/* Internal bookmarks XBEL bookmarks basic support */

/*
 * TODO: Decent XML output.
 * TODO: Validation of the document (with librxp?). An invalid document can
 *       crash elinks.
 * TODO: Support all the XBEL elements. */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif /* HAVE_CONFIG_H */

#include <ctype.h>
#include <errno.h>
#include <expat.h>
#include <stdio.h>
#include <stdlib.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include "elinks.h"

#include "bfu/dialog.h"
#include "bookmarks/bookmarks.h"
#include "bookmarks/backend/common.h"
#include "bookmarks/backend/xbel.h"
#include "intl/charsets.h"
#include "intl/gettext/libintl.h"
#include "util/conv.h"
#include "util/lists.h"
#include "util/string.h"

#define BOOKMARKS_XBEL_FILENAME		"bookmarks.xbel"


/* Elements' attributes */
struct attributes {
	LIST_HEAD(struct attributes);

	unsigned char *name;
	unsigned char *value;
};

/* Prototypes */
static void on_element_open(void *data, const char *name, const char **attr);
static void on_element_close(void *data, const char *name);
static void on_text(void *data, const XML_Char *text, int len);

static struct tree_node *new_node(struct tree_node *parent);
static void free_node(struct tree_node *node);
static void free_xbeltree(struct tree_node *node);
static struct tree_node *get_child(struct tree_node *node, unsigned char *name);
static unsigned char *get_attribute_value(struct tree_node *node,
					  unsigned char *name);


struct read_bookmarks_xbel {
	int utf8_cp;
};

static void read_bookmarks_xbel(FILE *f);
static unsigned char * filename_bookmarks_xbel(int writing);
static int xbeltree_to_bookmarks_list(const struct read_bookmarks_xbel *preload,
				      struct tree_node *root,
				      struct bookmark *current_parent);
static void write_bookmarks_list(struct secure_save_info *ssi,
				 LIST_OF(struct bookmark) *bookmarks_list,
				 int n, int folder_state);
static void write_bookmarks_xbel(struct secure_save_info *ssi,
				 LIST_OF(struct bookmark) *bookmarks_list);

/* Element */
struct tree_node {
	unsigned char *name;		/* Name of the element */
	unsigned char *text;		/* Text inside the element */
	LIST_OF(struct attributes) attrs;
	struct tree_node *parent;
	struct tree_node *children;

	struct tree_node *prev;
	struct tree_node *next;
};

static struct tree_node *root_node = NULL;
static struct tree_node *current_node = NULL;

/* This is 1 so that we won't fail miserably if we read bookmarks in a
 * different format. */
static int readok = 1;

static void
read_bookmarks_xbel(FILE *f)
{
	unsigned char in_buffer[BUFSIZ];
	XML_Parser p;
	int done = 0;
	int err = 0;
	struct read_bookmarks_xbel preload;

	readok = 0;

	p = XML_ParserCreate(NULL);
	if (!p) {
		ERROR(gettext("read_bookmarks_xbel(): Error in XML_ParserCreate()"));
		return;
	}

	XML_SetElementHandler(p, on_element_open, on_element_close);
	XML_SetCharacterDataHandler(p, on_text);

	while (!done && !err) {
		size_t len = fread(in_buffer, 1, BUFSIZ, f);

		if (ferror(f)) {
			ERROR(gettext("read_bookmarks_xbel(): Error reading %s"),
			      filename_bookmarks_xbel(0));
			err = 1;
		} else {

			done = feof(f);

			if (!err && !XML_Parse(p, in_buffer, len, done)) {
				usrerror(gettext("Parse error while processing "
				         "XBEL bookmarks in %s at line %d "
					 "column %d:\n%s"),
				      filename_bookmarks_xbel(0),
				      XML_GetCurrentLineNumber(p),
				      XML_GetCurrentColumnNumber(p),
				      XML_ErrorString(XML_GetErrorCode(p)));
				err = 1;
			}
		}
	}

	if (!err) {
		preload.utf8_cp = get_cp_index("UTF-8");
		readok = xbeltree_to_bookmarks_list(&preload,
						    root_node->children, /* Top node is xbel */
						    NULL);
	}

	XML_ParserFree(p);
	free_xbeltree(root_node);

}

static void
write_bookmarks_xbel(struct secure_save_info *ssi,
		     LIST_OF(struct bookmarks) *bookmarks_list)
{
	int folder_state = get_opt_bool("bookmarks.folder_state");
	/* We check for readok in filename_bookmarks_xbel(). */

	secure_fputs(ssi,
		"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
		"<!DOCTYPE xbel PUBLIC \"+//IDN python.org//DTD XML "
		"Bookmark Exchange Language 1.0//EN//XML\"\n"
		"		       "
		"\"http://www.python.org/topics/xml/dtds/xbel-1.0.dtd\">\n\n"
		"<xbel>\n\n\n");


	write_bookmarks_list(ssi, bookmarks_list, 0, folder_state);
	secure_fputs(ssi, "\n</xbel>\n");
}

static unsigned char *
filename_bookmarks_xbel(int writing)
{
	if (writing && !readok) return NULL;
	return BOOKMARKS_XBEL_FILENAME;
}

static void
indentation(struct secure_save_info *ssi, int num)
{
	int i;

	for (i = 0; i < num; i++)
		secure_fputs(ssi, "    ");
}

static void
print_xml_entities(struct secure_save_info *ssi, const unsigned char *str)
{
	struct string entitized = NULL_STRING;

	if (init_string(&entitized)
	    && add_html_to_string(&entitized, str, strlen(str))) {
		secure_fputs(ssi, entitized.source);
	} else {
		secsave_errno = SS_ERR_OUT_OF_MEM;
		ssi->err = ENOMEM;
	}

	done_string(&entitized);
}

static void
write_bookmarks_list(struct secure_save_info *ssi,
		     LIST_OF(struct bookmark) *bookmarks_list,
		     int n, int folder_state)
{
	struct bookmark *bm;

	foreach (bm, *bookmarks_list) {
		indentation(ssi, n + 1);

		if (bm->box_item->type == BI_FOLDER) {
			int expanded = folder_state && bm->box_item->expanded;

			secure_fputs(ssi, "<folder folded=\"");
			secure_fputs(ssi, expanded ? "no" : "yes");
			secure_fputs(ssi, "\">\n");

			indentation(ssi, n + 2);
			secure_fputs(ssi, "<title>");
			print_xml_entities(ssi, bm->title);
			secure_fputs(ssi, "</title>\n");

			if (!list_empty(bm->child))
				write_bookmarks_list(ssi, &bm->child, n + 2, folder_state);

			indentation(ssi, n + 1);
			secure_fputs(ssi, "</folder>\n\n");

		} else if (bm->box_item->type == BI_LEAF) {

			secure_fputs(ssi, "<bookmark href=\"");
			print_xml_entities(ssi, bm->url);
			secure_fputs(ssi, "\">\n");

			indentation(ssi, n + 2);
			secure_fputs(ssi, "<title>");
			print_xml_entities(ssi, bm->title);
			secure_fputs(ssi, "</title>\n");

			indentation(ssi, n + 1);
			secure_fputs(ssi, "</bookmark>\n\n");

		} else if (bm->box_item->type == BI_SEPARATOR) {
			secure_fputs(ssi, "<separator/>\n\n");
		}
	}
}

static void
on_element_open(void *data, const char *name, const char **attr)
{
	struct tree_node *node;

	node = new_node(current_node);
	if (!node) return;

	if (root_node) {
		if (current_node->children) {
			struct tree_node *tmp;

			tmp = current_node->children;
			current_node->children = node;
			current_node->children->next = tmp;
			current_node->children->prev = NULL;
		}
		else current_node->children = node;
	}
	else root_node = node;

	current_node = node;

	current_node->name = stracpy((unsigned char *) name);
	if (!current_node->name) {
		mem_free(current_node);
		return;
	}

	for (; *attr; attr += 2) {
		struct attributes *attribute = mem_calloc(1, sizeof(*attribute));
		unsigned char *name = stracpy((unsigned char *) attr[0]);
		unsigned char *value = stracpy((unsigned char *) attr[1]);

		if (!attribute || !name || !value) {
			mem_free_if(attribute);
			mem_free_if(name);
			mem_free_if(value);
			free_node(current_node);
			return;
		}

		attribute->name = name;
		attribute->value = value;

		add_to_list_end(current_node->attrs, attribute);
	}

}

static void
on_element_close(void *data, const char *name)
{
	current_node = current_node->parent;
}

static unsigned char *
delete_whites(const unsigned char *s)
{
	unsigned char *r;
	int last_was_space = 0, c = 0, i;
	int len = strlen(s);

	r = mem_alloc(len + 1);
	if (!r) return NULL;

	for (i = 0; i < len; i++) {
		/* Recognize only the whitespace characters listed
		 * in section 2.3 of XML 1.1.  U+0085 and U+2028 need
		 * not be recognized here because section 2.11 says
		 * the XML processor must translate them to U+000A.
		 * Do not use isspace() because the string is in UTF-8
		 * and individual bytes might not be characters at
		 * all.  */
		switch (s[i]) {
		case '\x20': case '\x09': case '\x0D': case '\x0A':
			if (last_was_space) continue;
			last_was_space = 1;
			r[c++] = ' ';
			break;
		default:
			last_was_space = 0;
			r[c++] = s[i];
			break;
		}
	}

	r[c] = '\0';

	/* XXX This should never return NULL, right? wrong! --fabio */
	/* r = mem_realloc(r, strlen(r + 1)); */

	return r;

}

static void
on_text(void *data, const XML_Char *text, int len)
{
	char *tmp;
	int len2 = 0;

	if (len) {
		len2 = current_node->text ? strlen(current_node->text) : 0;

		tmp = mem_realloc(current_node->text, (size_t) (len + 1 + len2));

		/* Out of memory */
		if (!tmp) return;

		strncpy(tmp + len2, text, len);
		tmp[len + len2] = '\0';
		current_node->text = delete_whites(tmp);

		mem_free(tmp);
	}
}

/* xbel_tree_to_bookmarks_list: returns 0 on fail,
 *				      1 on success */
static int
xbeltree_to_bookmarks_list(const struct read_bookmarks_xbel *preload,
			   struct tree_node *node,
			   struct bookmark *current_parent)
{
	struct bookmark *tmp;
	struct tree_node *title;
	static struct bookmark *lastbm;

	while (node) {
		if (!strcmp(node->name, "bookmark")) {
			unsigned char *href;

			title = get_child(node, "title");
			href = get_attribute_value(node, "href");

			intl_set_charset_by_index(preload->utf8_cp);
			tmp = add_bookmark(current_parent, 0,
					   /* The <title> element is optional */
					   title && title->text ? title->text
						 : (unsigned char *) gettext("No title"),
					   /* XXX: The href attribute isn't optional but
					    * we don't validate the source XML yet, so
					    * we can't always assume a non NULL value for
					    * get_attribute_value() */
					   href ? href
						: (unsigned char *) gettext("No URL"));

			/* Out of memory */
			if (!tmp) return 0;

			tmp->root = current_parent;
			lastbm = tmp;

		} else if (!strcmp(node->name, "folder")) {
			unsigned char *folded;

			title = get_child(node, "title");

			intl_set_charset_by_index(preload->utf8_cp);
			tmp = add_bookmark(current_parent, 0,
					   title && title->text ? title->text
						 : (unsigned char *) gettext("No title"),
					   NULL);

			/* Out of memory */
			if (!tmp) return 0;

			folded = get_attribute_value(node, "folded");
			if (folded && !strcmp(folded, "no"))
				tmp->box_item->expanded = 1;

			lastbm = tmp;

		} else if (!strcmp(node->name, "separator")) {
			tmp = add_bookmark(current_parent, 0, "-", "");

			/* Out of memory */
			if (!tmp) return 0;
			tmp->root = current_parent;
			lastbm = tmp;
		}

		if (node->children) {
			int ret;
			struct bookmark *parent_for_nested;

			/* If this node is a <folder> element, current parent
			 * changes */
			if (!strcmp(node->name, "folder"))
				parent_for_nested = lastbm;
			else
				parent_for_nested = current_parent;

			ret = xbeltree_to_bookmarks_list(preload,
							 node->children,
							 parent_for_nested);
			/* Out of memory */
			if (!ret) return 0;
		}

		node = node->next;
	}

	/* Success */
	return 1;
}

static void
free_xbeltree(struct tree_node *node)
{
	struct tree_node *next_node;

	while (node) {

		if (node->children)
			free_xbeltree(node->children);

		next_node = node->next;
		free_node(node);

		node = next_node;
	}
}

static struct tree_node *
get_child(struct tree_node *node, unsigned char *name)
{
	struct tree_node *ret;

	if (!node) return NULL;

	ret = node->children;

	while (ret) {
		if (!strcmp(name, ret->name)) {
			return ret;
		}
		ret = ret->next;
	}

	return NULL;
}

static unsigned char *
get_attribute_value(struct tree_node *node, unsigned char *name)
{
	struct attributes *attribute;

	foreach (attribute, node->attrs) {
		if (!strcmp(attribute->name, name)) {
			return attribute->value;
		}
	}

	return NULL;
}

static struct tree_node *
new_node(struct tree_node *parent)
{
	struct tree_node *node;

	node = mem_calloc(1, sizeof(*node));
	if (!node) return NULL;

	node->parent = parent ? parent : node;
	init_list(node->attrs);

	return node;
}

static void
free_node(struct tree_node *node)
{
	struct attributes *attribute;

	foreach (attribute, node->attrs) {
		/* on_element_open() ensures ->name and ->value aren't NULL. */
		mem_free(attribute->name);
		mem_free(attribute->value);
	}
	free_list(node->attrs); /* Don't free list during traversal */

	mem_free_if(node->name);
	mem_free_if(node->text);

	mem_free(node);
}

/* Read and write functions for the XBEL backend */
struct bookmarks_backend xbel_bookmarks_backend = {
	filename_bookmarks_xbel,
	read_bookmarks_xbel,
	write_bookmarks_xbel,
};
