/*
 * Font lookup and rendering functions
 *
 * Copyright (C) 2019  Patrick McDermott
 *
 * This file is part of fbcon2png.
 *
 * fbcon2png 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.
 *
 * fbcon2png 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 fbcon2png.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "font.h"

#include <limits.h>
#include <string.h>

#include <png.h>

#include <linux/font.h>
#include "image.h"

#define BIT_TO_BYTE(i)    ((i) / CHAR_BIT)
#define BITS_TO_BYTES(i)  BIT_TO_BYTE((i) + CHAR_BIT - 1)
#define BIT_BYTE_SHIFT(i) (CHAR_BIT - 1 - ((i) % CHAR_BIT))
#define FONT_H(f)         ((size_t) (f)->desc.height)
#define FONT_W(f)         ((size_t) (f)->desc.width)
#define FONT_W_BYTES(f)   BITS_TO_BYTES(FONT_W(f))

struct font {
	const struct font_desc desc;
};

static const struct font_desc *fonts[] = {
	&font_mplus_1mn_medium_10x14,
	&font_mplus_1mn_regular_12x17,
	&font_mplus_1mn_regular_14x19,
	&font_mplus_1mn_regular_16x22,
};

struct font *
font_find(const char *name)
{
	size_t i;

	if (!name) {
		return (struct font *) fonts[0];
	}

	for (i = 0; i < *(&fonts + 1) - fonts; ++i) {
		if (strcmp(fonts[i]->name, name) == 0) {
			return (struct font *) fonts[i];
		}
	}
	return (struct font *) fonts[0];
}

int
font_get_width(struct font *font)
{
	return font->desc.width;
}

int
font_get_height(struct font *font)
{
	return font->desc.height;
}

void
font_render(struct font *font, png_const_colorp fg, png_const_colorp bg,
		char ch, png_bytepp rows, int row, int col)
{
	size_t        y;
	size_t        r;
	size_t        x;
	size_t        c;
	size_t        byte;
	unsigned char font_ch;

	for (y = 0, r = row * FONT_H(font); y < FONT_H(font); ++y, ++r) {
		for (x = 0, c = col * FONT_W(font); x < FONT_W(font); ++x, ++c){
			byte = ((ch * FONT_H(font)) + y) * FONT_W_BYTES(font) +
				BIT_TO_BYTE(x);
			font_ch = font->desc.data[byte];
			if ((font_ch >> (BIT_BYTE_SHIFT(x))) & 0x01) {
				rows[r][c * IMAGE_PIXEL_SIZE + 0] = fg->red;
				rows[r][c * IMAGE_PIXEL_SIZE + 1] = fg->green;
				rows[r][c * IMAGE_PIXEL_SIZE + 2] = fg->blue;
			} else {
				rows[r][c * IMAGE_PIXEL_SIZE + 0] = bg->red;
				rows[r][c * IMAGE_PIXEL_SIZE + 1] = bg->green;
				rows[r][c * IMAGE_PIXEL_SIZE + 2] = bg->blue;
			}
		}
	}
}