var obju = require( "./object.js" );
var _newStackItem = function( t )
{
	var o = { "name": t, "attrs": "", "cont": "" };
	o[ "fd" ] = ( x ) => o.cont += x;
	return o;
};
module.exports = {
	encodeHtml: function ( str, br )
	{
		str = ( str + "" ).replace(/&/g, "&")
			.replace(/</g, "&lt;")
			.replace(/>/g, "&gt;")
			.replace(/"/g, "&quot;")
			.replace(/'/g, "&apos;")
		;
		if( br ) str = str.replace( /\n/g, "<br/>" );
		return str;
	}
	, http_str: function( str )
	{
		if( str.match( "^https?://" ) ) 
		{
			return str;
		}

		return "http://" + str;
	}
	, walk_tags: function( str, handler, _OP, _ED, _fineHandlers )
	{
		_fineHandlers ||= {};

		var l = str && str.length;
		var strOut = "";

		var tokenStack = new (obju.LStack)();

		var _fd_strOut = ( x ) => strOut += x;
		var _fd = _fd_strOut;

		var exitCurrentTag = () => {
			tokenStack.pop();
			_fd = tokenStack.empty() ? _fd_strOut : tokenStack.curr().fd;
		};

		var ctx = {
			"exitCurrentTag": exitCurrentTag
			, "stack": tokenStack
		};

		for( let i = 0; i < l; i ++ )
		{
			let c = str[i];
			let t = "", _a, _n;
			if( c === _OP )
			{
				let closeTag = ( str[ i + 1 ] === "/" );
				if( closeTag )
				{
					t = str[ ++i ];
				}

				for(
					_a = str[ ++i ], _n = _a.charCodeAt(0);
					// check alpha numeric
					( 65 <= _n && _n <= 90 ) || ( 97 <= _n && _n <= 122 ) || ( 48 <= _n && _n <= 57 );
					i ++, _a = str[i], _n = _a.charCodeAt(0)
				) t += _a;

				if( t === "" || t === "/" )
				{
					// Hits "<#" where # is not a valid tag name
					_fd( t + _a );
					continue;
				}

				if( _a === _ED )
				{
					// Hits "</abcd>"
					if( closeTag )
					{
						// Hits "...</abcd>" with no corresponding open tag
						if( tokenStack.empty() )
						{
							if( _fineHandlers.UnmatchedCloseTag )
							{
								_fineHandlers.UnmatchedCloseTag( ctx, t.substr( 1 ) );
							}
							else
							{
								throw new Error( `Syntax Error: Unexpected closing ${_OP}${t}${_ED}` );
							}
						}
						// Hits "<abcd...>...</abcd>"
						else if( t.substr( 1 ) === tokenStack.curr().name )
						{
							let st = tokenStack.pop();
							_fd = tokenStack.empty() ? _fd_strOut : tokenStack.curr().fd;
							_fd( handler( st.name, st.attrs, st.cont ) );
							continue;
						}
						// Hits "<abcd>...</efgh>"
						else
						{
							if( _fineHandlers.UnmatchedCloseTag )
							{
								_fineHandlers.UnmatchedCloseTag( ctx, t.substr( 1 ) );
							}
							else
							{
								throw new Error( `Syntax error: Unexpected closing ${_OP}${t}${_ED} after opened ${_OP}${tokenStack.curr().name}${_ED}` );
							}
						}
					}
					// Hits "<abcd>"
					else
					{
						tokenStack.add( _newStackItem( t ) );
						_fd = tokenStack.curr().fd;

						_fineHandlers.TagOpen && _fineHandlers.TagOpen( ctx );
						continue;
					}
				}
				else
				{
					// Hits "<abc#" where _a is "#"
					// Consume everything until we hit closing ">" or opening "<"
					tokenStack.add( _newStackItem( t ) );
					t = _a;
					for(
						_a = str[ ++i ];
						!( _a.startsWith( _OP ) || _a.startsWith( _ED ) );
						i ++, _a = str[i]
					) t += _a;

					// Hits "<abcd#...<"
					if( _a === _OP )
					{
						// Write "<abcd#..." into _fd and starts over
						//   <    : _OP
						//   abcd : tokenStack.pop().name
						//   #... : t
						_fd( _OP + tokenStack.pop().name + t ); i --;
						continue;
					}
					// Hits "<abcd#...>"
					else
					{
						// Write #... into abcd's attrs
						tokenStack.curr().attrs = t;
						_fd = tokenStack.curr().fd;

						_fineHandlers.TagOpen && _fineHandlers.TagOpen( ctx );
						continue;
					}
				}
			}
			else
			{
				_fd( c );
			}
		}

		return strOut;
	}
}