/* See LICENSE file for copyright and license details. */
#include "common.h"

#define FORCED_FLAGS (LIBSKRIFT_NO_LIGATURES   |\
                      LIBSKRIFT_NO_AUTOHINTING |\
                      LIBSKRIFT_NO_AUTOKERNING)

#define IMPLEMENTED_FLAGS (LIBSKRIFT_CORRECT_GAMMA |\
                           LIBSKRIFT_REMOVE_GAMMA  |\
                           FORCED_FLAGS) /* libschrift does not add gamma, so not handling is required */

#define HAVE_MULTIPLE_FLAGS(HAVE, CHECK) (((HAVE) & (CHECK)) & (((HAVE) & (CHECK)) - 1))

#define COPY_ARRAY(DEST_STRUCT, SRC_STRUCT, FIELD)\
	memcpy((DEST_STRUCT).FIELD, (SRC_STRUCT).FIELD, sizeof((SRC_STRUCT).FIELD))

static const struct libskrift_rendering default_rendering = LIBSKRIFT_DEFAULT_RENDERING;

int
libskrift_create_context(LIBSKRIFT_CONTEXT **ctxp, LIBSKRIFT_FONT **fonts, size_t nfonts, double height,
                         const struct libskrift_rendering *rendering)
{
	size_t i;

	if (!nfonts) {
		errno = EINVAL;
		return -1;
	}

	if (rendering) {
		if (HAVE_MULTIPLE_FLAGS(rendering->flags, LIBSKRIFT_CORRECT_GAMMA | LIBSKRIFT_REMOVE_GAMMA) ||
		    !rendering->grid_fineness) {
			errno = EINVAL;
			return -1;
		}
	}

	*ctxp = calloc(1, offsetof(LIBSKRIFT_CONTEXT, fonts) + nfonts * sizeof(*(*ctxp)->fonts));
	if (!*ctxp)
		return -1;

	(*ctxp)->schrift_ctx.font   = fonts[0]->font;
	(*ctxp)->schrift_ctx.yScale = height;
	for (i = 0; i < nfonts; i++) {
		(*ctxp)->fonts[i] = fonts[i];
		fonts[i]->refcount += 1;
	}

	if (rendering) {
		memcpy(&(*ctxp)->rendering, rendering, sizeof(*rendering));
		COPY_ARRAY((*ctxp)->rendering, default_rendering, prestroke_transformation_rotation);
		COPY_ARRAY((*ctxp)->rendering, default_rendering, left_transformation);
		COPY_ARRAY((*ctxp)->rendering, default_rendering, right_transformation);
		COPY_ARRAY((*ctxp)->rendering, default_rendering, top_transformation);
		COPY_ARRAY((*ctxp)->rendering, default_rendering, bottom_transformation);
		COPY_ARRAY((*ctxp)->rendering, default_rendering, poststroke_transformation_rotation);
		COPY_ARRAY((*ctxp)->rendering, default_rendering, char_transformation);
		COPY_ARRAY((*ctxp)->rendering, default_rendering, text_transformation);
	} else {
		memcpy(&(*ctxp)->rendering, &default_rendering, sizeof(default_rendering));
	}

	(*ctxp)->rendering.struct_version      = LIBSKRIFT_RENDERING_STRUCT_VERSION;
	(*ctxp)->rendering.hinting             = LIBSKRIFT_NONE;
	(*ctxp)->rendering.flags              &= IMPLEMENTED_FLAGS;
	(*ctxp)->rendering.flags              |= FORCED_FLAGS;
	(*ctxp)->rendering.grid_fineness       = 1;
	(*ctxp)->rendering.kerning             = 0;
	(*ctxp)->rendering.interletter_spacing = 0;

	if (!(*ctxp)->rendering.smoothing)
		(*ctxp)->rendering.smoothing = LIBSKRIFT_GREYSCALE;

	(*ctxp)->schrift_ctx.xScale = (*ctxp)->schrift_ctx.yScale;
	(*ctxp)->schrift_ctx.xScale *= (*ctxp)->rendering.horizontal_dpi / (*ctxp)->rendering.vertical_dpi;

	if ((*ctxp)->rendering.smoothing == LIBSKRIFT_SUBPIXEL) {
		if ((*ctxp)->rendering.subpixel_order == LIBSKRIFT_RGB) {
			(*ctxp)->schrift_ctx.xScale   *= 3;
			(*ctxp)->subpixel_horizontally = 1;
		} else if ((*ctxp)->rendering.subpixel_order == LIBSKRIFT_BGR) {
			(*ctxp)->schrift_ctx.xScale   *= 3;
			(*ctxp)->subpixel_horizontally = 1;
			(*ctxp)->subpixel_bgr          = 1;
		} else if ((*ctxp)->rendering.subpixel_order == LIBSKRIFT_VRGB) {
			(*ctxp)->schrift_ctx.yScale   *= 3;
			(*ctxp)->subpixel_vertically   = 1;
		} else if ((*ctxp)->rendering.subpixel_order == LIBSKRIFT_VBGR) {
			(*ctxp)->schrift_ctx.yScale   *= 3;
			(*ctxp)->subpixel_vertically   = 1;
			(*ctxp)->subpixel_bgr          = 1;
		} else {
			(*ctxp)->rendering.subpixel_order = LIBSKRIFT_NONE;
			(*ctxp)->rendering.smoothing = LIBSKRIFT_GREYSCALE;
		}
	}

	return 0;
}