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*/

package com.google.refine.commands.recon;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.http.Consts;
import org.apache.http.NameValuePair;
import org.apache.http.StatusLine;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.client.LaxRedirectStrategy;
import org.apache.http.message.BasicNameValuePair;

import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonInclude.Include;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.ObjectNode;
import com.google.refine.RefineServlet;
import com.google.refine.commands.Command;
import com.google.refine.expr.ExpressionUtils;
import com.google.refine.model.Column;
import com.google.refine.model.Project;
import com.google.refine.model.ReconType;
import com.google.refine.model.Row;
import com.google.refine.model.recon.StandardReconConfig.ReconResult;
import com.google.refine.util.ParsingUtilities;

public class GuessTypesOfColumnCommand extends Command {
    
    final static int DEFAULT_SAMPLE_SIZE = 10;
    private int sampleSize = DEFAULT_SAMPLE_SIZE;
     
    protected static class TypesResponse {
        @JsonProperty("code")
        protected String code;
        @JsonProperty("message")
        @JsonInclude(Include.NON_NULL)
        protected String message;
        @JsonProperty("types")
        @JsonInclude(Include.NON_NULL)
        List<TypeGroup> types;
        
        protected TypesResponse(
                String code,
                String message,
                List<TypeGroup> types) {
            this.code = code;
            this.message = message;
            this.types = types;
        }
    }
    
    @Override
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
    	if(!hasValidCSRFToken(request)) {
    		respondCSRFError(response);
    		return;
    	}
        
        try {
            Project project = getProject(request);
            String columnName = request.getParameter("columnName");
            String serviceUrl = request.getParameter("service");
            
            Column column = project.columnModel.getColumnByName(columnName);
            if (column == null) {
                respondJSON(response, new TypesResponse("error", "No such column", null));
            } else {
                List<TypeGroup> typeGroups = guessTypes(project, column, serviceUrl);
                respondJSON(response, new TypesResponse("ok", null, typeGroups));   
            }

        } catch (Exception e) {
            respondException(response, e);
        }
    }
    
    protected static class IndividualQuery {
        @JsonProperty("query")
        protected String query;
        @JsonProperty("limit")
        protected int limit;
        
        protected IndividualQuery(String query, int limit) {
            this.query = query;
            this.limit = limit;
        }
    }
    
    /**
     * Run relevance searches for the first n cells in the given column and
     * count the types of the results. Return a sorted list of types, from most
     * frequent to least. 
     * 
     * @param project
     * @param column
     * @return
     * @throws JSONException, IOException 
     */
    protected List<TypeGroup> guessTypes(Project project, Column column, String serviceUrl)
            throws IOException {
        Map<String, TypeGroup> map = new HashMap<String, TypeGroup>();
        
        int cellIndex = column.getCellIndex();
        
        List<String> samples = new ArrayList<String>(sampleSize);
        Set<String> sampleSet = new HashSet<String>();
        
        for (Row row : project.rows) {
            Object value = row.getCellValue(cellIndex);
            if (ExpressionUtils.isNonBlankData(value)) {
                String s = value.toString().trim();
                if (!sampleSet.contains(s)) {
                    samples.add(s);
                    sampleSet.add(s);
                    if (samples.size() >= sampleSize) {
                        break;
                    }
                }
            }
        }
        
        Map<String, IndividualQuery> queryMap = new HashMap<>();
        for (int i = 0; i < samples.size(); i++) {
            queryMap.put("q" + i, new IndividualQuery(samples.get(i), 3));
        }
        
        String queriesString = ParsingUtilities.defaultWriter.writeValueAsString(queryMap);
        try {
            RequestConfig defaultRequestConfig = RequestConfig.custom()
                    .setConnectTimeout(30 * 1000)
                    .build();

            HttpClientBuilder httpClientBuilder = HttpClients.custom()
                    .setUserAgent(RefineServlet.getUserAgent())
                    .setRedirectStrategy(new LaxRedirectStrategy())
                    .setDefaultRequestConfig(defaultRequestConfig);
            
            CloseableHttpClient httpClient = httpClientBuilder.build();
            HttpPost request = new HttpPost(serviceUrl);
            List<NameValuePair> body = Collections.singletonList(
                    new BasicNameValuePair("queries", queriesString));
            request.setEntity(new UrlEncodedFormEntity(body, Consts.UTF_8));
            
            try (CloseableHttpResponse response = httpClient.execute(request)) {
                StatusLine statusLine = response.getStatusLine();
                if (statusLine.getStatusCode() >= 400) {
                    throw new IOException("Failed  - code:" 
                            + Integer.toString(statusLine.getStatusCode()) 
                            + " message: " + statusLine.getReasonPhrase());
                }
                
                String s = ParsingUtilities.inputStreamToString(response.getEntity().getContent());
                ObjectNode o = ParsingUtilities.evaluateJsonStringToObjectNode(s);

                Iterator<JsonNode> iterator = o.iterator();
                while (iterator.hasNext()) {
                    JsonNode o2 = iterator.next();
                    if (!(o2.has("result") && o2.get("result") instanceof ArrayNode)) {
                        continue;
                    }

                    ArrayNode results = (ArrayNode) o2.get("result");
                    List<ReconResult> reconResults = ParsingUtilities.mapper.convertValue(results, new TypeReference<List<ReconResult>>() {});
                    int count = reconResults.size();

                    for (int j = 0; j < count; j++) {
                        ReconResult result = reconResults.get(j);
                        double score = 1.0 / (1 + j); // score by each result's rank

                        List<ReconType> types = result.types;
                        int typeCount = types.size();

                        for (int t = 0; t < typeCount; t++) {
                        	ReconType type = types.get(t);
                            double score2 = score * (typeCount - t) / typeCount;
                            if (map.containsKey(type.id)) {
                                TypeGroup tg = map.get(type.id);
                                tg.score += score2;
                                tg.count++;
                            } else {
                                map.put(type.id, new TypeGroup(type.id, type.name, score2));
                            }
                        }
                    }
                }
            }
        } catch (IOException e) {
            logger.error("Failed to guess cell types for load\n" + queriesString, e);
            throw e;
        }
        
        List<TypeGroup> types = new ArrayList<TypeGroup>(map.values());
        Collections.sort(types, new Comparator<TypeGroup>() {
            @Override
            public int compare(TypeGroup o1, TypeGroup o2) {
                int c = Math.min(sampleSize, o2.count) - Math.min(sampleSize, o1.count);
                if (c != 0) {
                    return c;
                }
                return (int) Math.signum(o2.score / o2.count - o1.score / o1.count);
            }
        });
        
        return types;
    }
    
    static protected class TypeGroup {
        @JsonProperty("id")
        protected String id;
        @JsonProperty("name")
        protected String name;
        @JsonProperty("count")
        protected int count;
        @JsonProperty("score")
        protected double score;
        
        TypeGroup(String id, String name, double score) {
            this.id = id;
            this.name = name;
            this.score = score;
            this.count = 1;
        }
    }
    
    // for testability
    protected void setSampleSize(int sampleSize) {
        this.sampleSize = sampleSize;
    }
}
