/*
 * Copyright 2004, 2005 Richard Wilson <info@tinct.net>
 *
 * This file is part of NetSurf, http://www.netsurf-browser.org/
 *
 * NetSurf is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * NetSurf is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/** \file
 * Interactive help (implementation).
 */

#include <assert.h>
#include <stdbool.h>
#include <stdio.h>
#include "oslib/help.h"
#include "oslib/os.h"
#include "oslib/taskmanager.h"
#include "oslib/wimp.h"
#include "desktop/tree.h"
#include "riscos/gui.h"
#include "riscos/help.h"
#include "riscos/menus.h"
#include "riscos/options.h"
#include "riscos/theme.h"
#include "riscos/treeview.h"
#include "riscos/wimp.h"
#include "riscos/wimp_event.h"
#include "utils/messages.h"
#include "utils/log.h"
#include "utils/utf8.h"
#include "utils/utils.h"


/*	Recognised help keys
	====================
	Help keys should be registered using the wimp_event system to be
	recognised. The only special case help values are:

	HelpIconbar		Iconbar (no icon suffix is used)
	HelpBrowser		Browser window [*]
	HelpHotlist		Hotlist window [*]
	HelpGHistory		Global history window [*]
	HelpCookies		Cookies window [*]

	HelpIconMenu		Iconbar menu
	HelpBrowserMenu		Browser window menu
	HelpHotlistMenu		Hotlist window menu
	HelpGHistoryMenu	Global history window menu
	HelpCookiesMenu		Cookie window menu

	The prefixes are followed by either the icon number (eg 'HelpToolbar7'),
	or a series of numbers representing the menu structure (eg
	'HelpBrowserMenu3-1-2').
	If '<key><identifier>' is not available, then simply '<key>' is then
	used. For example if 'HelpToolbar7' is not available then 'HelpToolbar'
	is then tried.
	If an item is greyed out then a suffix of 'g' is added (eg
	'HelpToolbar7g'). For this to work, windows must have bit 4 of the
	window flag byte set and the user must be running RISC OS 5.03 or
	greater.
	For items marked with an asterisk [*] a call must be made to determine
	the required help text as the window does not contain any icons. An
	example of this is the hotlist window where ro_gui_hotlist_help() is
	called.
*/


static void ro_gui_interactive_help_broadcast(wimp_message *message,
		char *token);
static os_t help_time = 0;


/**
 * Attempts to process an interactive help message request
 *
 * \param  message the request message
 */
void ro_gui_interactive_help_request(wimp_message *message)
{
	char message_token[32];
	char menu_buffer[4];
	wimp_selection menu_tree;
	help_full_message_request *message_data;
	wimp_w window;
	wimp_i icon;
	unsigned int index;
	bool greyed = false;
	wimp_menu *test_menu;
	os_error *error;
	const char *auto_text;
	int i;
	
	/* check we aren't turned off */
	if (!option_interactive_help)
		return;

	/* only accept help requests */
	if ((!message) || (message->action != message_HELP_REQUEST))
		return;

	/* remember the time of the request so we can track them */
	xos_read_monotonic_time(&help_time);

	/* set up our state */
	message_token[0] = 0x00;
	message_data = (help_full_message_request *)message;
	window = message_data->w;
	icon = message_data->i;

	/* do the basic window checks */
	auto_text = ro_gui_wimp_event_get_help_prefix(window);
	if (auto_text)
		sprintf(message_token, "%s%i", auto_text, (int)icon);
	else if (window == wimp_ICON_BAR)
		sprintf(message_token, "HelpIconbar");
	else if ((hotlist_tree) && (window == (wimp_w)hotlist_tree->handle)) {
		i = ro_gui_tree_help(message_data->pos.x, message_data->pos.y);
		sprintf(message_token,
				(i >= 0) ? "HelpTree%i" :"HelpHotlist%i", i);
	} else if ((global_history_tree) &&
			(window == (wimp_w)global_history_tree->handle)) {
		i = ro_gui_tree_help(message_data->pos.x, message_data->pos.y);
		sprintf(message_token,
				(i >= 0) ? "HelpTree%i" :"HelpGHistory%i", i);
	} else if ((cookies_tree) &&
			(window == (wimp_w)cookies_tree->handle)) {
		i = ro_gui_tree_help(message_data->pos.x, message_data->pos.y);
		sprintf(message_token,
				(i >= 0) ? "HelpTree%i" :"HelpCookies%i", i);
	} else if (ro_gui_window_lookup(window) != NULL)
		sprintf(message_token, "HelpBrowser%i", (int)icon);

	/* if we've managed to find something so far then we broadcast it */
	if (message_token[0]) {
		if ((icon >= 0) &&
				(ro_gui_get_icon_shaded_state(window, icon)))
			strcat(message_token, "g");
		ro_gui_interactive_help_broadcast(message,
				(char *)message_token);
		return;
	}

	/* if we are not on an icon, we can't be in a menu (which stops
	 * separators giving help for their parent) so we abort */
	if (icon == wimp_ICON_WINDOW)
		return;

	/* get the current menu tree */
	error = xwimp_get_menu_state(wimp_GIVEN_WINDOW_AND_ICON,
				&menu_tree, window, icon);
	if (error) {
		LOG(("xwimp_get_menu_state: 0x%x: %s",
				error->errnum, error->errmess));
		warn_user("WimpError", error->errmess);
		return;
	}
	if (menu_tree.items[0] == -1)
		return;

	/* get the menu prefix */
	if (current_menu == iconbar_menu)
		sprintf(message_token, "HelpIconMenu");
	else if (current_menu == browser_menu)
		sprintf(message_token, "HelpBrowserMenu");
	else if (current_menu == hotlist_menu)
		sprintf(message_token, "HelpHotlistMenu");
	else if (current_menu == global_history_menu)
		sprintf(message_token, "HelpGHistoryMenu");
	else if (current_menu == cookies_menu)
		sprintf(message_token, "HelpCookiesMenu");
	else
		return;

	/* decode the menu */
	index = 0;
	test_menu = current_menu;
	while (menu_tree.items[index] != -1) {
		greyed |= test_menu->entries[menu_tree.items[index]].icon_flags
				& wimp_ICON_SHADED;
		test_menu = test_menu->entries[menu_tree.items[index]].sub_menu;
		if (index == 0)
			sprintf(menu_buffer, "%i", menu_tree.items[index]);
		else
			sprintf(menu_buffer, "-%i", menu_tree.items[index]);
		strcat(message_token, menu_buffer);
		index++;
	}
	if (greyed)
		strcat(message_token, "g");
	ro_gui_interactive_help_broadcast(message, (char *)message_token);
}


/**
 * Broadcasts a help reply
 *
 * \param  message the original request message
 * \param  token the token to look up
 */
static void ro_gui_interactive_help_broadcast(wimp_message *message,
		char *token)
{
	const char *translated_token;
	help_full_message_reply *reply;
	char *base_token;
	char *local_token;
	os_error *error;
	utf8_convert_ret err;

	/* start off with an empty reply */
	reply = (help_full_message_reply *)message;
	reply->reply[0] = '\0';

	/* check if the message exists */
	translated_token = messages_get(token);
	if (translated_token == token) {
		/* no default help for 'g' suffix */
		if (token[strlen(token) - 1] != 'g') {
			/* find the base key from the token */
			base_token = token;
			while (base_token[0] != 0x00) {
				if ((base_token[0] == '-') ||
						((base_token[0] >= '0') &&
						(base_token[0] <= '9')))
					base_token[0] = 0x00;
				else
					++base_token;
			}
			translated_token = messages_get(token);
		}
	}

	/* copy our message string */
	if (translated_token != token) {
		/* convert to local encoding */
		err = utf8_to_local_encoding(translated_token, 0,
				&local_token);
		if (err != UTF8_CONVERT_OK) {
			/* badenc should never happen */
			assert(err != UTF8_CONVERT_BADENC);
			/* simply use UTF-8 string */
			strncpy(reply->reply, translated_token, 235);
		}
		else {
			strncpy(reply->reply, local_token, 235);
			free(local_token);
		}
		reply->reply[235] = '\0';
	}

	/* broadcast the help reply */
	reply->size = 256;
	reply->action = message_HELP_REPLY;
	reply->your_ref = reply->my_ref;
	error = xwimp_send_message(wimp_USER_MESSAGE, (wimp_message *)reply,
			reply->sender);
	if (error) {
		LOG(("xwimp_send_message: 0x%x: %s",
				error->errnum, error->errmess));
		warn_user("WimpError", error->errmess);
	}
}


/**
 * Checks if interactive help is running
 *
 * \return non-zero if interactive help is available, or 0 if not available
 */
bool ro_gui_interactive_help_available(void)
{
	taskmanager_task task;
	int context = 0;
	os_t time;
	os_error *error;

	/* generic test: any help request within the last 100cs */
	xos_read_monotonic_time(&time);
	if ((help_time + 100) > time)
		return true;

	/* special cases: check known application names */
	do {
		error = xtaskmanager_enumerate_tasks(context, &task,
				sizeof(taskmanager_task), &context, 0);
		if (error) {
			LOG(("xtaskmanager_enumerate_tasks: 0x%x: %s",
					error->errnum, error->errmess));
			warn_user("MiscError", error->errmess);
		}

		/* we can't just use strcmp due to string termination issues */
		if (!strncmp(task.name, "Help", 4) &&
				(task.name[4] < 32))
			return true;
		else if (!strncmp(task.name, "Bubble Help", 11) &&
				(task.name[11] < 32))
			return true;
		else if (!strncmp(task.name, "Floating Help", 13) &&
				(task.name[13] < 32))
			return true;
	} while (context >= 0);
	return false;
}


/**
 * Launches interactive help.
 */
void ro_gui_interactive_help_start(void)
{
	char *help_start;
	wimp_t task = 0;
	os_error *error;
	
	/* don't launch a second copy of anything */
	if (ro_gui_interactive_help_available())
		return;

	/* launch <Help$Start> */
	help_start = getenv("Help$Start");
	if ((help_start) && (help_start[0])) {
		error = xwimp_start_task("<Help$Start>", &task);
		if (error) {
			LOG(("xwimp_start_tast: 0x%x: %s",
					error->errnum, error->errmess));
			warn_user("WimpError", error->errmess);
			return;
		}
	}

	/* first attempt failed, launch !Help */
	if (!task) {
		error = xwimp_start_task("Resources:$.Apps.!Help", &task);
		if (error) {
			LOG(("xwimp_start_tast: 0x%x: %s",
					error->errnum, error->errmess));
			warn_user("WimpError", error->errmess);
			return;
		}
	}

	/* pretend we got a help request straight away */
	if (task) {
		error = xos_read_monotonic_time(&help_time);
		if (error) {
			LOG(("xwimp_read_monotonic_time: 0x%x: %s",
					error->errnum, error->errmess));
			warn_user("WimpError", error->errmess);
		}
	}
}