chore(Telemetry) #30079 : Move telemetry plugin into core - Part 1 (#…

…30520)

### Proposed Changes
* Migrates all the code from the `Telemetry` plug-in into our `core`
project.
* This is the first part of the process, so it just takes the code "as
is" from the plugin, and places it inside the `core` project. It only
includes a few adjustments on some Javadoc, code formatting, and the
addition of the `toString()` method in a few classes.
* These changes can safely co-exist with the current `Telemetry` plugin.
* In order to have a more effective Code Review process, the goal is to
have two pull requests:
  * The first one with the existing code from the plugin -- this one.
* The second one with the code changes in `core` that effectively add
the REST Endpoint, Web Interceptor, and Quartz Job which are currently
being added via the `Activator` class.

dotCMS/src/main/java/com/dotcms/telemetry/Metric.java

@@ -0,0 +1,83 @@
+package com.dotcms.telemetry;
+
+/**
+ * Represents all the information needed to identify a Metric:
+ * <ul>
+ *     <li>Name</li>
+ *     <li>Description</li>
+ *     <li>Category</li>
+ *     <li>Feature</li>
+ * </ul>
+ */
+public class Metric {
+
+    private final String name;
+    private final String description;
+    private final MetricCategory category;
+    private final MetricFeature feature;
+
+    public Metric(final Builder builder) {
+        this.name = builder.name;
+        this.description = builder.description;
+        this.category = builder.category;
+        this.feature = builder.feature;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public MetricCategory getCategory() {
+        return category;
+    }
+
+    public MetricFeature getFeature() {
+        return feature;
+    }
+
+    @Override
+    public String toString() {
+        return "Metric{" +
+                "name='" + name + '\'' +
+                ", description='" + description + '\'' +
+                ", category=" + category +
+                ", feature=" + feature +
+                '}';
+    }
+
+    public static class Builder {
+        String name;
+        String description;
+        MetricCategory category;
+        MetricFeature feature;
+
+        public Builder name(final String name) {
+            this.name = name;
+            return this;
+        }
+
+        public Builder description(final String description) {
+            this.description = description;
+            return this;
+        }
+
+        public Builder category(final MetricCategory category) {
+            this.category = category;
+            return this;
+        }
+
+        public Builder feature(final MetricFeature feature) {
+            this.feature = feature;
+            return this;
+        }
+
+        public Metric build() {
+            return new Metric(this);
+        }
+    }
+
+}

dotCMS/src/main/java/com/dotcms/telemetry/MetricCalculationError.java

@@ -0,0 +1,35 @@
+package com.dotcms.telemetry;
+
+import com.fasterxml.jackson.annotation.JsonUnwrapped;
+
+/**
+ * Represent an error that occurs while calculating the metric.
+ */
+public class MetricCalculationError {
+
+    @JsonUnwrapped
+    private final Metric metric;
+    private final String error;
+
+    public MetricCalculationError(Metric metric, String error) {
+        this.metric = metric;
+        this.error = error;
+    }
+
+    public Metric getType() {
+        return metric;
+    }
+
+    public String getError() {
+        return error;
+    }
+
+    @Override
+    public String toString() {
+        return "MetricCalculationError{" +
+                "metric=" + metric +
+                ", error='" + error + '\'' +
+                '}';
+    }
+
+}

dotCMS/src/main/java/com/dotcms/telemetry/MetricCategory.java

@@ -0,0 +1,27 @@
+package com.dotcms.telemetry;
+
+/**
+ * Represents the Metric Category where the {@link MetricType} belongs to
+ */
+public enum MetricCategory {
+
+    DIFFERENTIATING_FEATURES("Differentiating Features"),
+    PAID_FEATURES("Paid Features"),
+    PLATFORM_SPECIFIC_CUSTOMIZATION("Platform-Specific Customization"),
+    SOPHISTICATED_CONTENT_ARCHITECTURE("Sophisticated Content Architecture"),
+    POSITIVE_USER_EXPERIENCE("Positive User Experience (incl. content velocity)"),
+    PLATFORM_SPECIFIC_DEVELOPMENT("Platform-Specific Development"),
+    RECENT_ACTIVITY("Recent Activity"),
+    HISTORY_LEGACY_DEPRECATED_FEATURES("History (incl. legacy/deprecated features");
+
+    private final String label;
+
+    MetricCategory(final String label) {
+        this.label = label;
+    }
+
+    public String getLabel() {
+        return label;
+    }
+
+}

dotCMS/src/main/java/com/dotcms/telemetry/MetricFeature.java

@@ -0,0 +1,20 @@
+package com.dotcms.telemetry;
+
+/**
+ * Represents the dotCMS feature that the {@link MetricType} belongs to
+ */
+public enum MetricFeature {
+
+    CONTENTLETS,
+    LANGUAGES,
+    CONTENT_TYPES,
+    SITES,
+    URL_MAPS,
+    WORKFLOW,
+    USERS,
+    SITE_SEARCH,
+    IMAGE_API,
+    LAYOUT,
+    CONTENT_TYPE_FIELDS
+
+}

dotCMS/src/main/java/com/dotcms/telemetry/MetricType.java

@@ -0,0 +1,59 @@
+package com.dotcms.telemetry;
+
+import com.dotmarketing.exception.DotDataException;
+
+import java.util.Optional;
+
+/**
+ * This interface represents a Metric that needs to be calculated and included in a MetricSnapshot.
+ * For each of these a new concrete class implements this interface must be created. The interface
+ * provides a set of methods to define the metadata for the Metric, such as its name, description,
+ * category, and feature. It also includes a method to calculate the Metric's value.
+ * <ul>
+ *     <li>Metadata Methods: The getName, getDescription, getCategory, and getFeature methods can
+ *     be overridden to set the metadata for a specific Metric. The getMetric method creates a
+ *     Metric object using the values returned by these methods. The Metric class represents the
+ *     metadata of a single Metric.</li>
+ *     <li>Value Calculation Method: You can override the getValue method to define how the
+ *     Metric value is calculated. This method returns an object, so the value can be of any type.
+ *     To perform this calculation, you can use SQL queries, dotCMS API methods, Java core code, or
+ *     any other approach that suits your needs.</li>
+ * </ul>
+ * <p>Some of the Metrics to collect are:</p>
+ * <ul>
+ *     <li>Count of workflow schemes</li>
+ *     <li>Count of Site Search indexes</li>
+ *     <li>Count of sites</li>
+ *     <li>Count of content types with URL maps</li>
+ *     <li>etc</li>
+ * </ul>
+ *
+ * @see MetricCategory
+ * @see MetricFeature
+ */
+public interface MetricType {
+
+    String getName();
+
+    String getDescription();
+
+    MetricCategory getCategory();
+
+    MetricFeature getFeature();
+
+    Optional<Object> getValue();
+
+    default Metric getMetric() {
+        return new Metric.Builder()
+                .name(getName())
+                .description(getDescription())
+                .category(getCategory())
+                .feature(getFeature())
+                .build();
+    }
+
+    default Optional<MetricValue> getStat() throws DotDataException {
+        return getValue().map(o -> new MetricValue(this.getMetric(), o));
+    }
+
+}

dotCMS/src/main/java/com/dotcms/telemetry/MetricValue.java

@@ -0,0 +1,62 @@
+package com.dotcms.telemetry;
+
+import com.fasterxml.jackson.annotation.JsonIgnore;
+import com.fasterxml.jackson.annotation.JsonUnwrapped;
+import org.apache.commons.lang.math.NumberUtils;
+
+import java.text.DecimalFormat;
+
+/**
+ * Represents the value for a {@link MetricType}
+ */
+public class MetricValue {
+
+    private static final DecimalFormat FORMAT = new DecimalFormat("0.##");
+
+    @JsonUnwrapped
+    final Metric metric;
+
+    final Object value;
+
+    public MetricValue(final Metric metric, final Object value) {
+        this.metric = metric;
+        this.value = value;
+    }
+
+    /**
+     * Check if the value of the Metric is a numeric value.
+     *
+     * @return true if the value is a numeric value
+     */
+    @JsonIgnore
+    public boolean isNumeric() {
+        return NumberUtils.isNumber(value.toString());
+    }
+
+    public Metric getMetric() {
+        return metric;
+    }
+
+    /**
+     * Return the value of the Metric if it is a numeric value then return it as a String formatted
+     * with two decimals
+     *
+     * @return
+     */
+    public Object getValue() {
+        if (isNumeric()) {
+            return FORMAT.format(Double.parseDouble(value.toString()));
+        } else {
+            return value;
+        }
+    }
+
+    @Override
+    public String toString() {
+        return "MetricValue{" +
+                "metric=" + metric +
+                ", value=" + value +
+                '}';
+    }
+
+}

dotCMS/src/main/java/com/dotcms/telemetry/MetricsSnapshot.java

@@ -0,0 +1,93 @@
+package com.dotcms.telemetry;
+
+import com.fasterxml.jackson.annotation.JsonAnyGetter;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Represents a snapshot of metric statistics, including all calculated metrics, separated into
+ * numeric and non-numeric categories. It also contains a list of errors, indicating any metrics
+ * that encountered exceptions during calculation.
+ */
+public class MetricsSnapshot {
+
+    /**
+     * Collection of Numeric Metrics
+     */
+    final Collection<MetricValue> stats;
+
+    /**
+     * Collection of No Numeric Metrics
+     */
+    final Collection<MetricValue> notNumericStats;
+
+    /**
+     * Metric that thrown an Exception during the calculation process
+     */
+    final Collection<MetricCalculationError> errors;
+
+    public MetricsSnapshot(final Builder builder) {
+        this.stats = builder.stats;
+        this.notNumericStats = builder.notNumericStats;
+        this.errors = builder.errors;
+    }
+
+    @JsonProperty
+    public Collection<MetricValue> getStats() {
+        return stats;
+    }
+
+    @JsonProperty
+    public Collection<MetricCalculationError> getErrors() {
+        return errors;
+    }
+
+    @JsonAnyGetter
+    public Map<String, String> getNotNumericStats() {
+        final Map<String, String> result = new HashMap<>();
+
+        for (final MetricValue stat : notNumericStats) {
+            result.put(stat.getMetric().getName(), stat.getValue().toString());
+        }
+
+        return result;
+    }
+
+    @Override
+    public String toString() {
+        return "MetricsSnapshot{" +
+                "stats=" + stats +
+                ", notNumericStats=" + notNumericStats +
+                ", errors=" + errors +
+                '}';
+    }
+
+    public static class Builder {
+        private Collection<MetricValue> stats;
+        private Collection<MetricValue> notNumericStats;
+        private Collection<MetricCalculationError> errors;
+
+        public Builder stats(Collection<MetricValue> stats) {
+            this.stats = stats;
+            return this;
+        }
+
+        public Builder notNumericStats(Collection<MetricValue> notNumericStats) {
+            this.notNumericStats = notNumericStats;
+            return this;
+        }
+
+        public Builder errors(Collection<MetricCalculationError> errors) {
+            this.errors = errors;
+            return this;
+        }
+
+        public MetricsSnapshot build() {
+            return new MetricsSnapshot(this);
+        }
+    }
+
+}