#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <assert.h>

#include "cpdf.h"
#include "parse.h"
#include "filter.h"
#include "utils.h"
/* function compute number of locations of char c from buffer to character c 
 */
int strlenc(char *buffer, char c, char to)
{
	int i = 0;
	while (*buffer && *buffer != to) {
		if (*buffer == c)
			i++;
		buffer++;
	}
	return i;
}

/* function compute lenght of string to char to
 */
int strlento(char *buffer, char to)
{
	char *old = buffer;
	while (*buffer && *buffer != to)
		buffer++;
	return buffer - old;
}

/* convert hex to bin
 */
char *hex(char *buffer)
{
	char *hex_array, *end;
	char num[5] = { '0', 'x', '\0', '\0', '\0' };
	int i;
	if (*buffer != '<')
		return NULL;
	if ((i = strlento(buffer + 1, '>') >> 1) == 0)
		return NULL;
	end = hex_array = (char *) xmalloc(i);
	for (buffer++; *buffer != '>'; hex_array++) {
		num[2] = *buffer;
		if (*(buffer + 1) == '>') {
			num[3] = '0';
			buffer++;
		} else {
			num[3] = *(buffer + 1);
			buffer += 2;
		}
		*hex_array = (char) strtoul((char *) &num, NULL, 16);
	}
	return end;
}

/* interpreter for special characters in name string */
char *name(char *buffer)
{
	char *ret, *end;
	char num[5] = { '0', 'x', '\0', '\0', '\0' };
	if (*buffer != '/')
		return NULL;
	if (memchr(buffer, '#', MAXNAMELEN) == NULL)
		return buffer;
	end = ret = (char *) xmalloc(MAXNAMELEN);
	while (*buffer && *buffer != ' ') {
		if (*buffer == '#') {
			num[2] = *(buffer + 1);
			num[3] = *(buffer + 2);
			*ret = (char) strtoul(num, NULL, 16);
			ret++;
			buffer += 3;
		}
		*ret = *buffer;
		ret++;
		buffer++;
	}
	return end;
}

char **array(char *buffer)
{
	char **ret = NULL,*last;
	static char delim[2] = { '[', ']' };
	int index = 0, len,end = 0;
	last = buffer + 1;
	do {
		ret =
		    (char **) realloc(ret, (index + 1) * sizeof(char **));
		if (*buffer == '[' || *buffer == ']') {
			if (*buffer == '[') {
				ret[index] = &delim[0];
				end++;
			}
			else {
				ret[index] = &delim[1];
				end--;
			}
			buffer++;
			index++;
			continue;
		}
		while(1) {
		while (*buffer != ' ' && *buffer != ']' && *buffer != '\n') 
			buffer++;
		if(buffer - last == 0) {
			buffer++;
			continue;
		}
		else 
			break;
		}
		len = buffer - last;
		ret[index] = (char *) xcalloc(len + 1, sizeof(char));
		strncpy(ret[index], last, len);
		index++;
		if (*buffer != ']')
			last = ++buffer;
		else
			last = buffer;
	} while (end);
	return ret;
}


#define BUFLEN 255
char *read_obj(long offset)
{
	char entry[BUFLEN], *obj = NULL;
	int size = 0;
	fseek(fp, offset, SEEK_SET);
	fget(entry, BUFLEN, fp);
	do {
		fget(entry, BUFLEN, fp);
		size += strlen(entry) + 1;
		obj = resize(obj, size);
		strcat(obj, entry);
	} while (!strstr(entry, "endobj"));
	return obj;
}

int get_typenum(char *dictionary)
{
	char *p;
	p = strstr(dictionary, "Type");
	if (!p) {
	        if((p = strstr(dictionary,"stream")) != NULL)
		                return CONTENTS;
	        return DATA;				
	}
	for(p += 4;*p != '/';p++);
	p++;
	if (!strncmp(p, "Catalog", 7))
		return CATALOG;
	if (!strncmp(p, "Page", 4)) { 
		if(p[4] == 's')
			return PAGES;
		return PAGE;
	}
return DATA;
}

void *get_object(int num,int *type)
{
	void *ret = NULL;
	char *dict;
	struct object **obj;
	for (obj = objects; obj; obj++) {
		if ((*obj)->obj_num == num) {
			if ((*obj)->parsed) {
				if(type)
					*type = (*obj)->type;
				return (*obj)->parsed;
			}
			dict = read_obj((*obj)->offset);
				(*obj)->type = get_typenum(dict);
			if(type)
				*type = (*obj)->type;
			if((*obj)->type == CATALOG) {
				ret = fill_catalog(dict);
				break;
			}
			if((*obj)->type == PAGES) {
				ret = fill_pages(dict);
				break;
			}
			if((*obj)->type == PAGE) {
				ret = fill_page(dict);
				break;
			}
			if((*obj)->type == CONTENTS) {
				ret = fill_contents(dict);
				break;
			}
			if((*obj)->type == RESOURCES) {
				ret = fill_resources(dict);
				break;
			}
			if((*obj)->type == DATA) {
				(*obj)->parsed = dict;
				return dict;
			}
		}

	}
	free(dict);
	(*obj)->parsed = ret;
	return ret;
}

/* add object to object structure */
void add_obj(char *s)
{
	long old_off;
	struct object *o =
	    (struct object *) xcalloc(sizeof(struct object), 1);
	old_off = ftell(fp);
	sscanf(s, "%ld 00000 n", &o->offset);
	fseek(fp, o->offset, SEEK_SET);
	fget(s, XREFLINE, fp);
	sscanf(s, "%d 0 obj", &o->obj_num);
	fseek(fp, old_off, SEEK_SET);
	objects =
	    (struct object **) realloc(objects, obj_count * sizeof(char *));
	objects[obj_count - 1] = o;
	obj_count++;
	return;
}

/* get filter number */
char get_filternum(char *filter)
{
	if (!strncmp(filter, "FlateDecode", 11))
		return FLATEDECODE;
	if (!strncmp(filter, "DCTDecode", 9))
		return DCTDECODE;
	return -1;
}

/* get offset of start xref table */
long get_startxref(void)
{
	char startxref[XREFLINE];
	int i = XREFLINE - 2;
	long offset;
	startxref[XREFLINE - 1] = '\0';
	fstat(fp->_fileno, &fpstat);
	offset = fpstat.st_size - EOFSIZE;
	fseek(fp, offset, SEEK_SET);
	while (1) {
		startxref[i] = fgetc(fp);
		if (startxref[i] == '\r' || startxref[i] == '\n')
			break;
		i--;
		offset--;
		fseek(fp, offset, SEEK_SET);
	}
	return strtoul(&startxref[i + 1], NULL, 10);
}

void probe_ptree(int num)
{
	struct pages *pages;	
	int type,a;
	pages = (struct pages *) get_object(num,NULL); 
	pages->kids++;
	a = atoi(*pages->kids);
	pages = (struct pages *) get_object(a,&type);
	while(type != PAGE) {
		a = atoi(pages->kids[1]);
		pages = (struct pages *) get_object(a,&type);
	}
	page_tree[current_page] = a;
	return;
/*	while(1) {
		if(**pages->kids == ']' && !pages->parent)
			break;
		if(**pages->kids == ']') {
			free(pages->old_kids);
			pages = (struct pages *) get_object(pages->parent,NULL);
		}
		num = atoi(*pages->kids);
		p = (struct pages *) get_object(num,&type);
		if(type == PAGE) {
			page_tree[current_page] = num;
			current_page++;
			pages->kids += 3;
			continue;
		}
		pages->kids += 3;
		pages = p;			
	}
	return;*/
}

/* find objects and add it to object structure */
void parse_xref(void)
{
	char xref[XREFLINE];
	char *p;
	fseek(fp, get_startxref(), SEEK_SET);
	fget(xref, XREFLINE, fp);
	if (!strstr(xref, "xref")) {
		fprintf(stderr, "PDF document si corrupted!\n");
		/* reconstruction ? */
		return;
	}
	objects = NULL;
	obj_count = 1;
	do {
		fget(xref, XREFLINE, fp);
		do {
			fget(xref, XREFLINE, fp);
			if (!strncmp(xref, "trailer", 7))
				break;
			if (xref[XREFLINE - 3] == 'f')
				continue;
			add_obj(&xref[0]);
		} while (1);
		{
		char *tline = (char *) malloc(3 * XREFLINE);
		fget(tline, 3 * XREFLINE, fp);
		trailer.prev = 0;
		while (tline[0] != '>' && tline[1] != '>') {
			if ((p = strstr(tline, "Root")) != NULL)
				sscanf(p, "Root %d 0 R", &trailer.root);
			if ((p = strstr(tline, "Info")) != NULL)
				sscanf(p, "Info %d 0 R", &trailer.info);
			if ((p = strstr(tline, "Prev")) != NULL)
				sscanf(p, "Prev %ld", &trailer.prev);
			if ((p = strstr(tline, "Encrypt")) != NULL)
				sscanf(p,
				       "Encrypt %d 0 R", &trailer.encrypt);
			fget(tline, 3 * XREFLINE, fp);
		}
		free(tline);
		}
		if (!trailer.prev)
			break;
		fseek(fp, trailer.prev, SEEK_SET);
	} while (1);
	return;
}

int parse_catalog(void)
{
	struct catalog *c = NULL;
	c = (struct catalog *) get_object(trailer.root,NULL);
	if (!c) {
		/* error */
	}
	return c->pages;
}

void parse_pdf(void)
{
	int ret;
	struct pages *pages;
	parse_xref();
	ret = parse_catalog();
	pages = (struct pages *) get_object(ret,NULL);
	page_tree = (int *) xcalloc(pages->count, 1);
	current_page = 0;
	ret = parse_catalog();
	probe_ptree(ret);
	current_page = 0;
	loop();
	return;
}

struct catalog *fill_catalog(char *dictionary)
{
char *p;
struct catalog *catalog = (struct catalog *) xcalloc(sizeof(struct catalog),1);
p = strstr(dictionary,"Pages");
if(!p) {
	/* error*/
	return NULL;
}
sscanf(p,"Pages %d 0 R",&catalog->pages);
return catalog;
}

struct pages *fill_pages(char *dictionary)
{
	char *p;
	struct pages *pages =
	    (struct pages *) xcalloc(sizeof(struct pages), 1);
	p = strstr(dictionary, "Count");
	if (!p) {
		/* error */
		return NULL;
	}
	sscanf(p, "Count %d", &pages->count);
	p = strstr(dictionary, "Kids");
	if (!p) {
		/* error */
		return NULL;
	}
	pages->old_kids = pages->kids = array(p + 5);
	p = strstr(dictionary, "Parent");
	if(p) 
		sscanf(p,"Parent %d 0 R",&pages->parent);
	return pages;
}

struct page *fill_page(char *dictionary)
{
	struct page *page;
	char *p, **mediabox;
	int ref;
	page = (struct page *) xcalloc(sizeof(struct page), 1);
	p = strstr(dictionary, "Contents");
	if (!p) {
		/* error */
		return NULL;
	}
	if (p[9] == '<') {	/* if /Contents << */
		page->contents = fill_contents(dictionary);
	} else {
		sscanf(p, "Contents %d 0 R", &ref);
		page->contents = (struct contents *) get_object(ref,NULL);
	}
	p = strstr(dictionary, "Resources");
	if (!p) {
		/* error */
		return NULL;
	}
	if (p[10] == '<')	/* if /Resources << */
		page->resources = fill_resources(dictionary);
	else {
		sscanf(p, "Resources %d 0 R", &ref);
		page->resources = (struct resources *) get_object(ref,NULL);
	}
	p = strstr(dictionary, "MediaBox");
	if (!p) {
		/* error */
		return NULL;
	}
	mediabox = array(&p[9]);
	page->mediabox[0] = (short) strtoul(mediabox[1], NULL, 10);
	free(mediabox[1]);
	page->mediabox[1] = (short) strtoul(mediabox[2], NULL, 10);
	free(mediabox[2]);
	page->mediabox[2] = (short) strtoul(mediabox[3], NULL, 10);
	free(mediabox[3]);
	page->mediabox[3] = (short) strtoul(mediabox[4], NULL, 10);
	free(mediabox[4]);
	free(mediabox);
	p = strstr(dictionary, "Parent");
	if (!p) {
		/* error */
		return NULL;
	}
	sscanf(p, "Parent %d 0 R", &page->parent);
	p = strstr(dictionary, "Rotate");
	if (p)
		sscanf(p, "/Rotate %hd", &page->rotate);
	return page;
}

struct contents *fill_contents(char *dictionary)
{
	struct contents *content;
	char *p,*endstream;
	int i = 0;
	content = (struct contents *) xcalloc(sizeof(struct contents), 1);
	p = strstr(dictionary, "Length");
	if (!p) {
		/* error */
		free(content);
		return NULL;
	}
	
	sscanf(p, "Length %d", &content->length);
	for(p += 6;*p != '/';p++) 
		if(!strncmp(p,"0 R",3)) {
			p = (char *) get_object(content->length,NULL);
			sscanf(p,"%d\nendobj",&content->length);
		break;
		}	
	p = strstr(dictionary, "Filter");
	if (!p) {
		/* error */
		free(content);
		return NULL;
	}
	content->filter = get_filternum(&p[8]);
	p = strstr(dictionary, "stream") + sizeof("stream");
	if (!p) {
		/* error */
		free(content);
		return NULL;
	}
	content->stream = (unsigned char *) xcalloc(content->length,1);
	memcpy(content->stream,p,content->length);
	return content;
}

struct resources *fill_resources(char *dictionary)
{
	struct resources *resources;
	resources =
	    (struct resources *) xcalloc(sizeof(struct resources), 1);
	return resources;
}