From b67890d15d164c7affb2887e5737534628dc6227 Mon Sep 17 00:00:00 2001
From: Simon Willison <swillison@gmail.com>
Date: Wed, 29 Nov 2017 09:05:24 -0800
Subject: [PATCH] Auto-link column values that look like URLs

Refs #153
---
 datasette/app.py    |  5 +++++
 datasette/utils.py  | 15 +++++++++++++++
 tests/test_utils.py | 10 ++++++++++
 3 files changed, 30 insertions(+)

diff --git a/datasette/app.py b/datasette/app.py
index 82f2ddf2..397450f8 100644
--- a/datasette/app.py
+++ b/datasette/app.py
@@ -25,6 +25,7 @@ from .utils import (
     escape_sqlite_table_name,
     filters_should_redirect,
     get_all_foreign_keys,
+    is_url,
     InvalidSql,
     path_from_row_pks,
     path_with_added_args,
@@ -443,6 +444,10 @@ class RowTableShared(BaseView):
                     )
                 elif value is None:
                     display_value = jinja2.Markup('&nbsp;')
+                elif is_url(str(value).strip()):
+                    display_value = jinja2.Markup(
+                        '<a href="{url}">{url}</a>'.format(url=value.strip())
+                    )
                 else:
                     display_value = str(value)
                 cells.append({
diff --git a/datasette/utils.py b/datasette/utils.py
index e32d4f1f..2b567a05 100644
--- a/datasette/utils.py
+++ b/datasette/utils.py
@@ -441,3 +441,18 @@ def filters_should_redirect(special_args):
             ('_filter_value_{}'.format(number), None),
         ])
     return redirect_params
+
+
+whitespace_re = re.compile(r'\s')
+
+
+def is_url(value):
+    "Must start with http:// or https:// and contain JUST a URL"
+    if not isinstance(value, str):
+        return False
+    if not value.startswith('http://') and not value.startswith('https://'):
+        return False
+    # Any whitespace at all is invalid
+    if whitespace_re.search(value):
+        return False
+    return True
diff --git a/tests/test_utils.py b/tests/test_utils.py
index b7645014..18ce0971 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -151,3 +151,13 @@ def test_detect_fts():
     assert None is utils.detect_fts(conn, 'Dumb_Table')
     assert None is utils.detect_fts(conn, 'Test_View')
     assert 'Street_Tree_List_fts' == utils.detect_fts(conn, 'Street_Tree_List')
+
+
+@pytest.mark.parametrize('url,expected', [
+    ('http://www.google.com/', True),
+    ('https://example.com/', True),
+    ('www.google.com', False),
+    ('http://www.google.com/ is a search engine', False),
+])
+def test_is_url(url, expected):
+    assert expected == utils.is_url(url)