(Tcl) X.com OAuth 2.0 Authorization Code with PKCE

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

For more information, see https://docs.x.com/resources/fundamentals/authentication/oauth-2-0/authorization-code

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load ./chilkat.dll

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

set oauth2 [new_CkOAuth2]

# The port should match the Authorized Redirect URL in your X.com app, 
# which would look like "http://127.0.0.1:3017/"
# See the screenshot below of the App Settings in the X Developer Portal
CkOAuth2_put_LocalHost $oauth2 "127.0.0.1"
CkOAuth2_put_ListenPort $oauth2 3017

CkOAuth2_put_AuthorizationEndpoint $oauth2 "https://x.com/i/oauth2/authorize"
CkOAuth2_put_TokenEndpoint $oauth2 "https://api.x.com/2/oauth2/token"

# Replace this with your actual X.com OAuth2 Client ID and Client Secret
CkOAuth2_put_ClientId $oauth2 "OAUTH2_CLIENT_ID"
CkOAuth2_put_ClientSecret $oauth2 "OAUTH2_CLIENT_SECRET"

# This is for Require Proof Key for Code Exchange (PKCE)
# See OAuth2 PKCE Explained
CkOAuth2_put_CodeChallenge $oauth2 1
CkOAuth2_put_CodeChallengeMethod $oauth2 "S256"

# Space separated scopes...
CkOAuth2_put_Scope $oauth2 "tweet.read tweet.write users.read follows.read follows.write offline.access like.read like.write block.read block.write"

# 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 < 10000]  &&  [[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
}

puts "OAuth2 authorization granted!"

set json [new_CkJsonObject]

CkJsonObject_Load $json [CkOAuth2_accessTokenResponse $oauth2]
CkJsonObject_put_EmitCompact $json 0

# 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"] == 0} then {
    set dtExpire [new_CkDateTime]

    CkDateTime_SetFromCurrentSystemTime $dtExpire
    CkDateTime_AddSeconds $dtExpire [CkJsonObject_IntOf $json "expires_in"]
    CkJsonObject_AppendString $json "expires_on" [CkDateTime_getAsUnixTimeStr $dtExpire 0]
}

puts "Access Token Response = [CkJsonObject_emit $json]"

# A sample access token response:

# {
#   "token_type": "bearer",
#   "expires_in": 7200,
#   "access_token": "VmNDLVZiYUZwejY5Mkx3RblFTmo3ek1leTRGclMuZFVOUTVUTWpNbVZKb1N5OjE3NDAxNjk4MDVxNTE6MToxOaF0OjE",
#   "scope": "block.read follows.read offline.access tweet.write block.write like.write like.read users.read tweet.read follows.write",
#   "refresh_token": "eThOWVVFSTRqdVp3QTFndGsxM2ZGZmFyNWVrU0phM1JKbGdrbGNWRGJzb1loOjE3NDAwMjk4MDUxNTI6MTowOnJ0OjE"
# }

puts "Access Token = [CkOAuth2_accessToken $oauth2]"

# Save the JSON access token response to a file for subsequent use..
CkJsonObject_WriteFile $json "qa_data/tokens/x.json"

# 

delete_CkOAuth2 $oauth2
delete_CkJsonObject $json
delete_CkDateTime $dtExpire