orisano/go-adal

package adal

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

    "golang.org/x/oauth2/clientcredentials"
    "golang.org/x/xerrors"
)

type AuthenticationContext struct {
    Authority *Authority
}

func NewAuthenticationContext(tenant string, opts ...Option) (*AuthenticationContext, error) {
    if len(tenant) == 0 {
        return nil, xerrors.New("missing tenant")
    }

    options := defaultOption()
    for _, opt := range opts {
        opt(&options)
    }
    authorityURL := fmt.Sprintf("https://%s/%s", options.AuthorityHost, tenant)

    authority, err := NewAuthority(authorityURL, options.ValidateAuthority)
    if err != nil {
        return nil, xerrors.Errorf("create authority: %w", err)
    }
    return &AuthenticationContext{
        Authority: authority,
    }, nil
}

func (a *AuthenticationContext) Client(ctx context.Context, resource, clientID, clientSecret string) (*http.Client, error) {
    if len(resource) == 0 {
        return nil, xerrors.New("missing resource")
    }
    if len(clientID) == 0 {
        return nil, xerrors.New("missing clientID")
    }
    if len(clientSecret) == 0 {
        return nil, xerrors.New("missing clientSecret")
    }
    config := &clientcredentials.Config{
        ClientID:     clientID,
        ClientSecret: clientSecret,
        TokenURL:     a.Authority.TokenURL(),
        EndpointParams: url.Values{
            "resource": {resource},
        },
    }
    return config.Client(ctx), nil
}