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

import com.yahoo.slime.Cursor;
import com.yahoo.slime.Inspector;
import com.yahoo.slime.Slime;
import com.yahoo.slime.SlimeUtils;

import java.time.Instant;
import java.util.Arrays;

/**
 * A {@code Report} contains information about a node, typically found and published by host admin.
 *
 * <p>May serve as a base class for reports with richer information, e.g. values.
 *
 * @author hakonhall
 */
public class Report {

    /** The time the report was created, in milliseconds since Epoch. */
    public static final String CREATED_FIELD = "createdMillis";

    /** The type of the report. */
    public static final String TYPE_FIELD = "type";

    /** The description of the report. */
    public static final String DESCRIPTION_FIELD = "description";

    private final String reportId;
    private final Type type;
    private final Instant createdTime;
    private final String description;

    // This is the serialized report which is typically richer than we know of in this class. It's up to
    // clients of specific reports to query the details.
    private final Inspector reportInspector;

    public enum Type {
        /** The default type if none given, or not recognized. */
        UNSPECIFIED(false),
        /** The host has a soft failure and should be parked for manual inspection. */
        SOFT_FAIL(true),
        /** The host has a hard failure and should be given back to siteops. */
        HARD_FAIL(true);

        private final boolean badHost;

        /**
         * @param badHost Whether the host is actively trying to suspend itself and all children in anticipation
         *                of being failed out (by the {@code NodeFailer}. Will expire from failed to parked.
         */
        Type(boolean badHost) {
            this.badHost = badHost;
        }

        public boolean hostShouldBeFailed() {
            return badHost;
        }

        public boolean shouldExpireToParked() {
            return badHost;
        }
    }

    private Report(String reportId, Type type, Instant createdTime, String description, Inspector reportInspector) {
        this.reportId = reportId;
        this.type = type;
        this.createdTime = createdTime;
        this.description = description;
        this.reportInspector = reportInspector;
    }

    /** The ID of the report. */
    public String getReportId() { return reportId; }

    /** The type of the report. */
    public Type getType() { return type; }

    /** The time the report was created. */
    public Instant getCreatedTime() { return createdTime; }

    /** Whether this node has severe issues that to warrant failing it. */
    public boolean shouldFailNode() { return !getDescription().isEmpty(); }

    /** A textual summary of the report. */
    public String getDescription() { return description; }

    /** For exploring the JSON (Slime) of the report. */
    public Inspector getInspector() { return reportInspector; }

    /** Create the simplest possible report. */
    public static Report basicReport(String reportId, Type type, Instant createdTime, String description) {
        return new Report(reportId, type, createdTime, description,  new Slime().setObject());
    }

    /** The reportInspector will be used to serialize the full report later, including any createdTime and description. */
    public static Report fromSlime(String reportId, Inspector reportInspector) {
        String typeString = reportInspector.field(TYPE_FIELD).asString();
        Type type = Arrays.stream(Type.values())
                .filter(t -> t.name().equalsIgnoreCase(typeString))
                .findFirst()
                .orElse(Type.UNSPECIFIED);

        long millisSinceEpoch = reportInspector.field(CREATED_FIELD).asLong();
        if (millisSinceEpoch <= 0) {
            // Including null or not set.
            millisSinceEpoch = Instant.now().toEpochMilli();
        }
        Instant createdTime = Instant.ofEpochMilli(millisSinceEpoch);

        String description = reportInspector.field(DESCRIPTION_FIELD).asString();

        return new Report(reportId, type, createdTime, description, reportInspector);
    }

    public void toSlime(Cursor reportCursor) {
        SlimeUtils.copyObject(reportInspector, reportCursor);

        // In Slime, trying to overwrite an already existing field is a no-op.
        // We'll write the required fields now. If they weren't already set by the above copyObject,
        // in particular the created field, the below will be set it to the current timestamp which is what we want.
        if (type != Type.UNSPECIFIED) reportCursor.setString(TYPE_FIELD, type.name());
        reportCursor.setLong(CREATED_FIELD, createdTime.toEpochMilli());
        if (!description.isEmpty()) reportCursor.setString(DESCRIPTION_FIELD, description);
    }
}