/*!
 * Express - Utils
 * Copyright(c) 2010 TJ Holowaychuk <tj@vision-media.ca>
 * MIT Licensed
 */

/**
 * Check if `path` looks absolute.
 *
 * @param {String} path
 * @return {Boolean}
 * @api private
 */

exports.isAbsolute = function ( path ) {
	if ( '/' == path[0] ) {
		return true;
	}
	if ( ':' == path[1] && '\\' == path[2] ) {
		return true;
	}
};

/**
 * Merge object `b` with `a` giving precedence to
 * values in object `a`.
 *
 * @param {Object} a
 * @param {Object} b
 * @return {Object} a
 * @api private
 */

exports.union = function ( a, b ) {
	if ( a && b ) {
		var keys = Object.keys( b )
			, len = keys.length
			, key;
		for ( var i = 0; i < len; ++i ) {
			key = keys[i];
			if ( !a.hasOwnProperty( key ) ) {
				a[key] = b[key];
			}
		}
	}
	return a;
};

/**
 * Flatten the given `arr`.
 *
 * @param {Array} arr
 * @return {Array}
 * @api private
 */

exports.flatten = function ( arr, ret ) {
	var ret = ret || []
		, len = arr.length;
	for ( var i = 0; i < len; ++i ) {
		if ( Array.isArray( arr[i] ) ) {
			exports.flatten( arr[i], ret );
		} else {
			ret.push( arr[i] );
		}
	}
	return ret;
};

/**
 * Parse mini markdown implementation.
 * The following conversions are supported,
 * primarily for the "flash" middleware:
 *
 *    _foo_ or *foo* become <em>foo</em>
 *    __foo__ or **foo** become <strong>foo</strong>
 *    [A](B) becomes <a href="B">A</a>
 *
 * @param {String} str
 * @return {String}
 * @api private
 */

exports.miniMarkdown = function ( str ) {
	return String( str )
		.replace( /(__|\*\*)(.*?)\1/g, '<strong>$2</strong>' )
		.replace( /(_|\*)(.*?)\1/g, '<em>$2</em>' )
		.replace( /\[([^\]]+)\]\(([^)]+)\)/g, '<a href="$2">$1</a>' );
};

/**
 * Escape special characters in the given string of html.
 *
 * @param  {String} html
 * @return {String}
 * @api private
 */

exports.escape = function ( html ) {
	return String( html )
		.replace( /&/g, '&amp;' )
		.replace( /"/g, '&quot;' )
		.replace( /</g, '&lt;' )
		.replace( />/g, '&gt;' );
};

/**
 * Parse "Range" header `str` relative to the given file `size`.
 *
 * @param {Number} size
 * @param {String} str
 * @return {Array}
 * @api private
 */

exports.parseRange = function ( size, str ) {
	var valid = true;
	var arr = str.substr( 6 ).split( ',' ).map( function ( range ) {
		var range = range.split( '-' )
			, start = parseInt( range[0], 10 )
			, end = parseInt( range[1], 10 );

		// -500
		if ( isNaN( start ) ) {
			start = size - end;
			end = size - 1;
			// 500-
		} else if ( isNaN( end ) ) {
			end = size - 1;
		}

		// Invalid
		if ( isNaN( start ) || isNaN( end ) || start > end ) {
			valid = false;
		}

		return { start : start, end : end };
	} );
	return valid ? arr : undefined;
};

/**
 * Fast alternative to `Array.prototype.slice.call()`.
 *
 * @param {Arguments} args
 * @param {Number} n
 * @return {Array}
 * @api public
 */

exports.toArray = function ( args, i ) {
	var arr = []
		, len = args.length
		, i = i || 0;
	for ( ; i < len; ++i ) {
		arr.push( args[i] );
	}
	return arr;
};