package com.application.DB;

import com.google.auth.oauth2.GoogleCredentials;
import com.google.auth.oauth2.ServiceAccountCredentials;
import com.google.cloud.bigquery.*;

import java.io.File;
import java.io.FileInputStream;
import java.text.SimpleDateFormat;
import java.util.HashMap;
import java.util.Map;
import java.util.TimeZone;

import static com.application.DB.Constants.PROJECT_ID;

public class HelpingFunctions {


    static Map<String,String> manMoist = new HashMap<>();

    /**
     * Creates a simple date format to use for converting millis in numbers to a usefull date format
     *
     * @return returns the date format
     */
    static SimpleDateFormat getDateFormat() {
        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
        return dateFormat;
    }

    /**
     * Retrieves the credentials file
     *
     * @return the credentials
     * @throws Exception for potential errors
     */
    private static GoogleCredentials getCredentials() throws Exception {
        File credentialsPath = new File("./src/main/resources/com.application/sf-drying-optimization-1e234ad2b0f4.json");

        // Load credentials from JSON key file. If you can't set the GOOGLE_APPLICATION_CREDENTIALS
        // environment variable, you can explicitly load the credentials file to construct the
        // credentials.
        GoogleCredentials credentials;
        try (FileInputStream serviceAccountStream = new FileInputStream(credentialsPath)) {
            credentials = ServiceAccountCredentials.fromStream(serviceAccountStream);
        }
        return credentials;
    }

    /**
     * Creates a bigquery builder
     *
     * @return a builder
     * @throws Exception returns potential error
     */
    private static BigQuery getBuilder() throws Exception {
        // Step 1: Initialize BigQuery service
        // Here we set our project ID and get the `BigQuery` service object
        // this is the interface to our BigQuery instance that
        // we use to execute jobs on
        return BigQueryOptions.newBuilder().
                setCredentials(getCredentials()).
                setProjectId(PROJECT_ID)
                .build().getService();
    }

    /**
     * Creates a job for the database
     *
     * @param queryConfig query configuration information
     * @return a job
     * @throws Exception returns potential error
     */
    private static Job getJob(JobConfiguration queryConfig) throws Exception {
        // Step 3: Run the job on BigQuery
        // create a `Job` instance from the job configuration using the BigQuery service
        // the job starts executing once the `create` method executes

        Job queryJob = getBuilder().create(JobInfo.newBuilder(queryConfig).build());
        queryJob = queryJob.waitFor();
        // the waitFor method blocks until the job completes
        // and returns `null` if the job doesn't exist anymore
        if (queryJob == null) {
            throw new Exception("job no longer exists");
        }
        // once the job is done, check if any error occured
        if (queryJob.getStatus().getError() != null) {
            throw new Exception(queryJob.getStatus().getError().toString());
        }
        return queryJob;
    }

    /**
     * This function creates a query job that uses the query statement
     * in order to retrieve information from the database
     *
     * @param sqlStatement input for the query statement
     * @return returns the queryjob with the results
     * @throws Exception Throws exception in case of error
     */
    static TableResult createQueryJob(String sqlStatement) throws Exception {

        // Creates a job configuration
        Job queryJob = getJob(QueryJobConfiguration.newBuilder(sqlStatement).build());

        // Retrieves the results from the queryjob
        return queryJob.getQueryResults();

    }

    /**
     * Stores data about manual measurements for moisture level in the lumber
     *
     * @return a list containing the outdate for the lumber and the corresponding diff value
     */
    public static Map<String, String> getManMoist() {
        return manMoist;
    }

    /**
     * Function to iterate through all the Kwh values and storing them in a map
     *
     * @param data a map to store all the data
     * @param baseline a baseline to base all the next values of to get a zero point
     * @param result TableResult to iterate through
     * @param kwhNameParameter Name of the Kwh name parameter in the database
     * @param kwhTimestampNameParameter Name of the timestamp parameter in the database
     */
    static void iterateKwhValues(Map<String, Number> data, int baseline, TableResult result, String kwhNameParameter, String kwhTimestampNameParameter) {
        for (FieldValueList row : result.iterateAll()) {
            // Sets the baseline in order to reset the kWh counter
            if (baseline == 0) {
                baseline = row.get("" + kwhNameParameter + "").getNumericValue().intValue();
            }

            // kWh value
            int variantValue = row.get("" + kwhNameParameter + "").getNumericValue().intValue() - baseline; //-baseline

            // Retrieving the wanted data
            long timeStamp = row.get("" + kwhTimestampNameParameter + "").getTimestampValue() / 1000;
            // Riktig format, men i string
            String formatedTimeStamp = getDateFormat().format(timeStamp);

            // Checks for negative values
            if (variantValue > 0) {
                // Adding the data to a list in order to sort through later
                data.put(formatedTimeStamp, variantValue);
            }
        }
    }
}