<?php

namespace SilverStripe\Dev;

use SilverStripe\Core\Object;
use Iterator;

use SilverStripe\Control\Director;

/**
 * Class to handle parsing of CSV files, where the column headers are in the
 * first row.
 *
 * The idea is that you pass it another object to handle the actual processing
 * of the data in the CSV file.
 *
 * Usage:
 *
 * <code>
 * $parser = new CSVParser('myfile.csv');
 * $parser->mapColumns(array(
 *    'first name' => 'FirstName'
 *    'lastname' => 'Surname',
 *    'last name' => 'Surname',
 * ));
 * foreach($parser as $row) {
 *   // $row is a map of column name => column value
 *   $obj = new MyDataObject();
 *   $obj->update($row);
 *   $obj->write();
 * }
 * </code>
 */
class CSVParser extends Object implements Iterator
{

    /**
     * @var string $filename
     */
    protected $filename;

    /**
     * @var resource $fileHandle
     */
    protected $fileHandle;

    /**
     * Map of source columns to output columns.
     *
     * Once they get into this variable, all of the source columns are in
     * lowercase.
     *
     * @var array
     */
    protected $columnMap = array();

    /**
     * The header row used to map data in the CSV file.
     *
     * To begin with, this is null.  Once it has been set, data will get
     * returned from the CSV file.
     *
     * @var array
     */
    protected $headerRow = null;

    /**
     * A custom header row provided by the caller.
     *
     * @var array
     */
    protected $providedHeaderRow = null;

    /**
     * The data of the current row.
     *
     * @var array
     */
    protected $currentRow = null;

    /**
     * The current row number.
     *
     * 1 is the first data row in the CSV file; the header row, if it exists,
     * is ignored.
     *
     * @var int
     */
    protected $rowNum = 0;

    /**
     * The character for separating columns.
     *
     * @var string
     */
    protected $delimiter = ",";

    /**
     * The character for quoting columns.
     *
     * @var string
     */
    protected $enclosure = '"';

    /**
     * Open a CSV file for parsing.
     *
     * You can use the object returned in a foreach loop to extract the data.
     *
     * @param string $filename The name of the file.  If relative, it will be relative to the site's base dir
     * @param string $delimiter The character for seperating columns
     * @param string $enclosure The character for quoting or enclosing columns
     */
    public function __construct($filename, $delimiter = ",", $enclosure = '"')
    {
        $filename = Director::getAbsFile($filename);
        $this->filename = $filename;
        $this->delimiter = $delimiter;
        $this->enclosure = $enclosure;

        parent::__construct();
    }

    /**
     * Re-map columns in the CSV file.
     *
     * This can be useful for identifying synonyms in the file. For example:
     *
     * <code>
     * $csv->mapColumns(array(
     *   'firstname' => 'FirstName',
     *   'last name' => 'Surname',
     * ));
     * </code>
     *
     * @param array
     */
    public function mapColumns($columnMap)
    {
        if ($columnMap) {
            $lowerColumnMap = array();

            foreach ($columnMap as $k => $v) {
                $lowerColumnMap[strtolower($k)] = $v;
            }

            $this->columnMap = array_merge($this->columnMap, $lowerColumnMap);
        }
    }

    /**
     * If your CSV file doesn't have a header row, then you can call this
     * function to provide one.
     *
     * If you call this function, then the first row of the CSV will be
     * included in the data returned.
     *
     * @param array
     */
    public function provideHeaderRow($headerRow)
    {
        $this->providedHeaderRow = $headerRow;
    }

    /**
     * Open the CSV file for reading.
     */
    protected function openFile()
    {
        ini_set('auto_detect_line_endings', 1);
        $this->fileHandle = fopen($this->filename, 'r');

        if ($this->providedHeaderRow) {
            $this->headerRow = $this->remapHeader($this->providedHeaderRow);
        }
    }

    /**
     * Close the CSV file and re-set all of the internal variables.
     */
    protected function closeFile()
    {
        if ($this->fileHandle) {
            fclose($this->fileHandle);
        }

        $this->fileHandle = null;
        $this->rowNum = 0;
        $this->currentRow = null;
        $this->headerRow = null;
    }


    /**
     * Get a header row from the CSV file.
     */
    protected function fetchCSVHeader()
    {
        $srcRow = fgetcsv(
            $this->fileHandle,
            0,
            $this->delimiter,
            $this->enclosure
        );

        $this->headerRow = $this->remapHeader($srcRow);
    }

    /**
     * Map the contents of a header array using $this->mappedColumns.
     *
     * @param array
     *
     * @return array
     */
    protected function remapHeader($header)
    {
        $mappedHeader = array();

        foreach ($header as $item) {
            if (isset($this->columnMap[strtolower($item)])) {
                $item = $this->columnMap[strtolower($item)];
            }

            $mappedHeader[] = $item;
        }
        return $mappedHeader;
    }

    /**
     * Get a row from the CSV file and update $this->currentRow;
     *
     * @return array
     */
    protected function fetchCSVRow()
    {
        if (!$this->fileHandle) {
            $this->openFile();
        }

        if (!$this->headerRow) {
            $this->fetchCSVHeader();
        }

        $this->rowNum++;

        $srcRow = fgetcsv(
            $this->fileHandle,
            0,
            $this->delimiter,
            $this->enclosure
        );

        if ($srcRow) {
            $row = array();

            foreach ($srcRow as $i => $value) {
                // Allow escaping of quotes and commas in the data
                $value = str_replace(
                    array('\\'.$this->enclosure,'\\'.$this->delimiter),
                    array($this->enclosure, $this->delimiter),
                    $value
                );

                if (array_key_exists($i, $this->headerRow)) {
                    if ($this->headerRow[$i]) {
                        $row[$this->headerRow[$i]] = $value;
                    }
                } else {
                    user_error("No heading for column $i on row $this->rowNum", E_USER_WARNING);
                }
            }

            $this->currentRow = $row;
        } else {
            $this->closeFile();
        }

        return $this->currentRow;
    }

    /**
     * @ignore
     */
    public function __destruct()
    {
        $this->closeFile();
    }

    //// ITERATOR FUNCTIONS

    /**
     * @ignore
     */
    public function rewind()
    {
        $this->closeFile();
        $this->fetchCSVRow();
    }

    /**
     * @ignore
     */
    public function current()
    {
        return $this->currentRow;
    }

    /**
     * @ignore
     */
    public function key()
    {
        return $this->rowNum;
    }

    /**
     * @ignore
     */
    public function next()
    {
        $this->fetchCSVRow();

        return $this->currentRow;
    }

    /**
     * @ignore
     */
    public function valid()
    {
        return $this->currentRow ? true : false;
    }
}