#include <rtgui/rtgui_xml.h>
#include <rtgui/rtgui_system.h>

/* Internal states that the parser can be in at any given time. */
enum {
	STAT_START = 0,         /* starting base state, default state */
	STAT_TEXT,              /* text state */
	STAT_START_TAG,         /* start tag state */
	STAT_START_TAGNAME,     /* start tagname state */
	STAT_START_TAGNAME_END, /* start tagname ending state */
	STAT_END_TAG,           /* end tag state */
	STAT_END_TAGNAME,       /* end tag tagname state */
	STAT_END_TAGNAME_END,   /* end tag tagname ending */
	STAT_EMPTY_TAG,         /* empty tag state */
	STAT_SPACE,             /* linear whitespace state */
	STAT_ATTR_NAME,         /* attribute name state */
	STAT_ATTR_NAME_END,     /* attribute name ending state */
	STAT_ATTR_VAL,          /* attribute value starting state */
	STAT_ATTR_VAL2,         /* attribute value state */
	STAT_ERROR              /* error state */
};

/* character classes that we will match against; This could be expanded if
   need be, however, we are aiming for simple. */
enum {
	CLASS_TYPE_NONE = 0,       /* matches nothing, a base state */
	CLASS_TYPE_LEFT_ANGLE,     /* matches start tag '<' */
	CLASS_TYPE_SLASH,          /* matches forward slash */
	CLASS_TYPE_RIGHT_ANGLE,    /* matches end tag '>' */
	CLASS_TYPE_EQUALS,         /* matches equals sign */
	CLASS_TYPE_QUOTE,          /* matches double-quotes */
	CLASS_TYPE_LETTERS,        /* matches a-zA-Z letters and digits 0-9 */
	CLASS_TYPE_SPACE,          /* matches whitespace */
	CLASS_TYPE_ANY             /* matches any ASCII character; will match all
								above classes */
};

/* xml state transition table */
struct rtgui_xml_state
{
	rt_uint8_t state;
	rt_uint8_t class_type;
	rt_uint8_t next_state;
	rt_uint8_t event;
};

/* Note: States must be grouped in match order AND grouped together! */
static const struct rtgui_xml_state RTGUI_XML_STATES [] = {
   /* [0-2] starting state, which also serves as the default state in case
	  of error */
   { STAT_START,         CLASS_TYPE_SPACE,        STAT_SPACE,             EVENT_NONE },
   { STAT_START,         CLASS_TYPE_LEFT_ANGLE,   STAT_START_TAG,         EVENT_NONE },
   { STAT_START,         CLASS_TYPE_ANY,          STAT_TEXT,              EVENT_COPY },

   /* [3-5] space state handles linear white space */
   { STAT_SPACE,         CLASS_TYPE_SPACE,        STAT_SPACE,             EVENT_NONE },
   { STAT_SPACE,         CLASS_TYPE_LEFT_ANGLE,   STAT_START_TAG,         EVENT_TEXT },
   { STAT_SPACE,         CLASS_TYPE_ANY,          STAT_TEXT,              EVENT_COPY },

   /* [6-8] handle start tag */
   { STAT_START_TAG,     CLASS_TYPE_LETTERS,      STAT_START_TAGNAME,     EVENT_COPY },
   { STAT_START_TAG,     CLASS_TYPE_SLASH,        STAT_END_TAG,           EVENT_COPY },
   /* below added since some individuals get a little carried away with
	  spacing around tag names, e.g. < tag > */
   { STAT_START_TAG,     CLASS_TYPE_SPACE,        STAT_START_TAG,         EVENT_NONE },

   /* [9-12] handle start tag name */
   { STAT_START_TAGNAME, CLASS_TYPE_LETTERS,      STAT_START_TAGNAME,     EVENT_NONE },
   { STAT_START_TAGNAME, CLASS_TYPE_SPACE,        STAT_START_TAGNAME_END, EVENT_START },
   /* below added for tags without any space between tag and ending
	  slash, e.g., <br/> */
   { STAT_START_TAGNAME, CLASS_TYPE_SLASH,        STAT_EMPTY_TAG,         EVENT_END },
   { STAT_START_TAGNAME, CLASS_TYPE_RIGHT_ANGLE,  STAT_START,             EVENT_START },

   /* [13-16] handle start tag name end */
   { STAT_START_TAGNAME_END,  CLASS_TYPE_LETTERS, STAT_ATTR_NAME,         EVENT_COPY },
   /* below added to handle additional space in between attribute value
	  pairs in start tags, e.g., <tag attr="2" attr2="test" > */
   { STAT_START_TAGNAME_END,  CLASS_TYPE_SPACE,   STAT_START_TAGNAME_END, EVENT_NONE },
   { STAT_START_TAGNAME_END,  CLASS_TYPE_RIGHT_ANGLE, STAT_START,         EVENT_START },
   /* below supports tags that are self-closing, e.g., <br /> */
   { STAT_START_TAGNAME_END,  CLASS_TYPE_SLASH,   STAT_EMPTY_TAG,         EVENT_COPY },

   /* [17] handle empty tags, e.g., <br /> */
   { STAT_EMPTY_TAG,     CLASS_TYPE_RIGHT_ANGLE,  STAT_START,             EVENT_END },

   /* [18] handle end tag, e.g., <tag /> */
   { STAT_END_TAG,       CLASS_TYPE_LETTERS,      STAT_END_TAGNAME,       EVENT_NONE },

   /* [19-21] handle end tag name */
   { STAT_END_TAGNAME,   CLASS_TYPE_LETTERS,      STAT_END_TAGNAME,       EVENT_NONE },
   { STAT_END_TAGNAME,   CLASS_TYPE_RIGHT_ANGLE,  STAT_START,             EVENT_END },
   /* below adds support for spaces at the end of an end tag (before
	  closing bracket) */
   { STAT_END_TAGNAME,   CLASS_TYPE_SPACE,        STAT_END_TAGNAME_END,   EVENT_END },

   /* [22] handle ending of end tag name */
   { STAT_END_TAGNAME_END, CLASS_TYPE_SPACE,      STAT_END_TAGNAME_END,   EVENT_NONE },
   { STAT_END_TAGNAME_END, CLASS_TYPE_RIGHT_ANGLE,STAT_START,             EVENT_NONE },

   /* [23-25] handle text */
   { STAT_TEXT,          CLASS_TYPE_SPACE,        STAT_SPACE,             EVENT_NONE },
   { STAT_TEXT,          CLASS_TYPE_LEFT_ANGLE,   STAT_START_TAG,         EVENT_TEXT },
   { STAT_TEXT,          CLASS_TYPE_ANY,          STAT_TEXT,              EVENT_NONE },

   /* [26-30] handle attribute names */
   { STAT_ATTR_NAME,     CLASS_TYPE_LETTERS,      STAT_ATTR_NAME,         EVENT_COPY },
   /* below add support for space before the equals sign, e.g, <tag
	  attr ="2"> */
   { STAT_ATTR_NAME,     CLASS_TYPE_SPACE,        STAT_ATTR_NAME_END,     EVENT_NAME },
   { STAT_ATTR_NAME,     CLASS_TYPE_EQUALS,       STAT_ATTR_VAL,          EVENT_NAME },

   /* [31-33] attribute name end */
   { STAT_ATTR_NAME_END, CLASS_TYPE_SPACE,        STAT_ATTR_NAME_END,     EVENT_NONE },
   { STAT_ATTR_NAME_END, CLASS_TYPE_LETTERS,      STAT_ATTR_NAME,         EVENT_COPY },
   { STAT_ATTR_NAME_END, CLASS_TYPE_EQUALS,       STAT_ATTR_VAL,          EVENT_NONE },

   /* [34-35] handle attribute values, initial quote and spaces */
   { STAT_ATTR_VAL,      CLASS_TYPE_QUOTE,        STAT_ATTR_VAL2,         EVENT_NONE },
   /* below handles initial spaces before quoted attribute value */
   { STAT_ATTR_VAL,      CLASS_TYPE_SPACE,        STAT_ATTR_VAL,          EVENT_NONE },

   /* [36-37] handle actual attribute values */
   { STAT_ATTR_VAL2,     CLASS_TYPE_QUOTE,        STAT_START_TAGNAME_END, EVENT_VAL  },
   { STAT_ATTR_VAL2,     CLASS_TYPE_LETTERS,      STAT_ATTR_VAL2,         EVENT_COPY },
   { STAT_ATTR_VAL2,     CLASS_TYPE_SLASH,        STAT_ATTR_VAL2,         EVENT_NONE },

   /* End of table marker */
   { STAT_ERROR,         CLASS_TYPE_NONE,         STAT_ERROR,             EVENT_NONE }
};

struct rtgui_xml
{
	/* event handler */
	rtgui_xml_event_handler_t event_handler;
	void* user;

	char* buffer;				/* xml buffer */
	rt_size_t buffer_size;		/* buffer size */
	rt_size_t position;			/* current position in buffer */
	rt_uint16_t state, event;	/* current state and event */

	rt_bool_t copy;             /* copy text into tmp buffer */
	rt_bool_t halt;				/* halt parsing of document */
};

rtgui_xml_t* rtgui_xml_create(rt_size_t buffer_size, rtgui_xml_event_handler_t handler,
	void* user)
{
	rtgui_xml_t* xml = (rtgui_xml_t*) rtgui_malloc(sizeof(struct rtgui_xml));
	rt_memset(xml, 0, sizeof(rtgui_xml_t));

	xml->event_handler = handler;
	xml->user = user;

	/* create buffer */
	xml->buffer_size = buffer_size;
	xml->buffer = (char*)rtgui_malloc(xml->buffer_size);
	return xml;
}

void rtgui_xml_destroy(rtgui_xml_t* xml)
{
	if(xml)
	{
		rtgui_free(xml->buffer);
		rtgui_free(xml);
	}
}

const char* rtgui_xml_event_str(rt_uint8_t event)
{
	switch(event)
	{
	case EVENT_START:
		return "start tag";
	case EVENT_END:
		return "end tag";
	case EVENT_TEXT:
		return "text";
	case EVENT_NAME:
		return "attr name";
	case EVENT_VAL:
		return "attr val";
	case EVENT_END_DOC:
		return "end document";
	default:
		break;
	}
	return "err";
}

int rtgui_xml_parse(rtgui_xml_t* xml, const char* buf, rt_size_t len)
{
	int i, j, c, match;

#define is_space(ch)	\
	((rt_uint32_t)(ch - 9) < 5u  ||  ch == ' ')
#define is_alpha(ch)	\
	((rt_uint32_t)((ch | 0x20) - 'a') < 26u)
#define is_digit(ch)	\
	((rt_uint32_t)(ch - '0') < 10u)
#define is_letters(ch)	\
	(is_alpha(ch) || is_digit(ch) || (ch == '.'))

	for(i=0; i<len; i++)
	{
		if(xml->halt) break;

		c = buf[i] & 0xff;

		/* search in state table */
		for(j=0, match = 0; RTGUI_XML_STATES[j].state != STAT_ERROR; j++)
		{
			if(RTGUI_XML_STATES[j].state != xml->state)
				continue;

			switch(RTGUI_XML_STATES[j].class_type)
			{
			case CLASS_TYPE_LETTERS:
				match = is_letters(c);
				break;
			case CLASS_TYPE_LEFT_ANGLE:
				match = (c == '<');
				break;
			case CLASS_TYPE_SLASH:
				match = (c == '/');
				break;
			case CLASS_TYPE_RIGHT_ANGLE:
				match = (c == '>');
				break;
			case CLASS_TYPE_EQUALS:
				match = (c == '=');
				break;
			case CLASS_TYPE_QUOTE:
				match = (c == '"');
				break;
			case CLASS_TYPE_SPACE:
				match = is_space(c);
				break;
			case CLASS_TYPE_ANY:
				match = 1;
				break;
			default:
				break;
			}

			/* we matched a character class */
			if(match)
			{
				if(RTGUI_XML_STATES[j].event == EVENT_COPY)
				{
					xml->copy = RT_TRUE;
				}
				else if(RTGUI_XML_STATES[j].event != EVENT_NONE)
				{
					if(xml->copy == RT_TRUE)
					{
						/* basically we are guaranteed never to have an event of
						   type EVENT_COPY or EVENT_NONE here. */
						xml->event = RTGUI_XML_STATES[j].event;
						xml->buffer[xml->position] = 0; /* make a string */

						if(!xml->event_handler(RTGUI_XML_STATES[j].event,
											  xml->buffer, xml->position ,
											  xml->user))
						{
							xml->halt = 1; /* stop parsing from here out */
						}
						xml->position = 0;
						xml->copy = RT_FALSE;
					}
				}
				if(xml->copy == RT_TRUE)
				{
					/* check to see if we have room; one less for trailing
					   nul */
					if(xml->position < xml->buffer_size-1)
					{
						xml->buffer[xml->position] = buf[i];
						xml->position++;
					}
				}
				xml->state = RTGUI_XML_STATES[j].next_state; /* change state */
				break; /* break out of loop though state search */
			}
		}
	}

	return !xml->halt;
}
