package eu.dnetlib.bioschemas.api;

import eu.dnetlib.bioschemas.api.crawl.CrawlRecord;
import eu.dnetlib.bioschemas.api.scraper.BMUSEScraper;
import eu.dnetlib.bioschemas.api.scraper.ScrapeState;
import eu.dnetlib.bioschemas.api.scraper.ScrapeThread;
import eu.dnetlib.bioschemas.api.utils.UrlParser;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;

import java.io.*;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
import java.util.Objects;
import java.util.Properties;
import java.util.stream.Collectors;
import java.util.stream.Stream;


/** 
 * Runs the scrape. Collect a list of URLs (in the form of CrawlRecords) to scrape.
 *
 */
public class ServiceScrapeDriver {

	private static final String propertiesFile = "application.properties";

	private int waitTime = 1;
	private int numberOfPagesToCrawlInALoop;
	private int totalNumberOfPagesToCrawlInASession;
	private String outputFolder;
	private int pagesCounter = 0;
	private int scrapeVersion = 1;

	private String sitemapUrl;
	private String sitemapURLKey;
	private String maxScrapedPages;
	private String outputFilename;
	
	private static SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd 'at' HH:mm:ss z");

	private static final Log logger = LogFactory.getLog(ServiceScrapeDriver.class);

	public ServiceScrapeDriver(String sitemapUrl, String sitemapURLKey, String maxScrapedPages, String outputFilename) {
		this.sitemapUrl = sitemapUrl;
		this.sitemapURLKey = sitemapURLKey;
		this.maxScrapedPages = maxScrapedPages;
		this.outputFilename = outputFilename;
	}

	/**
	 * Runs the scrape process
	 *
	 */
	public void start() throws IOException {
		runScrape();
	}
	
	/** 
	 * Fires off threads
	 * Originally designed as a multi-threaded process; now reduced to a single thread as 
	 * the selenium webdriver is too expensive to run multi-threaded. However, the threading
	 * as been left in situ in case it is useful in the future.
	 * 
	 */
	private void runScrape() throws IOException {
		processProperties();
		String url = sitemapUrl.toLowerCase();
		Elements urls = UrlParser.getSitemapList(getSitemapUrl(), getSitemapURLKey());
		Stream<Element> urlStream = null;
		if (Objects.nonNull(maxScrapedPages)) {
			urlStream = urls.stream().limit(Long.parseLong(maxScrapedPages));
		} else {
			urlStream = urls.stream();
		}
		List<Element> sites = urlStream.collect(Collectors.toList());
		logger.info("Pages available for scraping: " + sites.size());

		List<CrawlRecord> pagesToPull = generatePagesToPull(sites);
		if (pagesToPull.isEmpty()) {
			logger.error("Cannot retrieve URLs");
			throw  new RuntimeException("No pages found from sitemap");
		}

		ScrapeState scrapeState = new ScrapeState(pagesToPull);

		logger.info("STARTING CRAWL: " + formatter.format(new Date(System.currentTimeMillis())));
		while (pagesCounter < totalNumberOfPagesToCrawlInASession) {
			logger.debug(pagesCounter + " scraped of " + totalNumberOfPagesToCrawlInASession);
			
			ScrapeThread scrape1 = new ScrapeThread(new BMUSEScraper(), scrapeState, waitTime, scrapeVersion);
			scrape1.setName("S1");
			scrape1.start();
			long startTime = System.nanoTime();
			
			try {
				scrape1.join();
			} catch (InterruptedException e) {
				logger.error("Exception waiting on thread");
				e.printStackTrace();
				return;				
			}
			
			if(!scrape1.isFileWritten()) {
				logger.error("Could not write output file so shutting down!");
				Date date = new Date(System.currentTimeMillis());
				logger.info("ENDING CRAWL after failure at: " + formatter.format(date));					
				return;
			}
			
			logger.debug("Value of isFileWritten: " + scrape1.isFileWritten());
			long endTime = System.nanoTime();
			long timeElapsed = endTime - startTime;
			logger.debug("Time in s to complete: " + timeElapsed / 1e+9);
			pagesCounter += numberOfPagesToCrawlInALoop;
			logger.debug("ENDED loop");
		}

		logger.info("ENDING CRAWL: " + formatter.format(new Date(System.currentTimeMillis())));

		File output = new File(outputFolder.concat("/").concat(outputFilename));
		if (output.exists()) {
			output.delete();
			output.createNewFile();
		}
		FileWriter fileWriter;
		BufferedWriter bufferedWriter;
		fileWriter = new FileWriter(output.getAbsoluteFile(), true); // true to append
		bufferedWriter = new BufferedWriter(fileWriter);

		List<CrawlRecord> processed = scrapeState.getPagesProcessed();
		for (int i=0;i<processed.size();i++) {
			try {
				bufferedWriter.write(processed.get(i).getNquads());
				bufferedWriter.newLine();
				bufferedWriter.flush();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		bufferedWriter.close();
		logger.info(" Data stored into  "+output.getAbsolutePath());
	}

	/**
	 * Get a list of URLs (in the form of CrawlRecords) that need to be scraped
	 * 
	 * @return List of URLs to be scraped
	 * @see CrawlRecord
	 */
	private List<CrawlRecord> generatePagesToPull(List<Element> sites) {
		List<CrawlRecord> crawls = sites
				.stream()
				.map(s -> {
					CrawlRecord crawlRecord = new CrawlRecord(s.text());
					String[] urlSplitted = crawlRecord.getUrl().split("/");
					String name = urlSplitted[urlSplitted.length - 1];
					crawlRecord.setName(name);
					return crawlRecord;
				})
				.collect(Collectors.toList());
		return crawls;
	}

	/**
	 * Updates properties based on properties file in src > main > resources
	 * 
	 */
	private void processProperties() {
		ClassLoader classLoader = ServiceScrapeDriver.class.getClassLoader();

		InputStream is = classLoader.getResourceAsStream(propertiesFile);
		if(is == null) {
			logger.error("     Cannot find " + propertiesFile + " file");
			throw new IllegalArgumentException(propertiesFile + "file is not found!");
		}

		Properties prop = new Properties();

		try {
			prop.load(is);
		} catch (IOException e) {
			logger.error("     Cannot load application.properties", e);
			System.exit(0);
		}

		waitTime = Integer.parseInt(prop.getProperty("waitTime").trim());
		logger.info("     waitTime: " + waitTime);
		outputFolder = prop.getProperty("outputFolder").trim();
		logger.info("     outputFolder: " + outputFolder);		
		numberOfPagesToCrawlInALoop = Integer.parseInt(prop.getProperty("numberOfPagesToCrawlInALoop").trim());
		logger.info("     numberOfPagesToCrawl: " + numberOfPagesToCrawlInALoop);
		totalNumberOfPagesToCrawlInASession = Integer.parseInt(prop.getProperty("totalNumberOfPagesToCrawlInASession").trim());
		logger.info("     totalNumberOfPagesToCrawlInASession: " + totalNumberOfPagesToCrawlInASession);
		scrapeVersion = Integer.parseInt(prop.getProperty("scrapeVersion").trim());
		logger.info("     scrapeVersion: " + scrapeVersion);		
		logger.info("\n\n\n");
	}

	public String getSitemapUrl() {
		return sitemapUrl;
	}

	public String getSitemapURLKey() {
		return sitemapURLKey;
	}

	private String getId(String pageUrl) {
		String[] parts = pageUrl.split("/");
		return parts[parts.length - 1];
	}
}