package org.hathitrust;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.URI;
import java.nio.charset.StandardCharsets;
//import java.nio.file.Files;
//import java.nio.file.Path;
//import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;

import org.apache.commons.compress.compressors.CompressorException;
import org.apache.commons.compress.compressors.CompressorInputStream;
import org.apache.commons.compress.compressors.CompressorStreamFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.spark.api.java.function.FlatMapFunction;
import org.json.JSONArray;
import org.json.JSONObject;

/*
class PagedJSON implements Function<String, Boolean> {

	private static final long serialVersionUID = 1L;

	public Boolean call(String s) { return s.contains("a"); }
}
 */


/* 
URI uri = URI.create ("hdfs://host:port/file path");
Configuration conf = new Configuration();
FileSystem file = FileSystem.get(uri, conf);
FSDataInputStream in = file.open(new Path(uri));

*/

class PagedJSON implements FlatMapFunction<String, String> 
{
	private static final long serialVersionUID = 1L;

	protected String _input_dir;
	
	public PagedJSON(String input_dir)
	{
		_input_dir = input_dir;
	}
	
	protected static BufferedReader getBufferedReaderForCompressedFile(String fileIn) 
			throws CompressorException, IOException 
	{
		URI uri = URI.create (fileIn);
		Configuration conf = new Configuration();
		FileSystem file = FileSystem.get(uri, conf);
		FSDataInputStream fin = file.open(new Path(uri));
			
	    //FileInputStream fin = new FileInputStream(fileIn);
	    BufferedInputStream bis = new BufferedInputStream(fin);
	    CompressorInputStream input = new CompressorStreamFactory().createCompressorInputStream(bis);
	    BufferedReader br2 = new BufferedReader(new InputStreamReader(input,"UTF8"));
	    return br2;
	}
	
	protected JSONObject readJSONFile(String filename)
	{
		//Path path = Paths.get(filename);

		StringBuilder sb = new StringBuilder();

		try {

			String str;
			BufferedReader br = getBufferedReaderForCompressedFile(_input_dir + "/" + filename);
			while ((str = br.readLine()) != null) {
				sb.append(str);
			    //System.out.println(str);
			}

	        br.close();
	        
	        //System.err.println("*****" + sb.toString());
	               
	        /*
			List<String> lines = Files.readAllLines(path,StandardCharsets.UTF_8);


			for (String line : lines) {
				sb.append(line);

			}
			*/
	        
		} 
		catch (Exception e) {
			e.printStackTrace();
		}

		JSONObject json_obj = new JSONObject(sb.toString());
		
		
		return json_obj;
		
		//return sb.toString();
	}

	public Iterator<String> call(String s) 
	{ 
		JSONObject extracted_feature_record = readJSONFile(s);
		
		String id = extracted_feature_record.getString("id");
		
		JSONObject ef_metadata = extracted_feature_record.getJSONObject("metadata");
		JSONObject ef_features = extracted_feature_record.getJSONObject("features");
		
		
		int ef_page_count = ef_features.getInt("pageCount");
		
		JSONArray ef_pages = ef_features.getJSONArray("pages");
		int ef_num_pages = ef_pages.length();
		
		ArrayList<String> ids = new ArrayList<String>(ef_num_pages);
		for (int i = 0; i < ef_page_count; i++) {
			ids.add(id + "." + i);
		}
		
		/*
		for (int i = 0; i < ef_num_pages; i++)
		{
		    //String post_id = ef_pages.getJSONObject(i).getString("post_id");
		    //......
		}
		*/
		//String pageName = json_obj.getJSONObject("pageInfo").getString("pageName");
/*
		JSONArray arr = obj.getJSONArray("posts");
		for (int i = 0; i < arr.length(); i++)
		{
		    String post_id = arr.getJSONObject(i).getString("post_id");
		    ......
		}
*/
		
		
		ids.add(id);
		
		return ids.iterator();
	}
}