package cuisine

import (
	"encoding/json"
	"log/slog"
	"net/http"

	"github.com/food-ai/backend/internal/infra/locale"
	"github.com/food-ai/backend/internal/infra/middleware"
	"github.com/jackc/pgx/v5/pgxpool"
)

type cuisineItem struct {
	Slug string `json:"slug"`
	Name string `json:"name"`
}

// NewListHandler returns an http.HandlerFunc for GET /cuisines.
// It queries the database directly, resolving translations via COALESCE.
func NewListHandler(pool *pgxpool.Pool) http.HandlerFunc {
	return func(responseWriter http.ResponseWriter, request *http.Request) {
		lang := locale.FromContext(request.Context())

		rows, queryError := pool.Query(request.Context(), `
			SELECT c.slug, COALESCE(ct.name, c.name) AS name
			FROM cuisines c
			LEFT JOIN cuisine_translations ct ON ct.cuisine_slug = c.slug AND ct.lang = $1
			ORDER BY c.sort_order`, lang)
		if queryError != nil {
			slog.ErrorContext(request.Context(), "list cuisines", "err", queryError)
			writeErrorJSON(responseWriter, request, http.StatusInternalServerError, "failed to load cuisines")
			return
		}
		defer rows.Close()

		items := make([]cuisineItem, 0)
		for rows.Next() {
			var item cuisineItem
			if scanError := rows.Scan(&item.Slug, &item.Name); scanError != nil {
				slog.ErrorContext(request.Context(), "scan cuisine row", "err", scanError)
				writeErrorJSON(responseWriter, request, http.StatusInternalServerError, "failed to load cuisines")
				return
			}
			items = append(items, item)
		}
		if rowsError := rows.Err(); rowsError != nil {
			slog.ErrorContext(request.Context(), "iterate cuisine rows", "err", rowsError)
			writeErrorJSON(responseWriter, request, http.StatusInternalServerError, "failed to load cuisines")
			return
		}

		responseWriter.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(responseWriter).Encode(map[string]any{"cuisines": items})
	}
}

func writeErrorJSON(responseWriter http.ResponseWriter, request *http.Request, status int, msg string) {
	responseWriter.Header().Set("Content-Type", "application/json")
	responseWriter.WriteHeader(status)
	_ = json.NewEncoder(responseWriter).Encode(map[string]any{"error": msg, "request_id": middleware.RequestIDFromCtx(request.Context())})
}