/*
 * $Id$
 */

#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "rxml.h"

/* Typedefs/Defines */

#define RXML_ERROR(a,b) { (a)->stdio_errno=errno; (a)->ecode=(b); return 0; };
#define RXML_MAX_LINE 1024
#define RXML_MAX_TEXT 1024
#define RXML_MAX_TAG 256

typedef struct _RXML {
    RXML_EVTHANDLER handler;
    char *fname;
    FILE *fhandle;
    void *udata;
    int stdio_errno;
    int ecode;
    int line;
    char *estring;
} RXML;


#ifndef FALSE
# define FALSE 0
# define TRUE  1
#endif /* FALSE */

#define E_RXML_SUCCESS    0x00
#define E_RXML_OPEN       0x01 | 0x80
#define E_RXML_READ       0x02 | 0x80
#define E_RXML_NEST       0x03
#define E_RXML_SPLIT      0x04
#define E_RXML_CLOSE      0x05
#define E_RXML_TAGSIZE    0x06
#define E_RXML_ENTITY     0x07

char *rxml_estrings[] = {
    "Success",
    "Could not open xml file: ",
    "Error reading file: ",
    "Parse error: Nested tags",
    "Parse error: Tag split over multiple lines",
    "Parse error: Unexpected '>'",
    "Parse error: tag too big",
    "Parse error: bad entity encoding",
    NULL
};

/* Forwards */
static int rxml_decode_string(char *string);

/**
 * decode an xml entity-encoded string in-place
 *
 * @param string string to encode
 * @returns 1 on success, 0 on error
 */
int rxml_decode_string(char *string) {
    char *src, *dst;
    int len;
    int cval;

    src=dst=string;

    while(*src) {
	if((*src) == '&') {
	    len = strlen(src);
	    if((len > 3) && (strncmp(src,"&gt;",4) == 0)) {
		*dst++ = '>';
		src += 4;
	    } else if((len > 3) && (strncmp(src,"&lt;",4) == 0)) {
		*dst++ = '<';
		src += 4;
	    } else if((len > 4) && (strncmp(src,"&amp;",5) == 0)) {
		*dst++ = '&';
		src += 5;
	    } else if((len > 5) && (strncmp(src,"&quot;",6) == 0)) {
		*dst++ = '"';
		src += 6;
	    } else if((len > 5) && (strncmp(src,"&apos;",6) == 0)) {
		*dst ++ = '\'';
		src += 6;
	    } else {
		/* &#xx; */
		if(!sscanf((char*)&src[2],"%d;",&cval))
		    return FALSE;

		*dst++ = cval;
		if(src[3] == ';') {
		    src += 4;
		} else if(src[4] == ';') {
		    src += 5;
		} else if(src[5] == ';') {
		    src += 6;
		} else {
		    return FALSE;
		}
	    }
	} else {
	    *dst++=*src++;
	}
    }

    *dst = '\0';
    return TRUE;
}

/**
 * open a file
 *
 * @param vp pointer to the opaque xml struct
 * @param file filename of file to open
 * @param handler handler function for events
 * @param udata opaque data structure to pass to the callback
 */
int rxml_open(RXMLHANDLE *vp, char *file, 
	      RXML_EVTHANDLER handler, void *udata) {
    RXML *pnew;

    pnew=(RXML*)malloc(sizeof(RXML));
    if(!pnew) {
	*vp = NULL;
	return FALSE;
    }

    memset(pnew,0x0,sizeof(RXML));
    *vp = pnew;

    pnew->handler = handler;
    pnew->fname = file;
    pnew->fhandle = fopen(file,"rb");
    pnew->udata = udata;
    pnew->line = 0;

    if(!pnew->fhandle)
	RXML_ERROR(pnew,E_RXML_OPEN);

    if(pnew->handler)
	pnew->handler(RXML_EVT_OPEN, pnew->udata, pnew->fname);

    return TRUE;
}

/**
 * close the currently open file
 *
 * @param vp xml struct containing info about the file to close
 */
int rxml_close(RXMLHANDLE vp) {
    RXML *ph = (RXML*)vp;

    if(ph->handler) ph->handler(RXML_EVT_CLOSE,ph->udata,ph->fname);
    if(ph->fhandle) fclose(ph->fhandle);
    if(ph->estring) free(ph->estring);

    free(ph);
    return TRUE;
}

/**
 * return a string describing the last error
 *
 * @param vp handle of the document with the error
 */
char *rxml_errorstring(RXMLHANDLE vp) {
    RXML *ph = (RXML*)vp;
    int len;
    char *estring=NULL;

    if(!ph) {
	return "Malloc error";
    }

    if(ph->estring) free(ph->estring);

    len = strlen(rxml_estrings[ph->ecode]) + 16;
    if((ph->ecode & 0x80)) {
	estring=strerror(ph->stdio_errno);
	len += strlen(estring);
    }

    ph->estring=(char*)malloc(len);
    if(!ph->estring)
	return "Double-fault malloc error";


    if((ph->ecode & 0x80)) {
	snprintf(ph->estring,len,"%s%s",rxml_estrings[ph->ecode],estring);
    } else {
	if(strncmp(rxml_estrings[ph->ecode],"Parse",5)==0) {
	    snprintf(ph->estring, len, "%s (Line:%d)",
		     rxml_estrings[ph->ecode], ph->line);
	} else {
	    snprintf(ph->estring,len, "%s", rxml_estrings[ph->ecode]);
	}
    }

    return ph->estring;
}

/**
 * walk through the xml file, sending events to the
 * callback handler.
 *
 * @param vp opaque doc struct of the doc to parse
 */
int rxml_parse(RXMLHANDLE vp) {
    char linebuffer[RXML_MAX_LINE];
    char tagbuffer[RXML_MAX_TAG];
    char textbuffer[RXML_MAX_TEXT];
    int in_text=0;
    int text_offset=0;
    int size;
    int offset;
    int in_tag=0;
    int tag_end=0;
    int tag_start=0;
    int single_tag;
    RXML *ph = (RXML*)vp;

    ph->line = 0;

    
    textbuffer[0] = '\0';

    /* walk through and read row by row */
    while(fgets(linebuffer,sizeof(linebuffer),ph->fhandle) != NULL) {
	ph->line++;
	offset=0;
	size=strlen(linebuffer);
	in_text=0;
	text_offset=0;
	while(offset < size) {
	    switch(linebuffer[offset]) {
	    case '<':
		if(in_tag)
		    RXML_ERROR(ph, E_RXML_NEST);

		in_tag=TRUE;
		tag_start=offset+1;
		tag_end=FALSE;
		if(linebuffer[tag_start] == '/') {
		    tag_end = TRUE;
		    offset++;
		    tag_start++;
		}

		offset++;

		in_text=0;
		break;

	    case '>':
		if(!in_tag)
		    RXML_ERROR(ph, E_RXML_CLOSE);

		in_tag=FALSE;
		if((offset - tag_start) > RXML_MAX_TAG)
		    RXML_ERROR(ph, E_RXML_TAGSIZE);

		strncpy(tagbuffer,&linebuffer[tag_start],offset-tag_start);
		tagbuffer[offset-tag_start] = '\0';

		if(tag_end) {
		    /* send the text before the tag end */
		    if((ph->handler) && (strlen(textbuffer))) {
			if(!rxml_decode_string(textbuffer))
			    RXML_ERROR(ph,E_RXML_ENTITY);

			ph->handler(RXML_EVT_TEXT,ph->udata,textbuffer);
		    }
		}

		in_text=1; 
		text_offset=0;
		textbuffer[0] = '\0';

		single_tag=0;
		if(tagbuffer[strlen(tagbuffer)-1] == '/') {
		    tagbuffer[strlen(tagbuffer)-1] = '\0';
		    single_tag=1;
		}

		if(ph->handler)
		    ph->handler(tag_end ? RXML_EVT_END : RXML_EVT_BEGIN,
				ph->udata,tagbuffer);

		/* send a follow-up end on a <tag/> - style tag */
		if((single_tag) && (ph->handler)) 
		    ph->handler(RXML_EVT_END,ph->udata,tagbuffer);

		offset++;
		break;

	    default:
		if((in_text) && (text_offset < (sizeof(textbuffer)-1))) {
		    /* get rid of EOL */
		    if((linebuffer[offset] != '\r') && 
		       (linebuffer[offset] != '\n')) {
			textbuffer[text_offset] = linebuffer[offset];
			text_offset++;
			textbuffer[text_offset] = '\x0';
		    }
		} else if (in_text) {
		    /* should warn of an overflow */
		}
		offset++;
		break;
	    }
	}
    }

    ph->stdio_errno=errno;
    if(ferror(ph->fhandle))
	RXML_ERROR(ph,E_RXML_READ);

    return TRUE;
}