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*/

package com.google.refine.browsing.facets;

import java.util.LinkedList;
import java.util.List;
import java.util.stream.Collectors;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonInclude.Include;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.google.refine.ProjectManager;
import com.google.refine.browsing.DecoratedValue;
import com.google.refine.browsing.FilteredRecords;
import com.google.refine.browsing.FilteredRows;
import com.google.refine.browsing.RecordFilter;
import com.google.refine.browsing.RowFilter;
import com.google.refine.browsing.filters.AllRowsRecordFilter;
import com.google.refine.browsing.filters.AnyRowRecordFilter;
import com.google.refine.browsing.filters.ExpressionEqualRowFilter;
import com.google.refine.browsing.util.ExpressionNominalValueGrouper;
import com.google.refine.expr.Evaluable;
import com.google.refine.expr.MetaParser;
import com.google.refine.expr.ParsingException;
import com.google.refine.model.Column;
import com.google.refine.model.Project;

public class ListFacet implements Facet {
    public static final String ERR_TOO_MANY_CHOICES = "Too many choices";
    
    /**
     * Wrapper to respect the serialization format
     */
    public static class DecoratedValueWrapper {
        @JsonProperty("v")
        public final DecoratedValue value;
        @JsonCreator
        public DecoratedValueWrapper(
                @JsonProperty("v") DecoratedValue value) {
            this.value = value;
        }
    }
    
    /*
     * Configuration
     */
    public static class ListFacetConfig implements FacetConfig {
        @JsonProperty("name")
        public String     name;
        @JsonProperty("expression")
        public String     expression;
        @JsonProperty("columnName")
        public String     columnName;
        @JsonProperty("invert")
        public boolean    invert;
        
        // If true, then facet won't show the blank and error choices
        @JsonProperty("omitBlank")
        public boolean omitBlank;
        @JsonProperty("omitError")
        public boolean omitError;
        
        @JsonIgnore
        public List<DecoratedValue> selection = new LinkedList<>();
        @JsonProperty("selectBlank")
        public boolean selectBlank;
        @JsonProperty("selectError")
        public boolean selectError;

        @JsonProperty("selection")
        public List<DecoratedValueWrapper> getWrappedSelection() {
            return selection.stream()
                    .map(e -> new DecoratedValueWrapper(e))
                    .collect(Collectors.toList());
        }
        
        @JsonProperty("selection")
        public void setSelection(List<DecoratedValueWrapper> wrapped) {
            selection = wrapped.stream()
                    .map(e -> e.value)
                    .collect(Collectors.toList());
        }
        
        @Override
        public Facet apply(Project project) {
            ListFacet facet = new ListFacet();
            facet.initializeFromConfig(this, project);
            return facet;
        }

        @Override
        public String getJsonType() {
            return "list";
        }
    }
    
    /**
     * Wrapper class for choice counts and selection status for blank and error
     */
    public static class OtherChoice {
        @JsonProperty("s")
        boolean selected;
        @JsonProperty("c")
        int count;
        public OtherChoice(
                @JsonProperty("s") boolean selected,
                @JsonProperty("c") int count) {
            this.selected = selected;
            this.count = count;
        }
    }
    
    ListFacetConfig _config = new ListFacetConfig();
    
    /*
     * Derived configuration
     */
    protected int        _cellIndex;
    protected Evaluable  _eval;
    protected String     _errorMessage;
    
    /*
     * Computed results
     */
    protected List<NominalFacetChoice> _choices = new LinkedList<NominalFacetChoice>();
    protected int _blankCount;
    protected int _errorCount;
    
    public ListFacet() {
    }
    
    @JsonProperty("name")
    public String getName() {
        return _config.name;
    }
    
    @JsonProperty("columnName")
    public String getColumnName() {
        return _config.columnName;
    }
    
    @JsonProperty("expression")
    public String getExpression() {
        return _config.expression;
    }
    
    @JsonProperty("invert")
    public boolean getInvert() {
        return _config.invert;
    }
    
    @JsonProperty("error")
    @JsonInclude(Include.NON_NULL)
    public String getError() {
        if (_errorMessage == null && _choices.size() > getLimit()) {
            return ERR_TOO_MANY_CHOICES;
        }
        return _errorMessage;
    }
    
    @JsonProperty("choiceCount")
    @JsonInclude(Include.NON_NULL)
    public Integer getChoiceCount() {
        if (_errorMessage == null && _choices.size() > getLimit()) {
            return _choices.size();
        }
        return null;
    }
    
    @JsonProperty("choices")
    @JsonInclude(Include.NON_NULL)
    public List<NominalFacetChoice> getChoices() {
        if (getError() == null) {
            return _choices;
        }
        return null;
    }
    
    @JsonProperty("blankChoice")
    @JsonInclude(Include.NON_NULL)
    public OtherChoice getBlankChoice() {
        if (getError() == null && !_config.omitBlank && (_config.selectBlank || _blankCount > 0)) {
            return new OtherChoice(_config.selectBlank, _blankCount);
        }
        return null;
    }
    
    @JsonProperty("errorChoice")
    @JsonInclude(Include.NON_NULL)
    public OtherChoice getErrorChoice() {
        if (getError() == null && !_config.omitError && (_config.selectError || _errorCount > 0)) {
            return new OtherChoice(_config.selectError, _errorCount);
        }
        return null;
    }
    
    protected int getLimit() {
        Object v = ProjectManager.singleton.getPreferenceStore().get("ui.browsing.listFacet.limit");
        if (v != null) {
            if (v instanceof Number) {
                return ((Number) v).intValue();
            } else {
                try {
                    int n = Integer.parseInt(v.toString());
                    return n;
                } catch (NumberFormatException e) {
                    // ignore
                }
            }
        }
        return 2000;
    }
        
    public void initializeFromConfig(ListFacetConfig config, Project project) {
        _config = config;
        if (_config.columnName.length() > 0) {
            Column column = project.columnModel.getColumnByName(_config.columnName);
            if (column != null) {
                _cellIndex = column.getCellIndex();
            } else {
                _errorMessage = "No column named " + _config.columnName;
            }
        } else {
            _cellIndex = -1;
        }
        
        try {
            _eval = MetaParser.parse(_config.expression);
        } catch (ParsingException e) {
            _errorMessage = e.getMessage();
        }
    }

    @Override
    public RowFilter getRowFilter(Project project) {
        return 
            _eval == null || 
            _errorMessage != null ||
            (_config.selection.size() == 0 && !_config.selectBlank && !_config.selectError) ? 
                null :
                new ExpressionEqualRowFilter(
                    _eval, 
                    _config.columnName,
                    _cellIndex, 
                    createMatches(), 
                    _config.selectBlank, 
                    _config.selectError,
                    _config.invert);
    }
    
    @Override
    public RecordFilter getRecordFilter(Project project) {
        RowFilter rowFilter = getRowFilter(project);
        return rowFilter == null ? null :
            (_config.invert ?
                    new AllRowsRecordFilter(rowFilter) :
                        new AnyRowRecordFilter(rowFilter));
    }

    @Override
    public void computeChoices(Project project, FilteredRows filteredRows) {
        if (_eval != null && _errorMessage == null) {
            ExpressionNominalValueGrouper grouper = 
                new ExpressionNominalValueGrouper(_eval, _config.columnName, _cellIndex);
            
            filteredRows.accept(project, grouper);
            
            postProcessGrouper(grouper);
        }
    }
    
    @Override
    public void computeChoices(Project project, FilteredRecords filteredRecords) {
        if (_eval != null && _errorMessage == null) {
            ExpressionNominalValueGrouper grouper = 
                new ExpressionNominalValueGrouper(_eval, _config.columnName, _cellIndex);
            
            filteredRecords.accept(project, grouper);
            
            postProcessGrouper(grouper);
        }
    }
    
    protected void postProcessGrouper(ExpressionNominalValueGrouper grouper) {
        _choices.clear();
        _choices.addAll(grouper.choices.values());
        
        for (DecoratedValue decoratedValue : _config.selection) {
            String valueString = decoratedValue.value.toString();
            
            if (grouper.choices.containsKey(valueString)) {
                grouper.choices.get(valueString).selected = true;
            } else {
                /*
                 *  A selected choice can have zero count if it is selected together
                 *  with other choices, and some other facets' constraints eliminate
                 *  all rows projected to this choice altogether. For example, if you
                 *  select both "car" and "bicycle" in the "type of vehicle" facet, and
                 *  then constrain the "wheels" facet to more than 2, then the "bicycle"
                 *  choice now has zero count even if it's still selected. The grouper 
                 *  won't be able to detect the "bicycle" choice, so we need to inject
                 *  that choice into the choice list ourselves.
                 */
                NominalFacetChoice choice = new NominalFacetChoice(decoratedValue);
                choice.count = 0;
                choice.selected = true;
                _choices.add(choice);
            }
        }
        
        _blankCount = grouper.blankCount;
        _errorCount = grouper.errorCount;
    }
    
    protected Object[] createMatches() {
        Object[] a = new Object[_config.selection.size()];
        for (int i = 0; i < a.length; i++) {
            a[i] = _config.selection.get(i).value;
        }
        return a;
    }
}
