Update Developer Guide with the latest documentation

docs/DeveloperGuide.md

@@ -237,7 +237,73 @@ The following activity diagram summarizes what happens when a user executes a ne
   * Pros: Will use less memory (e.g. for `delete`, just save the person being deleted).
   * Cons: We must ensure that the implementation of each individual command are correct.
 
-_{more aspects and alternatives to be added}_
+_{more aspects and alternatives to be added}
+
+### Add a patient
+
+#### Implementation
+
+The add patient feature is facilitated by `AddCommand`, `AddCommandParser` and `Person`. 
+
+Given below is an example usage scenario and how the add patient feature behaves at each step.
+
+Step 1. The user launches the application for the first time.
+
+Step 2. The user executes an Add Command (e.g. 'add n\Alice ic\A0055679T ad\01/01/2022 dob\01/01/2002 w\WA') to add a new patient to the address book. 
+
+n\: Indicates the name of the patient
+ic\: Indicates the NRIC of the patient
+ad\: Indicates the admission date of the patient
+dob\: Indicates the date of birth of the patient
+w\: Indicates the ward of the patient is currently in
+
+The `AddCommandParser` parses the user input, creating a new `AddCommand` object. 
+The `AddCommand` object then creates a new `Person` object with the parsed details.
+
+
+### List by tags and/or ward feature
+
+#### Implementation
+
+The filter by tags and/or ward mechanism is facilitated by `ListCommand`, `ListCommandParser` and `ListKeywordsPredicate`. Additionally, it implements the following operations:
+
+* `ListCommandParser#parse()` — Parses user input and creates a `ListCommand` object.
+
+Given below is an example usage scenario and how the filter by tags and/or ward mechanism behaves at each step.
+
+Step 1. The user launches the application for the first time.
+
+Step 2. The user executes `list t\diabetes` command to list patients with the diabetes tag in the address book. The `ListCommandParser` parses the user input, creating a new `ListCommand` and `ListKeywordPredicate` object as `predicate` (since there are keywords provided). `predicate` will filter the list of patients in the address book to only show patients with the diabetes tag. 
+
+![ListObjectDiagram](images/ListObjectDiagram.png)
+
+Step 3. For each patient in the address book, the `predicate` object will be passed to `Model#updateFilteredPersonList` check if the patient has the diabetes tag. If the patient has the diabetes tag, the patient will be shown in the list of patients.
+
+The following activity diagram summarizes what happens when a user executes a new command:
+
+<img src="images/ListCommandActivityDiagram.png" width="250" />
+
+#### Design considerations:
+
+**Aspect: Command to filter:**
+
+* **Alternative 1 (current choice):** Add the parameters to list command instead of find.
+    * Pros: More appropriate as `list` will produce a useful list of relevant contacts, whereas `find` implies that only one useful result is expected.
+    * Cons: May not have such a clear distinction between `list` and `find`, as user just wants to search for results.
+
+* **Alternative 2:** Add parameters to find command instead of list.
+    * Pros: Easy to use, one command will perform all search.
+    * Cons: Unable to differentiate usefulness.
+
+**Aspect: Filter by a ward or many wards:**
+
+* **Alternative 1 (current choice):** Allow filtering only by at most 1 ward input.
+    * Pros: More targeted; Nurses will only refer to the ward that they are in or are visiting. Otherwise, will filter across all wards.
+    * Cons: Does not allow looking at specific, multiple wards.
+
+* **Alternative 2:** Allow multiple ward tags.
+    * Pros: Easy to be more specific.
+    * Cons: Not relevant for the nurses use case. Allowing more wards also make it harder to filter fast.
 
 ### \[Proposed\] Data archiving
 

docs/diagrams/ListCommandActivityDiagram.puml

@@ -0,0 +1,21 @@
+@startuml
+skin rose
+skinparam ActivityFontSize 15
+skinparam ArrowFontSize 12
+
+start
+:User executes command;
+
+'Since the beta syntax does not support placing the condition outside the
+'diamond we place it as the true branch instead.
+
+if () then ([command has parameters])
+    :Create a new predicate;
+    :Filter the addressbook
+    using the predicate;
+    :Show the filtered contacts;
+else ([else])
+    : Show all contacts;
+endif
+stop
+@enduml

docs/diagrams/ListObjectDiagram.puml

@@ -0,0 +1,16 @@
+@startuml
+!include style.puml
+skinparam arrowThickness 1.1
+skinparam arrowColor MODEL_COLOR
+skinparam classBackgroundColor MODEL_COLOR
+
+class State1 as "<u>:ListCommand</u>"
+class State2 as "<u>:ListKeywordPredicate</u>"
+class State3 as "<u>wardKeyword:String</u>"
+class State4 as "<u>tagKeywords:List<String></u>"
+
+State1 -down-> "0..1" State2
+State2 -right-> "1" State3
+State2 -down-> "1" State4
+
+@enduml