package com.yahoo.metrics;

/**
 * @author gjoranv
 */
public enum Unit {

    BINARY(BaseUnit.BINARY, "Zero or one. Zero typically indicate \"false\" while one indicate \"true\""),
    BUCKET(BaseUnit.BUCKET, "A chunk of documents managed by a distributor service"),
    BYTE(BaseUnit.BYTE, "A collection of 8 bits"),
    BYTE_PER_SECOND(BaseUnit.BYTE, BaseUnit.SECOND, "A unit of storage capable of holding 8 bits"),
    CONNECTION(BaseUnit.CONNECTION, "A link used for communication between a client and a server"),
    DOCUMENT(BaseUnit.DOCUMENT, "Vespa document, a collection of fields defined in a schema file"),
    DOCUMENTID(BaseUnit.DOCUMENTID, "A unique document identifier"),
    FAILURE(BaseUnit.FAILURE, "Failures, typically for requests, operations or nodes"),
    FILE(BaseUnit.FILE, "Data file stored on the disk on a node"),
    FRACTION(BaseUnit.FRACTION, "A value in the range [0..1]. Higher values can occur for some metrics, but would indicate the value is outside of the allowed range."),
    HIT(BaseUnit.HIT, "Document that meets the filtering/restriction criteria specified by a given query"),
    HIT_PER_QUERY(BaseUnit.HIT, BaseUnit.QUERY, "Number of hits per query over a period of time"),
    INSTANCE(BaseUnit.INSTANCE, "Typically tenant or application"),
    ITEM(BaseUnit.ITEM, "Object or unit maintained in e.g. a queue"),
    MILLISECOND(BaseUnit.MILLISECOND, "Millisecond, 1/1000 of a second"),
    NANOSECOND(BaseUnit.NANOSECOND, "Nanosecond, 1/1000.000.000 of a second"),
    NODE(BaseUnit.NODE, "(Virtual) computer that is part of a Vespa cluster"),
    PACKET(BaseUnit.PACKET, "Collection of data transmitted over the network as a single unit"),
    OPERATION(BaseUnit.OPERATION, "A clearly defined task"),
    OPERATION_PER_SECOND(BaseUnit.OPERATION, BaseUnit.SECOND, "Number of operations per second"),
    PERCENTAGE(BaseUnit.PERCENTAGE, "A number expressed as a fraction of 100. Typically in the range [0..100]."),
    QUERY(BaseUnit.QUERY, "A request for matching, grouping and/or scoring documents stored in Vespa"),
    QUERY_PER_SECOND(BaseUnit.QUERY, BaseUnit.SECOND, "Number of queries per second."),
    RECORD(BaseUnit.RECORD, "A collection of information, typically a set of key/value, e.g. stored in a transaction log"),
    REQUEST(BaseUnit.REQUEST, "A request sent from a client to a server"),
    RESPONSE(BaseUnit.RESPONSE, "A response from a server to a client, typically as a response to a request"),
    RESTART(BaseUnit.RESTART, "A service or node restarts"),
    SCORE(BaseUnit.SCORE, "Relevance score for a document"),
    SECOND(BaseUnit.SECOND, "Time span of 1 second"),
    SESSION(BaseUnit.SESSION, "A set of operations taking place during one connection or as part of a higher level operation"),
    TASK(BaseUnit.TASK, "Piece of work executed by a server, e.g. to perform back-ground data maintenance"),
    THREAD(BaseUnit.THREAD, "Computer thread for executing e.g. tasks, operations or queries"),
    VERSION(BaseUnit.VERSION, "Software or config version"),
    WAKEUP(BaseUnit.WAKEUP, "Computer thread wake-ups for doing some work");


    private final BaseUnit unit;
    private final BaseUnit perUnit;
    private final String description;

    Unit(BaseUnit unit, String description) {
        this(unit, null, description);
    }

    Unit(BaseUnit unit, BaseUnit perUnit, String description) {
        this.unit = unit;
        this.perUnit = perUnit;
        this.description = description;
    }

    public String fullName() {
        return perUnit == null ?
                unit.fullName() :
                unit.fullName() + "/" + perUnit.fullName();
    }

    public String shortName() {
        return perUnit == null ?
                unit.shortName :
                unit.shortName + "/" + perUnit.shortName;
    }

    public String getDescription() {
        return description;
    }

    private enum BaseUnit {

        AREA("area"),
        BINARY("binary"),
        BUCKET("bucket"),
        BYTE("byte"),
        CONNECTION("connection"),
        DOCUMENT("document"),
        DOCUMENTID("documentid"),
        FAILURE("failure"),
        FILE("file"),
        FRACTION("fraction"),
        HIT("hit"),
        INSTANCE("instance"),
        ITEM("item"),
        MILLISECOND("millisecond", "ms"),
        NANOSECOND("nanosecond", "ns"),
        NODE("node"),
        OPERATION("operation"),
        PACKET("packet"),
        PERCENTAGE("percentage"),
        QUERY("query"),
        RECORD("record"),
        REQUEST("request"),
        RESPONSE("response"),
        RESTART("restart"),
        SCORE("score"),
        SECOND("second", "s"),
        SESSION("session"),
        TASK("task"),
        THREAD("thread"),
        VERSION("version"),
        WAKEUP("wakeup");

        private final String fullName;
        private final String shortName;

        BaseUnit(String fullName) {
            this(fullName, fullName);
        }

        BaseUnit(String fullName, String shortName) {
            this.fullName = fullName;
            this.shortName = shortName;
        }

        public String fullName() {
            return fullName;
        }

        public String shortName() {
            return shortName;
        }

    }
}