//go:build go1.18
// +build go1.18

// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License.

package azidentity

import (
	"context"

	"github.com/Azure/azure-sdk-for-go/sdk/azcore"
	"github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
	"github.com/Azure/azure-sdk-for-go/sdk/azcore/runtime"
	"github.com/AzureAD/microsoft-authentication-library-for-go/apps/confidential"
)

const credNameSecret = "ClientSecretCredential"

// ClientSecretCredentialOptions contains optional parameters for ClientSecretCredential.
type ClientSecretCredentialOptions struct {
	azcore.ClientOptions

	// AdditionallyAllowedTenants specifies additional tenants for which the credential may acquire tokens.
	// Add the wildcard value "*" to allow the credential to acquire tokens for any tenant in which the
	// application is registered.
	AdditionallyAllowedTenants []string

	// DisableInstanceDiscovery should be set true only by applications authenticating in disconnected clouds, or
	// private clouds such as Azure Stack. It determines whether the credential requests Microsoft Entra instance metadata
	// from https://login.microsoft.com before authenticating. Setting this to true will skip this request, making
	// the application responsible for ensuring the configured authority is valid and trustworthy.
	DisableInstanceDiscovery bool

	// Cache is a persistent cache the credential will use to store the tokens it acquires, making
	// them available to other processes and credential instances. The default, zero value means the
	// credential will store tokens in memory and not share them with any other credential instance.
	Cache Cache
}

// ClientSecretCredential authenticates an application with a client secret.
type ClientSecretCredential struct {
	client *confidentialClient
}

// NewClientSecretCredential constructs a ClientSecretCredential. Pass nil for options to accept defaults.
func NewClientSecretCredential(tenantID string, clientID string, clientSecret string, options *ClientSecretCredentialOptions) (*ClientSecretCredential, error) {
	if options == nil {
		options = &ClientSecretCredentialOptions{}
	}
	cred, err := confidential.NewCredFromSecret(clientSecret)
	if err != nil {
		return nil, err
	}
	msalOpts := confidentialClientOptions{
		AdditionallyAllowedTenants: options.AdditionallyAllowedTenants,
		Cache:                      options.Cache,
		ClientOptions:              options.ClientOptions,
		DisableInstanceDiscovery:   options.DisableInstanceDiscovery,
	}
	c, err := newConfidentialClient(tenantID, clientID, credNameSecret, cred, msalOpts)
	if err != nil {
		return nil, err
	}
	return &ClientSecretCredential{client: c}, nil
}

// GetToken requests an access token from Microsoft Entra ID. This method is called automatically by Azure SDK clients.
func (c *ClientSecretCredential) GetToken(ctx context.Context, opts policy.TokenRequestOptions) (azcore.AccessToken, error) {
	var err error
	ctx, endSpan := runtime.StartSpan(ctx, credNameSecret+"."+traceOpGetToken, c.client.azClient.Tracer(), nil)
	defer func() { endSpan(err) }()
	tk, err := c.client.GetToken(ctx, opts)
	return tk, err
}

var _ azcore.TokenCredential = (*ClientSecretCredential)(nil)