// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.config.application.api;

import com.yahoo.slime.*;

import com.yahoo.text.Utf8;

import java.io.*;

/**
 * Metadata about an application package.
 *
 * @author hmusum
 * @since 5.0
 */
public class ApplicationMetaData {
    private final String deployedByUser;
    private final String deployedFromDir;
    private final long deployTimestamp;
    private final long generation;
    private final long previousActiveGeneration;
    private final String checkSum;
    private final String appName;

    public ApplicationMetaData(File appDir, String deployedByUser, String deployedFromDir, Long deployTimestamp,
                               String checkSum, Long generation, long previousActiveGeneration) {
        this(deployedByUser, deployedFromDir, deployTimestamp, appDir.getName(), checkSum, generation, previousActiveGeneration);
    }

    public ApplicationMetaData(String deployedByUser, String deployedFromDir, Long deployTimestamp, String applicationName, String checkSum, Long generation, long previousActiveGeneration) {
        this.appName = applicationName;
        this.deployedByUser = deployedByUser;
        this.deployedFromDir = deployedFromDir;
        this.deployTimestamp = deployTimestamp;
        this.checkSum = checkSum;
        this.generation = generation;
        this.previousActiveGeneration = previousActiveGeneration;
    }

    /**
     * Gets the name of the application (name of the directory from which application was deployed.
     * Will return null if a problem occurred while getting metadata
     *
     * @return application name
     */
    public String getApplicationName() {
        return appName;
    }

    /**
     * Gets the user who deployed the application.
     * Will return null if a problem occurred while getting metadata
     *
     * @return user name for the user who ran "deploy-application"
     */
    public String getDeployedByUser() {
        return deployedByUser;
    }

    /**
     * Gets the directory where the application was deployed from.
     * Will return null if a problem occurred while getting metadata
     *
     * @return path to raw deploy directory (for the original application)
     */
    public String getDeployPath() {
        return deployedFromDir;
    }

    /**
     * Gets the time the application was deployed
     * Will return null if a problem occurred while getting metadata
     *
     * @return timestamp for when "deploy-application" was run. In ms.
     */
    public Long getDeployTimestamp() {
            return deployTimestamp;
    }

    /**
     * Gets the time the application was deployed
     * Will return null if a problem occurred while getting metadata
     *
     * @return timestamp for when "deploy-application" was run. In ms.
     */
    public Long getGeneration() {
            return generation;
    }

    /**
     * Returns an md5 hash of the contents of the application package
     * @return an md5sum of the application package
     */
    public String getCheckSum() {
        return checkSum;
    }

    /**
     * Returns the previously active generation at the point when this application was created.
     * @return a generation.
     */
    public long getPreviousActiveGeneration() {
        return previousActiveGeneration;
    }

    @Override
    public String toString() {
        return deployedByUser + ", " + deployedFromDir + ", " + deployTimestamp + ", " + generation + ", " + checkSum + ", " + previousActiveGeneration;
    }

    public static ApplicationMetaData fromJsonString(String jsonString) {
        try {
            Slime data = new Slime();
            new JsonDecoder().decode(data, Utf8.toBytes(jsonString));
            Inspector root = data.get();
            Inspector deploy = root.field("deploy");
            Inspector app = root.field("application");
            return new ApplicationMetaData(deploy.field("user").asString(), deploy.field("from").asString(), deploy.field("timestamp").asLong(), app.field("name").asString(), app.field("checksum").asString(), app.field("generation").asLong(), app.field("previousActiveGeneration").asLong());
        } catch (Exception e) {
            throw new IllegalArgumentException("Error parsing json metadata", e);
        }
    }

    public Slime getSlime() {
        Slime slime = new Slime();
        Cursor meta = slime.setObject();
        Cursor deploy = meta.setObject("deploy");
        deploy.setString("user", deployedByUser);
        deploy.setString("from", deployedFromDir);
        deploy.setLong("timestamp", deployTimestamp);
        Cursor app = meta.setObject("application");
        app.setString("name", appName);
        app.setString("checksum", checkSum);
        app.setLong("generation", generation);
        app.setLong("previousActiveGeneration", previousActiveGeneration);
        return slime;
    }

    public String asJsonString() {
        Slime slime = getSlime();
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        try {
            new JsonFormat(false).encode(baos, slime);
            return baos.toString("UTF-8");
        } catch (IOException e) {
            throw new RuntimeException("Unable to encode metadata", e);
        }
    }
}