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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.vespa.flags.json;
import com.fasterxml.jackson.databind.JsonNode;
import com.yahoo.vespa.flags.Deserializer;
import com.yahoo.vespa.flags.FetchVector;
import com.yahoo.vespa.flags.FlagId;
import com.yahoo.vespa.flags.FlagSource;
import com.yahoo.vespa.flags.RawFlag;
import com.yahoo.vespa.flags.json.wire.WireFlagData;
import com.yahoo.vespa.flags.json.wire.WireFlagDataList;
import com.yahoo.vespa.flags.json.wire.WireRule;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Objects;
import java.util.Optional;
import java.util.stream.Stream;
/**
* A data structure containing all data for a single flag, that can be serialized to/from JSON,
* and that can be used to implement {@link FlagSource}.
*
* @author hakonhall
*/
public class FlagData {
private final FlagId id;
private final List<Rule> rules;
private final FetchVector defaultFetchVector;
public FlagData(FlagId id) {
this(id, new FetchVector(), List.of());
}
public FlagData(FlagId id, FetchVector defaultFetchVector, Rule... rules) {
this(id, defaultFetchVector, List.of(rules));
}
public FlagData(FlagId id, FetchVector defaultFetchVector, List<Rule> rules) {
this.id = id;
this.rules = List.copyOf(rules);
this.defaultFetchVector = defaultFetchVector;
}
public FlagId id() {
return id;
}
public List<Rule> rules() {
return rules;
}
public boolean isEmpty() { return rules.isEmpty() && defaultFetchVector.isEmpty(); }
public FlagData partialResolve(FetchVector fetchVector) {
// Note: As a result of partialResolve, there could be e.g. two identical rules, and the latter will always be ignored by resolve().
// Consider deduping. Deduping is actually not specific to partialResolve and could be done e.g. at construction time.
List<Rule> newRules = new ArrayList<>();
for (var rule : rules) {
Optional<Rule> partialRule = rule.partialResolve(fetchVector);
if (partialRule.isPresent()) {
newRules.add(partialRule.get());
if (partialRule.get().conditions().isEmpty()) {
// Any following rule will always be ignored during resolution.
break;
}
}
}
newRules = optimizeRules(newRules);
FetchVector newDefaultFetchVector = defaultFetchVector.without(fetchVector.dimensions());
return new FlagData(id, newDefaultFetchVector, newRules);
}
public Optional<RawFlag> resolve(FetchVector fetchVector) {
return rules.stream()
.filter(rule -> rule.match(defaultFetchVector.with(fetchVector)))
.findFirst()
.flatMap(Rule::getValueToApply);
}
public String serializeToJson() {
return toWire().serializeToJson();
}
public byte[] serializeToUtf8Json() {
return toWire().serializeToBytes();
}
public void serializeToOutputStream(OutputStream outputStream) {
toWire().serializeToOutputStream(outputStream);
}
public JsonNode toJsonNode() {
return toWire().serializeToJsonNode();
}
/** Can be used with Jackson. */
public WireFlagData toWire() {
WireFlagData wireFlagData = new WireFlagData();
wireFlagData.id = id.toString();
if (!rules.isEmpty()) {
wireFlagData.rules = rules.stream().map(Rule::toWire).toList();
}
wireFlagData.defaultFetchVector = FetchVectorHelper.toWire(defaultFetchVector);
return wireFlagData;
}
/** E.g. verify all RawFlag can be deserialized. */
public void validate(Deserializer<?> deserializer) {
rules.stream()
.flatMap(rule -> rule.getValueToApply().map(Stream::of).orElse(null))
.forEach(deserializer::deserialize);
}
@Override
public String toString() {
return "FlagData{" +
"id=" + id +
", rules=" + rules +
", defaultFetchVector=" + defaultFetchVector +
'}';
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
FlagData flagData = (FlagData) o;
return id.equals(flagData.id) && rules.equals(flagData.rules) && defaultFetchVector.equals(flagData.defaultFetchVector);
}
@Override
public int hashCode() {
return Objects.hash(id, rules, defaultFetchVector);
}
public static FlagData deserializeUtf8Json(byte[] bytes) {
return fromWire(WireFlagData.deserialize(bytes));
}
public static FlagData deserialize(InputStream inputStream) {
return fromWire(WireFlagData.deserialize(inputStream));
}
public static FlagData deserialize(String string) {
return fromWire(WireFlagData.deserialize(string));
}
/** Can be used with Jackson. */
public static FlagData fromWire(WireFlagData wireFlagData) {
if (wireFlagData.id == null) {
throw new IllegalArgumentException("Flag ID missing");
}
return new FlagData(
new FlagId(wireFlagData.id),
FetchVectorHelper.fromWire(wireFlagData.defaultFetchVector),
rulesFromWire(wireFlagData.rules)
);
}
public static byte[] serializeListToUtf8Json(List<FlagData> list) {
return listToWire(list).serializeToBytes();
}
public static List<FlagData> deserializeList(byte[] bytes) {
return listFromWire(WireFlagDataList.deserializeFrom(bytes));
}
public static WireFlagDataList listToWire(List<FlagData> list) {
WireFlagDataList wireList = new WireFlagDataList();
wireList.flags = list.stream().map(FlagData::toWire).toList();
return wireList;
}
public static List<FlagData> listFromWire(WireFlagDataList wireList) {
return wireList.flags.stream().map(FlagData::fromWire).toList();
}
private static List<Rule> rulesFromWire(List<WireRule> wireRules) {
if (wireRules == null) return List.of();
return optimizeRules(wireRules.stream().map(Rule::fromWire).toList());
}
/** Take a raw list of rules from e.g. deserialization or partial resolution and normalize/simplify it. */
private static List<Rule> optimizeRules(List<Rule> rules) {
// Remove trailing rules without value, as absent value implies the code default.
// Removing trailing rules may further simplify when e.g. this results in no rules,
// which is equivalent to no flag data at all, and flag data may be deleted from a zone.
if (rules.isEmpty()) return rules;
if (rules.get(rules.size() - 1).getValueToApply().isPresent()) return rules;
var newRules = new ArrayList<>(rules);
while (newRules.size() > 0) {
Rule lastRule = newRules.get(newRules.size() - 1);
if (lastRule.getValueToApply().isEmpty()) {
newRules.remove(newRules.size() - 1);
} else {
break;
}
}
return newRules;
}
}
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