(Tcl) Get a Xero OAuth2 Access Token

Gets a Xero OAuth2 access token.

Note: This example requires Chilkat v10.1.2 or greater.

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load ./chilkat.dll

# For more information about the OAuth2, see OAuth 2.0 Authorization Flow

set oauth2 [new_CkOAuth2]

# For Xero OAuth2, set the listen port equal to the port used
# in the Authorized Redirect URL for the Client ID.
# For example, in this case the Authorized Redirect URL would be http://localhost:55568/
# Your app should choose a port not likely not used by any other application.
# See Xero OAuth2 for Desktop Apps for more information.
CkOAuth2_put_ListenPort $oauth2 55568

CkOAuth2_put_AuthorizationEndpoint $oauth2 "https://login.xero.com/identity/connect/authorize"
CkOAuth2_put_TokenEndpoint $oauth2 "https://identity.xero.com/connect/token"

# Replace these with actual values.
CkOAuth2_put_ClientId $oauth2 "XERO_APP_OAUTH2_CLIENT_ID"
CkOAuth2_put_ClientSecret $oauth2 "XERO_APP_OAUTH2_CLIENT_SECRET"
CkOAuth2_put_UseBasicAuth $oauth2 1

# See https://developer.xero.com/documentation/oauth2/scopes for a complete list of scopes.
# You will need to change the scopes depending on what access is needed..
CkOAuth2_put_Scope $oauth2 "openid profile email accounting.transactions accounting.attachments accounting.settings payroll.employees offline_access"

# Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
set url [CkOAuth2_startAuth $oauth2]
if {[CkOAuth2_get_LastMethodSuccess $oauth2] != 1} then {
    puts [CkOAuth2_lastErrorText $oauth2]
    delete_CkOAuth2 $oauth2
    exit
}

puts "url = $url"

# Launch the default browser on the system and navigate to the url.
# The LaunchBrowser method was added in Chilkat v10.1.2.
set success [CkOAuth2_LaunchBrowser $oauth2 $url]
if {$success == 0} then {
    puts [CkOAuth2_lastErrorText $oauth2]
    delete_CkOAuth2 $oauth2
    exit
}

# Wait for the user to approve or deny authorization in the browser.
set numMsWaited 0
while {expr [$numMsWaited < 90000]  &&  [[CkOAuth2_get_AuthFlowState $oauth2] < 3]} {
    CkOAuth2_SleepMs $oauth2 100
    set numMsWaited [expr $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 {[CkOAuth2_get_AuthFlowState $oauth2] < 3} then {
    CkOAuth2_Cancel $oauth2
    puts "No response from the browser!"
    delete_CkOAuth2 $oauth2
    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 {[CkOAuth2_get_AuthFlowState $oauth2] == 5} then {
    puts "OAuth2 failed to complete."
    puts [CkOAuth2_failureInfo $oauth2]
    delete_CkOAuth2 $oauth2
    exit
}

if {[CkOAuth2_get_AuthFlowState $oauth2] == 4} then {
    puts "OAuth2 authorization was denied."
    puts [CkOAuth2_accessTokenResponse $oauth2]
    delete_CkOAuth2 $oauth2
    exit
}

if {[CkOAuth2_get_AuthFlowState $oauth2] != 3} then {
    puts "Unexpected AuthFlowState:[CkOAuth2_get_AuthFlowState $oauth2]"
    delete_CkOAuth2 $oauth2
    exit
}

# Save the full JSON access token response to a file.
set sbJson [new_CkStringBuilder]

CkStringBuilder_Append $sbJson [CkOAuth2_accessTokenResponse $oauth2]
CkStringBuilder_WriteFile $sbJson "qa_data/tokens/xero-access-token.json" "utf-8" 0

# The saved JSON response looks like this:

# 	{
# 	 "access_token": "...",
# 	 "token_type": "Bearer",
# 	 "expires_in": 3600,
# 	 "refresh_token": "..."
# 	}
# 
puts "OAuth2 authorization granted!"
puts "Access Token = [CkOAuth2_accessToken $oauth2]"

delete_CkOAuth2 $oauth2
delete_CkStringBuilder $sbJson