Add documentation on how to overcome hardcoded vaccine schedules

- Add sample code updating the prerequisite offset days for MR 2 vaccine schedule in the sample app

README.md

@@ -12,6 +12,8 @@
    * [Pre-requisites](#pre-requisites)
    * [Installation Devices](#installation-devices)
    * [How to install](#how-to-install)
+* [Gotcha's when using the library](#gotchas-when-using-the-library)
+   * Vaccine schedule not changing after changing the vaccines.json file
 
 # Introduction
 
@@ -188,4 +190,13 @@ This can be done via the setting below in your implementation's _app.properties_
 
 ```
 vaccine.relaxation.days=2
-```
+```
+
+## Gotcha's when using the library
+
+1. Vaccine schedule not changing after changing the `vaccines.json` file!
+
+Some of the vaccine configurations are not dependent on change done to the `vaccines.json`, in this case you should check the current configuration [here](https://github.com/OpenSRP/opensrp-client-immunization/blob/67a15611b53c55e111a0b7bff4f32a02c27b2920/opensrp-immunization/src/main/java/org/smartregister/immunization/db/VaccineRepo.java#L37)
+and come-up with the correct configuration. Next step is to add the custom configuration to library. You should loop through the configurations array from `VaccineRepo.Vaccine[] ImmunizationLibrary.getInstance().getVaccines()` and add 
+modify the properties of the vaccine enum to whatever you need. You should then use `ImmunizationLibrary.getInstance().setVaccines(VaccineRepo.Vaccine[])`
+to re-set all the vaccine configs using the configurations array you retrieved.

sample/src/main/java/org/smartregister/immunization/sample/application/SampleApplication.java

@@ -5,15 +5,18 @@
 import org.smartregister.Context;
 import org.smartregister.CoreLibrary;
 import org.smartregister.immunization.ImmunizationLibrary;
+import org.smartregister.immunization.db.VaccineRepo;
 import org.smartregister.immunization.domain.VaccineSchedule;
 import org.smartregister.immunization.domain.jsonmapping.Vaccine;
 import org.smartregister.immunization.domain.jsonmapping.VaccineGroup;
 import org.smartregister.immunization.sample.BuildConfig;
 import org.smartregister.immunization.sample.repository.SampleRepository;
+import org.smartregister.immunization.sample.util.VaccineDuplicate;
 import org.smartregister.immunization.util.VaccinatorUtils;
 import org.smartregister.repository.Repository;
 import org.smartregister.view.activity.DrishtiApplication;
 
+import java.util.HashMap;
 import java.util.List;
 
 import static org.smartregister.util.Log.logError;
@@ -38,8 +41,31 @@ public void onCreate() {
         CoreLibrary.init(context);
         ImmunizationLibrary.init(context, getRepository(), null, BuildConfig.VERSION_CODE, BuildConfig.DATABASE_VERSION);
 
+        // This method updates some of the hardcoded vaccine definitions in VaccineRepo.Vaccine enum
+        updateHardcodedVaccineDefinition();
+
         initOfflineSchedules();
+    }
+
+    private void updateHardcodedVaccineDefinition() {
+        VaccineRepo.Vaccine[] vaccines = ImmunizationLibrary.getInstance().getVaccines();
+
+        HashMap<String, VaccineDuplicate> replacementVaccines = new HashMap<>();
+        replacementVaccines.put("MR 2", new VaccineDuplicate("MR 2", VaccineRepo.Vaccine.mr1, -1, 548, 183, "child"));
+
+        for (VaccineRepo.Vaccine vaccine: vaccines) {
+            if (replacementVaccines.containsKey(vaccine.display())) {
+                VaccineDuplicate vaccineDuplicate = replacementVaccines.get(vaccine.display());
+
+                vaccine.setCategory(vaccineDuplicate.category());
+                vaccine.setExpiryDays(vaccineDuplicate.expiryDays());
+                vaccine.setMilestoneGapDays(vaccineDuplicate.milestoneGapDays());
+                vaccine.setPrerequisite(vaccineDuplicate.prerequisite());
+                vaccine.setPrerequisiteGapDays(vaccineDuplicate.prerequisiteGapDays());
+            }
+        }
 
+        ImmunizationLibrary.getInstance().setVaccines(vaccines);
     }
 
     public static synchronized SampleApplication getInstance() {

sample/src/main/java/org/smartregister/immunization/sample/util/VaccineDuplicate.java

@@ -0,0 +1,52 @@
+package org.smartregister.immunization.sample.util;
+
+import org.smartregister.immunization.db.VaccineRepo;
+
+/**
+ * Created by Ephraim Kigamba - ekigamba@ona.io on 2019-08-29
+ */
+
+public class VaccineDuplicate {
+
+    private String display;
+    private VaccineRepo.Vaccine prerequisite;
+    private int expiryDays;
+    private int milestoneGapDays;
+    private int prerequisiteGapDays;
+    private String category;
+
+    public VaccineDuplicate(String display, VaccineRepo.Vaccine prerequisite, int expiryDays,
+                            int milestoneGapDays, int prerequisiteGapDays, String category) {
+        this.display = display;
+        this.prerequisite = prerequisite;
+        this.expiryDays = expiryDays;
+        this.milestoneGapDays = milestoneGapDays;
+        this.prerequisiteGapDays = prerequisiteGapDays;
+        this.category = category;
+    }
+
+    public String display() {
+        return display;
+    }
+
+    public VaccineRepo.Vaccine prerequisite() {
+        return prerequisite;
+    }
+
+    public int expiryDays() {
+        return expiryDays;
+    }
+
+    public int milestoneGapDays() {
+        return milestoneGapDays;
+    }
+
+    public int prerequisiteGapDays() {
+        return prerequisiteGapDays;
+    }
+
+    public String category() {
+        return category;
+    }
+
+}