<?php

class stTaskSchedulerImportCsvReader implements stTaskSchedulerImportReaderInterface
{
    /**
     * 
     * @var resource|null
     */
    protected $fh = null;

    /**
     * 
     * @var null|int
     */
    protected $count = null;

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

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

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

    /**
     * 
     * @var bool
     */
    protected $readHeaderFields;

    /**
     * @var int|null
     */
    protected $dataOffset = null;

    /**
     * @var array|null
     */
    protected $fields = null;

    public function __clone()
    {
        if (null !== $this->fh)
        {
            $this->fh = clone $this->fh;
        }
    }

    public function __construct(string $separator = ";", string $encoding = "UTF-8", $enclosure = '"', bool $readHeaderFields = true)
    {
        $this->separator = $separator;
        $this->encoding = $encoding;
        $this->enclosure = $enclosure;
        $this->readHeaderFields = $readHeaderFields;
    }

    public function __destruct()
    {
        $this->close();
    }

    public function getFiletypeExtension(): string 
    {
        return 'csv';
    }

    public function open(string $file): bool
    {
        $this->fh = fopen($file, "r");

        return false !== $this->fh;
    }

    public function isValid(): bool
    {
        try
        {
            $result = $this->read(function() {});
        }
        catch (stTaskSchedulerImportReaderException $e)
        {
            $result = false;
        }

        $this->rewind();

        return $result;
    }

    public function rewind(): void
    {
        rewind($this->fh);
    }

    public function count(): int
    {
        if (null === $this->count)
        {
            fseek($this->fh, 0, SEEK_END);
            $this->count = $this->getOffset();
            $this->rewind();
        }

        return $this->count;
    }

    public function setOffset(int $offset): void
    {
        fseek($this->fh, $offset);
    }

    public function getOffset(): int
    {
        return ftell($this->fh);
    }

    public function read(\Closure $callback): bool
    {    
        if ($this->readHeaderFields)
        {
            $fields = $this->getFields();

            if (!$this->getOffset() && $this->dataOffset)
            {
                $this->setOffset($this->dataOffset);
            }
        }    

        $data = $this->getNextLine();

        if ($data && $this->readHeaderFields)
        {
            $data = array_slice($data, 0, count($fields));

            $combinedData = array_combine($fields, $data);

            if (false === $combinedData)
            {
                throw new stTaskSchedulerImportReaderException(sprintf("The number of header fields is not equal to the number of read data fields (fields: \"%s\", data: \"%s\")",
                    implode('", "', $fields),
                    implode('", "', $data)
                )); 
            }

            $data = $combinedData;
        }

        if ($data)
        {
            if ("UTF-8" != $this->encoding)
            {
                $data = array_map(function($value) {
                    return iconv($this->encoding, "UTF-8//TRANSLIT", $value);
                }, $data);
            }

            $callback($data);
        }

        return !empty($data);
    }

    public function close(): void
    {
        if ($this->fh)
        {
            fclose($this->fh);
            $this->fh = null;
        }
    }

    /**
     * Czyta i zwraca następna linię z pliku csv
     *
     * @return array|null
     */
    private function getNextLine(): ?array
    {
        $data = fgetcsv($this->fh, null, $this->separator, $this->enclosure, "\0");

        return false !== $data ? array_map('trim', $data) : null;
    }

    /**
     * Odczytuje nazwy pól
     *
     * @return array|null
     */
    private function getFields(): ?array
    {
        $offset = $this->getOffset();

        if (null === $this->fields)
        {
            if ($offset > 0)
            {
                $this->rewind();
            }

            $this->fields = $this->getNextLine();
            $this->dataOffset = $this->getOffset();
            
            if ($offset > 0)
            {
                $this->setOffset($offset);
            }
        }
        
        return $this->fields;
    }
}