(Tcl) Dropbox: OAuth2 Authorization to Obtain an Access Token

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This example runs the OAuth 2.0 authorization flow that lets the user sign in to Dropbox and authorize your app.

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]

# The port should match the Authorized Redirect URL in your Dropbox app, 
# which would look like "http://localhost:3017/"
CkOAuth2_put_ListenPort $oauth2 3017

# IMPORTANT: One of the OAuth2 redirect URIs for your Dropbox app must be
# exactly this string:  http://localhost:3017/

CkOAuth2_put_AuthorizationEndpoint $oauth2 "https://www.dropbox.com/oauth2/authorize"
CkOAuth2_put_TokenEndpoint $oauth2 "https://api.dropboxapi.com/oauth2/token"

# Replace this with your actual Dropbox App Key
CkOAuth2_put_ClientId $oauth2 "DROPBOX_APP_KEY"

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

# Add token_access_type=offline to also get a refresh token in the response
CkOAuth2_AddAuthQueryParam $oauth2 "token_access_type" "offline"

# 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
}

puts "OAuth2 authorization granted!"

set json [new_CkJsonObject]

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

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

# A sample access token response:

# {
#   "access_token": "...",
#   "token_type": "bearer",
#   "expires_in": 14399,
#   "refresh_token": "...",
#   "scope": "account_info.read",
#   "uid": "562542581",
#   "account_id": "dbid:AACQhDS0E3_Vb72Ynd0F-GxGWdTI2qcTHzA"
# }

puts "Access Token = [CkOAuth2_accessToken $oauth2]"

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

delete_CkOAuth2 $oauth2
delete_CkJsonObject $json