/**
	COPYRIGHT © 2024 JOHN PEARCEY
	Distributed under the Boost Software License, Version 1.0.
		(See accompanying file LICENSE.txt or copy at
		https://www.boost.org/LICENSE_1_0.txt)
*/
module attributeHandler;

/**
 * Module mainly for attribute parsing for DB retrieval, and some other
 * common attribute functionality
 */

import std.stdio;


/**
 * Simple attribute parser.
 * 
 * Remember to escape the " and/or ' with " or ' if these values are required.
 */
class AttributeMap {
	
	string[string]		attrib_map;
	
	this( string strAtts="" ){		
		if(strAtts!=""){
			attrib_map = parse( strAtts );
		}
	}
	
	string[string] getAttribMap( ){
		return attrib_map;
	}
	
	int getAttribCount( ){
		return cast(int)(attrib_map.length);
	}

	string getAttribute( string name ){
		if( name in attrib_map ) return attrib_map[name];
		return null;
	}
	
	string getAttsAsString(){
		if(attrib_map.length==0) return "";
		string rtn = "";
		foreach( key; attrib_map.keys() ){
			rtn ~= key ~ "=\"" ~ attrib_map[key] ~ "\" ";
		}
		return rtn;		
	}
	
	void setAttribute( string name, string value){
		attrib_map[name] = value;
	}
	
	void removeAttribute( string name ){
		if( name in attrib_map ) attrib_map.remove(name);
	}
		
	static string[string] parse( string strAtts ){
		
		string[string] mapAtts;
		
		int state = 0;
		string nxtKey = "";
		string nxtVal = "";
		char cQtp = '\0';
		
		foreach( i,c; strAtts ){
			
			switch(state){
			case 0:
				// wait for a key
				switch(c){
				
				case '>':
					//this is the end of the element tag
					return mapAtts;
					
				case ' ', '\t':
					break;
					
				default:
					state += 1;
					nxtKey ~= c;					
				}
				break;
				
			case 1:
				//parsing a key
				switch(c){
					
				case ' ':
					if(nxtKey=="") break;
					goto case '=';
					
				case '=':
					state += 1;					
					break;

				default:
					nxtKey ~= c;					
				}
				break;
			
			case 2:
				
				//waiting for a value
				switch(c){
				case '"', '\'':
					cQtp = c;
					state += 1;					
					break;
					
				case '=', ' ', '\t':				
					break;
					
				default:
					// not a quote, must be the next attribute and the previous att has an empty value					
					mapAtts[nxtKey] = "";
					nxtKey = ""~c;
					state=0;
				}
				break;
				
			case 3:
				//looking for the value end, must be a quote
				switch(c){
					
				case '"','\'':
					if(cQtp!=c){
						nxtVal ~= c;
						break;
					}
					mapAtts[nxtKey] = nxtVal;
					nxtKey = "";
					nxtVal = "";
					state = 0;					
					break;
					
				default:
					nxtVal ~= c;
				}
				break;

			default:
			}
		}		
		return mapAtts;
	}
	
}


unittest{

	writeln( "Testing attribute parsing" );

	string strAtts = "  color=\"red\" 	font='big font'  nowrap v-align='top' border=\"\"  ";
	AttributeMap atts = new AttributeMap( strAtts );
	
	auto attMap =  atts.getAttribMap();
	foreach( key; attMap.keys() ){
		
		string value = attMap[key];
		
		switch(key){
			
		case "color":
			assert( value=="red");
			break;
			
		case "font":
			assert( value=="big font");
			break;
			
		case "nowrap":
		case "border":
			assert( value=="");
			break;
			
		case "v-align":
			assert( value=="top");
			break;
			
		default:	
			writeln("unknown key was: ", key);
			assert(false);
		}
	}

	
	atts = new AttributeMap( "" );
	attMap =  atts.getAttribMap();
	assert( attMap.length==0 );

	atts = new AttributeMap( "color='pink' > other garbage" );
	attMap =  atts.getAttribMap();
	assert( attMap.length==1 );	
	assert( attMap["color"]=="pink" );
	
}