package org.healthonnet.solr;

import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.Collection;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.Token;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.FlagsAttribute;
import org.apache.lucene.analysis.tokenattributes.OffsetAttribute;
import org.apache.lucene.analysis.tokenattributes.PayloadAttribute;
import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;
import org.apache.lucene.analysis.tokenattributes.TypeAttribute;
import org.apache.lucene.index.IndexReader;
import org.apache.solr.common.SolrException;
import org.apache.solr.common.params.CommonParams;
import org.apache.solr.common.params.ShardParams;
import org.apache.solr.common.params.SolrParams;
import org.apache.solr.common.util.NamedList;
import org.apache.solr.common.util.SimpleOrderedMap;
import org.apache.solr.handler.component.ResponseBuilder;
import org.apache.solr.handler.component.SpellCheckComponent;
import org.apache.solr.spelling.SolrSpellChecker;
import org.apache.solr.spelling.SpellingOptions;
import org.apache.solr.spelling.SpellingResult;

/**
 * Wrapper around the SpellCheckComponent that gives a more quiet output. It
 * only gives collations; does not give any suggestions. This is useful when you
 * set spellcheck.count to a large number, but you really only want to check the
 * collations. It avoids writing a ton of output and therefore cuts down on I/O.
 *
 * @author nolan
 *
 */
public class QuietSpellCheckComponent extends SpellCheckComponent {

    @Override
    @SuppressWarnings("unchecked")
    public void process(ResponseBuilder rb) throws IOException {
	SolrParams params = rb.req.getParams();
	if (!params.getBool(COMPONENT_NAME, false) || spellCheckers.isEmpty()) {
	    return;
	}
	boolean shardRequest = "true".equals(params.get(ShardParams.IS_SHARD));
	String q = params.get(SPELLCHECK_Q);
	SolrSpellChecker spellChecker = getSpellChecker(params);
	Collection<Token> tokens = null;
	if (q != null) {
	    // we have a spell check param, tokenize it with the query analyzer
	    // applicable for this spellchecker
	    tokens = getTokens(q, spellChecker.getQueryAnalyzer());
	} else {
	    q = rb.getQueryString();
	    if (q == null) {
		q = params.get(CommonParams.Q);
	    }
	    tokens = queryConverter.convert(q);
	}
	if (tokens != null && tokens.isEmpty() == false) {
	    if (spellChecker != null) {
		int count = params.getInt(SPELLCHECK_COUNT, 1);
		boolean onlyMorePopular = params.getBool(SPELLCHECK_ONLY_MORE_POPULAR, DEFAULT_ONLY_MORE_POPULAR);
		boolean extendedResults = params.getBool(SPELLCHECK_EXTENDED_RESULTS, false);
		NamedList response = new SimpleOrderedMap();
		IndexReader reader = rb.req.getSearcher().getReader();
		boolean collate = params.getBool(SPELLCHECK_COLLATE, false);
		float accuracy = params.getFloat(SPELLCHECK_ACCURACY, Float.MIN_VALUE);
		SolrParams customParams = getCustomParams(getDictionaryName(params), params, shardRequest);
		SpellingOptions options = new SpellingOptions(tokens, reader,
			count, onlyMorePopular, extendedResults, accuracy,
			customParams);
		SpellingResult spellingResult = spellChecker.getSuggestions(options);
		if (spellingResult != null) {
		    NamedList suggestions = toNamedList(shardRequest,
			    spellingResult, q, extendedResults, collate);
		    if (collate) {
			addCollationsToResponse(params, spellingResult, rb, q, suggestions);
		    }
		    // clear the spellingResult after making collations from it.
		    // This is the only change I'm making compared to
		    // SpellCheckComponent!
		    for (int i = suggestions.size() - 1; i >= 0; i--) {
			if ("collation".equals(suggestions.getName(i))) {
			    Object val = suggestions.getVal(i);
			    if (val instanceof NamedList
				    && ((NamedList) val).size() > 0
				    && "collationQuery".equals(((NamedList) val).getName(0))) {
				continue;
			    }
			}
			// otherwise it's a non-collation; delete it
			suggestions.remove(i);
		    }
		    response.add("suggestions", suggestions);
		    rb.rsp.add("spellcheck", response);
		}

	    } else {
		throw new SolrException(SolrException.ErrorCode.NOT_FOUND,
			"Specified dictionary does not exist.");
	    }
	}
    }

    private Collection<Token> getTokens(String q, Analyzer analyzer)
	    throws IOException {
	Collection<Token> result = new ArrayList<Token>();
	TokenStream ts = analyzer.reusableTokenStream("", new StringReader(q));
	ts.reset();
	// TODO: support custom attributes
	CharTermAttribute termAtt = ts.addAttribute(CharTermAttribute.class);
	OffsetAttribute offsetAtt = ts.addAttribute(OffsetAttribute.class);
	TypeAttribute typeAtt = ts.addAttribute(TypeAttribute.class);
	FlagsAttribute flagsAtt = ts.addAttribute(FlagsAttribute.class);
	PayloadAttribute payloadAtt = ts.addAttribute(PayloadAttribute.class);
	PositionIncrementAttribute posIncAtt = ts
		.addAttribute(PositionIncrementAttribute.class);

	while (ts.incrementToken()) {
	    Token token = new Token();
	    token.copyBuffer(termAtt.buffer(), 0, termAtt.length());
	    token.setOffset(offsetAtt.startOffset(), offsetAtt.endOffset());
	    token.setType(typeAtt.type());
	    token.setFlags(flagsAtt.getFlags());
	    token.setPayload(payloadAtt.getPayload());
	    token.setPositionIncrement(posIncAtt.getPositionIncrement());
	    result.add(token);
	}
	ts.end();
	ts.close();
	return result;
    }

    private String getDictionaryName(SolrParams params) {
	String dictName = params.get(SPELLCHECK_DICT);
	if (dictName == null) {
	    dictName = SolrSpellChecker.DEFAULT_DICTIONARY_NAME;
	}
	return dictName;
    }

}