From 790e815e043994282669b1229b180dfeb1a68a41 Mon Sep 17 00:00:00 2001
From: Flancian <0@flancia.org>
Date: Sat, 23 Jan 2021 22:30:44 +0100
Subject: [PATCH] Initial implementation of go/node0/node1

---
 app/agora.py | 44 ++++++++++++++++++++++++++++++++++++++------
 app/db.py    | 34 ++++++++++++++++++++++++++++++++--
 2 files changed, 70 insertions(+), 8 deletions(-)

diff --git a/app/agora.py b/app/agora.py
index a5dc5a4..76c7b71 100644
--- a/app/agora.py
+++ b/app/agora.py
@@ -84,18 +84,50 @@ def go(node):
 
 @bp.route('/push/<node>/<other>')
 def push(node, other):
-    #import pprint
-    #response = []
-    #response.append("node: {}".format(node))
-    #response.append("other: {}".format(other))
     n = G.node(node)
     o = G.node(other)
     pushing = n.pushing(o)
-    #response.append(pushing)
 
-    #return Response(pprint.pformat(response))
     return Response(pushing)
 
+# [default action](https://anagora.org/node/default-action)
+@bp.route('/go/<node0>/<node1>')
+def default_action(node0, node1):
+    """Redirects to the URL in the given node in a block that starts with [[<action>]], if there is one."""
+    # TODO(flancian): all node-scoped stuff should move to actually use node objects.
+    # TODO(flancian): make [[go]] call this?
+    try:
+        n0 = db.nodes_by_wikilink(node0)
+    except KeyError:
+        return redirect("https://anagora.org/node/%s" % node0)
+    try:
+        n1 = db.nodes_by_wikilink(node1)
+    except KeyError:
+        return redirect("https://anagora.org/node/%s" % node1)
+
+    if len(n0) == 0 and len(n1) == 0:
+        # No nodes with this name.
+        # Redirect to composite node, which might exist and provides search.
+        return redirect(f'https://anagora.org/node/{node0}-{node1}')
+
+    if len(n0) != 0:
+        links = n0[0].filter(node1)
+    elif len(n1) != 0:
+        links += n1[0].filter(node0)
+
+    if len(links) == 0:
+        # No matching links found.
+        # Redirect to composite node, which might exist and provides search.
+        # TODO(flancian): flash an explanation :)
+        return redirect(f'https://anagora.org/node/{node0}-{node1}')
+
+    if len(links) > 1:
+        # TODO(flancian): to be implemented.
+        # Likely default to one of the links, show all of them but redirect to default within n seconds.
+        current_app.logger.warning('Code to manage nodes with more than one go link is not Not implemented.')
+
+    return redirect(links[0])
+
 @bp.route('/jump')
 def jump():
     """Redirects to a context; in "jump" mode, a node *always* exists (nodes map one to one to all possible queries)."""
diff --git a/app/db.py b/app/db.py
index 3add96b..ef6eac2 100644
--- a/app/db.py
+++ b/app/db.py
@@ -162,6 +162,13 @@ class Node:
             links.extend(subnode.go())
         return links 
 
+    def filter(self, other):
+        # There's surely a much better way to do this. Alas :)
+        links = []
+        for subnode in self.subnodes:
+            links.extend(subnode.filter(other))
+        return links 
+
     # The following section is particularly confusing.
     # Some functions return wikilinks, some return full blown nodes.
     # We probably want to converge on the latter.
@@ -352,6 +359,26 @@ class Subnode:
                 sanitized_golinks.append('https://' + golink)
         return sanitized_golinks
 
+    def filter(self, other):
+        """
+        other is a string.
+        returns a set of links contained in this subnode
+        in blocks of the form:
+        - [[other]] protocol://example.org/url
+
+        protocol defaults to https.
+        might pick up magic like resolving social network issues later :)
+        """
+        links = subnode_to_actions(self, other, blocks_only=True)
+        sanitized_links = []
+        for link in links:
+            if '://' in link:
+                sanitized_links.append(link)
+            else:
+                # hack hack.
+                sanitized_links.append('https://' + link)
+        return sanitized_links
+
     def pull_nodes(self):
         """
         returns a set of nodes pulled (anagora.org/node/pull) in this subnode
@@ -401,11 +428,14 @@ class VirtualSubnode(Subnode):
         self.node = self.wikilink
 
 
-def subnode_to_actions(subnode, action):
+def subnode_to_actions(subnode, action, blocks_only=False):
     # hack hack.
     if subnode.mediatype != 'text/plain':
         return []
-    action_regex ='\[\[' + action + '\]\] (.*?)$'
+    if blocks_only:
+        action_regex ='- \[\[' + action + '\]\] (.*?)$'
+    else:
+        action_regex ='\[\[' + action + '\]\] (.*?)$'
     content = subnode.content
     actions = []
     for line in content.splitlines():