/*
 * Copyright (c) 2019 Andri Yngvason
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

#include "rfb-proto.h"
#include "util.h"
#include "vec.h"
#include "zrle.h"
#include "miniz.h"

#include <stdint.h>
#include <unistd.h>
#include <stdlib.h>
#include <endian.h>
#include <stdbool.h>
#include <assert.h>
#include <uv.h>
#include <pixman.h>

#define POPCOUNT(x) __builtin_popcount(x)   
#define UDIV_UP(a, b) (((a) + (b) - 1) / (b))

void pixel_format_into_native(struct rfb_pixel_format *fmt)
{
#if __BYTE_ORDER__ == __LITTLE_ENDIAN__
	if (!fmt->big_endian_flag)
		return;

	fmt->big_endian_flag = 0;
#else
	if (fmt->big_endian_flag)
		return;

	fmt->big_endian_flag = 1;
#endif

	fmt->red_shift = fmt->bits_per_pixel - fmt->red_shift;
	fmt->green_shift = fmt->bits_per_pixel - fmt->green_shift;
	fmt->blue_shift = fmt->bits_per_pixel - fmt->blue_shift;
}

void pixel32_to_cpixel(uint8_t *restrict dst,
		       const struct rfb_pixel_format* dst_fmt,
		       const uint32_t *restrict src,
		       const struct rfb_pixel_format* src_fmt,
		       size_t bytes_per_cpixel, size_t len)
{
	assert(src_fmt->true_colour_flag);
	assert(src_fmt->bits_per_pixel == 32);
	assert(src_fmt->depth <= 32);
	assert(dst_fmt->true_colour_flag);
	assert(dst_fmt->bits_per_pixel <= 32);
	assert(dst_fmt->depth <= 24);
	assert(bytes_per_cpixel <= 3 && bytes_per_cpixel >= 1);

	uint32_t src_red_shift = src_fmt->red_shift;
	uint32_t src_green_shift = src_fmt->green_shift;
	uint32_t src_blue_shift = src_fmt->blue_shift;

	uint32_t dst_red_shift = dst_fmt->red_shift;
	uint32_t dst_green_shift = dst_fmt->green_shift;
	uint32_t dst_blue_shift = dst_fmt->blue_shift;

	uint32_t src_red_max = src_fmt->red_max;
	uint32_t src_green_max = src_fmt->green_max;
	uint32_t src_blue_max = src_fmt->blue_max;

	uint32_t dst_red_max = dst_fmt->red_max;
	uint32_t dst_green_max = dst_fmt->green_max;
	uint32_t dst_blue_max = dst_fmt->blue_max;

	uint32_t src_red_bits = POPCOUNT(src_fmt->red_max);
	uint32_t src_green_bits = POPCOUNT(src_fmt->green_max);
	uint32_t src_blue_bits = POPCOUNT(src_fmt->blue_max);

	uint32_t dst_red_bits = POPCOUNT(dst_fmt->red_max);
	uint32_t dst_green_bits = POPCOUNT(dst_fmt->green_max);
	uint32_t dst_blue_bits = POPCOUNT(dst_fmt->blue_max);

	uint32_t dst_endian_correction;

#define CONVERT_PIXELS(cpx, px) \
	{ \
		uint32_t r, g, b; \
		r = ((px >> src_red_shift) & src_red_max) << dst_red_bits \
			>> src_red_bits << dst_red_shift; \
		g = ((px >> src_green_shift) & src_green_max) << dst_green_bits \
			>> src_green_bits << dst_green_shift; \
		b = ((px >> src_blue_shift) & src_blue_max) << dst_blue_bits \
			>> src_blue_bits << dst_blue_shift; \
		cpx = r | g | b; \
	}

	switch (bytes_per_cpixel) {
	case 3:
		if (dst_fmt->bits_per_pixel == 32 && dst_fmt->depth <= 24) {
			uint32_t min_dst_shift = dst_red_shift;
			if (min_dst_shift > dst_green_shift)
				min_dst_shift = dst_green_shift;
			if (min_dst_shift > dst_blue_shift)
				min_dst_shift = dst_blue_shift;

			dst_red_shift -= min_dst_shift;
			dst_green_shift -= min_dst_shift;
			dst_blue_shift -= min_dst_shift;
		}

		dst_endian_correction = dst_fmt->big_endian_flag ? 16 : 0;

		while (len--) {
			uint32_t cpx, px = *src++;

			CONVERT_PIXELS(cpx, px)

			*dst++ = (cpx >> (16 ^ dst_endian_correction)) & 0xff;
			*dst++ = (cpx >> 8) & 0xff;
			*dst++ = (cpx >> (0 ^ dst_endian_correction)) & 0xff;
		}
		break;
	case 2:
		dst_endian_correction = dst_fmt->big_endian_flag ? 8 : 0;

		while (len--) {
			uint32_t cpx, px = *src++;

			CONVERT_PIXELS(cpx, px)

			*dst++ = (cpx >> (8 ^ dst_endian_correction)) & 0xff;
			*dst++ = (cpx >> (0 ^ dst_endian_correction)) & 0xff;
		}
		break;
	case 1:
		while (len--) {
			uint32_t cpx, px = *src++;

			CONVERT_PIXELS(cpx, px)

			*dst++ = cpx & 0xff;
		}
		break;
	default:
		abort();
	}

#undef CONVERT_PIXELS
}

static inline int find_colour_in_palette(uint32_t *palette, int len,
					 uint32_t colour)
{
	for (int i = 0; i < len; ++i)
		if (palette[i] == colour)
			return i;

	return -1;
}

int zrle_get_tile_palette(uint32_t *palette, const uint32_t *src, size_t length)
{
	int n = 0;

	/* TODO: Maybe ignore the alpha channel */
	palette[n++] = src[0];

	for (size_t i = 0; i < length; ++i) {
		uint32_t colour = src[i];

		if (find_colour_in_palette(palette, n, colour) < 0) {
			if (n >= 16)
				return -1;

			palette[n++] = colour;
		}
	}

	return n;
}

void zrle_encode_unichrome_tile(struct vec *dst,
				const struct rfb_pixel_format *dst_fmt,
				uint32_t colour,
				const struct rfb_pixel_format *src_fmt)
{
	int bytes_per_cpixel = dst_fmt->depth / 8;

	vec_fast_append_8(dst, 1);

	pixel32_to_cpixel(((uint8_t*)dst->data) + 1, dst_fmt, &colour, src_fmt,
			  bytes_per_cpixel, 1);

	dst->len += bytes_per_cpixel;
}

void encode_run_length(struct vec *dst, uint8_t index, int run_length)
{
	if (run_length == 1) {
		vec_fast_append_8(dst, index);
		return;
	}

	vec_fast_append_8(dst, index | 128);

	while (run_length > 255) {
		vec_fast_append_8(dst, 255);
		run_length -= 255;
	}

	vec_fast_append_8(dst, run_length - 1);
}

void zrle_encode_packed_tile(struct vec *dst,
			     const struct rfb_pixel_format *dst_fmt,
			     const uint32_t *src,
			     const struct rfb_pixel_format *src_fmt,
			     size_t length,
			     uint32_t *palette, int palette_size)
{
	int bytes_per_cpixel = dst_fmt->depth / 8;

	uint8_t cpalette[16 * 3];
	pixel32_to_cpixel((uint8_t*)cpalette, dst_fmt, palette,
			  src_fmt, bytes_per_cpixel, palette_size);

	vec_fast_append_8(dst, 128 | palette_size);

	vec_append(dst, cpalette, palette_size * bytes_per_cpixel);

	int index;
	int run_length = 1;

	for (size_t i = 1; i < length; ++i) {
		if (src[i] == src[i - 1]) {
			run_length++;
			continue;
		}

		index = find_colour_in_palette(palette, palette_size,
					       src[i - 1]);
		encode_run_length(dst, index, run_length);
		run_length = 1;
	}

	if (run_length > 0) {
		index = find_colour_in_palette(palette, palette_size,
					       src[length - 1]);
		encode_run_length(dst, index, run_length);
	}
}

void zrle_copy_tile(uint32_t *dst, const uint32_t *src, int stride,
		    int width, int height)
{
	for (int y = 0; y < height; ++y)
		memcpy(dst + y * width, src + y * stride, width * 4);
}

void zrle_encode_tile(struct vec *dst, const struct rfb_pixel_format *dst_fmt,
		      const uint32_t *src,
		      const struct rfb_pixel_format *src_fmt,
		      size_t length)
{
	int bytes_per_cpixel = dst_fmt->depth / 8;

	vec_clear(dst);

	uint32_t palette[16];
	int palette_size = zrle_get_tile_palette(palette, src, length);

	if (palette_size == 1) {
		zrle_encode_unichrome_tile(dst, dst_fmt, palette[0], src_fmt);
		return;
	}

	if (palette_size > 1) {
		zrle_encode_packed_tile(dst, dst_fmt, src, src_fmt, length,
					palette, palette_size);
		return;
	}

	vec_fast_append_8(dst, 0);

	pixel32_to_cpixel(((uint8_t*)dst->data) + 1, dst_fmt, src, src_fmt,
			  bytes_per_cpixel, length);

	dst->len += bytes_per_cpixel * length;
}

int zrle_deflate(struct vec* dst, const struct vec* src, z_stream* zs,
		 bool flush)
{
	int r = Z_STREAM_ERROR;

	zs->next_in = src->data;
	zs->avail_in = src->len;

	do {
		if (dst->len == dst->cap && vec_reserve(dst, dst->cap * 2) < 0)
			return -1;

		zs->next_out = ((Bytef*)dst->data) + dst->len;
		zs->avail_out = dst->cap - dst->len;

		r = deflate(zs, flush ? Z_SYNC_FLUSH : Z_NO_FLUSH);
		assert(r != Z_STREAM_ERROR);

		dst->len = zs->next_out - (Bytef*)dst->data;
	} while (zs->avail_out == 0);

	assert(zs->avail_in == 0);

	return 0;
}

int zrle_encode_box(struct vec* out, const struct rfb_pixel_format *dst_fmt,
		    const uint8_t *src, const struct rfb_pixel_format *src_fmt,
		    int x, int y, int stride, int width, int height,
		    z_stream* zs)
{
	int r = -1;
	int bytes_per_cpixel = dst_fmt->depth / 8;
	int chunk_size = 1 + bytes_per_cpixel * 64 * 64;
	struct vec in;

	uint32_t *tile = malloc(64 * 64 * 4);
	if (!tile)
		goto failure;

	if (vec_init(&in, 1 + bytes_per_cpixel * 64 * 64) < 0)
		goto failure;

	struct rfb_server_fb_rect rect = {
		.encoding = htonl(RFB_ENCODING_ZRLE),
		.x = htons(x),
		.y = htons(y),
		.width = htons(width),
		.height = htons(height),
	};

	r = vec_append(out, &rect, sizeof(rect));
	if (r < 0)
		goto failure;

	/* Reserve space for size */
	size_t size_index = out->len;
	vec_append_zero(out, 4);

	int n_tiles = UDIV_UP(width, 64) * UDIV_UP(height, 64);

	for (int i = 0; i < n_tiles; ++i) {
		int tile_x = (i % UDIV_UP(width, 64)) * 64;
		int tile_y = (i / UDIV_UP(width, 64)) * 64;

		int tile_width = width - tile_x >= 64 ? 64 : width - tile_x;
		int tile_height = height - tile_y >= 64 ? 64 : height - tile_y;

		zrle_copy_tile(tile,
			       ((uint32_t*)src) + x + tile_x + (y + tile_y) * stride,
			       stride, tile_width, tile_height);

		zrle_encode_tile(&in, dst_fmt, tile, src_fmt,
				 tile_width * tile_height);

		r = zrle_deflate(out, &in, zs, i == n_tiles - 1);
		if (r < 0)
			goto failure;
	}

	uint32_t out_size = htonl(out->len - size_index - 4);
	memcpy(((uint8_t*)out->data) + size_index, &out_size, sizeof(out_size));

failure:
	vec_destroy(&in);
	free(tile);
	return r;
#undef CHUNK
}

int zrle_encode_frame(z_stream *zs,
		      struct vec* dst,
		      const struct rfb_pixel_format *dst_fmt,
		      const uint8_t *src,
		      const struct rfb_pixel_format *src_fmt,
		      int width, int height,
		      struct pixman_region16 *region)
{
	int rc = -1;

	int n_rects = 0;
	struct pixman_box16 *box = pixman_region_rectangles(region, &n_rects);
	if (n_rects > UINT16_MAX) {
		box = pixman_region_extents(region);
		n_rects = 1;
	}

	struct rfb_server_fb_update_msg head = {
		.type = RFB_SERVER_TO_CLIENT_FRAMEBUFFER_UPDATE,
		.n_rects = htons(n_rects),
	};

	rc = vec_append(dst, &head, sizeof(head));
	if (rc < 0)
		return -1;

	for (int i = 0; i < n_rects; ++i) {
		int x = box[i].x1;
		int y = box[i].y1;
		int box_width = box[i].x2 - x;
		int box_height = box[i].y2 - y;

		rc = zrle_encode_box(dst, dst_fmt, src, src_fmt, x, y,
				     width, box_width, box_height, zs);
		if (rc < 0)
			return -1;
	}

	return 0;
}