(Tcl) Microsoft Graph -- Renew Expiring Access Token (Azure AD v2.0 Endpoint)

Demonstrates how to renew an expiring access token using the refresh token. This example is for renewing an access token using the Azure AD v2.0 endpoint (not the Azure AD endpoint).

An app needs to watch for the expiration of these tokens and renew the expiring access token before the refresh token expires.

This example requires Chilkat v9.5.0.67 or greater.

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load ./chilkat.dll

# This example requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

# We previously obtained an access token and saved the JSON to a file using this example:
# Get Access Token using Azure AD v2.0 Endpoint

# This example will examine the JSON and expiration date, and if near expiration will
# refresh the access token.

set json [new_CkJsonObject]

set success [CkJsonObject_LoadFile $json "qa_data/tokens/microsoftGraph.json"]
if {$success != 1} then {
    delete_CkJsonObject $json
    exit
}

# The contents of the JSON look like this:
# {
#   "token_type": "Bearer",
#   "scope": "User.Read Mail.ReadWrite Mail.Send",
#   "expires_in": 3600,
#   "ext_expires_in": 0,
#   "access_token": "EwBAA8l6B...",
#   "refresh_token": "MCRMdbe6Cd...",
#   "id_token": "eyJ0eXAiOiJ...",
#   "expires_on": "1494112119"
# }

# The "expires_on" value is a Unix time.
set dtExpire [new_CkDateTime]

CkDateTime_SetFromUnixTime $dtExpire 0 [CkJsonObject_IntOf $json "expires_on"]

# If this date/time expires within 10 minutes of the current system time, refresh the token.
if {[CkDateTime_ExpiresWithin $dtExpire 10 "minutes"] != 1} then {
    puts "No need to refresh, the access token won't expire within the next 10 minutes."
    delete_CkJsonObject $json
    delete_CkDateTime $dtExpire
    exit
}

# OK, we need to refresh the access token by sending a POST like this:
# 

# 	POST https://login.microsoftonline.com/common/oauth2/v2.0/token HTTP/1.1
# 	Host: login.microsoftonline.com
# 	Content-Type: application/x-www-form-urlencoded
# 	Content-Length: ***
# 
# 	grant_type=refresh_token
# 	&redirect_uri=http%3A%2F%2Flocalhost%3A3017%2F
# 	&client_id=8b8539cd-7b75-427f-bef1-4a6264fd4940
# 	&client_secret=PJW3dznGfyNSm3rM9aHeXWGKsTMepKXT1Eqy45XXdU4%3D
# 	&refresh_token=AAABAAAAvPM1KaPlrEqdFSBzjqfTGM74--...

set req [new_CkHttpRequest]

CkHttpRequest_AddParam $req "grant_type" "refresh_token"
CkHttpRequest_AddParam $req "redirect_uri" "http://localhost:3017/"
CkHttpRequest_AddParam $req "client_id" "MICROSOFT-GRAPH-CLIENT-ID"
CkHttpRequest_AddParam $req "client_secret" "MICROSOFT-GRAPH-CLIENT-SECRET"
CkHttpRequest_AddParam $req "refresh_token" [CkJsonObject_stringOf $json "refresh_token"]

set http [new_CkHttp]

# resp is a CkHttpResponse
set resp [CkHttp_PostUrlEncoded $http "https://login.microsoftonline.com/common/oauth2/v2.0/token" $req]
if {[CkHttp_get_LastMethodSuccess $http] != 1} then {
    puts [CkHttp_lastErrorText $http]
    delete_CkJsonObject $json
    delete_CkDateTime $dtExpire
    delete_CkHttpRequest $req
    delete_CkHttp $http
    exit
}

# Load the JSON response.
CkJsonObject_Load $json [CkHttpResponse_bodyStr $resp]
CkJsonObject_put_EmitCompact $json 0

# Show the JSON response.
puts [CkJsonObject_emit $json]

puts "Response status code: [CkHttpResponse_get_StatusCode $resp]"

# If the response status code is not 200, then it's an error.
if {[CkHttpResponse_get_StatusCode $resp] != 200} then {
    delete_CkJsonObject $json
    delete_CkDateTime $dtExpire
    delete_CkHttpRequest $req
    delete_CkHttp $http
    exit
}

delete_CkHttpResponse $resp

# If an "expires_on" member does not exist, then add the JSON member by
# getting the current system date/time and adding the "expires_in" seconds.
# This way we'll know when the token expires.
if {[CkJsonObject_HasMember $json "expires_on"] != 1} then {
    CkDateTime_SetFromCurrentSystemTime $dtExpire
    CkDateTime_AddSeconds $dtExpire [CkJsonObject_IntOf $json "expires_in"]
    CkJsonObject_AppendString $json "expires_on" [CkDateTime_getAsUnixTimeStr $dtExpire 0]
}

# Save the refreshed access token JSON to a file for future requests.
set fac [new_CkFileAccess]

CkFileAccess_WriteEntireTextFile $fac "qa_data/tokens/microsoftGraph.json" [CkJsonObject_emit $json] "utf-8" 0

delete_CkJsonObject $json
delete_CkDateTime $dtExpire
delete_CkHttpRequest $req
delete_CkHttp $http
delete_CkFileAccess $fac