Add configurable about this dataset links (#907)

* add about arg

* add simple url validator

* attach about link to config api

* add links to configDefaults

* add conditional link in top left and menu item

* whitespace

* change to lower case

* move --about arg before click.command()

if this fixes it I have no idea why

* change link>URL

* be more descriptive about URL

* Make error more explicit

* refactor attach_data to accept about

* format

* change icon

* add trailing parenthesis

* whitespace

server/cli/launch.py

@@ -6,6 +6,7 @@ from os.path import splitext, basename
 import sys
 import warnings
 import webbrowser
+from urllib.parse import urlparse
 
 import click
 
@@ -23,7 +24,11 @@ def common_args(func):
     """
     Decorator to contain CLI args that will be common to both CLI and GUI: title and engine args.
     """
+
     @click.option("--title", "-t", help="Title to display (if omitted will use file name).")
+    @click.option("--about",
+                  help="A URL to more information about the dataset."
+                       "(This must be an absolute URL including HTTP(S) protocol)")
     @click.option(
         "--embedding",
         "-e",
@@ -58,6 +63,7 @@ def common_args(func):
     @functools.wraps(func)
     def wrapper(*args, **kwargs):
         return func(*args, **kwargs)
+
     return wrapper
 
 
@@ -117,6 +123,7 @@ def launch(
         diffexp_lfc_cutoff,
         title,
         scripts,
+        about,
         experimental_label_file
 ):
     """Launch the cellxgene data viewer.
@@ -197,6 +204,20 @@ def launch(
         if lf_ext and lf_ext != ".csv":
             raise click.FileError(basename(experimental_label_file), hint="label file type must be .csv")
 
+    if about:
+        def url_check(url):
+            try:
+                result = urlparse(url)
+                if all([result.scheme, result.netloc]):
+                    return True
+                else:
+                    return False
+            except ValueError:
+                return False
+
+        if not url_check(about):
+            raise click.ClickException("Must provide an absolute URL for --about. (Example format: http://example.com)")
+
     # Setup app
     cellxgene_url = f"http://{host}:{port}"
 
@@ -221,7 +242,7 @@ def launch(
     from server.app.scanpy_engine.scanpy_engine import ScanpyEngine
 
     try:
-        server.attach_data(ScanpyEngine(data_locator, e_args), title=title)
+        server.attach_data(ScanpyEngine(data_locator, e_args), title=title, about=about)
     except ScanpyFileError as e:
         raise click.ClickException(f"{e}")