<?php
// Own namespace
namespace Org\Mxchange\CoreFramework\Index\File;

// Import framework stuff
use Org\Mxchange\CoreFramework\EntryPoint\ApplicationEntryPoint;
use Org\Mxchange\CoreFramework\Factory\Object\ObjectFactory;
use Org\Mxchange\CoreFramework\Filesystem\File\BaseBinaryFile;
use Org\Mxchange\CoreFramework\Filesystem\File\BinaryFile;
use Org\Mxchange\CoreFramework\Index\BaseIndex;
use Org\Mxchange\CoreFramework\Index\Indexable;
use Org\Mxchange\CoreFramework\Utils\Arrays\ArrayUtils;
use Org\Mxchange\CoreFramework\Utils\Strings\StringUtils;

// Import SPL stuff
use \OutOfBoundsException;
use \SplFileInfo;
use \UnexpectedValueException;

/**
 * A general file-based index class
 *
 * @author		Roland Haeder <webmaster@ship-simu.org>
 * @version		0.0.0
 * @copyright	Copyright (c) 2007, 2008 Roland Haeder, 2009 - 2021 Core Developer Team
 * @license		GNU GPL 3.0 or any newer version
 * @link		http://www.ship-simu.org
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
abstract class BaseFileIndex extends BaseIndex implements FileIndexer {
	/**
	 * Minimum block length
	 */
	private static $minimumBlockLength = 0;

	/**
	 * Protected constructor
	 *
	 * @param	$className	Name of class
	 * @return	void
	 */
	protected function __construct (string $className) {
		// Call parent constructor
		parent::__construct($className);
	}

	/**
	 * Reads the file header
	 *
	 * @return	void
	 * @throws	UnexpectedValueException	If header length or count of elements is invalid
	 */
	public function readIndexHeader () {
		// First rewind to beginning as the header sits at the beginning ...
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('BASE-FILE-INDEX: CALLED!');
		$this->getIteratorInstance()->rewind();

		// Get header size
		$headerSize = $this->getIteratorInstance()->getBinaryFileInstance()->getHeaderSize();

		// Then read it (see constructor for calculation)
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-INDEX: headerSize=%d', $headerSize));
		$data = $this->getIteratorInstance()->getBinaryFileInstance()->read($headerSize);

		// Have all requested bytes been read?
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-INDEX: Read %d bytes (%d wanted).', strlen($data), $this->getIteratorInstance()->getBinaryFileInstance()->getHeaderSize()));
		if (strlen($data) != $this->getIteratorInstance()->getBinaryFileInstance()->getHeaderSize()) {
			// Invalid header length
			throw new UnexpectedValueException(sprintf('data(%d)=%s is not expected length %d',
				strlen($data),
				$data,
				$this->getIteratorInstance()->getBinaryFileInstance()->getHeaderSize()
			));
		} elseif (empty(trim($data, chr(0)))) {
			// Empty file header
			/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('BASE-FILE-INDEX: File header is empty - EXIT!');
			return;
		} elseif (substr($data, -1, 1) != chr(BinaryFile::SEPARATOR_HEADER_ENTRIES)) {
			// Bad last character
			throw new UnexpectedValueException(sprintf('data=%s does not end with "%s"',
				$data,
				chr(BinaryFile::SEPARATOR_HEADER_ENTRIES)
			));
		}

		// Okay, then remove it
		$data = substr($data, 0, -1);

		// And update seek position
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('BASE-FILE-INDEX: Calling this->iteratorInstance->binaryFileInstance->updateSeekPosition() ...');
		$this->getIteratorInstance()->getBinaryFileInstance()->updateSeekPosition();

		/*
		 * Now split it:
		 *
		 * 0 => magic
		 * 1 => total entries
		 */
		$header = explode(chr(BinaryFile::SEPARATOR_HEADER_DATA), $data);

		// Map numeric entries to associative (alpha-numeric) elements
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-INDEX: HEADER_INDEX_ELEMENT_COUNT=%d,header()=%d', BinaryFile::HEADER_INDEX_ELEMENT_COUNT, count($header)));
		//* PRINTR-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-INDEX: header(%d)=%s', count($header), print_r($header, true)));
		$header = ArrayUtils::mapNumericKeysToAssociative($header, [
			BinaryFile::HEADER_NAME_MAGIC,
			BinaryFile::HEADER_NAME_TOTAL_ENTRIES,
		]);

		// Check if the array has only 2 elements
		if (count($header) != BinaryFile::HEADER_INDEX_ELEMENT_COUNT) {
			// Bad header
			throw new UnexpectedValueException(sprintf('header()=%d is not expected value %d', count($header), BinaryFile::HEADER_INDEX_ELEMENT_COUNT));
		} elseif ($header[BinaryFile::HEADER_NAME_MAGIC] !== Indexable::INDEX_MAGIC) {
			// Magic must be in first element
			throw new UnexpectedValueException(sprintf('header[%s]=%s is not the expected magic (%s)', BinaryFile::HEADER_NAME_MAGIC, $header[BinaryFile::HEADER_NAME_MAGIC], Indexable::INDEX_MAGIC));
		} elseif (strlen($header[BinaryFile::HEADER_NAME_TOTAL_ENTRIES]) != BinaryFile::LENGTH_COUNT) {
			// Length of total entries not matching
			throw new UnexpectedValueException(sprintf('header[%s](%d)=%s does not have expected length %d', BinaryFile::HEADER_NAME_TOTAL_ENTRIES, strlen($header[BinaryFile::HEADER_NAME_TOTAL_ENTRIES]), $header[BinaryFile::HEADER_NAME_TOTAL_ENTRIES], BinaryFile::LENGTH_COUNT));
		}

		// Decode count
		$header[BinaryFile::HEADER_NAME_TOTAL_ENTRIES] = hex2bin($header[BinaryFile::HEADER_NAME_TOTAL_ENTRIES]);

		// Set it here
		$this->getIteratorInstance()->getBinaryFileInstance()->setHeader($header);

		// Trace message
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('BASE-FILE-INDEX: EXIT!');
	}

	/**
	 * Flushes the file header
	 *
	 * @return	void
	 */
	public function flushFileHeader () {
		// Put all informations together
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('BASE-FILE-INDEX: CALLED!');
		$header = sprintf('%s%s%s%s',
			// Magic
			Indexable::INDEX_MAGIC,

			// Separator header data
			chr(BinaryFile::SEPARATOR_HEADER_DATA),

			// Total entries
			str_pad(StringUtils::dec2hex($this->getIteratorInstance()->getBinaryFileInstance()->getCounter()), BinaryFile::LENGTH_COUNT, '0', STR_PAD_LEFT),

			// Separator header<->entries
			chr(BinaryFile::SEPARATOR_HEADER_ENTRIES)
		);

		// Write it to disk (header is always at seek position 0)
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-INDEX: Calling this->iteratorInstance->binaryFileInstance->writeAtPosition(0, header=%s) ...', $header));
		$this->getIteratorInstance()->getBinaryFileInstance()->writeAtPosition(0, $header);

		// Trace message
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('BASE-FILE-INDEX: EXIT!');
	}

	/**
	 * Initializes this file-based index
	 *
	 * @param	$fileInfoInstance	An instance of a SplFileInfo class
	 * @return	void
	 * @todo	Currently the index file is not cached, please implement a memory-handling class and if enough RAM is found, cache the whole index file.
	 */
	protected function initFileIndex (SplFileInfo $fileInfoInstance) {
		// Get a file i/o pointer instance for index file
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-INDEX: fileInfoInstance[%s]=%s - CALLED!', get_class($fileInfoInstance), $fileInfoInstance));
		$fileInstance = ObjectFactory::createObjectByConfiguredName('index_file_class', array($fileInfoInstance, $this));

		// Get iterator instance
		$iteratorInstance = ObjectFactory::createObjectByConfiguredName('file_iterator_class', [$fileInstance]);

		// Set iterator here
		$this->setIteratorInstance($iteratorInstance);

		// Calculate header size
		$headerSize = (
			strlen(Indexable::INDEX_MAGIC) +
			strlen(chr(BinaryFile::SEPARATOR_HEADER_DATA)) +
			BinaryFile::LENGTH_COUNT +
			strlen(chr(BinaryFile::SEPARATOR_HEADER_ENTRIES))
		);

		// Set it
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-INDEX: Setting headerSize=%d ...', $headerSize));
		$this->getIteratorInstance()->getBinaryFileInstance()->setHeaderSize($headerSize);

		// Init counters and gaps array
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('BASE-FILE-INDEX: Calling this->iteratorInstance->binaryFileInstance->initCountersGapsArray() ...');
		$this->getIteratorInstance()->getBinaryFileInstance()->initCountersGapsArray();

		// Default is not created
		$created = false;

		// Is the file's header initialized?
		if (!$this->getIteratorInstance()->getBinaryFileInstance()->isFileHeaderInitialized()) {
			// First pre-allocate a bit
			/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('BASE-FILE-INDEX: Calling this->iteratorInstance->binaryFileInstance->preAllocateFile(index) ...');
			$this->getIteratorInstance()->getBinaryFileInstance()->preAllocateFile('index');

			// Then write file header
			/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('BASE-FILE-INDEX: Calling this->iteratorInstance->binaryFileInstance->createFileHeader() ...');
			$this->getIteratorInstance()->getBinaryFileInstance()->createFileHeader();

			// Mark as freshly created
			$created = true;
		}

		// Load the file header
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('BASE-FILE-INDEX: Calling this->readIndexHeader() ...');
		$this->readIndexHeader();

		// Freshly created?
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-INDEX: created=%d', intval($created)));
		if (!$created) {
			// Analyze file structure
			/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('BASE-FILE-INDEX: Calling this->iteratorInstance->binaryFileInstance->analyzeFileStructure() ...');
			$this->getIteratorInstance()->getBinaryFileInstance()->analyzeFileStructure();
		}

		// Trace message
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('BASE-FILE-INDEX: EXIT!');
	}

	/**
	 * Calculates minimum length for one entry/block
	 *
	 * @return	$length		Minimum length for one entry/block
	 */
	public function calculateMinimumBlockLength () {
		// Is it "cached"?
		//* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('BASE-FILE-INDEX: CALLED!');
		if (self::$minimumBlockLength == 0) {
			// Calulcate it
			//* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('BASE-FILE-INDEX: Calculating ...');
			self::$minimumBlockLength = (
				// Type
				BinaryFile::LENGTH_TYPE + strlen(chr(BinaryFile::SEPARATOR_TYPE_POSITION)) +
				// Position
				BinaryFile::LENGTH_POSITION + strlen(chr(BinaryFile::SEPARATOR_ENTRIES))
			);
		}

		// Return it
		//* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-INDEX: self::minimumBlockLength=%d - EXIT!', self::$minimumBlockLength));
		return self::$minimumBlockLength;
	}

	/**
	 * "Getter" for file size
	 *
	 * @return	$fileSize	Size of currently loaded file
	 */
	public function getFileSize () {
		// Call iterator's method
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('BASE-FILE-INDEX: CALLED!');
		$fileSize = $this->getIteratorInstance()->getBinaryFileInstance()->getFileSize();

		// Return it
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-INDEX: fileSize=%d - EXIT!', $fileSize));
		return $fileSize;
	}

	/**
	 * Searches for next suitable gap the given length of data can fit in
	 * including padding bytes.
	 *
	 * @param	$length			Length of raw data
	 * @return	$seekPosition	Found next gap's seek position
	 * @throws	InvalidArgumentException	If the parameter is not valid
	 * @todo	Unfinished work
	 */
	public function searchNextGap (int $length) {
		// Validate parameter
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-INDEX: length=%d - CALLED!', $length));
		if ($length <= 0) {
			// Throw IAE
			throw new InvalidArgumentException(sprintf('length=%d is not valid', $length));
		}

		// Debug message
		/* DEBUG-DIE: */ ApplicationEntryPoint::exitApplication(sprintf('[%s:%d]: length=%d,this=%s', __METHOD__, __LINE__, $length, print_r($this, true)));
	}

	/**
	 * Writes at given position by seeking to it.
	 *
	 * @param	$seekPosition	Seek position in file
	 * @param	$dataStream		Data to be written
	 * @return	mixed			Number of writes bytes or false on error
	 * @throws	OutOfBoundsException	If the position is not seekable
	 * @throws	InvalidArgumentException	If a parameter is not valid
	 */
	public function writeAtPosition (int $seekPosition, string $dataStream) {
		// Validate parameter
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-INDEX: seekPosition=%d,dataStream(%d)=%s - CALLED!', $seekPosition, strlen($dataStream), $dataStream));
		if ($seekPosition < 0) {
			// Invalid seek position
			throw new OutOfBoundsException(sprintf('seekPosition=%d is not valid.', $seekPosition));
		} elseif (empty($dataStream)) {
			// Empty dataStream
			throw new InvalidArgumentException('Parameter "dataStream" is empty');
		}

		// Call iterated object's method
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-INDEX: Calling this->iteratorInstance->binaryFileInstance->writeAtPosition(%d, %s) ...', $seekPosition, $dataStream));
		$status = $this->getIteratorInstance()->getBinaryFileInstance()->writeAtPosition($seekPosition, $dataStream);

		// Return status
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('BASE-FILE-INDEX: status[%s]=%d - EXIT!', gettype($status), $status));
		return $status;
	}

	/**
	 * Checks if this index has been fully and properly loaded.
	 *
	 * @return	$isLoaded	Whether this index has been loaded
	 */
	public function isIndexLoaded () {
		// Is the file gaps-only?
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('BASE-FILE-INDEX: CALLED!');
		if ($this->getIteratorInstance()->getBinaryFileInstance()->isFileGapsOnly()) {
			// Then skip below code as this implies the file has been fully analyzed and "loaded"
			/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('BASE-FILE-INDEX: Underlaying file is gaps-only: Returning TRUE ... - EXIT!');
			return TRUE;
		}

		// Debug message
		/* DEBUG-DIE: */ ApplicationEntryPoint::exitApplication(sprintf('[%s:%d]: this=%s', __METHOD__, __LINE__, print_r($this, true)));
	}

}