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Adds function for token lifecycle management #13

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Merged
johnnyt merged 1 commit into from
Oct 7, 2025
Merged

Adds function for token lifecycle management #13

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66 changes: 66 additions & 0 deletions lib/msg/auth.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -314,6 +314,72 @@ defmodule Msg.Auth do
end
end

@doc """
Gets an access token using client credentials (application-only) flow.

This is similar to `Msg.Client.fetch_token!/1` but returns token metadata
for lifecycle management, making it suitable for TokenManager implementations.

## Parameters

- `credentials` - Map with `:client_id`, `:client_secret`, and `:tenant_id`

## Returns

- `{:ok, token_response}` - Map with access_token, expires_in, and token_type
- `{:error, error}` - OAuth error response

## Examples

{:ok, token_info} = Msg.Auth.get_app_token(%{
client_id: "app-id",
client_secret: "secret",
tenant_id: "tenant-id"
})

# Store token with accurate expiry
expires_at = DateTime.add(DateTime.utc_now(), token_info.expires_in, :second)
store_token(token_info.access_token, expires_at)

## Difference from `Msg.Client.fetch_token!/1`

- Returns `{:ok, metadata}` instead of raising
- Includes `expires_in` for accurate lifecycle management
- Designed for token managers, not immediate client creation
"""
@spec get_app_token(credentials()) ::
{:ok, %{access_token: String.t(), expires_in: integer(), token_type: String.t()}}
| {:error, term()}
def get_app_token(%{client_id: client_id, client_secret: client_secret, tenant_id: tenant_id}) do
token_url = "https://login.microsoftonline.com/#{tenant_id}/oauth2/v2.0/token"

params = [
grant_type: "client_credentials",
client_id: client_id,
client_secret: client_secret,
scope: "https://graph.microsoft.com/.default"
]

headers = [{"content-type", "application/x-www-form-urlencoded"}]
body = URI.encode_query(params)

case Req.post(token_url, headers: headers, body: body) do
{:ok, %{status: 200, body: response_body}} ->
{:ok,
%{
access_token: response_body["access_token"],
token_type: response_body["token_type"],
expires_in: response_body["expires_in"]
}}

{:ok, %{status: status, body: error_body}} ->
{:error, %{status: status, body: error_body}}

{:error, error} ->
{:error, error}
end
end

# Private helpers

defp maybe_add_state(params, nil), do: params
Expand Down
7 changes: 7 additions & 0 deletions test/msg/auth_test.exs
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Original file line number Diff line number Diff line change
Expand Up @@ -91,4 +91,11 @@ defmodule Msg.AuthTest do
assert function_exported?(Msg.Auth, :refresh_access_token, 2)
end
end

describe "get_app_token/1" do
test "returns expected response shape" do
# Verify function signature
assert function_exported?(Msg.Auth, :get_app_token, 1)
end
end
end
22 changes: 22 additions & 0 deletions test/msg/integration/auth_test.exs
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Original file line number Diff line number Diff line change
Expand Up @@ -190,4 +190,26 @@ defmodule Msg.Integration.AuthTest do
assert String.contains?(tokens.scope, "Calendars.ReadWrite")
end
end

describe "get_app_token/1" do
test "returns access token with metadata", %{credentials: credentials} do
{:ok, token_info} = Auth.get_app_token(credentials)

assert is_binary(token_info.access_token)
assert token_info.token_type == "Bearer"
assert is_integer(token_info.expires_in)
assert token_info.expires_in > 0
end

test "returns error for invalid credentials" do
invalid_creds = %{
client_id: "invalid-id",
client_secret: "invalid-secret",
tenant_id: "invalid-tenant"
}

assert {:error, %{status: status}} = Auth.get_app_token(invalid_creds)
assert status == 400
end
end
end