package handlers

import (
	"context"
	"fmt"
	"net/http"

	"git.haelnorr.com/h/golib/hws"
	"git.haelnorr.com/h/oslstats/internal/db"
	"git.haelnorr.com/h/oslstats/internal/respond"
	"git.haelnorr.com/h/oslstats/internal/validation"
	"github.com/pkg/errors"
	"github.com/uptrace/bun"
)

// IsUnique creates a handler that checks field uniqueness
// Returns 200 OK if unique, 409 Conflict if not unique
func IsUnique(
	s *hws.Server,
	conn *db.DB,
	model any,
	field string,
) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		getter, err := validation.ParseForm(r)
		if err != nil {
			respond.BadRequest(w, err)
			return
		}
		value := getter.String(field).TrimSpace().Required().Value
		if !getter.Validate() {
			respond.BadRequest(w, err)
			return
		}
		unique := false
		if ok := conn.WithNotifyTx(s, w, r, func(ctx context.Context, tx bun.Tx) (bool, error) {
			unique, err = db.IsUnique(ctx, tx, model, field, value)
			if err != nil {
				return false, errors.Wrap(err, "db.IsUnique")
			}
			return true, nil
		}); !ok {
			return
		}
		if unique {
			respond.OK(w)
		} else {
			err := fmt.Errorf("'%s' is not unique for field '%s'", value, field)
			respond.Conflict(w, err)
		}
	})
}