// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.config.provision.zone;

import com.yahoo.config.provision.Environment;
import com.yahoo.config.provision.RegionName;

import java.util.Objects;

/**
 * Unique identifier for a Zone; use when referencing them.
 * <p>
 * Serialised form is 'environment.region'.
 *
 * @author jonmv
 */
public class ZoneId {

    private static final ZoneId CONTROLLER = from(Environment.prod, RegionName.from("controller"));

    /**
     * The ZoneId associated with the controller, distinct from all other zones in the system, but a constant across systems.
     *
     * <p>The controller may also be associated with a real zone, i.e. with a region defining the location like
     * aws-us-east-1a.  Because such a zone ID is different for different systems, and may clash with a prod zone in the
     * same region and system, the virtual zone ID is often used.</p>
     */
    public static ZoneId ofVirtualControllerZone() { return CONTROLLER; }

    private final Environment environment;
    private final RegionName region;

    private ZoneId(Environment environment, RegionName region) {
        this.environment = Objects.requireNonNull(environment, "environment must be non-null");
        this.region = Objects.requireNonNull(region, "region must be non-null");
    }

    public static ZoneId from(Environment environment, RegionName region) {
        return new ZoneId(environment, region);
    }

    public static ZoneId from(String environment, String region) {
        return from(Environment.from(environment), RegionName.from(region));
    }

    /** Create from a serialised ZoneId. Inverse of {@code ZoneId.value()}. */
    public static ZoneId from(String value) {
        String[] parts = value.split("\\.");
        switch (parts.length) {
            case 2:
                return from(parts[0], parts[1]);
            case 4:
                // Deprecated: parts[0] == cloud, parts[1] == system
                // TODO: Figure out whether this can be removed
                return from(parts[2], parts[3]);
            default:
                throw new IllegalArgumentException("Cannot deserialize zone id '" + value + "'");
        }
    }

    public static ZoneId defaultId() {
        return new ZoneId(Environment.defaultEnvironment(), RegionName.defaultName());
    }

    public Environment environment() {
        return environment;
    }

    public RegionName region() {
        return region;
    }

    /** Returns the serialised value of this. Inverse of {@code ZoneId.from(String value)}. */
    public String value() {
        return environment + "." + region;
    }

    @Override
    public String toString() {
        return value();
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        ZoneId zoneId = (ZoneId) o;
        return environment == zoneId.environment &&
               Objects.equals(region, zoneId.region);
    }

    @Override
    public int hashCode() {
        return Objects.hash(environment, region);
    }

}