package com.metaweb.gridworks.commands.row;

import java.io.IOException;
import java.util.Properties;

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

import org.json.JSONException;
import org.json.JSONObject;
import org.json.JSONWriter;

import com.metaweb.gridworks.browsing.Engine;
import com.metaweb.gridworks.browsing.FilteredRecords;
import com.metaweb.gridworks.browsing.FilteredRows;
import com.metaweb.gridworks.browsing.RecordVisitor;
import com.metaweb.gridworks.browsing.RowVisitor;
import com.metaweb.gridworks.browsing.Engine.Mode;
import com.metaweb.gridworks.commands.Command;
import com.metaweb.gridworks.model.Project;
import com.metaweb.gridworks.model.Record;
import com.metaweb.gridworks.model.Row;
import com.metaweb.gridworks.sorting.SortingRecordVisitor;
import com.metaweb.gridworks.sorting.SortingRowVisitor;
import com.metaweb.gridworks.util.ParsingUtilities;
import com.metaweb.gridworks.util.Pool;

public class GetRowsCommand extends Command {
	
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        
        try {
            Project project = getProject(request);
            Engine engine = getEngine(request, project);
            
            int start = Math.min(project.rows.size(), Math.max(0, getIntegerParameter(request, "start", 0)));
            int limit = Math.min(project.rows.size() - start, Math.max(0, getIntegerParameter(request, "limit", 20)));
            
            Pool pool = new Pool();
            Properties options = new Properties();
            options.put("project", project);
            options.put("reconCandidateOmitTypes", true);
            options.put("pool", pool);
            
            response.setCharacterEncoding("UTF-8");
            response.setHeader("Content-Type", "application/json");
            
            JSONWriter writer = new JSONWriter(response.getWriter());
            writer.object();
            
            RowWritingVisitor rwv = new RowWritingVisitor(start, limit, writer, options);
            
            JSONObject sortingJson = null;
            try{
                String json = request.getParameter("sorting");
                sortingJson = (json == null) ? null : 
                	ParsingUtilities.evaluateJsonStringToObject(json);
            } catch (JSONException e) {
            }

            if (engine.getMode() == Mode.RowBased) {
                FilteredRows filteredRows = engine.getAllFilteredRows();
                RowVisitor visitor = rwv;
                
                if (sortingJson != null) {
                	SortingRowVisitor srv = new SortingRowVisitor(visitor);
                	
                	srv.initializeFromJSON(project, sortingJson);
            		if (srv.hasCriteria()) {
            			visitor = srv;
            		}
                }
                
                writer.key("mode"); writer.value("row-based");
                writer.key("rows"); writer.array();
                filteredRows.accept(project, visitor);
                writer.endArray();
                writer.key("filtered"); writer.value(rwv.total);
                writer.key("total"); writer.value(project.rows.size());
            } else {
                FilteredRecords filteredRecords = engine.getFilteredRecords();
                RecordVisitor visitor = rwv;
                
                if (sortingJson != null) {
                	SortingRecordVisitor srv = new SortingRecordVisitor(visitor);
                	
                	srv.initializeFromJSON(project, sortingJson);
            		if (srv.hasCriteria()) {
            			visitor = srv;
            		}
                }
                
                writer.key("mode"); writer.value("record-based");
                writer.key("rows"); writer.array();
                filteredRecords.accept(project, visitor);
                writer.endArray();
                writer.key("filtered"); writer.value(rwv.total);
                writer.key("total"); writer.value(project.recordModel.getRecordCount());
            }
            
            
            writer.key("start"); writer.value(start);
            writer.key("limit"); writer.value(limit);
            writer.key("pool"); pool.write(writer, options);
            
            writer.endObject();
        } catch (Exception e) {
            respondException(response, e);
        }
    }
    
    static protected class RowWritingVisitor implements RowVisitor, RecordVisitor {
        final int 		  start;
        final int 		  limit;
        final JSONWriter  writer;
        final Properties  options;
        
        public int total;
        
        public RowWritingVisitor(int start, int limit, JSONWriter writer, Properties options) {
            this.start = start;
            this.limit = limit;
            this.writer = writer;
            this.options = options;
        }
        
        @Override
        public void start(Project project) {
        	// nothing to do
        }
        
        @Override
        public void end(Project project) {
        	// nothing to do
        }
        
        public boolean visit(Project project, int rowIndex, Row row) {
            if (total >= start && total < start + limit) {
                internalVisit(project, rowIndex, row);
            }
        	total++;
        	
            return false;
        }
        
        @Override
        public boolean visit(Project project, Record record) {
            if (total >= start && total < start + limit) {
                internalVisit(project, record);
            }
        	total++;
        	
            return false;
        }
        
        public boolean internalVisit(Project project, int rowIndex, Row row) {
            try {
                options.put("rowIndex", rowIndex);
                row.write(writer, options);
            } catch (JSONException e) {
            }
            return false;
        }
        
        protected boolean internalVisit(Project project, Record record) {
            options.put("recordIndex", record.recordIndex);
            
        	for (int r = record.fromRowIndex; r < record.toRowIndex; r++) {
                try {
                	Row row = project.rows.get(r);
                	
                    options.put("rowIndex", r);
                    
                    row.write(writer, options);
                    
                } catch (JSONException e) {
                }
                
                options.remove("recordIndex");
        	}
        	return false;
        }
    }
}