package com.google.refine.importers;

import java.io.IOException;
import java.io.InputStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

import org.apache.poi.common.usermodel.Hyperlink;
import org.apache.poi.hssf.usermodel.HSSFDateUtil;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

import com.google.refine.ProjectMetadata;
import com.google.refine.model.Cell;
import com.google.refine.model.Column;
import com.google.refine.model.Project;
import com.google.refine.model.Recon;
import com.google.refine.model.ReconCandidate;
import com.google.refine.model.Row;
import com.google.refine.model.Recon.Judgment;

public class ExcelImporter implements StreamImporter {
    protected boolean _xmlBased;

    @Override
    public void read(InputStream inputStream, Project project, ProjectMetadata metadata, Properties options) throws ImportException {
        int ignoreLines = ImporterUtilities.getIntegerOption("ignore", options, -1);
        int headerLines = ImporterUtilities.getIntegerOption("header-lines", options, 1);
        int limit = ImporterUtilities.getIntegerOption("limit", options, -1);
        int skip = ImporterUtilities.getIntegerOption("skip", options, 0);

        Workbook wb = null;
        try {
            wb = _xmlBased ?
                new XSSFWorkbook(inputStream) :
                new HSSFWorkbook(new POIFSFileSystem(inputStream));
        } catch (IOException e) {
            throw new ImportException(
                "Attempted to parse file as Excel file but failed. " +
                "Try to use Excel to re-save the file as a different Excel version or as TSV and upload again.",
                e
            );
        }
        
        Sheet sheet = wb.getSheetAt(0);
        
        int firstRow = sheet.getFirstRowNum();
        int lastRow = sheet.getLastRowNum();
        
        List<String>         columnNames = new ArrayList<String>();
        Set<String>          columnNameSet = new HashSet<String>();
        Map<String, Integer> columnRootNameToIndex = new HashMap<String, Integer>();
        
        int                  rowsWithData = 0;
        Map<String, Recon>   reconMap = new HashMap<String, Recon>();
        
        for (int r = firstRow; r <= lastRow; r++) {
            org.apache.poi.ss.usermodel.Row row = sheet.getRow(r);
            if (row == null) {
                continue;
            } else if (ignoreLines > 0) {
                ignoreLines--;
                continue;
            }
            
            short firstCell = row.getFirstCellNum();
            short lastCell = row.getLastCellNum();
            if (firstCell < 0 || firstCell > lastCell) {
                continue;
            }
            
            /*
             *  Still processing header lines
             */
            if (headerLines > 0) {
                headerLines--;
                
                for (int c = firstCell; c <= lastCell; c++) {
                    org.apache.poi.ss.usermodel.Cell cell = row.getCell(c);
                    if (cell != null) {
                        Serializable value = extractCell(cell);
                        String text = value != null ? value.toString() : null;
                        if (text != null && text.length() > 0) {
                            while (columnNames.size() < c + 1) {
                                columnNames.add(null);
                            }
                            
                            String existingName = columnNames.get(c);
                            String name = (existingName == null) ? text : (existingName + " " + text);
                            
                            columnNames.set(c, name);
                        }
                    }
                }
                
                if (headerLines == 0) {
                    for (int i = 0; i < columnNames.size(); i++) {
                        String rootName = columnNames.get(i);
                        if (rootName == null) {
                            continue;
                        }
                        setUnduplicatedColumnName(rootName, columnNames, i, columnNameSet, columnRootNameToIndex);
                    }
                }
                
            /*
             *  Processing data rows
             */
            } else {
                Row newRow = new Row(columnNames.size());
                boolean hasData = false;
                
                for (int c = firstCell; c <= lastCell; c++) {
                    org.apache.poi.ss.usermodel.Cell cell = row.getCell(c);
                    if (cell == null) {
                        continue;
                    }
                    
                    Cell ourCell = extractCell(cell, reconMap);
                    if (ourCell != null) {
                        while (columnNames.size() < c + 1) {
                            columnNames.add(null);
                        }
                        if (columnNames.get(c) == null) {
                            setUnduplicatedColumnName("Column", columnNames, c, columnNameSet, columnRootNameToIndex);
                        }
                        
                        newRow.setCell(c, ourCell);
                        hasData = true;
                    }
                }
                
                if (hasData) {
                    rowsWithData++;
                    
                    if (skip <= 0 || rowsWithData > skip) {
                        project.rows.add(newRow);
                        project.columnModel.setMaxCellIndex(newRow.cells.size());
                        
                        if (limit > 0 && project.rows.size() >= limit) {
                            break;
                        }
                    }
                }
            }
        }
        
        /*
         *  Create columns
         */
        for (int c = 0; c < columnNames.size(); c++) {
            String name = columnNames.get(c);
            if (name != null) {
                Column column = new Column(c, name);
                project.columnModel.columns.add(column);
            }
        }
    }
    
    protected void setUnduplicatedColumnName(
        String rootName, List<String> columnNames, int index, Set<String> columnNameSet, Map<String, Integer> columnRootNameToIndex) {
        if (columnNameSet.contains(rootName)) {
            int startIndex = columnRootNameToIndex.containsKey(rootName) ? columnRootNameToIndex.get(rootName) : 2;
            while (true) {
                String name = rootName + " " + startIndex;
                if (columnNameSet.contains(name)) {
                    startIndex++;
                } else {
                    columnNames.set(index, name);
                    columnNameSet.add(name);
                    break;
                }
            }
            
            columnRootNameToIndex.put(rootName, startIndex + 1);
        } else {
            columnNames.set(index, rootName);
            columnNameSet.add(rootName);
        }
    }
    
    protected Serializable extractCell(org.apache.poi.ss.usermodel.Cell cell) {
        int cellType = cell.getCellType();
        if (cellType == org.apache.poi.ss.usermodel.Cell.CELL_TYPE_ERROR ||
            cellType == org.apache.poi.ss.usermodel.Cell.CELL_TYPE_BLANK) {
            return null;
        }
        if (cellType == org.apache.poi.ss.usermodel.Cell.CELL_TYPE_FORMULA) {
            cellType = cell.getCachedFormulaResultType();
        }
        
        Serializable value = null;
        if (cellType == org.apache.poi.ss.usermodel.Cell.CELL_TYPE_BOOLEAN) {
            value = cell.getBooleanCellValue();
        } else if (cellType == org.apache.poi.ss.usermodel.Cell.CELL_TYPE_NUMERIC) {
            double d = cell.getNumericCellValue();
            
            if (HSSFDateUtil.isCellDateFormatted(cell)) {
                value = HSSFDateUtil.getJavaDate(d);
            } else {
                value = d;
            }
        } else {
            String text = cell.getStringCellValue().trim();
            if (text.length() > 0) {
                value = text;
            }
        }
        
        return value;
    }
    
    protected Cell extractCell(org.apache.poi.ss.usermodel.Cell cell, Map<String, Recon> reconMap) {
        Serializable value = extractCell(cell);
        
        if (value != null) {
            Recon recon = null;
            
            Hyperlink hyperlink = cell.getHyperlink();
            if (hyperlink != null) {
                String url = hyperlink.getAddress();
                
                if (url.startsWith("http://") ||
                    url.startsWith("https://")) {
                    
                    final String sig = "freebase.com/view";
                    
                    int i = url.indexOf(sig);
                    if (i > 0) {
                        String id = url.substring(i + sig.length());
                        
                        int q = id.indexOf('?');
                        if (q > 0) {
                            id = id.substring(0, q);
                        }
                        int h = id.indexOf('#');
                        if (h > 0) {
                            id = id.substring(0, h);
                        }
                        
                        if (reconMap.containsKey(id)) {
                            recon = reconMap.get(id);
                            recon.judgmentBatchSize++;
                        } else {
                            recon = new Recon(0, null, null);
                            recon.service = "import";
                            recon.match = new ReconCandidate(id, value.toString(), new String[0], 100);
                            recon.matchRank = 0;
                            recon.judgment = Judgment.Matched;
                            recon.judgmentAction = "auto";
                            recon.judgmentBatchSize = 1;
                            recon.addCandidate(recon.match);
                            
                            reconMap.put(id, recon);
                        }
                        
                    }
                }
            }
            
            return new Cell(value, recon);
        } else {
            return null;
        }
    }
    
    @Override
    public boolean canImportData(String contentType, String fileName) {
        if (contentType != null) {
            contentType = contentType.toLowerCase().trim();
            if ("application/msexcel".equals(contentType) ||
                "application/x-msexcel".equals(contentType) ||
                "application/x-ms-excel".equals(contentType) ||
                "application/vnd.ms-excel".equals(contentType) ||
                "application/x-excel".equals(contentType) ||
                "application/xls".equals(contentType)) {
                this._xmlBased = false;
                return true;
            } else if("application/x-xls".equals(contentType)) {
                this._xmlBased = true;
                return true;
            }
        } else if (fileName != null) {
            fileName = fileName.toLowerCase();
            if (fileName.endsWith(".xls")) {
                this._xmlBased = false;
                return true;
            } else if (fileName.endsWith(".xlsx")) {
                this._xmlBased = true;
                return true;
            }
        }
        return false;
    }
}