package chatclient

import (
	"context"
	"fmt"
	"strings"

	"google.golang.org/grpc/credentials"
)

type TokenProvider func(ctx context.Context) (string, error)

func StaticToken(token string) TokenProvider {
	return func(context.Context) (string, error) {
		if strings.TrimSpace(token) == "" {
			return "", fmt.Errorf("%w: empty service token", ErrInvalidConfig)
		}
		return token, nil
	}
}

type tokenCredentials struct {
	provider                 TokenProvider
	requireTransportSecurity bool
}

func (c tokenCredentials) GetRequestMetadata(ctx context.Context, _ ...string) (map[string]string, error) {
	token, err := c.provider(ctx)
	if err != nil {
		return nil, err
	}
	if strings.TrimSpace(token) == "" {
		return nil, fmt.Errorf("%w: empty service token", ErrInvalidConfig)
	}
	return map[string]string{"authorization": "Bearer " + token}, nil
}

func (c tokenCredentials) RequireTransportSecurity() bool {
	return c.requireTransportSecurity
}

var _ credentials.PerRPCCredentials = tokenCredentials{}