#117 #148 Constraints class loading JSON

app/src/main/java/org/redcross/openmapkit/Constraints.java

@@ -0,0 +1,71 @@
+package org.redcross.openmapkit;
+
+import com.spatialdev.osm.model.OSMElement;
+
+import org.apache.commons.io.FileUtils;
+import org.json.JSONObject;
+import org.redcross.openmapkit.odkcollect.ODKCollectHandler;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+
+public class Constraints {
+
+    // We're just keeping these guys static so they only get loaded up once.
+    private static JSONObject defaultConstraints;
+    private static Map<String, JSONObject> formConstraints = new HashMap<>();
+
+    private OSMElement osmElement;
+    private JSONObject activeFormConstraints;
+
+    boolean active = true;
+
+    public Constraints(OSMElement osmElement) {
+        this.osmElement = osmElement;
+
+        loadConstraintsJson();
+    }
+
+    private void loadConstraintsJson() {
+        if (defaultConstraints == null) {
+            try {
+                File defaultConstraintsFile = ExternalStorage.fetchConstraintsFile("default");
+                String defaultConstraintsStr = FileUtils.readFileToString(defaultConstraintsFile);
+                defaultConstraints = new JSONObject(defaultConstraintsStr);
+            } catch (Exception e) {
+                active = false;
+            }
+        }
+
+        if (!ODKCollectHandler.isODKCollectMode()) return;
+
+        String formId = ODKCollectHandler.getODKCollectData().getFormId();
+        activeFormConstraints = formConstraints.get(formId);
+        if (activeFormConstraints == null) {
+            try {
+                File formConstraintsFile = ExternalStorage.fetchConstraintsFile(formId);
+                String formConstraintsStr = FileUtils.readFileToString(formConstraintsFile);
+                JSONObject json = new JSONObject(formConstraintsStr);
+                formConstraints.put(formId, json);
+            } catch (Exception e) {
+                // do nothing
+                // We typically do not need a constraints specific to a given form,
+                // so this is normal.
+            }
+        }
+    }
+
+    /**
+     * If there is no default.json constraints file, we have nothing to work with,
+     * so the constraint functionality is disabled.
+     *
+     * @return boolean if the constraint is active
+     */
+    public boolean isActive() {
+        return active;
+    }
+
+
+}

app/src/main/java/org/redcross/openmapkit/ExternalStorage.java

@@ -6,6 +6,7 @@
 import android.util.Log;
 
 import org.apache.commons.io.FilenameUtils;
+import org.json.JSONObject;
 
 import java.io.BufferedReader;
 import java.io.File;
@@ -359,7 +360,12 @@ private static void copyAssetsFileToExternalStorage(Context context, String file
 
     }
 
-
+    public static File fetchConstraintsFile(String formName) {
+        File storageDir = Environment.getExternalStorageDirectory();
+        File appDir = new File(storageDir, APP_DIR);
+        File constraintsDir = new File(appDir, CONSTRAINTS_DIR);
+        return new File(constraintsDir, formName + ".json");
+    }