package org.greenstone.gsdl3.gs3build.util;

public class HTMLTag implements HTMLObject
{ String tagtext;
  String name;
  int	 docpos;
  int    endpos;

  public static final String HTML_ELEMENT_TYPE = "Element";

  public HTMLTag(String tagtext, int docpos, int endpos)
  { this.tagtext = tagtext;
    this.name    = null;
    this.docpos  = docpos;
    if (this.docpos < 0)
    { this.endpos = -1;
    }
    else
    { this.endpos = endpos;
    }
  }

  public HTMLTag(String tagtext)
  { this.tagtext 	= tagtext;
    this.docpos		= -1;
    this.name			= null;
  }

  public String getHTMLType()
  { return HTML_ELEMENT_TYPE;
  }

	public HTMLTag endTag()
	{ HTMLTag end;
		String	endtext;

		endtext = "</"+this.xtagName()+">";

		end = new HTMLTag(endtext);
		return end;
	}

	public boolean tagIsOpening()
	{ return (this.tagtext.charAt(1) != '/');
	}

	/**
	 *  Tells you if a tag is a singleton tag - TODO: complete list
	 */
	public boolean tagIsSingleton()
	{	String tagName = this.tagName();
		
		return (tagName.equals("img"));
	}

	/**
	 *  @return: the name of a tag including any leading '/'
	 */
	public String tagName()
	{ int offset, start, end;
		String reply;

		if (this.name != null)
		{	return this.name;
		}
	
		// NB: a starting '<' and an ending '>' are guaranteed
		offset = 1; // skip <
		while (this.tagtext.charAt(offset) <= 32 ||
					 this.tagtext.charAt(offset) == 127)
		{ offset ++;
		}
		start = offset;
		while (this.tagtext.charAt(offset) > 32 &&
					 this.tagtext.charAt(offset) != '>' &&
					 this.tagtext.charAt(offset) != 127)
		{ offset ++;
		}
		end = offset;

		reply = this.tagtext.substring(start, end);
		reply = reply.toLowerCase();

		this.name	= reply;

		return reply;
	}

	// Returns the name of the tag *minus* any leading / for
	// closing tags
	public String xtagName()
	{ String reply;

		reply = this.tagName();
		if (reply == null || reply.length() == 0)
		{	return null;
		}

		if (reply.charAt(0) == '/')
		{ if (reply.length() > 1)
			{	reply = reply.substring(1, reply.length());
			}
			else
			{ reply = "";
			}
		}
		return reply;
	}

	public String endTagName()
	{	String reply;

		reply = "/" + xtagName();
		return reply;
	}

	public boolean isClosing()
	{ String name;

		name	= this.tagName();
		if (name.charAt(0) == '/')
		{	return true;
		}
		return false;
	}

	public int tagLevel()
	{ String	name;
		int			level;

		level = 7;

		name = this.xtagName();
		if (name.charAt(0) == 'h')
		{ level = Integer.parseInt(name.substring(1, 2));
		}
		
		return level;
	}

	public int startPos()
	{	return this.docpos;
	}

	public int endPos()
	{	return this.endpos;
	}

	static public boolean isTag(String text)
	{ if (text.charAt(0) == '<')
		{ return true;
		}
		return false;
	}

	public String toString()
	{	return this.tagtext;
	}

	//
	// Returns the value of the identifier given as a string
	//
	public String idValue(String idName)
	{	int offset, start, end;
		int idstart, idend, valuestart, valueend;
		boolean isvalue, isquoted, isstopped;
		char		quotechar;
		String reply;

		// NB: a starting '<' and an ending '>' are guaranteed
		offset = 1; // skip <
		while (this.tagtext.charAt(offset) <= 32 ||
					 this.tagtext.charAt(offset) == 127)
		{ offset ++;
		}
		start = offset;
		while (this.tagtext.charAt(offset) > 32 &&
					 this.tagtext.charAt(offset) != '>' &&
					 this.tagtext.charAt(offset) != 127)
		{ offset ++;
		}
		end = offset;
		// End of tag name

		if (this.tagtext.charAt(offset) == '>')
		{ return null;
		}

		isstopped = false;
		while (!isstopped)
		{	isvalue		= false;
			isquoted	= false;
			valuestart = -1;
			valueend = -1;

			while (this.tagtext.charAt(offset) <= 32 ||
						this.tagtext.charAt(offset) == 127)
			{ offset ++;
			}
			idstart = offset;

			if (this.tagtext.charAt(offset) == '>')
			{ break;
			}

			while (this.tagtext.charAt(offset) > 32 &&
						 this.tagtext.charAt(offset) != '=' &&
						 this.tagtext.charAt(offset) != '>' &&
						 this.tagtext.charAt(offset) != 127)
			{ offset ++;
			}
			idend = offset;

			while (this.tagtext.charAt(offset) <= 32 ||
						 this.tagtext.charAt(offset) == 127)
			{ offset ++;
			}

			if (this.tagtext.charAt(offset) == '=')
			{ isvalue = true;
				quotechar = ' ';
				offset ++;				

				while (this.tagtext.charAt(offset) <= 32 ||
							 this.tagtext.charAt(offset) == 127)
				{ offset ++;
				}
				if (this.tagtext.charAt(offset) == '"' ||
						this.tagtext.charAt(offset) == '\'')
				{ quotechar = this.tagtext.charAt(offset);
					isquoted = true;
					offset ++;
				}
				valuestart = offset;

				while (offset < this.tagtext.length() &&
							 (isquoted && this.tagtext.charAt(offset) != quotechar) ||
							 (!isquoted && this.tagtext.charAt(offset) > 32 &&
							   this.tagtext.charAt(offset) != '>'))
				{ offset ++;
				}
				valueend = offset;
			}

			if (offset >= this.tagtext.length() ||
					this.tagtext.charAt(offset) == '>')
			{ isstopped = true;
			}
			offset ++;

			reply = this.tagtext.substring(idstart, idend);
			reply = reply.toLowerCase();

			if (reply.equalsIgnoreCase(idName))
			{ if (isvalue)
				{ return this.tagtext.substring(valuestart, valueend);
				}
				else
				{ return reply;
				}
			}
		}
		return null;
	}
}