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Copyright 2011, Google Inc.
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*/

package com.google.refine.operations.cell;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import org.apache.commons.lang.Validate;

import com.google.refine.expr.ExpressionUtils;
import com.google.refine.history.HistoryEntry;
import com.google.refine.model.AbstractOperation;
import com.google.refine.model.Cell;
import com.google.refine.model.Column;
import com.google.refine.model.Project;
import com.google.refine.model.Row;
import com.google.refine.model.changes.MassRowColumnChange;
import com.google.refine.operations.OperationDescription;

public class KeyValueColumnizeOperation extends AbstractOperation {

    final protected String _keyColumnName;
    final protected String _valueColumnName;
    final protected String _noteColumnName;

    @JsonCreator
    public KeyValueColumnizeOperation(
            @JsonProperty("keyColumnName") String keyColumnName,
            @JsonProperty("valueColumnName") String valueColumnName,
            @JsonProperty("noteColumnName") String noteColumnName) {
        _keyColumnName = keyColumnName;
        _valueColumnName = valueColumnName;
        _noteColumnName = noteColumnName;
    }

    @Override
    public void validate() {
        Validate.notNull(_keyColumnName, "Missing key column name");
        Validate.notNull(_valueColumnName, "Missing value column name");
        // _noteColumnName can be null
    }

    @JsonProperty("keyColumnName")
    public String getKeyColumnName() {
        return _keyColumnName;
    }

    @JsonProperty("valueColumnName")
    public String getValueColumnName() {
        return _valueColumnName;
    }

    @JsonProperty("noteColumnName")
    public String getNoteColumnName() {
        return _noteColumnName;
    }

    @Override
    protected String getBriefDescription(Project project) {
        return _noteColumnName == null ? OperationDescription.cell_key_value_columnize_brief(_keyColumnName, _valueColumnName)
                : OperationDescription.cell_key_value_columnize_note_column_brief(_keyColumnName, _valueColumnName, _noteColumnName);
    }

    @Override
    protected HistoryEntry createHistoryEntry(Project project, long historyEntryID) throws Exception {
        int keyColumnIndex = project.columnModel.getColumnIndexByName(_keyColumnName);
        int valueColumnIndex = project.columnModel.getColumnIndexByName(_valueColumnName);
        int noteColumnIndex = _noteColumnName == null ? -1 : project.columnModel.getColumnIndexByName(_noteColumnName);
        Column keyColumn = project.columnModel.getColumnByName(_keyColumnName);
        Column valueColumn = project.columnModel.getColumnByName(_valueColumnName);
        Column noteColumn = _noteColumnName == null ? null : project.columnModel.getColumnByName(_noteColumnName);

        List<Column> unchangedColumns = new ArrayList<Column>();
        List<Column> oldColumns = project.columnModel.columns;
        for (int i = 0; i < oldColumns.size(); i++) {
            if (i != keyColumnIndex &&
                    i != valueColumnIndex &&
                    i != noteColumnIndex) {
                unchangedColumns.add(oldColumns.get(i));
            }
        }

        List<Column> newColumns = new ArrayList<Column>();
        List<Column> newNoteColumns = new ArrayList<Column>();
        Map<String, Column> keyValueToColumn = new HashMap<String, Column>();
        Map<String, Column> keyValueToNoteColumn = new HashMap<String, Column>();
        Map<String, Row> groupByCellValuesToRow = new HashMap<String, Row>();

        List<Row> newRows = new ArrayList<Row>();
        List<Row> oldRows = project.rows;
        Row reusableRow = null;
        List<Row> currentRows = new ArrayList<Row>();
        String recordKey = null; // key which indicates the start of a record
        if (unchangedColumns.isEmpty()) {
            reusableRow = new Row(1);
            newRows.add(reusableRow);
            currentRows.clear();
            currentRows.add(reusableRow);
        }

        for (int r = 0; r < oldRows.size(); r++) {
            Row oldRow = oldRows.get(r);

            Object key = oldRow.getCellValue(keyColumn.getCellIndex());
            if (!ExpressionUtils.isNonBlankData(key)) {
                if (unchangedColumns.isEmpty()) {
                    // For degenerate 2 column case (plus optional note column),
                    // start a new row when we hit a blank line
                    reusableRow = new Row(newColumns.size());
                    newRows.add(reusableRow);
                    currentRows.clear();
                    currentRows.add(reusableRow);
                } else {
                    // Copy rows with no key
                    newRows.add(buildNewRow(unchangedColumns, oldRow, unchangedColumns.size()));
                }
                continue;
            }

            String keyString = key.toString();
            // Start a new row on our beginning of record key
            // TODO: Add support for processing in record mode instead of just by rows
            if (keyString.equals(recordKey) || recordKey == null) {
                reusableRow = new Row(newColumns.size());
                newRows.add(reusableRow);
                currentRows.clear();
                currentRows.add(reusableRow);
            }
            Column newColumn = keyValueToColumn.get(keyString);
            if (newColumn == null) {
                // Allocate new column
                newColumn = new Column(
                        project.columnModel.allocateNewCellIndex(),
                        project.columnModel.getUnduplicatedColumnName(keyString));
                keyValueToColumn.put(keyString, newColumn);
                newColumns.add(newColumn);

                // We assume first key encountered is the beginning of record key
                // TODO: make customizable?
                if (recordKey == null) {
                    recordKey = keyString;
                }
            }

            /*
             * NOTE: If we have additional columns, we currently merge all rows that have identical values in those
             * columns and then add our new columns.
             */
            if (unchangedColumns.size() > 0) {
                StringBuffer sb = new StringBuffer();
                for (int c = 0; c < unchangedColumns.size(); c++) {
                    Column unchangedColumn = unchangedColumns.get(c);
                    Object cellValue = oldRow.getCellValue(unchangedColumn.getCellIndex());
                    if (c > 0) {
                        sb.append('\0');
                    }
                    if (cellValue != null) {
                        sb.append(cellValue.toString());
                    }
                }
                String unchangedCellValues = sb.toString();

                reusableRow = groupByCellValuesToRow.get(unchangedCellValues);
                if (reusableRow == null ||
                        reusableRow.getCellValue(valueColumn.getCellIndex()) != null) {
                    reusableRow = buildNewRow(unchangedColumns, oldRow, newColumn.getCellIndex() + 1);
                    groupByCellValuesToRow.put(unchangedCellValues, reusableRow);
                    newRows.add(reusableRow);
                }
            }

            Cell cell = oldRow.getCell(valueColumn.getCellIndex());
            if (unchangedColumns.size() == 0) {
                int index = newColumn.getCellIndex();
                Row row = getAvailableRow(currentRows, newRows, index);
                row.setCell(index, cell);
            } else {
                // TODO: support repeating keys in this mode too
                reusableRow.setCell(newColumn.getCellIndex(), cell);
            }

            if (noteColumn != null) {
                Object noteValue = oldRow.getCellValue(noteColumn.getCellIndex());
                if (ExpressionUtils.isNonBlankData(noteValue)) {
                    Column newNoteColumn = keyValueToNoteColumn.get(keyString);
                    if (newNoteColumn == null) {
                        // Allocate new column
                        newNoteColumn = new Column(
                                project.columnModel.allocateNewCellIndex(),
                                project.columnModel.getUnduplicatedColumnName(
                                        noteColumn.getName() + " : " + keyString));
                        keyValueToNoteColumn.put(keyString, newNoteColumn);
                        newNoteColumns.add(newNoteColumn);
                    }

                    int newNoteCellIndex = newNoteColumn.getCellIndex();
                    Object existingNewNoteValue = reusableRow.getCellValue(newNoteCellIndex);
                    if (ExpressionUtils.isNonBlankData(existingNewNoteValue)) {
                        Cell concatenatedNoteCell = new Cell(
                                existingNewNoteValue.toString() + ";" + noteValue.toString(), null);
                        reusableRow.setCell(newNoteCellIndex, concatenatedNoteCell);
                    } else {
                        reusableRow.setCell(newNoteCellIndex, oldRow.getCell(noteColumn.getCellIndex()));
                    }
                }
            }
        }

        List<Column> allColumns = new ArrayList<Column>(unchangedColumns);
        allColumns.addAll(newColumns);
        allColumns.addAll(newNoteColumns);

        // clean up the empty rows
        for (int i = newRows.size() - 1; i >= 0; i--) {
            if (newRows.get(i).isEmpty())
                newRows.remove(i);
        }

        return new HistoryEntry(
                historyEntryID,
                project,
                getBriefDescription(null),
                this,
                new MassRowColumnChange(allColumns, newRows));
    }

    private Row getAvailableRow(List<Row> currentRows, List<Row> newRows, int index) {
        for (Row row : currentRows) {
            if (row.getCell(index) == null) {
                return row;
            }
        }
        // If we couldn't find a row with an empty spot, we'll need a new row
        Row row = new Row(index);
        newRows.add(row);
        currentRows.add(row);
        return row;
    }

    private Row buildNewRow(List<Column> unchangedColumns, Row oldRow, int size) {
        Row reusableRow = new Row(size);
        for (int c = 0; c < unchangedColumns.size(); c++) {
            Column unchangedColumn = unchangedColumns.get(c);
            int cellIndex = unchangedColumn.getCellIndex();
            reusableRow.setCell(cellIndex, oldRow.getCell(cellIndex));
        }
        return reusableRow;
    }
}
