IncrementalActivityAdaptor.diff

diff --git a/src/eu/e43/impeller/content/PumpContentProvider.java b/src/eu/e43/impeller/content/PumpContentProvider.java
index a4df53d..0486b48 100644
--- a/src/eu/e43/impeller/content/PumpContentProvider.java
+++ b/src/eu/e43/impeller/content/PumpContentProvider.java
@@ -84,6 +84,7 @@ public class PumpContentProvider extends ContentProvider {
         ms_activityProjection.put("_json",          "activity_object._json");
         addStateProjections(ms_activityProjection,  "activity.object");
 
+        ms_feedProjection.put("_ID",                "feed_entries._ID");
         ms_feedProjection.put("id",                 "feed_entries.id");
         ms_feedProjection.put("published",          "feed_entries.published");
         ms_feedProjection.put("verb",               "activity.verb");
diff --git a/src/eu/e43/impeller/fragment/FeedFragment.java b/src/eu/e43/impeller/fragment/FeedFragment.java
index 3c6fdfd..c9c406b 100644
--- a/src/eu/e43/impeller/fragment/FeedFragment.java
+++ b/src/eu/e43/impeller/fragment/FeedFragment.java
@@ -37,8 +37,7 @@ import eu.e43.impeller.content.PumpContentProvider;
  */
 public class FeedFragment
         extends ListFragment
-        implements LoaderManager.LoaderCallbacks<Cursor>,
-        SyncStatusObserver
+        implements SyncStatusObserver
 {
     Account             m_account;
     ActivityAdapter     m_adapter;
@@ -77,9 +76,9 @@ public class FeedFragment
             m_account = getMainActivity().getAccount();
         }
 
-        m_adapter = new ActivityAdapter(getMainActivity());
-        getLoaderManager().initLoader(0, null, this);
+        m_adapter = new ActivityAdapter(getMainActivity(), m_feedId);
         setListAdapter(m_adapter);
+        getListView().setOnScrollListener(m_adapter);
 
         getMainActivity().onAddFeedFragment(this);
 
@@ -152,54 +151,6 @@ public class FeedFragment
     }
 
     @Override
-    public Loader<Cursor> onCreateLoader(int i, Bundle bundle) {
-        Uri uri =
-                Uri.parse(PumpContentProvider.FEED_URL).buildUpon()
-                        .appendPath(m_account.name)
-                        .build();
-
-        switch(m_feedId) {
-            case MAJOR_FEED:
-                return new CursorLoader(getActivity(), uri,
-                        new String[] { "_json", "replies", "likes", "shares" },
-                        "verb='share' OR (verb='post' AND object.objectType<>'comment')", null,
-                        "feed_entries._ID DESC");
-
-            case MINOR_FEED:
-                return new CursorLoader(getActivity(), uri,
-                        new String[] { "_json", "replies", "likes", "shares" },
-                        "NOT (verb='share' OR (verb='post' AND object.objectType<>'comment'))", null,
-                        "feed_entries._ID DESC");
-
-            case DIRECT_FEED:
-                throw new RuntimeException("Not yet implemented");
-
-            default:
-                throw new RuntimeException("Bad ID");
-        }
-    }
-
-    @Override
-    public void onLoadFinished(Loader<Cursor> objectLoader, Cursor o) {
-        if(objectLoader != null && o != null) {
-            o.setNotificationUri(
-                    getActivity().getContentResolver(),
-                    ((CursorLoader) objectLoader).getUri());
-        }
-        m_adapter.updateCursor(o);
-
-        if(m_jumpToSelection) {
-            int pos = getSelectedItemPosition();
-            if(pos >= 0) showItemByPosition(pos);
-        }
-    }
-
-    @Override
-    public void onLoaderReset(Loader<Cursor> objectLoader) {
-        m_adapter.updateCursor(null);
-    }
-
-    @Override
     public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
         inflater.inflate(R.menu.feed, menu);
         m_menu = menu;
diff --git a/src/eu/e43/impeller/uikit/ActivityAdapter.java b/src/eu/e43/impeller/uikit/ActivityAdapter.java
index bd7b36b..8d9804e 100644
--- a/src/eu/e43/impeller/uikit/ActivityAdapter.java
+++ b/src/eu/e43/impeller/uikit/ActivityAdapter.java
@@ -18,12 +18,21 @@ package eu.e43.impeller.uikit;
 import org.json.JSONException;
 import org.json.JSONObject;
 
+import android.content.ContentResolver;
+import android.content.CursorLoader;
+import android.database.ContentObserver;
 import android.database.Cursor;
+import android.database.DataSetObserver;
+import android.net.Uri;
+import android.os.AsyncTask;
+import android.os.Handler;
 import android.text.Html;
+import android.util.Log;
 import android.util.LruCache;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
+import android.widget.AbsListView;
 import android.widget.BaseAdapter;
 import android.widget.Checkable;
 import android.widget.FrameLayout;
@@ -31,47 +40,274 @@ import android.widget.ImageView;
 import android.widget.TextView;
 
 import java.util.HashMap;
+import java.util.Vector;
 
 import eu.e43.impeller.R;
 import eu.e43.impeller.Utils;
 import eu.e43.impeller.activity.ActivityWithAccount;
+import eu.e43.impeller.content.PumpContentProvider;
+import eu.e43.impeller.fragment.FeedFragment;
 
-public class ActivityAdapter extends BaseAdapter {
+public class ActivityAdapter
+        extends BaseAdapter
+        implements AbsListView.OnScrollListener
+{
 	static final String TAG = "ActivityAdapter";
-	
-    Cursor                      m_cursor;
+
+    FeedFragment.FeedID m_feedId;
 	ActivityWithAccount m_ctx;
+    Uri m_uri;
+
+    HashMap<String, Integer>    m_objectPositions = new HashMap<String, Integer>();;
+    boolean m_objectPositionsUpToDate = false;
 
-    HashMap<String, Integer>    m_objectPositions;
-    int m_lastScannedObjectPosition;
+    // Shown range
+    int m_rangeStart = 0;
+    Vector<JSONObject> m_objects = new Vector<JSONObject>();
 
-    LruCache<Integer, JSONObject> m_objects = new LruCache<Integer, JSONObject>(20);
+    // Observer registration
+    Observer m_observer;
+    int m_registrationCount = 0;
+    DataLoader m_dataLoader;
+    boolean m_isForwardUpdate;
+    private boolean m_isReplaceUpdate = false;
+    private boolean m_dataUpdatePending = false;
 
-	public ActivityAdapter(ActivityWithAccount ctx) {
-		m_cursor = null;
-		m_ctx  = ctx;
-        m_objectPositions = new HashMap<String, Integer>();
+    public ActivityAdapter(ActivityWithAccount ctx, FeedFragment.FeedID feedId) {
+		m_ctx      = ctx;
+        m_feedId   = feedId;
+
+        m_uri = Uri.parse(PumpContentProvider.FEED_URL).buildUpon()
+                .appendPath(m_ctx.getAccount().name)
+                .build();
+
+        m_observer = new Observer(null);
+        onScroll(null, 0, 0, 0);
 	}
 
+    @Override
+    public void registerDataSetObserver(DataSetObserver observer) {
+        super.registerDataSetObserver(observer);
+        m_registrationCount++;
+        if(m_registrationCount == 1) {
+            m_ctx.getContentResolver().registerContentObserver(m_uri, true, m_observer);
+            doDataUpdate();
+        }
+    }
+
+    @Override
+    public void unregisterDataSetObserver(DataSetObserver observer) {
+        super.unregisterDataSetObserver(observer);
+        m_registrationCount--;
+        if(m_registrationCount == 0) {
+            m_ctx.getContentResolver().unregisterContentObserver(m_observer);
+        }
+    }
+
     public int findItemById(String id) {
+        if(!m_objectPositionsUpToDate) {
+            for(int i = 0; i < m_objects.size(); i++) {
+                JSONObject act = m_objects.get(i);
+                JSONObject obj = act.optJSONObject("object");
+                if(obj != null) {
+                    String objId = obj.optString("id");
+                    if(objId != null)
+                        m_objectPositions.put(objId, i + m_rangeStart);
+                }
+            }
+            m_objectPositionsUpToDate = true;
+        }
+
         Integer pos = m_objectPositions.get(id);
-        if(pos == null) {
-            if(m_cursor == null) return -1;
-
-            if(!m_cursor.moveToPosition(m_lastScannedObjectPosition)) return -1;
-            do {
-                String objId = m_cursor.getString(1);
-                pos = m_cursor.getPosition();
-                m_objectPositions.put(id, pos);
-                if(id.equals(objId)) {
-                    m_lastScannedObjectPosition = pos;
-                    return pos;
+        if(pos == null) pos = -1;
+        return pos;
+    }
+
+    @Override
+    public void onScrollStateChanged(AbsListView absListView, int i) {}
+
+    // We want to hold ~20 items on either side of the current visible area "in memory"
+    // Validate that this is so
+
+    private int m_lastFirstVisible = 0;
+    private int m_lastVisibleCount = 0;
+
+    @Override
+    public void onScroll(AbsListView listView, int firstVisible, int visibleCount, int totalCount) {
+        m_lastFirstVisible = firstVisible;
+        m_lastVisibleCount = visibleCount;
+        int rangeEnd = m_rangeStart + m_objects.size();
+        int limit = 0;
+        int lastID = -666;
+
+        if(m_dataLoader != null) {
+            return;
+        } if(Math.max(firstVisible - 20, 0) < m_rangeStart) {
+            // Need update backwards
+            limit  = m_rangeStart - (firstVisible - 30);
+            lastID = m_objects.get(0).optInt("_ID");
+            m_isForwardUpdate = false;
+        } else if((firstVisible + visibleCount + 20) > rangeEnd) {
+            // Need update forwards
+            limit = (firstVisible + visibleCount + 30) - rangeEnd;
+            if(m_objects.isEmpty()) {
+                lastID = Integer.MAX_VALUE;
+            } else {
+                lastID = m_objects.lastElement().optInt("_ID");
+            }
+            m_isForwardUpdate = true;
+        } else return;
+
+        m_dataLoader = new DataLoader();
+        m_dataLoader.execute(lastID, 30);
+    }
+
+    private class DataLoader extends AsyncTask<Integer, Void, Vector<JSONObject>> {
+
+        @Override
+        protected Vector<JSONObject> doInBackground(Integer... integers) {
+            int lastID = integers[0];
+            int limit  = integers[1];
+
+            Log.d(TAG, "Want " + limit + " items from " + lastID + " forward? " + m_isForwardUpdate);
+
+            String searchClause, sortClause;
+            if(m_isForwardUpdate) {
+                searchClause = "feed_entries._ID < ?";
+                sortClause = "feed_entries._ID DESC ";
+            } else {
+                searchClause = "feed_entries._ID > ?";
+                sortClause = "feed_entries._ID ASC ";
+            }
+            sortClause += "LIMIT " + Integer.toString(limit);
+
+            ContentResolver cr = m_ctx.getContentResolver();
+            Cursor c;
+            switch(m_feedId) {
+                case MAJOR_FEED:
+                    c = cr.query(m_uri,
+                            new String[] { "_ID", "_json", "replies", "likes", "shares" },
+                            "(verb='share' OR (verb='post' AND object.objectType<>'comment')) AND " + searchClause,
+                            new String[] { Integer.toString(lastID) },
+                            sortClause);
+                    break;
+
+                case MINOR_FEED:
+                    c = cr.query(m_uri,
+                            new String[] { "_ID", "_json", "replies", "likes", "shares" },
+                            "NOT (verb='share' OR (verb='post' AND object.objectType<>'comment')) AND " + searchClause,
+                            new String[] { Integer.toString(lastID) },
+                            sortClause);
+                    break;
+
+                case DIRECT_FEED:
+                    throw new RuntimeException("Not yet implemented");
+
+                default:
+                    throw new RuntimeException("Bad ID");
+            }
+
+            try {
+                Vector<JSONObject> foundObjs = new Vector<JSONObject>();
+                while(c.moveToNext()) {
+                    int      id = c.getInt(0);
+                    String json = c.getString(1);
+                    int replies = c.getInt(2);
+                    int likes   = c.getInt(3);
+                    int shares  = c.getInt(4);
+
+                    JSONObject act = new JSONObject(json);
+                    act.put("_replies", replies);
+                    act.put("_likes",   likes);
+                    act.put("_shares",  shares);
+                    act.put("_ID",      id);
+
+                    if(m_isForwardUpdate) {
+                        foundObjs.add(act);
+                    } else {
+                        foundObjs.add(0, act);
+                    }
+                }
+
+                return foundObjs;
+            } catch(JSONException ex) {
+                throw new RuntimeException(ex);
+            } finally {
+                c.close();
+            }
+        }
+
+        @Override
+        protected void onPostExecute(Vector<JSONObject> jsonObjects) {
+            if(m_isReplaceUpdate) {
+                m_rangeStart -=
+                m_objects = jsonObjects;
+            } else if(m_isForwardUpdate) {
+                m_objects.addAll(jsonObjects);
+
+                if(m_objects.size() > 100) {
+                    int numToRemove = m_objects.size() - 100;
+                    m_objects = new Vector<JSONObject>(m_objects.subList(0, numToRemove));
+                    m_rangeStart += numToRemove;
+                }
+            } else {
+                m_objects.addAll(0, jsonObjects);
+                m_rangeStart -= jsonObjects.size();
+
+                if(m_objects.size() > 100) {
+                    m_objects = new Vector<JSONObject>(m_objects.subList(100, m_objects.size()));
                 }
-            } while(m_cursor.moveToNext());
-            return -1;
-        } else return pos;
+            }
+
+            Log.v(TAG, "Completed fetch, have " + m_objects.size() + " objects starting at " + m_rangeStart);
+
+            m_objectPositions.clear();
+            m_objectPositionsUpToDate = false;
+            m_dataLoader = null;
+            m_isReplaceUpdate = false;
+
+            if(m_dataUpdatePending) {
+                doDataUpdate();
+            } else {
+                onScroll(null, m_lastFirstVisible, m_lastVisibleCount, 0);
+            }
+            notifyDataSetChanged();
+        }
+    }
+
+    class Observer extends ContentObserver {
+        public Observer(Handler handler) {
+            super(handler);
+        }
+
+        @Override
+        public void onChange(boolean selfChange, Uri uri) {
+            if(m_dataLoader != null) {
+                m_dataUpdatePending = true;
+            } else {
+                doDataUpdate();
+            }
+        }
+    };
+
+    private void doDataUpdate() {
+        if(m_objects.size() == 0) {
+            onScroll(null, m_lastFirstVisible, m_lastVisibleCount, 0);
+            return;
+        }
+        m_dataUpdatePending = false;
+
+        m_dataLoader = new DataLoader();
+        m_isForwardUpdate = false;
+        m_isReplaceUpdate = true;
+
+        int startID = m_objects.lastElement().optInt("_ID");
+        int limit = Math.min(m_objects.size() + 20, 100);
+
+        m_dataLoader.execute(startID, limit);
     }
 
+
     private static class Wrapper extends FrameLayout implements Checkable {
         private boolean m_checked = false;
 
@@ -101,57 +337,40 @@ public class ActivityAdapter extends BaseAdapter {
             setChecked(!m_checked);
         }
     }
-
-    public void updateCursor(Cursor c) {
-        if(m_cursor != null && m_cursor != c) m_cursor.close();
-        m_cursor = c;
-        m_objects.evictAll();
-        m_lastScannedObjectPosition = 0;
-        m_objectPositions.clear();
-        notifyDataSetChanged();
-    }
 	
 	public void close() {
-        if(m_cursor != null)
-            m_cursor.close();
-		m_cursor = null;
+        if(m_dataLoader != null)
+            m_dataLoader.cancel(false);
 	}
 
 	@Override
 	public int getCount() {
-        if(m_cursor != null)
-		    return m_cursor.getCount();
-        else
-            return 0;
+        return m_rangeStart + m_objects.size();
 	}
 
-	@Override
-	public Object getItem(int position) {
-        JSONObject act = m_objects.get(position);
-        if(act != null) {
-            return act;
-        } else {
-            try {
-                m_cursor.moveToPosition(position);
-                act = new JSONObject(m_cursor.getString(0));
-                JSONObject obj = act.optJSONObject("object");
-                if(obj != null) {
-                    String id = obj.optString("id");
-                    if(id != null) {
-                        m_objectPositions.put(id, position);
-                    }
-                }
+    @Override
+    public boolean hasStableIds() {
+        return true;
+    }
 
-                act.put("_replies", m_cursor.getInt(1));
-                act.put("_likes",   m_cursor.getInt(2));
-                act.put("_shares",  m_cursor.getInt(3));
+    @Override
+    public long getItemId(int id) {
+        JSONObject obj = getItem(id);
+        if(obj != null) {
+            return obj.optInt("_ID");
+        } else {
+            return -id;
+        }
+    }
 
-                m_objects.put(position, act);
-                m_objectPositions.put(m_cursor.getString(1), position);
-                return act;
-            } catch(JSONException e) {
-                throw new RuntimeException(e);
-            }
+	@Override
+	public JSONObject getItem(int position) {
+        if(position < m_rangeStart) {
+            return null;
+        } else if(position >= m_rangeStart + m_objects.size()) {
+            return null;
+        } else {
+            return m_objects.get(position - m_rangeStart);
         }
 	}
 
@@ -165,7 +384,7 @@ public class ActivityAdapter extends BaseAdapter {
 	@Override
 	public int getViewTypeCount()
 	{
-		return 2;
+		return 3;
 	}
 	
 	@Override
@@ -176,6 +395,9 @@ public class ActivityAdapter extends BaseAdapter {
 	}
 	
 	public int getItemViewType(JSONObject act) {
+        if(act == null) {
+            return 2;
+        }
 		JSONObject obj = act.optJSONObject("object");
 		if(obj == null) {
 			return 1;
@@ -250,18 +472,22 @@ public class ActivityAdapter extends BaseAdapter {
 	    		imgDescription.setText(e.getMessage());
 	    	}
 	    	break;
+        case 2:
+            // null (not loaded)
+            if(v == null) {
+                LayoutInflater vi = LayoutInflater.from(m_ctx);
+                v = vi.inflate(android.R.layout.simple_list_item_1, null);
+                ((TextView)v).setText("Loading...");
+                v = new Wrapper(v);
+            }
 	    }
 
         int replies = json.optInt("_replies");
         int likes   = json.optInt("_likes");
         int shares  = json.optInt("_shares");
-        Utils.updateStatebar(v, replies, likes, shares);
+        if(type != 2)
+            Utils.updateStatebar(v, replies, likes, shares);
 		
 		return v;
 	}
-
-	@Override
-	public long getItemId(int id) {
-		return id;
-	}
 }