Added initial code brought over from datasette-paste

Closes #1

Made very slight modifications - mainly replacing 'paste' with 'import'

Revision history of this code is here:
https://github.com/datasette/datasette-paste/commits/b16ded30471cdb2737026cf4c43a1c61438ebe19/

README.md

@@ -15,7 +15,19 @@ datasette install datasette-import
 ```
 ## Usage
 
-Usage instructions go here.
+This plugin adds a database action item called "Create table with imported data".
+
+This action is available to users with the `create-table` permission.
+
+It links to a page that allows users to upload files or paste in CSV, TSV or JSON data, and then use that to create and populate a new table in Datasette.
+
+CSV and TSV data must have headers on the first row.
+
+JSON data must be an array of objects with the same keys, or a container object object where one of the keys is an array of objects.
+
+## Credits
+
+The CSV and TSV parsing is performed using [Papa Parse](https://www.papaparse.com/), an MIT licensed JavaScript library that is bundled with this plugin.
 
 ## Development
 

datasette_import/__init__.py

@@ -1 +1,60 @@
-from datasette import hookimpl
+from datasette import hookimpl, Response, Forbidden
+
+
+async def import_create_table(datasette, request):
+    database = request.url_vars["database"]
+    if not await can_import(datasette, request.actor, database):
+        raise Forbidden("Permission denied to import data")
+    return Response.html(
+        await datasette.render_template(
+            "import_create_table.html",
+            {
+                "database": database,
+                "papaparse_url": datasette.urls.static_plugins(
+                    "datasette-import", "papaparse-5-4-1.min.js"
+                ),
+            },
+            request=request,
+        )
+    )
+
+
+@hookimpl
+def register_routes():
+    return [
+        (r"^/(?P<database>[^/]+)/-/import$", import_create_table),
+    ]
+
+
+@hookimpl
+def database_actions(datasette, actor, database):
+    async def inner():
+        if not await can_import(datasette, actor, database):
+            return []
+        return [
+            {
+                "href": datasette.urls.database(database) + "/-/import",
+                "label": "Create table with imported data",
+                "description": "Import using JSON, CSV or TSV data (e.g. from Google Sheets)",
+            }
+        ]
+
+    return inner
+
+
+async def can_import(datasette, actor, database_name, to_table=None):
+    if actor is None:
+        return False
+    if not to_table:
+        # Need create-table for database
+        can_create_table = await datasette.permission_allowed(
+            actor, "create-table", resource=database_name
+        )
+        if not can_create_table:
+            return False
+        return True
+    else:
+        # Need insert-row for that table
+        return await datasette.permission_allowed(
+            actor, "insert-row", resource=(database_name, to_table)
+        )