Merge branch 'prep-providers-for-download-progress' into 'master'

Improve order by/selection logic for database layer.

This was extracted from the postponed !311.

The order by stuff previously only allowed specifying a particular field. We should also be able to sort based on arbitrary expressions, and such expressions will require the ability to bind arguments using the "?" syntax. This change provides a Java abstraction for the order by, and improves the handling of selection arguments that need to bind to "?" so that both the selection (i.e. `WHERE` clause) and the `ORDER BY` clause can provide arguments as required.

See merge request !329

app/src/main/java/org/fdroid/fdroid/data/ApkProvider.java

@@ -488,10 +488,10 @@ public class ApkProvider extends FDroidProvider {
         for (final String field : projection) {
             queryBuilder.addField(field);
         }
-        queryBuilder.addSelection(query.getSelection());
+        queryBuilder.addSelection(query);
         queryBuilder.addOrderBy(sortOrder);
 
-        Cursor cursor = db().rawQuery(queryBuilder.toString(), query.getArgs());
+        Cursor cursor = db().rawQuery(queryBuilder.toString(), queryBuilder.getArgs());
         cursor.setNotificationUri(getContext().getContentResolver(), uri);
         return cursor;
     }

app/src/main/java/org/fdroid/fdroid/data/AppProvider.java

@@ -317,7 +317,7 @@ public class AppProvider extends FDroidProvider {
         }
 
         public void addSelection(AppQuerySelection selection) {
-            addSelection(selection.getSelection());
+            super.addSelection(selection);
             if (selection.naturalJoinToInstalled()) {
                 naturalJoinToInstalledTable();
             }
@@ -828,12 +828,11 @@ public class AppProvider extends FDroidProvider {
         }
 
         Query query = new Query();
-
         query.addSelection(selection);
         query.addFields(projection); // TODO: Make the order of addFields/addSelection not dependent on each other...
         query.addOrderBy(sortOrder);
 
-        Cursor cursor = db().rawQuery(query.toString(), selection.getArgs());
+        Cursor cursor = db().rawQuery(query.toString(), query.getArgs());
         cursor.setNotificationUri(getContext().getContentResolver(), uri);
         return cursor;
     }

app/src/main/java/org/fdroid/fdroid/data/OrderClause.java

@@ -0,0 +1,25 @@
+package org.fdroid.fdroid.data;
+
+public class OrderClause {
+
+    public final String expression;
+    private String[] args;
+
+    public OrderClause(String expression) {
+        this.expression = expression;
+    }
+
+    public OrderClause(String field, String[] args, boolean isAscending) {
+        this.expression = field + " " + (isAscending ? "ASC" : "DESC");
+        this.args = args;
+    }
+
+    @Override
+    public String toString() {
+        return expression;
+    }
+
+    public String[] getArgs() {
+        return args;
+    }
+}

app/src/main/java/org/fdroid/fdroid/data/QueryBuilder.java

@@ -1,5 +1,8 @@
 package org.fdroid.fdroid.data;
 
+import android.support.annotation.Nullable;
+import android.text.TextUtils;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -8,7 +11,8 @@ abstract class QueryBuilder {
     private final List<String> fields = new ArrayList<>();
     private final StringBuilder tables = new StringBuilder(getRequiredTables());
     private String selection;
-    private String orderBy;
+    private String[] selectionArgs;
+    private final List<OrderClause> orderBys = new ArrayList<>();
 
     protected abstract String getRequiredTables();
 
@@ -58,12 +62,51 @@ abstract class QueryBuilder {
         fields.add(fieldBuilder.toString());
     }
 
-    public void addSelection(String selection) {
-        this.selection = selection;
+    public void addSelection(@Nullable QuerySelection selection) {
+        if (selection == null) {
+            this.selection = null;
+            this.selectionArgs = null;
+        } else {
+            this.selection = selection.getSelection();
+            this.selectionArgs = selection.getArgs();
+        }
     }
 
+    /**
+     * Add an order by, which includes an expression and optionally ASC or DESC afterward.
+     */
     public void addOrderBy(String orderBy) {
-        this.orderBy = orderBy;
+        if (orderBy != null) {
+            orderBys.add(new OrderClause(orderBy));
+        }
+    }
+
+    public void addOrderBy(@Nullable OrderClause orderClause) {
+        if (orderClause != null) {
+            orderBys.add(orderClause);
+        }
+    }
+
+    public String[] getArgs() {
+        List<String> args = new ArrayList<>();
+
+        if (selectionArgs != null) {
+            for (String arg : selectionArgs) {
+                args.add(arg);
+            }
+        }
+
+        for (OrderClause orderBy : orderBys) {
+            if (orderBy.getArgs() != null) {
+                for (String arg : orderBy.getArgs()) {
+                    args.add(arg);
+                }
+            }
+        }
+
+        String[] strings = new String[args.size()];
+        args.toArray(strings);
+        return strings;
     }
 
     protected final void leftJoin(String table, String alias, String condition) {
@@ -94,14 +137,7 @@ abstract class QueryBuilder {
     }
 
     private String fieldsSql() {
-        StringBuilder sb = new StringBuilder();
-        for (int i = 0; i < fields.size(); i++) {
-            if (i > 0) {
-                sb.append(',');
-            }
-            sb.append(fields.get(i));
-        }
-        return sb.toString();
+        return TextUtils.join(", ", fields);
     }
 
     private String whereSql() {
@@ -109,7 +145,11 @@ abstract class QueryBuilder {
     }
 
     private String orderBySql() {
-        return orderBy != null ? " ORDER BY " + orderBy : "";
+        if (orderBys.size() == 0) {
+            return "";
+        } else {
+            return " ORDER BY " + TextUtils.join(", ", orderBys);
+        }
     }
 
     private String groupBySql() {

app/src/main/java/org/fdroid/fdroid/data/QuerySelection.java

@@ -19,7 +19,7 @@ public class QuerySelection {
 
     public QuerySelection(String selection) {
         this.selection = selection;
-        this.args = null;
+        this.args = new String[] {};
     }
 
     public QuerySelection(String selection, String[] args) {