PowerShell Requires Chilkat v10.1.2+
Dynamics CRM OAuth2 Access Token

Demonstrates how to get a Microsoft Dynamics CRM OAuth2 access token from a desktop (installed) application or script.
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Add-Type -Path "C:\chilkat\ChilkatDotNet47-x64\ChilkatDotNet47.dll"

$success = $false

#  To further clarify, see OAuth 2.0 Authorization Flow

$oauth2 = New-Object Chilkat.OAuth2

#  This should be the port in the localhost redirect URL for your app.
#  Important: Make sure the redirect URI in your Azure app registration 
#  is exactly "http://localhost:3017/".  Don't forget the ending "/" char.
#  The redirect URL would look like "http://localhost:3017/" if the port number is 3017.
$oauth2.ListenPort = 3017

#  Get the endpoints from the Azure Portal in the "endpoints" section of App Registrations..
#  The DYNAMICS-ENDPOINT-GUID is a Tenant dynamics-endpoint-guid  such as 1b54e7ee-d61b-4f12-a621-a6b2805b98c2
$oauth2.AuthorizationEndpoint = "https://login.microsoftonline.com/DYNAMICS-ENDPOINT-GUID/oauth2/authorize"
$oauth2.TokenEndpoint = "https://login.microsoftonline.com/DYNAMICS-ENDPOINT-GUID/oauth2/token"

#  Replace these with actual values.
$oauth2.ClientId = "DYNAMICS-CRM-CLIENT-ID"
$oauth2.ClientSecret = "DYNAMICS-CRM-SECRET-KEY"

$oauth2.Resource = "https://mydynamicsdomain.api.crm.dynamics.com"

$oauth2.RedirectAllowHtml = "<html><body><p>Thank you for granting access.</p></bod></html>"
$oauth2.RedirectDenyHtml = "<html><body><p>Maybe next time...</p></bod></html>"

#  Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
$url = $oauth2.StartAuth()
if ($oauth2.LastMethodSuccess -ne $true) {
    $($oauth2.LastErrorText)
    exit
}

#  We can pre-check the URL by sending a GET to catch any up-front errors.
#  If we receive JSON with an error in response, then we don't proceed any farther.

#  If we receive an HTML response, and the response status = 200, then all should be OK.
#  We can proceed by displaying an interactive browser loaded with the url.
$http = New-Object Chilkat.Http
$sbPreCheck = New-Object Chilkat.StringBuilder
$success = $http.QuickGetSb($url,$sbPreCheck)
if (($http.LastStatus -ne 200) -or ($sbPreCheck.StartsWith("{",$true) -ne $true)) {
    $("JSON Error Response:")
    $($sbPreCheck.GetAsString())
    exit
}

#  If the HTTP request itself failed, then examine the error.
if ($success -eq $false) {
    $($http.LastErrorText)
    exit
}

#  OK.. the pre-flight check seems OK, go ahead with getting the interactive user authorization..

#  Launch the default browser on the system and navigate to the url.
#  The LaunchBrowser method was added in Chilkat v10.1.2.
$success = $oauth2.LaunchBrowser($url)
if ($success -eq $false) {
    $($oauth2.LastErrorText)
    exit
}

#  Wait for the user to approve or deny authorization in the browser.
$numMsWaited = 0
while (($numMsWaited -lt 90000) -and ($oauth2.AuthFlowState -lt 3)) {
    $oauth2.SleepMs(100)
    $numMsWaited = $numMsWaited + 100
}

#  If the browser does not respond within the specified time, AuthFlowState will be:
#  
#  1: Waiting for Redirect – The OAuth2 background thread is waiting for the browser's redirect request.
#  2: Waiting for Final Response – The thread is awaiting the final access token response.
#  In either case, cancel the background task initiated by StartAuth.

if ($oauth2.AuthFlowState -lt 3) {
    $oauth2.Cancel()
    $("No response from the browser!")
    exit
}

#  Check AuthFlowState to determine if authorization was granted, denied, or failed:
#  
#  3: Success – OAuth2 flow completed, the background thread exited, and the successful response is in AccessTokenResponse.
#  4: Access Denied – OAuth2 flow completed, the background thread exited, and the error response is in AccessTokenResponse.
#  5: Failure – OAuth2 flow failed before completion, the background thread exited, and error details are in FailureInfo.

if ($oauth2.AuthFlowState -eq 5) {
    $("OAuth2 failed to complete.")
    $($oauth2.FailureInfo)
    exit
}

if ($oauth2.AuthFlowState -eq 4) {
    $("OAuth2 authorization was denied.")
    $($oauth2.AccessTokenResponse)
    exit
}

if ($oauth2.AuthFlowState -ne 3) {
    $("Unexpected AuthFlowState:" + $oauth2.AuthFlowState)
    exit
}

$("OAuth2 authorization granted!")
$("Access Token = " + $oauth2.AccessToken)

#  Get the full JSON response:
$json = New-Object Chilkat.JsonObject
$json.Load($oauth2.AccessTokenResponse)
$json.EmitCompact = $false

#  The JSON response looks like this:

#  {
#    "token_type": "Bearer",
#    "scope": "user_impersonation",
#    "expires_in": "3599",
#    "ext_expires_in": "0",
#    "expires_on": "1524783438",
#    "not_before": "1524779538",
#    "resource": "https://mydomain.api.crm.dynamics.com",
#    "access_token": "...",
#    "refresh_token": "...",
#    "id_token": "..."
#  }

#  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 ($json.HasMember("expires_on") -ne $true) {
    $dtExpire = New-Object Chilkat.CkDateTime
    $dtExpire.SetFromCurrentSystemTime()
    $dtExpire.AddSeconds($json.IntOf("expires_in"))
    $json.AppendString("expires_on",$dtExpire.GetAsUnixTimeStr($false))
}

$($json.Emit())

#  Save the JSON to a file for future requests.
$fac = New-Object Chilkat.FileAccess
$fac.WriteEntireTextFile("qa_data/tokens/dynamicsCrm.json",$json.Emit(),"utf-8",$false)