/* context.c - X context management
 *
 * Raster graphics library
 *
 * Copyright (c) 1997-2003 Alfredo K. Kojima
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library 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
 *  Library General Public License for more details.
 *
 *  You should have received a copy of the GNU Library General Public
 *  License along with this library; if not, write to the Free
 *  Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
 *  MA 02110-1301, USA.
 */

#include <config.h>

#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xatom.h>
#include <X11/Xmu/StdCmap.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

#include <math.h>

#include "wraster.h"
#include "scale.h"


static Bool bestContext(Display * dpy, int screen_number, RContext * context);

static const RContextAttributes DEFAULT_CONTEXT_ATTRIBS = {
	RC_UseSharedMemory | RC_RenderMode | RC_ColorsPerChannel,	/* flags */
	RDitheredRendering,	/* render_mode */
	4,			/* colors_per_channel */
	0,
	0,
	0,
	0,
	True,			/* use_shared_memory */
	RMitchellFilter,
	RUseStdColormap
};

/*
 *
 * Colormap allocation for PseudoColor visuals:
 *
 *
 * switch standardColormap:
 * 	none:
 * 		allocate colors according to colors_per_channel
 *
 * 	best/default:
 * 		if there's a std colormap defined then use it
 *
 * 		else
 * 			create a std colormap and set it
 */

/*
 *----------------------------------------------------------------------
 * allocateStandardPseudoColor
 * 	Creates the internal colormap for PseudoColor, setting the
 * color values according to the supplied standard colormap.
 *
 * Returns: -
 *
 * Side effects: -
 *
 * Notes: -
 *----------------------------------------------------------------------
 */
static Bool allocateStandardPseudoColor(RContext * ctx, XStandardColormap * stdcmap)
{
	int i;

	ctx->ncolors = stdcmap->red_max * stdcmap->red_mult
	    + stdcmap->green_max * stdcmap->green_mult + stdcmap->blue_max * stdcmap->blue_mult + 1;

	if (ctx->ncolors <= 1) {
		RErrorCode = RERR_INTERNAL;
		puts("wraster: bad standard colormap");

		return False;
	}

	ctx->colors = malloc(sizeof(XColor) * ctx->ncolors);
	if (!ctx->colors) {
		RErrorCode = RERR_NOMEMORY;

		return False;
	}

	ctx->pixels = malloc(sizeof(unsigned long) * ctx->ncolors);
	if (!ctx->pixels) {

		free(ctx->colors);
		ctx->colors = NULL;

		RErrorCode = RERR_NOMEMORY;

		return False;
	}

#define calc(max,mult) (((i / stdcmap->mult) % \
    (stdcmap->max + 1)) * 65535) / stdcmap->max

	for (i = 0; i < ctx->ncolors; i++) {
		ctx->colors[i].pixel = i + stdcmap->base_pixel;
		ctx->colors[i].red = calc(red_max, red_mult);
		ctx->colors[i].green = calc(green_max, green_mult);
		ctx->colors[i].blue = calc(blue_max, blue_mult);

		ctx->pixels[i] = ctx->colors[i].pixel;
	}

#undef calc

	return True;
}

static Bool setupStandardColormap(RContext * ctx, Atom property)
{
	if (!XmuLookupStandardColormap(ctx->dpy, ctx->screen_number,
				       ctx->visual->visualid, ctx->depth, property, True, True)) {
		RErrorCode = RERR_STDCMAPFAIL;

		return False;
	}
	return True;
}

static Bool allocatePseudoColor(RContext * ctx)
{
	XColor *colors;
	XColor avcolors[256];
	int avncolors;
	int i, ncolors, r, g, b;
	int retries;
	int cpc = ctx->attribs->colors_per_channel;

	ncolors = cpc * cpc * cpc;

	if (ncolors > (1 << ctx->depth)) {
		/* reduce colormap size */
		cpc = ctx->attribs->colors_per_channel = 1 << ((int)ctx->depth / 3);
		ncolors = cpc * cpc * cpc;
	}

	assert(cpc >= 2 && ncolors <= (1 << ctx->depth));

	colors = malloc(sizeof(XColor) * ncolors);
	if (!colors) {
		RErrorCode = RERR_NOMEMORY;
		return False;
	}

	ctx->pixels = malloc(sizeof(unsigned long) * ncolors);
	if (!ctx->pixels) {
		free(colors);
		RErrorCode = RERR_NOMEMORY;
		return False;
	}

	i = 0;

	if ((ctx->attribs->flags & RC_GammaCorrection) && ctx->attribs->rgamma > 0
	    && ctx->attribs->ggamma > 0 && ctx->attribs->bgamma > 0) {
		double rg, gg, bg;
		double tmp;

		/* do gamma correction */
		rg = 1.0 / ctx->attribs->rgamma;
		gg = 1.0 / ctx->attribs->ggamma;
		bg = 1.0 / ctx->attribs->bgamma;
		for (r = 0; r < cpc; r++) {
			for (g = 0; g < cpc; g++) {
				for (b = 0; b < cpc; b++) {
					colors[i].red = (r * 0xffff) / (cpc - 1);
					colors[i].green = (g * 0xffff) / (cpc - 1);
					colors[i].blue = (b * 0xffff) / (cpc - 1);
					colors[i].flags = DoRed | DoGreen | DoBlue;

					tmp = (double)colors[i].red / 65536.0;
					colors[i].red = (unsigned short)(65536.0 * pow(tmp, rg));

					tmp = (double)colors[i].green / 65536.0;
					colors[i].green = (unsigned short)(65536.0 * pow(tmp, gg));

					tmp = (double)colors[i].blue / 65536.0;
					colors[i].blue = (unsigned short)(65536.0 * pow(tmp, bg));

					i++;
				}
			}
		}

	} else {
		for (r = 0; r < cpc; r++) {
			for (g = 0; g < cpc; g++) {
				for (b = 0; b < cpc; b++) {
					colors[i].red = (r * 0xffff) / (cpc - 1);
					colors[i].green = (g * 0xffff) / (cpc - 1);
					colors[i].blue = (b * 0xffff) / (cpc - 1);
					colors[i].flags = DoRed | DoGreen | DoBlue;
					i++;
				}
			}
		}
	}
	/* try to allocate the colors */
	for (i = 0; i < ncolors; i++) {
		if (!XAllocColor(ctx->dpy, ctx->cmap, &(colors[i]))) {
			colors[i].flags = 0;	/* failed */
		} else {
			colors[i].flags = DoRed | DoGreen | DoBlue;
		}
	}
	/* try to allocate close values for the colors that couldn't
	 * be allocated before */
	avncolors = (1 << ctx->depth > 256 ? 256 : 1 << ctx->depth);
	for (i = 0; i < avncolors; i++)
		avcolors[i].pixel = i;

	XQueryColors(ctx->dpy, ctx->cmap, avcolors, avncolors);

	for (i = 0; i < ncolors; i++) {
		if (colors[i].flags == 0) {
			int j;
			unsigned long cdiff = 0xffffffff, diff;
			unsigned long closest = 0;

			retries = 2;

			while (retries--) {
				/* find closest color */
				for (j = 0; j < avncolors; j++) {
					r = (colors[i].red - avcolors[i].red) >> 8;
					g = (colors[i].green - avcolors[i].green) >> 8;
					b = (colors[i].blue - avcolors[i].blue) >> 8;
					diff = r * r + g * g + b * b;
					if (diff < cdiff) {
						cdiff = diff;
						closest = j;
					}
				}
				/* allocate closest color found */
				colors[i].red = avcolors[closest].red;
				colors[i].green = avcolors[closest].green;
				colors[i].blue = avcolors[closest].blue;
				if (XAllocColor(ctx->dpy, ctx->cmap, &colors[i])) {
					colors[i].flags = DoRed | DoGreen | DoBlue;
					break;	/* succeeded, don't need to retry */
				}
#ifdef WRLIB_DEBUG
				fputs("close color allocation failed. Retrying...\n", stderr);
#endif
			}
		}
	}

	ctx->colors = colors;
	ctx->ncolors = ncolors;

	/* fill the pixels shortcut array */
	for (i = 0; i < ncolors; i++) {
		ctx->pixels[i] = ctx->colors[i].pixel;
	}

	return True;
}

static XColor *allocateGrayScale(RContext * ctx)
{
	XColor *colors;
	XColor avcolors[256];
	int avncolors;
	int i, ncolors, r, g, b;
	int retries;
	int cpc = ctx->attribs->colors_per_channel;

	ncolors = cpc * cpc * cpc;

	if (ctx->vclass == StaticGray) {
		/* we might as well use all grays */
		ncolors = 1 << ctx->depth;
	} else {
		if (ncolors > (1 << ctx->depth)) {
			/* reduce colormap size */
			cpc = ctx->attribs->colors_per_channel = 1 << ((int)ctx->depth / 3);
			ncolors = cpc * cpc * cpc;
		}

		assert(cpc >= 2 && ncolors <= (1 << ctx->depth));
	}

	if (ncolors >= 256 && ctx->vclass == StaticGray) {
		/* don't need dithering for 256 levels of gray in StaticGray visual */
		ctx->attribs->render_mode = RBestMatchRendering;
	}

	colors = malloc(sizeof(XColor) * ncolors);
	if (!colors) {
		RErrorCode = RERR_NOMEMORY;
		return False;
	}
	for (i = 0; i < ncolors; i++) {
		colors[i].red = (i * 0xffff) / (ncolors - 1);
		colors[i].green = (i * 0xffff) / (ncolors - 1);
		colors[i].blue = (i * 0xffff) / (ncolors - 1);
		colors[i].flags = DoRed | DoGreen | DoBlue;
	}
	/* try to allocate the colors */
	for (i = 0; i < ncolors; i++) {
#ifdef WRLIB_DEBUG
		fprintf(stderr, "trying:%x,%x,%x\n", colors[i].red, colors[i].green, colors[i].blue);
#endif
		if (!XAllocColor(ctx->dpy, ctx->cmap, &(colors[i]))) {
			colors[i].flags = 0;	/* failed */
#ifdef WRLIB_DEBUG
			fprintf(stderr, "failed:%x,%x,%x\n", colors[i].red, colors[i].green, colors[i].blue);
#endif
		} else {
			colors[i].flags = DoRed | DoGreen | DoBlue;
#ifdef WRLIB_DEBUG
			fprintf(stderr, "success:%x,%x,%x\n", colors[i].red, colors[i].green, colors[i].blue);
#endif
		}
	}
	/* try to allocate close values for the colors that couldn't
	 * be allocated before */
	avncolors = (1 << ctx->depth > 256 ? 256 : 1 << ctx->depth);
	for (i = 0; i < avncolors; i++)
		avcolors[i].pixel = i;

	XQueryColors(ctx->dpy, ctx->cmap, avcolors, avncolors);

	for (i = 0; i < ncolors; i++) {
		if (colors[i].flags == 0) {
			int j;
			unsigned long cdiff = 0xffffffff, diff;
			unsigned long closest = 0;

			retries = 2;

			while (retries--) {
				/* find closest color */
				for (j = 0; j < avncolors; j++) {
					r = (colors[i].red - avcolors[i].red) >> 8;
					g = (colors[i].green - avcolors[i].green) >> 8;
					b = (colors[i].blue - avcolors[i].blue) >> 8;
					diff = r * r + g * g + b * b;
					if (diff < cdiff) {
						cdiff = diff;
						closest = j;
					}
				}
				/* allocate closest color found */
#ifdef WRLIB_DEBUG
				fprintf(stderr, "best match:%x,%x,%x => %x,%x,%x\n",
					colors[i].red, colors[i].green, colors[i].blue,
					avcolors[closest].red, avcolors[closest].green, avcolors[closest].blue);
#endif
				colors[i].red = avcolors[closest].red;
				colors[i].green = avcolors[closest].green;
				colors[i].blue = avcolors[closest].blue;
				if (XAllocColor(ctx->dpy, ctx->cmap, &colors[i])) {
					colors[i].flags = DoRed | DoGreen | DoBlue;
					break;	/* succeeded, don't need to retry */
				}
#ifdef WRLIB_DEBUG
				fputs("close color allocation failed. Retrying...\n", stderr);
#endif
			}
		}
	}
	return colors;
}

static Bool setupPseudoColorColormap(RContext * context)
{
	Atom property = 0;

	if (context->attribs->standard_colormap_mode == RCreateStdColormap) {
		property = XInternAtom(context->dpy, "RGB_DEFAULT_MAP", False);

		if (!setupStandardColormap(context, property)) {
			return False;
		}
	}

	if (context->attribs->standard_colormap_mode != RIgnoreStdColormap) {
		XStandardColormap *maps;
		int count, i;

		if (!property) {
			property = XInternAtom(context->dpy, "RGB_BEST_MAP", False);
			if (!XGetRGBColormaps(context->dpy,
					      DefaultRootWindow(context->dpy), &maps, &count, property)) {
				maps = NULL;
			}

			if (!maps) {
				property = XInternAtom(context->dpy, "RGB_DEFAULT_MAP", False);
				if (!XGetRGBColormaps(context->dpy,
						      DefaultRootWindow(context->dpy), &maps, &count, property)) {
					maps = NULL;
				}
			}
		} else {
			if (!XGetRGBColormaps(context->dpy,
					      DefaultRootWindow(context->dpy), &maps, &count, property)) {
				maps = NULL;
			}
		}

		if (maps) {
			int theMap = -1;

			for (i = 0; i < count; i++) {
				if (maps[i].visualid == context->visual->visualid) {
					theMap = i;
					break;
				}
			}

			if (theMap < 0) {
				puts("wrlib: no std cmap found");
			}

			if (theMap >= 0 && allocateStandardPseudoColor(context, &maps[theMap])) {

				context->std_rgb_map = XAllocStandardColormap();

				*context->std_rgb_map = maps[theMap];

				context->cmap = context->std_rgb_map->colormap;

				XFree(maps);

				return True;
			}

			XFree(maps);
		}
	}

	context->attribs->standard_colormap_mode = RIgnoreStdColormap;

	/* RIgnoreStdColormap and fallback */
	return allocatePseudoColor(context);
}

static char *mygetenv(const char *var, int scr)
{
	char *p;
	char varname[64];

	snprintf(varname, sizeof(varname), "%s%i", var, scr);
	p = getenv(varname);
	if (!p) {
		p = getenv(var);
	}
	return p;
}

static void gatherconfig(RContext * context, int screen_n)
{
	char *ptr;

	ptr = mygetenv("WRASTER_GAMMA", screen_n);
	if (ptr) {
		float g1, g2, g3;
		if (sscanf(ptr, "%f/%f/%f", &g1, &g2, &g3) != 3 || g1 <= 0.0 || g2 <= 0.0 || g3 <= 0.0) {
			printf("wrlib: invalid value(s) for gamma correction \"%s\"\n", ptr);
		} else {
			context->attribs->flags |= RC_GammaCorrection;
			context->attribs->rgamma = g1;
			context->attribs->ggamma = g2;
			context->attribs->bgamma = g3;
		}
	}
	ptr = mygetenv("WRASTER_COLOR_RESOLUTION", screen_n);
	if (ptr) {
		int i;
		if (sscanf(ptr, "%d", &i) != 1 || i < 2 || i > 6) {
			printf("wrlib: invalid value for color resolution \"%s\"\n", ptr);
		} else {
			context->attribs->flags |= RC_ColorsPerChannel;
			context->attribs->colors_per_channel = i;
		}
	}
}

static void getColormap(RContext * context, int screen_number)
{
	Colormap cmap = None;
	XStandardColormap *cmaps;
	int ncmaps, i;

	if (XGetRGBColormaps(context->dpy,
			     RootWindow(context->dpy, screen_number), &cmaps, &ncmaps, XA_RGB_DEFAULT_MAP)) {
		for (i = 0; i < ncmaps; ++i) {
			if (cmaps[i].visualid == context->visual->visualid) {
				cmap = cmaps[i].colormap;
				break;
			}
		}
		XFree(cmaps);
	}
	if (cmap == None) {
		XColor color;

		cmap = XCreateColormap(context->dpy,
				       RootWindow(context->dpy, screen_number), context->visual, AllocNone);

		color.red = color.green = color.blue = 0;
		XAllocColor(context->dpy, cmap, &color);
		context->black = color.pixel;

		color.red = color.green = color.blue = 0xffff;
		XAllocColor(context->dpy, cmap, &color);
		context->white = color.pixel;

	}
	context->cmap = cmap;
}

static int count_offset(unsigned long mask)
{
	int i;

	i = 0;
	while ((mask & 1) == 0) {
		i++;
		mask = mask >> 1;
	}
	return i;
}

RContext *RCreateContext(Display * dpy, int screen_number, const RContextAttributes * attribs)
{
	RContext *context;
	XGCValues gcv;

	context = malloc(sizeof(RContext));
	if (!context) {
		RErrorCode = RERR_NOMEMORY;
		return NULL;
	}
	memset(context, 0, sizeof(RContext));

	context->dpy = dpy;

	context->screen_number = screen_number;

	context->attribs = malloc(sizeof(RContextAttributes));
	if (!context->attribs) {
		free(context);
		RErrorCode = RERR_NOMEMORY;
		return NULL;
	}
	if (!attribs)
		*context->attribs = DEFAULT_CONTEXT_ATTRIBS;
	else
		*context->attribs = *attribs;

	if (!(context->attribs->flags & RC_StandardColormap)) {
		context->attribs->standard_colormap_mode = RUseStdColormap;
	}

	if (!(context->attribs->flags & RC_ScalingFilter)) {
		context->attribs->flags |= RC_ScalingFilter;
		context->attribs->scaling_filter = RMitchellFilter;
	}

	/* get configuration from environment variables */
	gatherconfig(context, screen_number);
	wraster_change_filter(context->attribs->scaling_filter);
	if ((context->attribs->flags & RC_VisualID)) {
		XVisualInfo *vinfo, templ;
		int nret;

		templ.screen = screen_number;
		templ.visualid = context->attribs->visualid;
		vinfo = XGetVisualInfo(context->dpy, VisualIDMask | VisualScreenMask, &templ, &nret);
		if (!vinfo || nret == 0) {
			free(context);
			RErrorCode = RERR_BADVISUALID;
			return NULL;
		}

		if (vinfo[0].visual == DefaultVisual(dpy, screen_number)) {
			context->attribs->flags |= RC_DefaultVisual;
		} else {
			XSetWindowAttributes attr;
			unsigned long mask;

			context->visual = vinfo[0].visual;
			context->depth = vinfo[0].depth;
			context->vclass = vinfo[0].class;
			getColormap(context, screen_number);
			attr.colormap = context->cmap;
			attr.override_redirect = True;
			attr.border_pixel = 0;
			attr.background_pixel = 0;
			mask = CWBorderPixel | CWColormap | CWOverrideRedirect | CWBackPixel;
			context->drawable =
			    XCreateWindow(dpy, RootWindow(dpy, screen_number), 1, 1,
					  1, 1, 0, context->depth, CopyFromParent, context->visual, mask, &attr);
		}
		XFree(vinfo);
	}

	/* use default */
	if (!context->visual) {
		if ((context->attribs->flags & RC_DefaultVisual)
		    || !bestContext(dpy, screen_number, context)) {
			context->visual = DefaultVisual(dpy, screen_number);
			context->depth = DefaultDepth(dpy, screen_number);
			context->cmap = DefaultColormap(dpy, screen_number);
			context->drawable = RootWindow(dpy, screen_number);
			context->black = BlackPixel(dpy, screen_number);
			context->white = WhitePixel(dpy, screen_number);
			context->vclass = context->visual->class;
		}
	}

	gcv.function = GXcopy;
	gcv.graphics_exposures = False;
	context->copy_gc = XCreateGC(dpy, context->drawable, GCFunction | GCGraphicsExposures, &gcv);

	if (context->vclass == PseudoColor || context->vclass == StaticColor) {
		if (!setupPseudoColorColormap(context)) {
			free(context);
			return NULL;
		}
	} else if (context->vclass == GrayScale || context->vclass == StaticGray) {
		context->colors = allocateGrayScale(context);
		if (!context->colors) {
			free(context);
			return NULL;
		}
	} else if (context->vclass == TrueColor) {
		/* calc offsets to create a TrueColor pixel */
		context->red_offset = count_offset(context->visual->red_mask);
		context->green_offset = count_offset(context->visual->green_mask);
		context->blue_offset = count_offset(context->visual->blue_mask);
		/* disable dithering on 24 bits visuals */
		if (context->depth >= 24)
			context->attribs->render_mode = RBestMatchRendering;
	}

	/* check avaiability of MIT-SHM */
#ifdef USE_XSHM
	if (!(context->attribs->flags & RC_UseSharedMemory)) {
		context->attribs->flags |= RC_UseSharedMemory;
		context->attribs->use_shared_memory = True;
	}

	if (context->attribs->use_shared_memory) {
		int major, minor;
		Bool sharedPixmaps;

		context->flags.use_shared_pixmap = 0;

		if (!XShmQueryVersion(context->dpy, &major, &minor, &sharedPixmaps)) {
			context->attribs->use_shared_memory = False;
		} else {
			if (XShmPixmapFormat(context->dpy) == ZPixmap)
				context->flags.use_shared_pixmap = sharedPixmaps;
		}
	}
#endif

	return context;
}

void RDestroyContext(RContext *context)
{
	if (context) {
		if (context->copy_gc)
			XFreeGC(context->dpy, context->copy_gc);
		if (context->attribs) {
			if ((context->attribs->flags & RC_VisualID) &&
			    !(context->attribs->flags & RC_DefaultVisual))
				XDestroyWindow(context->dpy, context->drawable);
			free(context->attribs);
		}
		free(context);
	}
}

static Bool bestContext(Display * dpy, int screen_number, RContext * context)
{
	XVisualInfo *vinfo = NULL, rvinfo;
	int best = -1, numvis, i;
	long flags;
	XSetWindowAttributes attr;

	rvinfo.class = TrueColor;
	rvinfo.screen = screen_number;
	flags = VisualClassMask | VisualScreenMask;

	vinfo = XGetVisualInfo(dpy, flags, &rvinfo, &numvis);
	if (vinfo) {		/* look for a TrueColor, 24-bit or more (pref 24) */
		for (i = numvis - 1, best = -1; i >= 0; i--) {
			if (vinfo[i].depth == 24)
				best = i;
			else if (vinfo[i].depth > 24 && best < 0)
				best = i;
		}
	}
	if (best > -1) {
		context->visual = vinfo[best].visual;
		context->depth = vinfo[best].depth;
		context->vclass = vinfo[best].class;
		getColormap(context, screen_number);
		attr.colormap = context->cmap;
		attr.override_redirect = True;
		attr.border_pixel = 0;
		context->drawable =
		    XCreateWindow(dpy, RootWindow(dpy, screen_number),
				  1, 1, 1, 1, 0, context->depth,
				  CopyFromParent, context->visual,
				  CWBorderPixel | CWColormap | CWOverrideRedirect, &attr);
	}
	if (vinfo)
		XFree((char *)vinfo);

	if (best < 0)
		return False;
	else
		return True;
}
