/**
* This program is partly based on Ken Been's TigerReader.
* This program reads the tiger dataset directly from www.census.gov
* Require : File links.txt containing all the url information of the counties.
* Usage:
*	java TigerDowloader state outputfile
*   e.g. java TigerDowloader NY nylines.txt
* the first four lines of the output are the min and max of latitude and the min and max of longitude.
* each line correponds to a polyline boudary.
*/

import java.net.*;
import java.io.*;
import java.util.*;
import java.util.zip.*;
import java.math.*;

public class TigerDownloader
{
	String baseurl="http://www.census.gov/geo/www/tiger/rd_2ktiger/";
	
	final static private int LINE_RECORD_SIZE = 230;
	final static private int SHAPE_RECORD_SIZE = 210;
	long XMIN,YMIN,XMAX,YMAX;
	
	int numSeg;
	int numChain;
	TreeSet lineSet = new TreeSet();
	
	TigerDownloader(){
		XMAX=YMAX=Long.MIN_VALUE;
		XMIN=YMIN=Long.MAX_VALUE;
	}
	
	private static int readIntoArray(InputStream inputStream, byte[] buf)throws IOException{
		int numRead = inputStream.read(buf, 0, buf.length);
	    int totalRead = numRead;
	
	    while (numRead >= 0 && totalRead < buf.length) {
	      numRead = inputStream.read(buf, totalRead, buf.length - totalRead);
	      if (numRead >= 0)
	        totalRead += numRead;
	    }
	    return totalRead;
	}
	
	public void read(String state)
	{
		numSeg=0;
		numChain=0;
		//int oldSize=0;
		try{
			HashMap idMap =new HashMap();
			InputStream iin=new FileInputStream("links.txt");
			BufferedReader iins= new BufferedReader(new InputStreamReader(iin));
			String subname;
			while((subname=iins.readLine())!=null){
				if(!subname.startsWith(state))continue;
				System.out.println("downloading file "+subname+".");
				URL ur = new URL(baseurl+subname);
				InputStream in=ur.openStream();
				ZipInputStream zis=new ZipInputStream(in);
				ZipEntry entry = zis.getNextEntry();
				int recordCount = (int)entry.getSize() / LINE_RECORD_SIZE;
				for(int i=0;i<recordCount;i++)
				{
					byte[] buf = new byte[LINE_RECORD_SIZE];
	            	readIntoArray(zis, buf);
	            	if(buf[15]!='1')continue;// read the boundry only
	            	numSeg++;
					String lineID=new String(buf,5,10);
					String startp=new String(buf,190,19);
					String endp=new String(buf,209,19);
					updateMinMax(startp);
					updateMinMax(endp);
					String leftp,rightp;
					if(LeftOf(startp,endp)){
						leftp=startp;
						rightp=endp;
					}else{
						leftp=endp;
						rightp=startp;
					}
					String seg=startp+endp;
					if(!lineSet.contains(seg)){
						idMap.put(lineID,seg);
						lineSet.add(seg);
					}
				}
				//System.out.println("New segments read: "+numSeg+"; Total segments :"+(lineSet.size()-oldSize));
				//oldSize=lineSet.size();
				//For type 2 Data
				entry = zis.getNextEntry();
				recordCount = (int)entry.getSize() / SHAPE_RECORD_SIZE;
				for(int i=0;i<recordCount;i++)
				{
					byte[] buf = new byte[LINE_RECORD_SIZE];
	            	readIntoArray(zis, buf);
	            	String lineID=new String(buf,5,10);
					if(idMap.get(lineID)==null) continue;
					String endpoints=(String)idMap.get(lineID);
					if(endpoints.length()>42)continue;//more than two points there, means there are details in it.
					String detail="";
					for(int k=18;k<=189;k+=19)
					{
						String pp=new String(buf,k,19);
						if (pp.equals("+000000000+00000000"))break;
						detail+=pp;
						numChain++;
					}
					detail=endpoints.substring(0,19)+detail+endpoints.substring(19);
					idMap.put(lineID,detail);
					lineSet.remove(endpoints);
					lineSet.add(detail);
				}
				in.close();zis.close();
			}
			iin.close();iins.close();
		}catch(IOException e){System.out.println(e);}
		System.out.println("Number of polygon lines : "+numSeg+"\nNumber of segments : "+(numSeg+numChain));
	
	}
	
	private boolean LeftOf(String p1,String p2){
		//System.out.println(p1+"--"+p2);
		long x1=new Integer(p1.substring(1,10)).longValue();
		long x2=new Integer(p1.substring(1,10)).longValue();
		return(x1<=x2);
	}

	private void updateMinMax(String s){
		long x=new Long(s.substring(1,10)).longValue();
		long y=new Long(s.substring(11)).longValue();
		if(x<XMIN)XMIN=x;
		if(x>XMAX)XMAX=x;
		if(y<YMIN)YMIN=y;
		if(y>YMAX)YMAX=y;
		return;
	}
	
	public void output(String filename){
		try{
			OutputStreamWriter outs= new OutputStreamWriter(new FileOutputStream(filename));
			Object[] lines=(Object[])lineSet.toArray();
			outs.write(XMIN+"\n"+XMAX+"\n"+YMIN+"\n"+YMAX+"\n");
			for(int i=0;i<lineSet.size(); i++){
				String s=(String)lines[i];
				outs.write(s+"\n");
			}
			outs.flush();
			outs.close();
		}catch(IOException e){System.out.println(e);}
	}
	
	public static void main(String[] options) 
	{
		if(options.length!=2){
			System.out.println("Usage : java TigerDowloader state outputfile\ne.g. java TigerDowloader NY nylines.txt");
			System.exit(-1);
		}
		String state = options[0];
		String filename = options[1];
		TigerDownloader td= new TigerDownloader();
		td.read(state);
		td.output(filename);
	 }
}