// plasmaSwitchboardQueueEntry.java 
// --------------------------------
// part of YaCy
// (C) by Michael Peter Christen; mc@anomic.de
// first published on http://www.anomic.de
// Frankfurt, Germany, 2005
// last major change: 04.07.2005
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
// Using this software in any meaning (reading, learning, copying, compiling,
// running) means that you agree that the Author(s) is (are) not responsible
// for cost, loss of data or any harm that may be caused directly or indirectly
// by usage of this softare or this documentation. The usage of this software
// is on your own risk. The installation and usage (starting/running) of this
// software may allow other people or application to access your computer and
// any attached devices and is highly dependent on the configuration of the
// software which must be done by the user of the software; the author(s) is
// (are) also not responsible for proper configuration and usage of the
// software, even if provoked by documentation provided together with
// the software.
//
// Any changes to this file according to the GPL as documented in the file
// gpl.txt aside this file in the shipment you received can be done to the
// lines that follows this copyright notice here, but changes must not be
// done inside the copyright notive above. A re-distribution must contain
// the intact and unchanged copyright notice.
// Contributions and changes to the program code must be marked as such.

package de.anomic.plasma;

import java.io.File;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Date;

import de.anomic.htmlFilter.htmlFilterContentScraper;
import de.anomic.http.httpHeader;
import de.anomic.kelondro.kelondroStack;
import de.anomic.server.serverCodings;
import de.anomic.yacy.yacySeedDB;

public class plasmaSwitchboardQueue {
    
    private kelondroStack sbQueueStack;
    private plasmaCrawlProfile profiles;
    private plasmaHTCache htCache;
    private plasmaCrawlLURL lurls;

    public plasmaSwitchboardQueue(plasmaHTCache htCache, plasmaCrawlLURL lurls, File sbQueueStackPath, int bufferkb, plasmaCrawlProfile profiles) throws IOException {
        this.profiles = profiles;
        this.htCache = htCache;
        this.lurls = lurls;
        
        if (sbQueueStackPath.exists())
            sbQueueStack = new kelondroStack(sbQueueStackPath, 0);
        else
            sbQueueStack = new kelondroStack(sbQueueStackPath, 0, new int[] {
                plasmaURL.urlStringLength,
                plasmaURL.urlHashLength,
                11,
                1,
                yacySeedDB.commonHashLength,
                plasmaURL.urlCrawlDepthLength,
                plasmaURL.urlCrawlProfileHandleLength,
                plasmaURL.urlDescrLength
            });
        
    }
    
    public int size() {
        return sbQueueStack.size();
    }
    
    public void push(Entry entry) throws IOException {
        sbQueueStack.push(new byte[][]{
            entry.url.toString().getBytes(),
            (entry.referrerHash == null) ? plasmaURL.dummyHash.getBytes() : entry.referrerHash.getBytes(),
            serverCodings.enhancedCoder.encodeBase64Long((entry.ifModifiedSince == null) ? 0 : entry.ifModifiedSince.getTime(), 11).getBytes(),
            new byte[entry.flags],
            (entry.initiator == null) ? plasmaURL.dummyHash.getBytes() : entry.initiator.getBytes(),
            serverCodings.enhancedCoder.encodeBase64Long((long) entry.depth, plasmaURL.urlCrawlDepthLength).getBytes(),
            (entry.profileHandle == null) ? plasmaURL.dummyHash.getBytes() : entry.profileHandle.getBytes(),
            (entry.anchorName == null) ? "-".getBytes() : entry.anchorName.getBytes()
        });
    }
    
    public Entry pop() throws IOException {
        if (sbQueueStack.size() == 0) return null;
        return new Entry(sbQueueStack.pot());
    }
    
    public Entry get(int index) throws IOException {
        if ((index < 0) || (index >= sbQueueStack.size())) throw new ArrayIndexOutOfBoundsException();
        return new Entry(sbQueueStack.bot(index));
    }
    
    public void close() {
        if (sbQueueStack != null) try {
            sbQueueStack.close();
        } catch (IOException e) {
            
        }
        sbQueueStack = null;
    }
    
    public void finalize() {
        close();
    }
    
    public Entry newEntry(URL url, String referrer, Date ifModifiedSince, boolean requestWithCookie,
                     String initiator, int depth, String profilehandle, String anchorName) {
        return new Entry(url, referrer, ifModifiedSince, requestWithCookie, initiator, depth, profilehandle, anchorName);
    }
    
    public class Entry {
        private URL url;              // plasmaURL.urlStringLength
        private String referrerHash;  // plasmaURL.urlHashLength
        private Date ifModifiedSince; // 6
        private byte flags;           // 1
        private String initiator;     // yacySeedDB.commonHashLength
        private int depth;            // plasmaURL.urlCrawlDepthLength
        private String profileHandle; // plasmaURL.urlCrawlProfileHandleLength
        private String anchorName;    // plasmaURL.urlDescrLength
        
        // computed values
        private plasmaCrawlProfile.entry profileEntry;
        private httpHeader responseHeader;
        private URL referrerURL;
        
        public Entry(URL url, String referrer, Date ifModifiedSince, boolean requestWithCookie,
                     String initiator, int depth, String profileHandle, String anchorName) {
            this.url = url;
            this.referrerHash = referrer;
            this.ifModifiedSince = ifModifiedSince;
            this.flags = (requestWithCookie) ? (byte) 1 : (byte) 0;
            this.initiator = initiator;
            this.depth = depth;
            this.profileHandle = profileHandle;
            this.anchorName = anchorName;
            
            this.profileEntry = null;
            this.responseHeader = null;
            this.referrerURL = null;
        }
        
        public Entry(byte[][] row) {
            long ims = serverCodings.enhancedCoder.decodeBase64Long(new String(row[2]));
            byte flags = (row[3] == null) ? 0 : row[3][0];
            try {
                this.url = new URL(new String(row[0]));
            } catch (MalformedURLException e) {
                this.url = null;
            }
            this.referrerHash = new String(row[1]);
            this.ifModifiedSince = (ims == 0) ? null : new Date(ims);
            this.flags = ((flags & 1) == 1) ? (byte) 1 : (byte) 0;
            this.initiator = new String(row[4]);
            this.depth = (int) serverCodings.enhancedCoder.decodeBase64Long(new String(row[5]));
            this.profileHandle = new String(row[6]);
            this.anchorName = (row[7] == null) ? null : new String(row[7]);
            
            this.profileEntry = null;
            this.responseHeader = null;
            this.referrerURL = null;
        }
        
        public URL url() {
            return url;
        }
        
        public String normalizedURLString() {
            return htmlFilterContentScraper.urlNormalform(url);
        }
        
        public String urlHash() {
            return plasmaURL.urlHash(url);
        }
        
        public boolean requestedWithCookie() {
            return (flags & 1) == 1;
        }
        
        public File cacheFile() {
            return htCache.getCachePath(url);
        }
        
        public boolean proxy() {
            return (initiator == null) || (initiator.equals(plasmaURL.dummyHash));
        }
    
        public String initiator() {
            return initiator;
        }
        
        public int depth() {
            return depth;
        }
        
        public long size() {
            if (cacheFile().exists()) return cacheFile().length(); else return 0;
        }
        
        public plasmaCrawlProfile.entry profile() {
            if (profileEntry == null) profileEntry = profiles.getEntry(profileHandle);
            return profileEntry;
        }
        
        public httpHeader responseHeader() {
            if (responseHeader == null) try {
                responseHeader = htCache.getCachedResponse(plasmaURL.urlHash(url));
            } catch (IOException e) {
                e.printStackTrace();
                return null;
            }
            return responseHeader;
        }
        
        public URL referrerURL() {
            if (referrerURL == null) {
                if ((referrerHash == null) || (referrerHash.equals(plasmaURL.dummyHash))) return null;
                referrerURL = lurls.getEntry(referrerHash).url();
            }
            return referrerURL;
        }
        
        public String anchorName() {
            return anchorName;
        }
        
	public String shallIndexCacheForProxy() {
	    // decide upon header information if a specific file should be indexed
	    // this method returns null if the answer is 'YES'!
	    // if the answer is 'NO' (do not index), it returns a string with the reason
	    // to reject the crawling demand in clear text
	    
            // check profile
            if (!(profile().localIndexing())) return "Indexing_Not_Allowed";
            
	    // -CGI access in request
	    // CGI access makes the page very individual, and therefore not usable in caches
	     if ((plasmaHTCache.isPOST(normalizedURLString())) && (!(profile().crawlingQ()))) return "Dynamic_(POST)";
             if ((plasmaHTCache.isCGI(normalizedURLString())) && (!(profile().crawlingQ()))) return "Dynamic_(CGI)";
	    
	    // -authorization cases in request
	    // we checked that in shallStoreCache
	    
	    // -ranges in request
	    // we checked that in shallStoreCache

            // a picture cannot be indexed
	    if (plasmaHTCache.noIndexingURL(normalizedURLString())) return "Media_Content_(forbidden)";
	    
	    // -cookies in request
	    // unfortunately, we cannot index pages which have been requested with a cookie
	    // because the returned content may be special for the client
	    if (requestedWithCookie()) {
		//System.out.println("***not indexed because cookie");
		return "Dynamic_(Requested_With_Cookie)";
	    }

	    // -set-cookie in response
	    // the set-cookie from the server does not indicate that the content is special
	    // thus we do not care about it here for indexing

            if (responseHeader() != null) {
                
                // a picture cannot be indexed
                if (plasmaHTCache.isPicture(responseHeader())) return "Media_Content_(Picture)";
                if (!(plasmaHTCache.isText(responseHeader()))) return "Media_Content_(not_text)";
	    
                // -if-modified-since in request
                // if the page is fresh at the very moment we can index it
                if ((ifModifiedSince != null) && (responseHeader().containsKey(httpHeader.LAST_MODIFIED))) {
                    // parse date
                    Date d = responseHeader().lastModified();
                    if (d == null) d = new Date();
                    // finally, we shall treat the cache as stale if the modification time is after the if-.. time
                    if (d.after(ifModifiedSince)) {
                        //System.out.println("***not indexed because if-modified-since");
                        return "Stale_(Last-Modified>Modified-Since)";
                    }
                }
                
                // -pragma in cached response
                if ((responseHeader().containsKey(httpHeader.PRAGMA)) &&
                        (((String) responseHeader().get(httpHeader.PRAGMA)).toUpperCase().equals("NO-CACHE"))) return "Denied_(pragma_no_cache)";
                
                // see for documentation also:
                // http://www.web-caching.com/cacheability.html
                
                
                // calculate often needed values for freshness attributes
                Date date           = responseHeader().date();
                Date expires        = responseHeader().expires();
                Date lastModified   = responseHeader().lastModified();
                String cacheControl = (String) responseHeader.get(httpHeader.CACHE_CONTROL);
                
                // look for freshnes information
                
                // -expires in cached response
                // the expires value gives us a very easy hint when the cache is stale
                // sometimes, the expires date is set to the past to prevent that a page is cached
                // we use that information to see if we should index it
                if (expires != null) {
                    Date yesterday = new Date((new Date()).getTime() - plasmaHTCache.oneday);
                    if (expires.before(yesterday)) return "Stale_(Expired)";
                }
                
                // -lastModified in cached response
                // this information is too weak to use it to prevent indexing
                // even if we can apply a TTL heuristic for cache usage
                
                // -cache-control in cached response
                // the cache-control has many value options.
                if (cacheControl != null) {
                    cacheControl = cacheControl.trim().toUpperCase();
                /* we have the following cases for cache-control:
                "public" -- can be indexed
                "private", "no-cache", "no-store" -- cannot be indexed
                "max-age=<delta-seconds>" -- stale/fresh dependent on date
                 */
                    if (cacheControl.startsWith("PUBLIC")) {
                        // ok, do nothing
                    } else if ((cacheControl.startsWith("PRIVATE")) ||
                            (cacheControl.startsWith("NO-CACHE")) ||
                            (cacheControl.startsWith("NO-STORE"))) {
                        // easy case
                        return "Stale_(denied_by_cache-control=" + cacheControl+ ")";
                    } else if (cacheControl.startsWith("MAX-AGE=")) {
                        // we need also the load date
                        if (date == null) return "Stale_(no_date_given_in_response)";
                        try {
                            long ttl = 1000 * Long.parseLong(cacheControl.substring(8)); // milliseconds to live
                            if ((new Date()).getTime() - date.getTime() > ttl) {
                                //System.out.println("***not indexed because cache-control");
                                return "Stale_(expired_by_cache-control)";
                            }
                        } catch (Exception e) {
                            return "Error_(" + e.getMessage() + ")";
                        }
                    }
                }
            }
	    return null;
	}
        
        	
	public String shallIndexCacheForCrawler() {
	    // decide upon header information if a specific file should be indexed
	    // this method returns null if the answer is 'YES'!
	    // if the answer is 'NO' (do not index), it returns a string with the reason
	    // to reject the crawling demand in clear text
	    
            // check profile
            if (!(profile().localIndexing())) return "Indexing_Not_Allowed";
            
	    // -CGI access in request
	    // CGI access makes the page very individual, and therefore not usable in caches
	     if ((plasmaHTCache.isPOST(normalizedURLString())) && (!(profile().crawlingQ()))) return "Dynamic_(POST)";
             if ((plasmaHTCache.isCGI(normalizedURLString())) && (!(profile().crawlingQ()))) return "Dynamic_(CGI)";
	    
	    // -authorization cases in request
	    // we checked that in shallStoreCache
	    
	    // -ranges in request
	    // we checked that in shallStoreCache
	    
	    // a picture cannot be indexed
            if (responseHeader() != null) {
                if (plasmaHTCache.isPicture(responseHeader())) return "Media_Content_(Picture)";
                if (!(plasmaHTCache.isText(responseHeader()))) return "Media_Content_(not_text)";
            }
	    if (plasmaHTCache.noIndexingURL(normalizedURLString())) return "Media_Content_(forbidden)";

	    // -if-modified-since in request
	    // if the page is fresh at the very moment we can index it
            // -> this does not apply for the crawler
	    
	    // -cookies in request
	    // unfortunately, we cannot index pages which have been requested with a cookie
	    // because the returned content may be special for the client
            // -> this does not apply for a crawler

	    // -set-cookie in response
	    // the set-cookie from the server does not indicate that the content is special
	    // thus we do not care about it here for indexing
            // -> this does not apply for a crawler

	    // -pragma in cached response
            // -> in the crawler we ignore this
            
	    // look for freshnes information
	    
	    // -expires in cached response
	    // the expires value gives us a very easy hint when the cache is stale
	    // sometimes, the expires date is set to the past to prevent that a page is cached
	    // we use that information to see if we should index it
	    // -> this does not apply for a crawler
	    
	    // -lastModified in cached response
	    // this information is too weak to use it to prevent indexing
	    // even if we can apply a TTL heuristic for cache usage
	    
 	    // -cache-control in cached response
	    // the cache-control has many value options.
	    // -> in the crawler we ignore this
	    
	    return null;
	}
        
    }
}