// X Window System-specific code
// Copyright (c) 2004 Jan Wassenberg
//
// This program 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; either version 2 of the
// License, or (at your option) any later version.
//
// This program 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.
//
// Contact info:
//   Jan.Wassenberg@stud.uni-karlsruhe.de
//   http://www.stud.uni-karlsruhe.de/~urkt/

#include "precompiled.h"

#ifdef HAVE_X

#include <Xlib.h>
#include <stdlib.h>
#include <Xatom.h>

#include "lib/lib.h"
#include "lib/debug.h"
#include "lib/sysdep/gfx.h"
#include "SDL/SDL.h"
#include "SDL/SDL_syswm.h"

#include <algorithm>

static Display *SDL_Display;
static Window SDL_Window;
static void (*Lock_Display)(void);
static void (*Unlock_Display)(void);
static wchar_t *selection_data=NULL;
static size_t selection_size=0;

// useful for choosing a video mode. not called by detect().
// if we fail, outputs are unchanged (assumed initialized to defaults)
LibError gfx_get_video_mode(int* xres, int* yres, int* bpp, int* freq)
{
	Display* disp = XOpenDisplay(0);
	if(!disp)
		WARN_RETURN(ERR::FAIL);

	int screen = XDefaultScreen(disp);
	
	/* 2004-07-13
	NOTE: The XDisplayWidth/Height functions don't actually return the current
	display mode - they return the size of the root window. This means that
	users with "Virtual Desktops" bigger than what their monitors/graphics
	card can handle will have to set their 0AD screen resolution manually.
	
	There's supposed to be an X extension that can give you the actual display
	mode, probably including refresh rate info etc, but it's not worth
	researching and implementing that at this stage.
	*/
	
	if(xres)
		*xres = XDisplayWidth (disp, screen);
	if(yres)
		*yres = XDisplayHeight(disp, screen);
	if(bpp)
		*bpp = XDefaultDepth(disp, screen);
	if(freq)
		*freq = 0;
	XCloseDisplay(disp);
	return INFO::OK;
}


// useful for determining aspect ratio. not called by detect().
// if we fail, outputs are unchanged (assumed initialized to defaults)
LibError gfx_get_monitor_size(int& width_mm, int& height_mm)
{
	Display* disp = XOpenDisplay(0);
	if(!disp)
		WARN_RETURN(ERR::FAIL);

	int screen = XDefaultScreen(disp);
	
	width_mm=XDisplayWidthMM(disp, screen);
	height_mm=XDisplayHeightMM(disp, screen);
	
	XCloseDisplay(disp);
	return INFO::OK;
}

/*
Oh, boy, this is heavy stuff...

<User-End Stuff - Definitions and Conventions>
http://www.freedesktop.org/standards/clipboards-spec/clipboards.txt
<Technical, API stuff>
http://www.mail-archive.com/xfree86@xfree86.org/msg15594.html
http://michael.toren.net/mirrors/doc/X-copy+paste.txt
http://devdocs.wesnoth.org/clipboard_8cpp-source.html
http://tronche.com/gui/x/xlib/window-information/XGetWindowProperty.html
http://www.jwz.org/doc/x-cut-and-paste.html

The basic run-down on X Selection Handling:
* One window owns the "current selection" at any one time
* Accessing the Selection (i.e. "paste"), Step-by-step
	* Ask the X server for the current selection owner
	* Ask the selection owner window to convert the selection into a format
	we can understand (XA_STRING - Latin-1 string - for now)
	* The converted result is stored as a property of the *selection owner*
	window. It is possible to specify the current application window as the
	target - but that'd require some X message handling... easier to skip that..
	* The final step is to acquire the property value of the selection owner
	window

Notes:
An "Atom" is a server-side object that represents a string by an index into some
kind of table or something. Pretty much like a handle that refers to one unique
string. Atoms are used here to refer to property names and value formats.

Expansions:
* Implement UTF-8 format support (should be interresting for international users)

*/
wchar_t *sys_clipboard_get()
{
	Display *disp=XOpenDisplay(NULL);
	if (!disp)
		return NULL;

	// We use CLIPBOARD as the default, since the CLIPBOARD semantics are much
	// closer to windows semantics.
	Atom selSource=XInternAtom(disp, "CLIPBOARD", False);

	Window selOwner=XGetSelectionOwner(disp, selSource);
	if (selOwner == None)
	{
		// However, since many apps don't use CLIPBOARD, but use PRIMARY instead
		// we use XA_PRIMARY as a fallback clipboard. This is true for xterm,
		// for example.
		selSource=XA_PRIMARY;
		selOwner=XGetSelectionOwner(disp, selSource);
	}
	if (selOwner != None) {
		Atom pty=XInternAtom(disp, "SelectionPropertyTemp", False);
		XConvertSelection(disp, selSource, XA_STRING, pty, selOwner, CurrentTime);
		XFlush(disp);
		
		Atom type;
		int format=0, result=0;
		unsigned long len=0, bytes_left=0, dummy=0;
		unsigned char *data=NULL;
		
		// Get the length of the property and some attributes
		// bytes_left will contain the length of the selection
		result = XGetWindowProperty (disp, selOwner, pty,
			0, 0,			// offset - len
			0,				// Delete 0==FALSE
			AnyPropertyType,//flag
			&type,			// return type
			&format,		// return format
			&len, &bytes_left,
			&data);
		if (result != Success)
			debug_printf("clipboard_get: result: %d type:%d len:%d format:%d bytes_left:%d\n", 
				result, (int)type, len, format, bytes_left);
		if (result == Success && bytes_left > 0)
		{
			result = XGetWindowProperty (disp, selOwner, 
				pty, 0, bytes_left, 0,
				AnyPropertyType, &type, &format,
				&len, &dummy, &data);
			
			if (result == Success)
			{
				debug_printf("clipboard_get: XGetWindowProperty succeeded, returning data\n");
				debug_printf("clipboard_get: data was: \"%s\", type was %d, XA_STRING atom is %d\n", data, type, XA_STRING);
				
				if (type == XA_STRING) //Latin-1: Just copy into low byte of wchar_t
				{
					wchar_t *ret=(wchar_t *)malloc((bytes_left+1)*sizeof(wchar_t));
					std::copy(data, data+bytes_left, ret);
					ret[bytes_left]=0;
					return ret;
				}
				// TODO: Handle UTF8 strings
			}
			else
			{
				debug_printf("clipboard_get: XGetWindowProperty failed!\n");
				return NULL;
			}
		}
	}
	
	return NULL;
}

LibError sys_clipboard_free(wchar_t *clip_buf)
{
	free(clip_buf);
	return INFO::OK;
}

/**
 * An SDL Event filter that intercepts other applications' requests for the
 * X selection buffer.
 *
 * @see x11_clipboard_init
 * @see sys_clipboard_set
 */
int clipboard_filter(const SDL_Event *event)
{
	/* Pass on all non-window manager specific events immediately */
	/* And do nothing if we don't actually have a clip-out to send out */
	if (event->type != SDL_SYSWMEVENT || !selection_data)
		return 1;

	/* Handle window-manager specific clipboard events */
	/* (Note: libsdl must be compiled with X11 support (SDL_VIDEO_DRIVER_X11 in SDL_config.h) -
	   else you'll get errors like "'struct SDL_SysWMmsg' has no member named 'xevent'") */
	switch (event->syswm.msg->event.xevent.type) {
		/* Copy the selection from our buffer to the requested property, and
		convert to the requested target format */
		case SelectionRequest: {
			XSelectionRequestEvent *req;
			XEvent sevent;

			req = &event->syswm.msg->event.xevent.xselectionrequest;
			sevent.xselection.type = SelectionNotify;
			sevent.xselection.display = req->display;
			sevent.xselection.selection = req->selection;
			sevent.xselection.target = req->target;
			sevent.xselection.property = None;
			sevent.xselection.requestor = req->requestor;
			sevent.xselection.time = req->time;
			// Simply strip all non-Latin1 characters and replace with '?'
			// We should support XA_UTF8
			if (req->target == XA_STRING)
			{
				size_t size = wcslen(selection_data);
				u8 *buf = (u8 *)alloca(size);
				
				for (size_t i=0;i<size;i++)
				{
					buf[i] = selection_data[i]<0x100?selection_data[i]:'?';
				}
			
				XChangeProperty(SDL_Display, req->requestor, req->property,
            		sevent.xselection.target, 8, PropModeReplace,
					buf, size);
				sevent.xselection.property = req->property;
			}
			// TODO Add more target formats
			XSendEvent(SDL_Display,req->requestor,False,0,&sevent);
			XSync(SDL_Display, False);
		}
		break;
	}

	return 1;
}

/**
 * Initialization for X clipboard handling, called on-demand by
 * sys_clipboard_set.
 */
LibError x11_clipboard_init()
{
	SDL_SysWMinfo info;

	SDL_VERSION(&info.version);
	if ( SDL_GetWMInfo(&info) )
	{
		/* Save the information for later use */
		if ( info.subsystem == SDL_SYSWM_X11 )
		{
			SDL_Display = info.info.x11.display;
			SDL_Window = info.info.x11.window;
			Lock_Display = info.info.x11.lock_func;
			Unlock_Display = info.info.x11.unlock_func;

			/* Enable the special window hook events */
			SDL_EventState(SDL_SYSWMEVENT, SDL_ENABLE);
			SDL_SetEventFilter(clipboard_filter);

			return INFO::OK;
		}
		else
		{
			return ERR::FAIL;
		}
	}

	return INFO::OK;
}

/**
 * Set the Selection (i.e. "copy")
 *
 * Step-by-step (X11)
 * <ul>
 * <li>Store the selection text in a local buffer
 * <li>Tell the X server that we want to own the selection
 * <li>Listen for Selection events and respond to them as appropriate
 * </ul>
 */
LibError sys_clipboard_set(const wchar_t *str)
{
	ONCE(x11_clipboard_init());

	debug_printf("sys_clipboard_set: %ls\n", str);

	if (selection_data)
	{
		free(selection_data);
		selection_data = NULL;
	}
	
	selection_size = (wcslen(str)+1)*sizeof(wchar_t);
	selection_data = (wchar_t *)malloc(selection_size);
	wcscpy(selection_data, str);

	Lock_Display();
	// Like for the clipboard_get code above, we rather use CLIPBOARD than
	// PRIMARY - more windows'y behaviour there.
	Atom clipboard_atom = XInternAtom(SDL_Display, "CLIPBOARD", False);
	XSetSelectionOwner(SDL_Display, clipboard_atom, SDL_Window, CurrentTime);
	XSetSelectionOwner(SDL_Display, XA_PRIMARY, SDL_Window, CurrentTime);
	Unlock_Display();
	
	return INFO::OK;
}

#endif	// #ifdef HAVE_X