<?php
/**
 * Source map generator
 *
 * @private
 */
class Less_SourceMap_Generator extends Less_Configurable {

	/**
	 * What version of source map does the generator generate?
	 */
	private const VERSION = 3;

	/**
	 * Array of default options
	 *
	 * @var array
	 */
	protected $defaultOptions = [
			// an optional source root, useful for relocating source files
			// on a server or removing repeated values in the 'sources' entry.
			// This value is prepended to the individual entries in the 'source' field.
			'sourceRoot'			=> '',

			// an optional name of the generated code that this source map is associated with.
			'sourceMapFilename'		=> null,

			// url of the map
			'sourceMapURL'			=> null,

			// absolute path to a file to write the map to
			'sourceMapWriteTo'		=> null,

			// output source contents?
			'outputSourceFiles'		=> false,

			// base path for filename normalization
			'sourceMapRootpath'		=> '',

			// base path for filename normalization
			'sourceMapBasepath'   => ''
	];

	/**
	 * The base64 VLQ encoder
	 *
	 * @var Less_SourceMap_Base64VLQ
	 */
	protected $encoder;

	/**
	 * Array of mappings
	 *
	 * @var array
	 */
	protected $mappings = [];

	/**
	 * The root node
	 *
	 * @var Less_Tree_Ruleset
	 */
	protected $root;

	/**
	 * Array of contents map
	 *
	 * @var array
	 */
	protected $contentsMap = [];

	/**
	 * File to content map
	 *
	 * @var array
	 */
	protected $sources = [];
	protected $source_keys = [];

	/**
	 * Constructor
	 *
	 * @param Less_Tree_Ruleset $root The root node
	 * @param array $contentsMap
	 * @param array $options Array of options
	 */
	public function __construct( Less_Tree_Ruleset $root, $contentsMap, $options = [] ) {
		$this->root = $root;
		$this->contentsMap = $contentsMap;
		$this->encoder = new Less_SourceMap_Base64VLQ();

		$this->SetOptions( $options );

		$this->options['sourceMapRootpath'] = $this->fixWindowsPath( $this->options['sourceMapRootpath'], true );
		$this->options['sourceMapBasepath'] = $this->fixWindowsPath( $this->options['sourceMapBasepath'], true );
	}

	/**
	 * PHP version of JavaScript's `encodeURIComponent` function
	 *
	 * @param string $string The string to encode
	 * @return string The encoded string
	 */
	private static function encodeURIComponent( $string ) {
		$revert = [ '%21' => '!', '%2A' => '*', '%27' => "'", '%28' => '(', '%29' => ')' ];
		return strtr( rawurlencode( $string ), $revert );
	}

	/**
	 * Generates the CSS
	 *
	 * @return string
	 */
	public function generateCSS() {
		$output = new Less_Output_Mapped( $this->contentsMap, $this );

		// catch the output
		$this->root->genCSS( $output );

		$sourceMapUrl				= $this->getOption( 'sourceMapURL' );
		$sourceMapFilename			= $this->getOption( 'sourceMapFilename' );
		$sourceMapContent			= $this->generateJson();
		$sourceMapWriteTo			= $this->getOption( 'sourceMapWriteTo' );

		if ( !$sourceMapUrl && $sourceMapFilename ) {
			$sourceMapUrl = $this->normalizeFilename( $sourceMapFilename );
		}

		// write map to a file
		if ( $sourceMapWriteTo ) {
			$this->saveMap( $sourceMapWriteTo, $sourceMapContent );
		}

		// inline the map
		if ( !$sourceMapUrl ) {
			$sourceMapUrl = sprintf( 'data:application/json,%s', self::encodeURIComponent( $sourceMapContent ) );
		}

		if ( $sourceMapUrl ) {
			$output->add( sprintf( '/*# sourceMappingURL=%s */', $sourceMapUrl ) );
		}

		return $output->toString();
	}

	/**
	 * Saves the source map to a file
	 *
	 * @param string $file The absolute path to a file
	 * @param string $content The content to write
	 * @throws Exception If the file could not be saved
	 */
	protected function saveMap( $file, $content ) {
		$dir = dirname( $file );
		// directory does not exist
		if ( !is_dir( $dir ) ) {
			// FIXME: create the dir automatically?
			throw new Exception( sprintf( 'The directory "%s" does not exist. Cannot save the source map.', $dir ) );
		}
		// FIXME: proper saving, with dir write check!
		if ( file_put_contents( $file, $content ) === false ) {
			throw new Exception( sprintf( 'Cannot save the source map to "%s"', $file ) );
		}
		return true;
	}

	/**
	 * Normalizes the filename
	 *
	 * @param string $filename
	 * @return string
	 */
	protected function normalizeFilename( $filename ) {
		$filename = $this->fixWindowsPath( $filename );

		$rootpath = $this->getOption( 'sourceMapRootpath' );
		$basePath = $this->getOption( 'sourceMapBasepath' );

		// "Trim" the 'sourceMapBasepath' from the output filename.
		if ( is_string( $basePath ) && strpos( $filename, $basePath ) === 0 ) {
			$filename = substr( $filename, strlen( $basePath ) );
		}

		// Remove extra leading path separators.
		if ( strpos( $filename, '\\' ) === 0 || strpos( $filename, '/' ) === 0 ) {
			$filename = substr( $filename, 1 );
		}

		return $rootpath . $filename;
	}

	/**
	 * Adds a mapping
	 *
	 * @param int $generatedLine The line number in generated file
	 * @param int $generatedColumn The column number in generated file
	 * @param int $originalLine The line number in original file
	 * @param int $originalColumn The column number in original file
	 * @param array $fileInfo The original source file
	 */
	public function addMapping( $generatedLine, $generatedColumn, $originalLine, $originalColumn, $fileInfo ) {
		$this->mappings[] = [
			'generated_line' => $generatedLine,
			'generated_column' => $generatedColumn,
			'original_line' => $originalLine,
			'original_column' => $originalColumn,
			'source_file' => $fileInfo['currentUri']
		];

		$this->sources[$fileInfo['currentUri']] = $fileInfo['filename'];
	}

	/**
	 * Generates the JSON source map
	 *
	 * @return string
	 * @see https://docs.google.com/document/d/1U1RGAehQwRypUTovF1KRlpiOFze0b-_2gc6fAH0KY0k/edit#
	 */
	protected function generateJson() {
		$sourceMap = [];
		$mappings = $this->generateMappings();

		// File version (always the first entry in the object) and must be a positive integer.
		$sourceMap['version'] = self::VERSION;

		// An optional name of the generated code that this source map is associated with.
		$file = $this->getOption( 'sourceMapFilename' );
		if ( $file ) {
			$sourceMap['file'] = $file;
		}

		// An optional source root, useful for relocating source files on a server or removing repeated values in the 'sources' entry.	This value is prepended to the individual entries in the 'source' field.
		$root = $this->getOption( 'sourceRoot' );
		if ( $root ) {
			$sourceMap['sourceRoot'] = $root;
		}

		// A list of original sources used by the 'mappings' entry.
		$sourceMap['sources'] = [];
		foreach ( $this->sources as $source_uri => $source_filename ) {
			$sourceMap['sources'][] = $this->normalizeFilename( $source_filename );
		}

		// A list of symbol names used by the 'mappings' entry.
		$sourceMap['names'] = [];

		// A string with the encoded mapping data.
		$sourceMap['mappings'] = $mappings;

		if ( $this->getOption( 'outputSourceFiles' ) ) {
			// An optional list of source content, useful when the 'source' can't be hosted.
			// The contents are listed in the same order as the sources above.
			// 'null' may be used if some original sources should be retrieved by name.
			$sourceMap['sourcesContent'] = $this->getSourcesContent();
		}

		// less.js compat fixes
		if ( count( $sourceMap['sources'] ) && empty( $sourceMap['sourceRoot'] ) ) {
			unset( $sourceMap['sourceRoot'] );
		}

		return json_encode( $sourceMap );
	}

	/**
	 * Returns the sources contents
	 *
	 * @return array|null
	 */
	protected function getSourcesContent() {
		if ( empty( $this->sources ) ) {
			return;
		}
		$content = [];
		foreach ( $this->sources as $sourceFile ) {
			$content[] = file_get_contents( $sourceFile );
		}
		return $content;
	}

	/**
	 * Generates the mappings string
	 *
	 * @return string
	 */
	public function generateMappings() {
		if ( !count( $this->mappings ) ) {
			return '';
		}

		$this->source_keys = array_flip( array_keys( $this->sources ) );

		// group mappings by generated line number.
		$groupedMap = $groupedMapEncoded = [];
		foreach ( $this->mappings as $m ) {
			$groupedMap[$m['generated_line']][] = $m;
		}
		ksort( $groupedMap );

		$lastGeneratedLine = $lastOriginalIndex = $lastOriginalLine = $lastOriginalColumn = 0;

		foreach ( $groupedMap as $lineNumber => $line_map ) {
			while ( ++$lastGeneratedLine < $lineNumber ) {
				$groupedMapEncoded[] = ';';
			}

			$lineMapEncoded = [];
			$lastGeneratedColumn = 0;

			foreach ( $line_map as $m ) {
				$mapEncoded = $this->encoder->encode( $m['generated_column'] - $lastGeneratedColumn );
				$lastGeneratedColumn = $m['generated_column'];

				// find the index
				if ( $m['source_file'] ) {
					$index = $this->findFileIndex( $m['source_file'] );
					if ( $index !== false ) {
						$mapEncoded .= $this->encoder->encode( $index - $lastOriginalIndex );
						$lastOriginalIndex = $index;

						// lines are stored 0-based in SourceMap spec version 3
						$mapEncoded .= $this->encoder->encode( $m['original_line'] - 1 - $lastOriginalLine );
						$lastOriginalLine = $m['original_line'] - 1;

						$mapEncoded .= $this->encoder->encode( $m['original_column'] - $lastOriginalColumn );
						$lastOriginalColumn = $m['original_column'];
					}
				}

				$lineMapEncoded[] = $mapEncoded;
			}

			$groupedMapEncoded[] = implode( ',', $lineMapEncoded ) . ';';
		}

		return rtrim( implode( $groupedMapEncoded ), ';' );
	}

	/**
	 * Finds the index for the filename
	 *
	 * @param string $filename
	 * @return int|false
	 */
	protected function findFileIndex( $filename ) {
		return $this->source_keys[$filename];
	}

	/**
	 * fix windows paths
	 * @param string $path
	 * @param bool $addEndSlash
	 * @return string
	 */
	public function fixWindowsPath( $path, $addEndSlash = false ) {
		$slash = ( $addEndSlash ) ? '/' : '';
		if ( !empty( $path ) ) {
			$path = str_replace( '\\', '/', $path );
			$path = rtrim( $path, '/' ) . $slash;
		}

		return $path;
	}

}