Implements stats feature (#114)

* Add StatsCommandParser

* Add StatsCommand

* Add methods in ParseUtil

* Add prefix in CliSyntax

* Add StatsFactory

* Add Statistic

* Add default statistic

* Add BarChartPanel

* Add LineChartPanel

* Add PieChartPanel

* Refactor code

* Add javadoc and refactor code

* Add update statistic when model is edited

* Refactor code for statistic in model

* Add statistic methods in modelstub in test

* Edit values return for barchart

* Add javadoc comments

* Add newline at EOF in fxml

* Add restrictions to number of days between start date and end date for stats command

* Refactor code

* Update user guide

* Add newline at EOF in data/exercisedatabases.json

* Change strings in ParserUtil and store as final String in Date and Statistic

Closes #71, closes #72 and closes #73

docs/UserGuide.adoc

@@ -215,8 +215,10 @@ Format: `stats t/CAT_NAME h/CHART_TYPE [s/START_DATE] [d/END_DATE]`
 
 ****
 * Supported chart types: Pie Chart, Line Chart, Bar Chart
+* Supported category: exercise, calories
 * If no `START_DATE` and `END_DATE` are provided, the recent 7 days of history will be used.
 * If any date is provided, both `START_DATE` and `END_DATE` dates must be there.
+* The maximum range between `START_DATE` and `END_DATE` is 31 days.
 ****
 
 Example:

src/main/java/seedu/exercise/logic/Logic.java

@@ -7,6 +7,7 @@
 import seedu.exercise.commons.core.State;
 import seedu.exercise.logic.commands.CommandResult;
 import seedu.exercise.logic.commands.exceptions.CommandException;
+import seedu.exercise.logic.commands.statistic.Statistic;
 import seedu.exercise.logic.parser.exceptions.ParseException;
 import seedu.exercise.model.ReadOnlyResourceBook;
 import seedu.exercise.model.conflict.Conflict;
@@ -79,6 +80,11 @@ public interface Logic {
      */
     void setGuiSettings(GuiSettings guiSettings);
 
+    /**
+     * Returns the Statistic object currently in focus.
+     */
+    Statistic getStatistic();
+
     /**
      * Returns the conflict that needs to be resolved in {@code Model}.
      *

src/main/java/seedu/exercise/logic/LogicManager.java

@@ -16,6 +16,7 @@
 import seedu.exercise.logic.commands.CommandResult;
 import seedu.exercise.logic.commands.ResolveCommand;
 import seedu.exercise.logic.commands.exceptions.CommandException;
+import seedu.exercise.logic.commands.statistic.Statistic;
 import seedu.exercise.logic.parser.ExerciseBookParser;
 import seedu.exercise.logic.parser.exceptions.ParseException;
 import seedu.exercise.model.Model;
@@ -114,9 +115,14 @@ public void setGuiSettings(GuiSettings guiSettings) {
     }
 
     @Override
+    public Statistic getStatistic() {
+        return model.getStatistic();
+    }
+
     public Conflict getConflict() {
         requireMainAppState(State.IN_CONFLICT);
         return model.getConflict();
+
     }
 
     /**

src/main/java/seedu/exercise/logic/commands/AddExerciseCommand.java

@@ -62,6 +62,7 @@ public CommandResult execute(Model model) throws CommandException {
         }
 
         model.addExercise(exerciseToAdd);
+        model.updateStatistic();
         eventPayload.put(KEY_EXERCISE_TO_ADD, exerciseToAdd);
         EventHistory.getInstance().addCommandToUndoStack(this);
         return new CommandResult(String.format(MESSAGE_SUCCESS, exerciseToAdd));
@@ -75,6 +76,7 @@ public EventPayload<Exercise> getPayload() {
     @Override
     public String getResourceType() {
         return RESOURCE_TYPE;
+
     }
 
     @Override

src/main/java/seedu/exercise/logic/commands/DeleteExerciseCommand.java

@@ -42,6 +42,7 @@ public CommandResult execute(Model model) throws CommandException {
         Exercise exerciseToDelete = lastShownList.get(targetIndex.getZeroBased());
         eventPayload.put(KEY_EXERCISE_TO_DELETE, exerciseToDelete);
         model.deleteExercise(exerciseToDelete);
+        model.updateStatistic();
         EventHistory.getInstance().addCommandToUndoStack(this);
         return new CommandResult(String.format(MESSAGE_DELETE_EXERCISE_SUCCESS, exerciseToDelete));
     }

src/main/java/seedu/exercise/logic/commands/EditCommand.java

@@ -96,6 +96,7 @@ public CommandResult execute(Model model) throws CommandException {
         model.setExercise(exerciseToEdit, editedExercise);
         EventHistory.getInstance().addCommandToUndoStack(this);
         model.updateFilteredExerciseList(Model.PREDICATE_SHOW_ALL_EXERCISES);
+        model.updateStatistic();
         return new CommandResult(String.format(MESSAGE_EDIT_EXERCISE_SUCCESS, editedExercise));
     }
 

src/main/java/seedu/exercise/logic/commands/RedoCommand.java

@@ -27,8 +27,8 @@ public CommandResult execute(Model model) throws CommandException {
         }
 
         Event eventToRedo = eventHistory.redo(model);
+        model.updateStatistic();
         return new CommandResult(
             String.format(MESSAGE_SUCCESS, eventToRedo));
     }
-
 }

src/main/java/seedu/exercise/logic/commands/UndoCommand.java

@@ -29,7 +29,7 @@ public CommandResult execute(Model model) throws CommandException {
         }
 
         Event eventToUndo = eventHistory.undo(model);
+        model.updateStatistic();
         return new CommandResult(String.format(MESSAGE_SUCCESS, eventToUndo));
     }
-
 }

src/main/java/seedu/exercise/logic/commands/statistic/Statistic.java

@@ -0,0 +1,106 @@
+package seedu.exercise.logic.commands.statistic;
+
+import static java.util.Objects.requireNonNull;
+import static seedu.exercise.commons.util.CollectionUtil.requireAllNonNull;
+
+import java.util.ArrayList;
+
+import seedu.exercise.model.property.Date;
+
+/**
+ * Represents a Statistic with data needed to generate chart.
+ */
+public class Statistic {
+
+    public static final String MESSAGE_INVALID_CATEGORY = "Category can only be \'exercise\' or \'calories\'";
+    public static final String MESSAGE_INVALID_CHART_TYPE = "Chart type can only be \'piechart\' or "
+             + "\'linechart\' or \'barchart\'";
+
+    private String category;
+    private String chart;
+    private Date startDate;
+    private Date endDate;
+    private ArrayList<String> properties;
+    private ArrayList<Double> values;
+
+    /**
+     * Every field must be present and not null.
+     */
+    public Statistic(String category, String chart, Date startDate, Date endDate,
+                     ArrayList<String> properties, ArrayList<Double> values) {
+        requireAllNonNull(category, chart, startDate, endDate, properties, values);
+        this.category = category;
+        this.chart = chart;
+        this.startDate = startDate;
+        this.endDate = endDate;
+        this.properties = properties;
+        this.values = values;
+    }
+
+    /**
+     * Resets the existing data of this {@code Statistic} with {@code newStatistic}.
+     */
+    public void resetData(Statistic newStatistic) {
+        requireNonNull(newStatistic);
+        setCategory(newStatistic.getCategory());
+        setChart(newStatistic.getChart());
+        setStartDate(newStatistic.getStartDate());
+        setEndDate(newStatistic.getEndDate());
+        setProperties(newStatistic.getProperties());
+        setValues(newStatistic.getValues());
+    }
+
+    private void setCategory(String category) {
+        requireNonNull(category);
+        this.category = category;
+    }
+
+    private void setChart(String chart) {
+        requireNonNull(chart);
+        this.chart = chart;
+    }
+
+    private void setStartDate(Date startDate) {
+        requireNonNull(startDate);
+        this.startDate = startDate;
+    }
+
+    private void setEndDate(Date endDate) {
+        requireNonNull(endDate);
+        this.endDate = endDate;
+    }
+
+    private void setProperties(ArrayList<String> properties) {
+        requireNonNull(properties);
+        this.properties = properties;
+    }
+
+    private void setValues(ArrayList<Double> values) {
+        requireNonNull(values);
+        this.values = values;
+    }
+
+    public String getCategory() {
+        return category;
+    }
+
+    public String getChart() {
+        return chart;
+    }
+
+    public Date getStartDate() {
+        return startDate;
+    }
+
+    public Date getEndDate() {
+        return endDate;
+    }
+
+    public ArrayList<String> getProperties() {
+        return properties;
+    }
+
+    public ArrayList<Double> getValues() {
+        return values;
+    }
+}

src/main/java/seedu/exercise/logic/commands/statistic/StatsCommand.java

@@ -0,0 +1,65 @@
+package seedu.exercise.logic.commands.statistic;
+
+import static java.util.Objects.requireNonNull;
+import static seedu.exercise.logic.parser.CliSyntax.PREFIX_CATEGORY;
+import static seedu.exercise.logic.parser.CliSyntax.PREFIX_CHART;
+import static seedu.exercise.logic.parser.CliSyntax.PREFIX_END_DATE;
+import static seedu.exercise.logic.parser.CliSyntax.PREFIX_START_DATE;
+
+import seedu.exercise.logic.commands.Command;
+import seedu.exercise.logic.commands.CommandResult;
+import seedu.exercise.model.Model;
+import seedu.exercise.model.ReadOnlyResourceBook;
+import seedu.exercise.model.property.Date;
+import seedu.exercise.model.resource.Exercise;
+
+/**
+ * Generate statistic with given parameters.
+ */
+public class StatsCommand extends Command {
+
+    public static final String COMMAND_WORD = "stats";
+
+    public static final String MESSAGE_STATS_DISPLAY_SUCCESS = "Chart displayed.";
+
+    public static final String MESSAGE_USAGE = "Parameters: "
+        + PREFIX_CATEGORY + "CATEGORY "
+        + PREFIX_CHART + "CHART TYPE "
+        + PREFIX_START_DATE + "START DATE "
+        + PREFIX_END_DATE + "END DATE " + "\n"
+        + "Example: " + COMMAND_WORD + " "
+        + PREFIX_CATEGORY + "calories "
+        + PREFIX_CHART + "barchart "
+        + PREFIX_START_DATE + "30/03/2019 "
+        + PREFIX_END_DATE + "05/04/2019 ";
+
+    private final String chart;
+    private final String category;
+    private final Date startDate;
+    private final Date endDate;
+
+    /**
+     * Creates a StatsCommand to generate statistic.
+     */
+    public StatsCommand(String chart, String category, Date startDate, Date endDate) {
+        this.chart = chart;
+        this.category = category;
+        this.startDate = startDate;
+        this.endDate = endDate;
+    }
+
+    @Override
+    public CommandResult execute(Model model) {
+        requireNonNull(model);
+        ReadOnlyResourceBook<Exercise> exercises = model.getExerciseBookData();
+        StatsFactory statsFactory = new StatsFactory(exercises, chart, category, startDate, endDate);
+        Statistic statistic = statsFactory.generateStatistic();
+        model.setStatistic(statistic);
+        return new CommandResult(MESSAGE_STATS_DISPLAY_SUCCESS);
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        return other == this;
+    }
+}