/*
 * Copyright (c) 2019 - 2022 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 "vec.h"
#include "neatvnc.h"
#include "pixels.h"
#include "fb.h"
#include "enc-util.h"
#include "encoder.h"
#include "rcbuf.h"

#include <stdint.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>
#include <pixman.h>
#include <zlib.h>
#include <aml.h>

#define TILE_LENGTH 64

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

struct encoder* zrle_encoder_new(void);

struct zrle_encoder {
	struct encoder encoder;

	struct rfb_pixel_format output_format;

	struct nvnc_fb* current_fb;
	struct pixman_region16 current_damage;

	struct rcbuf *current_result;

	z_stream zs;

	struct aml_work* work;
};

struct encoder_impl encoder_impl_zrle;

static inline struct zrle_encoder* zrle_encoder(struct encoder* encoder)
{
	assert(encoder->impl == &encoder_impl_zrle);
	return (struct zrle_encoder*)encoder;
}

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;
}

static 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;
}

static 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 = calc_bytes_per_cpixel(dst_fmt);

	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;
}

static 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);
}

static 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 = calc_bytes_per_cpixel(dst_fmt);

	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);
	}
}

static 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);
}

static 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 = calc_bytes_per_cpixel(dst_fmt);

	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;
}

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

		int r = deflate(zs, flush ? Z_SYNC_FLUSH : Z_NO_FLUSH);
		if (r == Z_STREAM_ERROR)
			return -1;

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

	assert(zs->avail_in == 0);

	return 0;
}

static int zrle_encode_box(struct zrle_encoder* self, struct vec* out,
                           const struct rfb_pixel_format* dst_fmt,
                           const struct nvnc_fb* fb,
                           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 = calc_bytes_per_cpixel(dst_fmt);
	struct vec in;

	uint16_t x_pos = self->encoder.x_pos;
	uint16_t y_pos = self->encoder.y_pos;

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

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

	r = encode_rect_head(out, RFB_ENCODING_ZRLE, x_pos + x, y_pos + y,
			width, height);
	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, TILE_LENGTH) * UDIV_UP(height, TILE_LENGTH);

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

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

		int y_off = y + tile_y;

		zrle_copy_tile(tile,
		               ((uint32_t*)fb->addr) + x + tile_x + y_off * 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
}

static int zrle_encode_frame(struct zrle_encoder* self, z_stream* zs,
		struct vec* dst, const struct rfb_pixel_format* dst_fmt,
		struct nvnc_fb* src, const struct rfb_pixel_format* src_fmt,
		struct pixman_region16* region)
{
	int rc = -1;

	self->encoder.n_rects = 0;

	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;
	}

	rc = nvnc_fb_map(src);
	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(self, dst, dst_fmt, src, src_fmt, x, y,
		                     src->stride, box_width, box_height, zs);
		if (rc < 0)
			return -1;
	}

	self->encoder.n_rects = n_rects;
	return 0;
}

static void zrle_encoder_do_work(void* obj)
{
	struct zrle_encoder* self = aml_get_userdata(obj);
	int rc;

	struct nvnc_fb* fb = self->current_fb;
	assert(fb);

	// TODO: Calculate the ideal buffer size based on the size of the
	// damaged area.
	size_t buffer_size = nvnc_fb_get_stride(fb) * nvnc_fb_get_height(fb) *
		nvnc_fb_get_pixel_size(fb);

	struct vec dst;
	rc = vec_init(&dst, buffer_size);
	assert(rc == 0);

	struct rfb_pixel_format src_fmt;
	rc = rfb_pixfmt_from_fourcc(&src_fmt, nvnc_fb_get_fourcc_format(fb));
	assert(rc == 0);

	rc = zrle_encode_frame(self, &self->zs, &dst, &self->output_format, fb,
			&src_fmt, &self->current_damage);
	assert(rc == 0);

	self->current_result = rcbuf_new(dst.data, dst.len);
	assert(self->current_result);
}

static void zrle_encoder_on_done(void* obj)
{
	struct zrle_encoder* self = aml_get_userdata(obj);

	assert(self->current_result);

	uint64_t pts = nvnc_fb_get_pts(self->current_fb);
	nvnc_fb_unref(self->current_fb);
	self->current_fb = NULL;

	pixman_region_clear(&self->current_damage);

	struct rcbuf* result = self->current_result;
	self->current_result = NULL;

	aml_unref(self->work);
	self->work = NULL;

	encoder_finish_frame(&self->encoder, result, pts);

	rcbuf_unref(result);
}

struct encoder* zrle_encoder_new(void)
{
	struct zrle_encoder* self = calloc(1, sizeof(*self));
	if (!self)
		return NULL;

	self->encoder.impl = &encoder_impl_zrle;

	int rc = deflateInit2(&self->zs,
			/* compression level: */ 1,
			/*            method: */ Z_DEFLATED,
			/*       window bits: */ 15,
			/*         mem level: */ 9,
			/*          strategy: */ Z_DEFAULT_STRATEGY);
	if (rc != Z_OK)
		goto deflate_failure;

	pixman_region_init(&self->current_damage);

	return (struct encoder*)self;

deflate_failure:
	free(self);
	return NULL;
}

static void zrle_encoder_destroy(struct encoder* encoder)
{
	struct zrle_encoder* self = zrle_encoder(encoder);
	pixman_region_fini(&self->current_damage);
	deflateEnd(&self->zs);
	if (self->work)
		aml_unref(self->work);
	free(self);
}

static void zrle_encoder_set_output_format(struct encoder* encoder,
		const struct rfb_pixel_format* pixfmt)
{
	struct zrle_encoder* self = zrle_encoder(encoder);
	memcpy(&self->output_format, pixfmt, sizeof(self->output_format));
}

static int zrle_encoder_encode(struct encoder* encoder, struct nvnc_fb* fb,
		struct pixman_region16* damage)
{
	struct zrle_encoder* self = zrle_encoder(encoder);

	assert(!self->current_fb);

	self->work = aml_work_new(zrle_encoder_do_work, zrle_encoder_on_done,
			self, NULL);
	if (!self->work)
		return -1;

	self->current_fb = fb;
	nvnc_fb_ref(self->current_fb);
	pixman_region_copy(&self->current_damage, damage);

	int rc = aml_start(aml_get_default(), self->work);
	if (rc < 0) {
		aml_unref(self->work);
		self->work = NULL;
		pixman_region_clear(&self->current_damage);
		nvnc_fb_unref(self->current_fb);
		self->current_fb = NULL;
	}

	return rc;
}

struct encoder_impl encoder_impl_zrle = {
	.destroy = zrle_encoder_destroy,
	.set_output_format = zrle_encoder_set_output_format,
	.encode = zrle_encoder_encode,
};
