<?php

namespace Box\Spout\Reader;

use Box\Spout\Common\Exception\IOException;
use Box\Spout\Reader\Exception\ReaderNotOpenedException;

/**
 * Class AbstractReader
 *
 * @package Box\Spout\Reader
 * @abstract
 */
abstract class AbstractReader implements ReaderInterface {

	/** @var bool Indicates whether the stream is currently open */
	protected $isStreamOpened = false;

	/** @var \Box\Spout\Common\Helper\GlobalFunctionsHelper Helper to work with global functions */
	protected $globalFunctionsHelper;

	/** @var \Box\Spout\Reader\Common\ReaderOptions Reader's customized options */
	protected $options;

	/**
	 * Returns the reader's current options
	 *
	 * @return \Box\Spout\Reader\Common\ReaderOptions
	 */
	abstract protected function getOptions();

	/**
	 * Returns whether stream wrappers are supported
	 *
	 * @return bool
	 */
	abstract protected function doesSupportStreamWrapper();

	/**
	 * Opens the file at the given file path to make it ready to be read
	 *
	 * @param  string $filePath Path of the file to be read
	 * @return void
	 */
	abstract protected function openReader( $filePath);

	/**
	 * Returns an iterator to iterate over sheets.
	 *
	 * @return \Iterator To iterate over sheets
	 */
	abstract protected function getConcreteSheetIterator();

	/**
	 * Closes the reader. To be used after reading the file.
	 *
	 * @return AbstractReader
	 */
	abstract protected function closeReader();

	/**
	 * @param \Box\Spout\Common\Helper\GlobalFunctionsHelper $globalFunctionsHelper
	 * @return AbstractReader
	 */
	public function setGlobalFunctionsHelper( $globalFunctionsHelper ) {
		$this->globalFunctionsHelper = $globalFunctionsHelper;
		return $this;
	}

	/**
	 * Sets whether date/time values should be returned as PHP objects or be formatted as strings.
	 *
	 * @api
	 * @param bool $shouldFormatDates
	 * @return AbstractReader
	 */
	public function setShouldFormatDates( $shouldFormatDates ) {
		$this->getOptions()->setShouldFormatDates( $shouldFormatDates );
		return $this;
	}

	/**
	 * Sets whether empty rows should be returned or skipped.
	 *
	 * @api
	 * @param bool $shouldPreserveEmptyRows
	 * @return AbstractReader
	 */
	public function setShouldPreserveEmptyRows( $shouldPreserveEmptyRows ) {
		$this->getOptions()->setShouldPreserveEmptyRows( $shouldPreserveEmptyRows );
		return $this;
	}

	/**
	 * Prepares the reader to read the given file. It also makes sure
	 * that the file exists and is readable.
	 *
	 * @api
	 * @param  string $filePath Path of the file to be read
	 * @return void
	 * @throws \Box\Spout\Common\Exception\IOException If the file at the given path does not exist, is not readable or is corrupted
	 */
	public function open( $filePath ) {
		if ( $this->isStreamWrapper( $filePath ) && ( ! $this->doesSupportStreamWrapper() || ! $this->isSupportedStreamWrapper( $filePath ) ) ) {
			throw new IOException( "Could not open $filePath for reading! Stream wrapper used is not supported for this type of file." );
		}

		if ( ! $this->isPhpStream( $filePath ) ) {
			// we skip the checks if the provided file path points to a PHP stream
			if ( ! $this->globalFunctionsHelper->file_exists( $filePath ) ) {
				throw new IOException( "Could not open $filePath for reading! File does not exist." );
			} elseif ( ! $this->globalFunctionsHelper->is_readable( $filePath ) ) {
				throw new IOException( "Could not open $filePath for reading! File is not readable." );
			}
		}

		try {
			$fileRealPath = $this->getFileRealPath( $filePath );
			$this->openReader( $fileRealPath );
			$this->isStreamOpened = true;
		} catch ( \Exception $exception ) {
			throw new IOException( "Could not open $filePath for reading! ({$exception->getMessage()})" );
		}
	}

	/**
	 * Returns the real path of the given path.
	 * If the given path is a valid stream wrapper, returns the path unchanged.
	 *
	 * @param string $filePath
	 * @return string
	 */
	protected function getFileRealPath( $filePath ) {
		if ( $this->isSupportedStreamWrapper( $filePath ) ) {
			return $filePath;
		}

		// Need to use realpath to fix "Can't open file" on some Windows setup
		return realpath( $filePath );
	}

	/**
	 * Returns the scheme of the custom stream wrapper, if the path indicates a stream wrapper is used.
	 * For example, php://temp => php, s3://path/to/file => s3...
	 *
	 * @param string $filePath Path of the file to be read
	 * @return string|null The stream wrapper scheme or NULL if not a stream wrapper
	 */
	protected function getStreamWrapperScheme( $filePath ) {
		$streamScheme = null;
		if ( preg_match( '/^(\w+):\/\//', $filePath, $matches ) ) {
			$streamScheme = $matches[1];
		}
		return $streamScheme;
	}

	/**
	 * Checks if the given path is an unsupported stream wrapper
	 * (like local path, php://temp, mystream://foo/bar...).
	 *
	 * @param string $filePath Path of the file to be read
	 * @return bool Whether the given path is an unsupported stream wrapper
	 */
	protected function isStreamWrapper( $filePath ) {
		return ( $this->getStreamWrapperScheme( $filePath ) !== null );
	}

	/**
	 * Checks if the given path is an supported stream wrapper
	 * (like php://temp, mystream://foo/bar...).
	 * If the given path is a local path, returns true.
	 *
	 * @param string $filePath Path of the file to be read
	 * @return bool Whether the given path is an supported stream wrapper
	 */
	protected function isSupportedStreamWrapper( $filePath ) {
		$streamScheme = $this->getStreamWrapperScheme( $filePath );
		return ( $streamScheme !== null ) ?
			in_array( $streamScheme, $this->globalFunctionsHelper->stream_get_wrappers() ) :
			true;
	}

	/**
	 * Checks if a path is a PHP stream (like php://output, php://memory, ...)
	 *
	 * @param string $filePath Path of the file to be read
	 * @return bool Whether the given path maps to a PHP stream
	 */
	protected function isPhpStream( $filePath ) {
		$streamScheme = $this->getStreamWrapperScheme( $filePath );
		return ( $streamScheme === 'php' );
	}

	/**
	 * Returns an iterator to iterate over sheets.
	 *
	 * @api
	 * @return \Iterator To iterate over sheets
	 * @throws \Box\Spout\Reader\Exception\ReaderNotOpenedException If called before opening the reader
	 */
	public function getSheetIterator() {
		if ( ! $this->isStreamOpened ) {
			throw new ReaderNotOpenedException( 'Reader should be opened first.' );
		}

		return $this->getConcreteSheetIterator();
	}

	/**
	 * Closes the reader, preventing any additional reading
	 *
	 * @api
	 * @return void
	 */
	public function close() {
		if ( $this->isStreamOpened ) {
			$this->closeReader();

			$sheetIterator = $this->getConcreteSheetIterator();
			if ( $sheetIterator ) {
				$sheetIterator->end();
			}

			$this->isStreamOpened = false;
		}
	}
}