), '')"
	case "urunIlkGrubu":
		expr = "COALESCE(LTRIM(RTRIM(ProductAtt42Desc)), '')"
	case "urunAnaGrubu":
		expr = "COALESCE(LTRIM(RTRIM(ProductAtt01Desc)), '')"
	case "urunAltGrubu":
		expr = "COALESCE(LTRIM(RTRIM(ProductAtt02Desc)), '')"
	case "icerik":
		expr = "COALESCE(LTRIM(RTRIM(ProductAtt41Desc)), '')"
	case "karisim":
		expr = "COALESCE(LTRIM(RTRIM(ProductAtt29Desc)), '')"
	default:
		return nil, fmt.Errorf("invalid field")
	}

	// NOTE: We keep the same base constraints as the listing query.
	// q: prefix match to keep it sargable-ish.
	args := make([]any, 0, 8)
	where := []string{
		"ProductAtt42 IN ('SERI', 'AKSESUAR')",
		"IsBlocked = 0",
		"LEN(LTRIM(RTRIM(ProductCode))) = 13",
	}
	if len(scopeUrunIlkGrubu) > 0 && field != "urunIlkGrubu" {
		// Cascade scope: allow limiting options by the already selected "Urun Ilk Grubu" (desc).
		// We filter by desc value because UI uses desc fields.
		placeholders := make([]string, 0, len(scopeUrunIlkGrubu))
		for _, v := range scopeUrunIlkGrubu {
			v = strings.TrimSpace(v)
			if v == "" {
				continue
			}
			placeholders = append(placeholders, fmt.Sprintf("@p%d", len(args)+1))
			args = append(args, v)
		}
		if len(placeholders) > 0 {
			where = append(where, fmt.Sprintf("COALESCE(LTRIM(RTRIM(ProductAtt42Desc)), '') IN (%s)", strings.Join(placeholders, ", ")))
		}
	}
	if q != "" {
		// For productCode, allow contains if user types middle; for others use prefix.
		if field == "productCode" {
			where = append(where, expr+fmt.Sprintf(" LIKE @p%d", len(args)+1))
			args = append(args, "%"+q+"%")
		} else {
			where = append(where, expr+fmt.Sprintf(" LIKE @p%d", len(args)+1))
			args = append(args, q+"%")
		}
	}
	whereSQL := strings.Join(where, " AND ")

	sqlText := fmt.Sprintf(`
SELECT TOP (%d)
  X.val
FROM (
  SELECT DISTINCT NULLIF(%s, '') AS val
  FROM ProductFilterWithDescription('TR')
  WHERE %s
) X
WHERE X.val IS NOT NULL
ORDER BY X.val ASC;
`, limit, expr, whereSQL)

	rows, err := mssql.QueryContext(ctx, sqlText, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	out := make([]string, 0, limit)
	for rows.Next() {
		var v sql.NullString
		if err := rows.Scan(&v); err != nil {
			return nil, err
		}
		if s := strings.TrimSpace(v.String); s != "" {
			out = append(out, s)
		}
	}
	return out, rows.Err()
}