/*
# Licensed Materials - Property of IBM
# Copyright IBM Corp. 2016,2017  
 */
package com.ibm.streamsx.topology.internal.streaminganalytics;

import static com.ibm.streamsx.topology.context.AnalyticsServiceProperties.SERVICE_NAME;
import static com.ibm.streamsx.topology.context.AnalyticsServiceProperties.VCAP_SERVICES;
import static com.ibm.streamsx.topology.internal.gson.GsonUtilities.array;
import static com.ibm.streamsx.topology.internal.gson.GsonUtilities.jstring;

import java.io.File;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;

/**
 * Utilities to get the correct VCAP services
 * information for submission to Streaming Analytics Service.
 *
 */
public class VcapServices {
    
    /**
     * Get the top-level VCAP services object.
     * 
     * Object can be:
     * JsonObject - assumed to contain VCAP_SERVICES
     * String -  assumed to contain serialized VCAP_SERVICES JSON
     * File - assumed to be a file containing serialized VCAP_SERVICES JSON
     */
    private static JsonObject getVCAPServices(JsonElement rawServices) throws IOException {
                
        JsonParser parser = new JsonParser();
        String vcapString;

        if (rawServices == null) {
            vcapString = System.getenv("VCAP_SERVICES");
            if (vcapString == null) {
                throw new IllegalStateException("VCAP_SERVICES are not defined, please set environment variable VCAP_SERVICES or configuration property: " + VCAP_SERVICES);
            }
        } else if (rawServices.isJsonObject()) {
            return rawServices.getAsJsonObject();
        } else if (rawServices.isJsonPrimitive()) {
            String rawString = rawServices.getAsString();
            if (rawString.startsWith(File.separator)) {  
                Path vcapFile = Paths.get(rawString);
                vcapString = new String(Files.readAllBytes(vcapFile), StandardCharsets.UTF_8);
            } else
                vcapString = rawString;
        } else {
            throw new IllegalArgumentException("Unknown VCAP_SERVICES object class: " + rawServices.getClass());
        }
        
        return parser.parse(vcapString).getAsJsonObject();
    }
    
    /**
     * Get the specific streaming analytics service from the service name
     * and the vcap services.
     * @param getter How to get the value from the container given a key

     * @throws IOException
     */
    public static JsonObject getVCAPService(JsonObject deploy) throws IOException {
        JsonObject services = getVCAPServices(deploy.get(VCAP_SERVICES));
        
        JsonArray streamsServices = array(services, "streaming-analytics");
        if (streamsServices == null || streamsServices.size() == 0)
            throw new IllegalStateException("No streaming-analytics services defined in VCAP_SERVICES");
        
        String serviceName = jstring(deploy, SERVICE_NAME);

        if (serviceName != null)
            serviceName = serviceName.trim();
        
        if (serviceName == null || serviceName.isEmpty())
            throw new IllegalStateException("Streaming Analytics service name is not defined, please set configuration property: " + SERVICE_NAME);
                
        JsonObject service = null;
        if (!serviceName.isEmpty()) {
            for (JsonElement ja : streamsServices) {
                JsonObject possibleService = ja.getAsJsonObject();
                if (serviceName.equals(possibleService.get("name").getAsString())) {
                    service = possibleService;
                    break;
                }
            }
        }
        if (service == null)
            throw new IllegalStateException(
                    "No streaming-analytics services defined in VCAP_SERVICES with name: " + serviceName);
        
        return service;
    }
}