feat: add option to use license file as API key

doc/modules/ROOT/pages/install.adoc

@@ -38,7 +38,9 @@ image::install_blender_addons.jpg[Install Blender Add-ons]
 
 6. Setup add-on preferences if you are using a version of *Skybrush Studio for Blender* other than the free community edition:
 
-    API Key:: Enter the API key received that is used when communicating with the Skybrush Studio server.
+    API Key:: If you have received an API Key for communicating with the Skybrush Studio server, paste it here.
+
+    License file:: If you have received a License file for communicating with the Skybrush Studio server, give its full path here to use it as your API Key.
 
     Server URL:: Enter the URL of a dedicated Skybrush Studio server if you are using a dedicated server.
 
@@ -50,11 +52,17 @@ To turn on online access, open Blender and go to Edit -> Preferences -> System,
 
 === 5. Install Skybrush Studio Server
 
+==== 5.1 Cloud server for community users
+
 If you are a community user, you do _not_ need to install the *Skybrush Studio Server* as you can rely on our cloud-based community server.
 
-If you are using a paid, professional version of *Skybrush Studio*, you will receive a precompiled copy of *Skybrush Studio Server* and a corresponding license file upon purchase of the software.
+==== 5.2 Cloud server for pro users
+
+If you are using a paid, professional version of *Skybrush Studio*, you will receive a license file upon purchase of the software. This license file shall be used as an API key that enables your pro features while using the cloud-based *Skybrush Studio Server* (see setup instructions above on how to use your License file as your API Key).
+
+==== 5.3 Local server for VIP users
 
-After successful installation of *Skybrush Studio Server*, your licence file named `skybrush-studio-server.cml` has to be copied to the folder where you installed the server itself. You might need system administrator privileges to write into this folder.
+Upon special agreement, you may also receive a precompiled copy of *Skybrush Studio Server* for local use. In this case, after successful installation, your license file named `skybrush-studio-server.cml` has to be copied to the folder where you installed the server itself. You might need system administrator privileges to write into this folder.
 
 The terminal log of *Skybrush Studio Server* will give you instant feedback about the presence and content of your currently used license file upon execution of the server.
 

doc/modules/ROOT/pages/panels/safety_and_export/export.adoc

@@ -55,7 +55,7 @@ The validation report starts with a summary of flight statistics and safety test
 
 .IMPORTANT
 ****
-The validation .pdf is created by a local or remote instance of *Skybrush Studio Server* running in the background. As creating the validation report is resource intensive, access to this feature might be disabled on our public server and might be only available through a paid license option. If you need but do not have access, mailto:[email protected][contact us] for obtaining the proper *Skybrush Studio Server* licence.
+The validation .pdf is created by a local or remote instance of *Skybrush Studio Server* running in the background. As creating the validation report is resource intensive, access to this feature might be disabled on our public server and might be only available through a paid license option. If you need but do not have access, mailto:[email protected][contact us] for obtaining the proper *Skybrush Studio Server* license.
 ****
 
 If you press the btn:[Export to validation .pdf] button, you have to choose the path and filename of your output file. There are also some parameters you can setup conveniently:

src/modules/sbstudio/api/base.py

@@ -1,6 +1,7 @@
 import json
 import re
 
+from base64 import b64encode
 from contextlib import contextmanager
 from gzip import compress
 from http.client import HTTPResponse
@@ -106,6 +107,9 @@ def save_to_file(self, filename: Path) -> None:
 
 
 _API_KEY_REGEXP = re.compile(r"^[a-zA-Z0-9-_.]*$")
+_LICENSE_API_KEY_REGEXP = re.compile(
+    r"^License [A-Za-z0-9+/=]{4,}([A-Za-z0-9+/=]{2})*$"
+)
 
 
 class SkybrushStudioAPI:
@@ -126,27 +130,42 @@ def validate_api_key(key: str) -> str:
         Raises:
             ValueError: if the key cannot be a valid API key
         """
-        if not _API_KEY_REGEXP.match(key):
-            raise ValueError("Invalid API key")
+        if key.startswith("License"):
+            if not _LICENSE_API_KEY_REGEXP.match(key):
+                raise ValueError("Invalid license-type API key")
+        else:
+            if not _API_KEY_REGEXP.match(key):
+                raise ValueError("Invalid API key")
         return key
 
     def __init__(
         self,
         url: str = COMMUNITY_SERVER_URL,
         api_key: Optional[str] = None,
+        license_file: Optional[str] = None,
     ):
         """Constructor.
 
         Parameters:
             url: the root URL of the Skybrush Studio API; defaults to the public
                 online service
             api_key: the API key used to authenticate with the server
+            license_file: the path to a license file to be used as the API Key
         """
         self._api_key = None
         self._root = None  # type: ignore
         self._request_context = create_default_context()
 
-        self.api_key = api_key
+        if api_key and license_file:
+            raise SkybrushStudioAPIError(
+                "Cannot use API key and license file at the same time"
+            )
+
+        if license_file:
+            self.api_key = self._convert_license_file_to_api_key(license_file)
+        else:
+            self.api_key = api_key
+
         self.url = url
 
     @property
@@ -158,6 +177,26 @@ def api_key(self) -> Optional[str]:
     def api_key(self, value: Optional[str]) -> None:
         self._api_key = self.validate_api_key(value) if value else None
 
+    def _convert_license_file_to_api_key(self, file: str) -> str:
+        """Parses a license file and transforms it to an API key.
+
+        Returns:
+            the license file parsed as an API key
+
+        Raises:
+            ValueError: if the file cannot be read as an API key
+        """
+        if not Path(file).exists():
+            raise ValueError("License file does not exist")
+
+        try:
+            with open(file, "rb") as fp:
+                api_key = f"License {b64encode(fp.read()).decode('ascii')}"
+        except Exception:
+            raise ValueError("Could not read license file") from None
+
+        return api_key
+
     @property
     def url(self) -> str:
         """The URL where the API can be accessed."""

src/modules/sbstudio/plugin/api.py

@@ -1,3 +1,5 @@
+import logging
+
 from contextlib import contextmanager
 from functools import lru_cache
 from typing import Iterator, Optional, TypeVar
@@ -13,21 +15,35 @@
 
 T = TypeVar("T")
 
+#############################################################################
+# configure logger
+
+log = logging.getLogger(__name__)
+
 
 @lru_cache(maxsize=1)
-def _get_api_from_url_and_key(url: str, key: str):
-    """Constructs a Skybrush Studio API object from a root URL and an API key.
+def _get_api_from_url_and_key_or_license(url: str, key: str, license_file: str):
+    """Constructs a Skybrush Studio API object from a root URL and an API key
+    or a license file.
 
     Memoized so we do not need to re-construct the same instance as long as
     the user does not change the add-on settings.
     """
     global _fallback_api_key
 
-    result = SkybrushStudioAPI()
-
-    result.api_key = key or _fallback_api_key
-    if url:
-        result.url = url
+    try:
+        result = SkybrushStudioAPI(
+            api_key=key or (None if license_file else _fallback_api_key),
+            license_file=license_file or None,
+        )
+        if url:
+            result.url = url
+    except ValueError as ex:
+        log.error(f"Could not initialize Skybrush Studio API: {str(ex)}")
+        raise
+    except Exception as ex:
+        log.error(f"Unhandled exception in Skybrush Studio API initialization: {ex!r}")
+        raise
 
     # This is bad practice, but the default installation of Blender does not find
     # the SSL certificates on macOS and there are reports about similar problems
@@ -48,12 +64,14 @@ def get_api() -> SkybrushStudioAPI:
 
     api_key: str
     server_url: str
+    license_file: str
 
     prefs = get_preferences()
     api_key = str(prefs.api_key).strip()
+    license_file = str(prefs.license_file).strip()
     server_url = str(prefs.server_url).strip()
 
-    return _get_api_from_url_and_key(server_url, api_key)
+    return _get_api_from_url_and_key_or_license(server_url, api_key, license_file)
 
 
 @contextmanager

src/modules/sbstudio/plugin/model/global_settings.py

@@ -17,6 +17,12 @@ class DroneShowAddonGlobalSettings(AddonPreferences):
 
     bl_idname = "ui_skybrush_studio"
 
+    license_file = StringProperty(
+        name="License file",
+        description="Full path to the license file to be used as the API Key",
+        subtype="FILE_PATH",
+    )
+
     api_key = StringProperty(
         name="API Key",
         description="API Key that is used when communicating with the Skybrush Studio server",
@@ -45,6 +51,7 @@ def draw(self, context):
         layout = self.layout
 
         layout.prop(self, "api_key")
+        layout.prop(self, "license_file")
         layout.prop(self, "server_url")
 
         row = layout.row()