Filter.java

package org.datadog.jmxfetch;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Set;
import java.util.regex.Pattern;


class Filter {
    HashMap<String, Object> filter;
    Pattern domainRegex;
    ArrayList<Pattern> beanRegexes = null;
    ArrayList<String> excludeTags = null;
    HashMap<String, String> additionalTags = null;

    /**
     * A simple class to manipulate include/exclude filter elements more easily
     * A filter may contain:
     * - A domain (key: 'domain') or a domain regex (key: 'domain_regex')
     * - Bean names (key: 'bean' or 'bean_name') or bean regexes (key: 'bean_regex')
     * - Attributes (key: 'attribute')
     * - Additional bean parameters (other keys)
     */

    @SuppressWarnings("unchecked")
    public Filter(Object filter) {
        HashMap<String, Object> castFilter;
        if (filter != null) {
            castFilter = (HashMap<String, Object>) filter;
        } else {
            castFilter = new HashMap<String, Object>();
        }
        this.filter = castFilter;
    }

    public String toString() {
        return this.filter.toString();
    }

    public Set<String> keySet() {
        return filter.keySet();
    }

    @SuppressWarnings({ "unchecked", "serial" })
    private static ArrayList<String> toStringArrayList(final Object toCast) {
        // Return object as an ArrayList wherever it's defined as
        // list or not
        //
        // ### Example
        // object:
        //                  - firstValue
        //                  - secondValue
        // ### OR
        // object: singleValue
        // ###
        try{
            return (ArrayList<String>) toCast;
        } catch (ClassCastException e){
            return new ArrayList<String>() {{
                add(((String) toCast));
            }};
        }
    }


    public ArrayList<String> getBeanNames() {
        if (isEmptyBeanName()){
            return new ArrayList<String>();
        }
        final Object beanNames = (filter.get("bean") != null) ? filter.get("bean") : filter.get("bean_name");
        // Return bean names as an ArrayList wherever it's defined as
        // list or not
        //
        // ### Example
        // bean:
        //                  - org.apache.cassandra.db:type=Caches,keyspace=system,cache=HintsColumnFamilyKeyCache
        //                  - org.datadog.jmxfetch.test:type=type=SimpleTestJavaApp
        // ### OR
        // bean: org.datadog.jmxfetch.test:type=type=SimpleTestJavaApp
        // ###
        return toStringArrayList(beanNames);
    }

    private static ArrayList<Pattern> toPatternArrayList(final Object toCast) {
        ArrayList<Pattern> patternArrayList = new ArrayList<Pattern>();
        ArrayList<String> stringArrayList = toStringArrayList(toCast);
        for (String string : stringArrayList) {
            patternArrayList.add(Pattern.compile(string));
        }

        return patternArrayList;
    }

    public ArrayList<Pattern> getBeanRegexes() {
        // Return bean regexes as an ArrayList of Pattern whether it's defined as
        // a list or not

        if (this.beanRegexes == null) {
            if (filter.get("bean_regex") == null){
                this.beanRegexes = new ArrayList<Pattern>();
            } else {
                final Object beanRegexNames = filter.get("bean_regex");
                this.beanRegexes = toPatternArrayList(beanRegexNames);
            }
        }

        return this.beanRegexes;
    }

    public ArrayList<String> getExcludeTags() {
        // Return excluded tags  as an ArrayList whether it's defined as a list or not

        if (this.excludeTags == null) {
            if (filter.get("exclude_tags") == null){
                this.excludeTags = new ArrayList<String>();
            } else {
                final Object exclude_tags = filter.get("exclude_tags");
                this.excludeTags = toStringArrayList(exclude_tags);
            }
        }

        return this.excludeTags;
    }

    public HashMap<String, String> getAdditionalTags() {
        // Return additional tags

        if (this.additionalTags == null) {
            if (filter.get("tags") == null){
                this.additionalTags = new HashMap<String, String>();
            } else {
                this.additionalTags = (HashMap<String, String>)filter.get("tags");
            }
        }

        return this.additionalTags;
    }

    public String getDomain() {
        return (String) filter.get("domain");
    }

    public Pattern getDomainRegex() {
        if (this.filter.get("domain_regex") == null) {
            return null;
        }

        if (this.domainRegex == null) {
            this.domainRegex = Pattern.compile((String) this.filter.get("domain_regex"));
        }

        return this.domainRegex;
    }

    public Object getAttribute() {
        return filter.get("attribute");
    }

    public ArrayList<String> getParameterValues(String parameterName) {
        // Return bean attributes values as an ArrayList wherever it's defined as
        // list or not
        //
        // ### Example
        // bean_parameter:
        //                  - exampleType1
        //                  - exampleType2
        // ### OR
        // bean_parameter: onlyOneType
        // ###
        final Object beanValues = filter.get(parameterName);
        return toStringArrayList(beanValues);
    }

    public boolean isEmptyBeanName() {
        return (filter.get("bean") == null && filter.get("bean_name") == null);
    }

}