Feature: Environment Variable Configuration
  As a developer
  I want the tracker to work with environment variables
  So that configuration is flexible and secure

  Background:
    Given a temporary credentials directory

  Scenario: Create tracker using spreadsheet ID from environment
    Given valid service account credentials
    And environment variable GOOGLE_SHEETS_ID is set
    When I create a tracker using create_tracker function without spreadsheet ID
    Then the tracker should use spreadsheet ID from environment
    And the tracker should authenticate successfully

  Scenario: Create tracker using worksheet name from environment
    Given valid service account credentials
    And environment variable GOOGLE_SHEETS_ID is set
    And environment variable GOOGLE_SHEETS_WORKSHEET_NAME is set to "CustomSheet"
    When I create a tracker using create_tracker function
    Then the tracker should use custom worksheet name from environment
    And the tracker should authenticate successfully

  Scenario: Create tracker with default worksheet name when not in environment
    Given valid service account credentials
    And environment variable GOOGLE_SHEETS_ID is set
    And environment variable GOOGLE_SHEETS_WORKSHEET_NAME is not set
    When I create a tracker using create_tracker function
    Then the tracker should use default worksheet name "Sheet1"
    And the tracker should authenticate successfully

  Scenario: Create tracker fails when spreadsheet ID not in environment
    Given valid service account credentials
    And environment variable GOOGLE_SHEETS_ID is not set
    When I create a tracker using create_tracker function without spreadsheet ID
    Then the tracker should be None

  Scenario: Create tracker with credentials path from environment
    Given valid service account credentials
    And environment variable GOOGLE_SHEETS_CREDENTIALS_PATH is set
    And environment variable GOOGLE_SHEETS_ID is set
    When I create a tracker using create_tracker function without credentials path
    Then the tracker should use credentials path from environment
    And the tracker should authenticate successfully

  Scenario: Create tracker prioritizes explicit parameters over environment
    Given valid service account credentials
    And environment variable GOOGLE_SHEETS_ID is set to "env-spreadsheet-id"
    And environment variable GOOGLE_SHEETS_WORKSHEET_NAME is set to "EnvSheet"
    When I create a tracker with explicit spreadsheet ID and worksheet name
    Then the tracker should use explicit parameters
    And not use environment variables

  Scenario: Handle exception during tracker creation
    Given invalid service account credentials
    And environment variable GOOGLE_SHEETS_ID is set
    When I create a tracker using create_tracker function
    Then the tracker should be None
    And no exception should be raised