/*
Crafter®.Graphics
Copyright (C) 2025 Catcrafts®
Catcrafts.net

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 3.0 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
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
*/

module;

#include <errno.h>
#include <fcntl.h>
#include <linux/input.h>
#include <sys/mman.h>
#include <unistd.h>
#include <wayland-cursor.h>
#include <xkbcommon/xkbcommon.h>
#include <vulkan/vulkan.h>
#include <vulkan/vulkan_wayland.h>
#include <wayland-client.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <time.h>
#include <unistd.h>
#include <string.h>
#include <print>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <unistd.h>
#include <wayland-client.h>
#include <wayland-client-protocol.h>
#include <linux/input-event-codes.h>

export module Crafter.Graphics:WindowWaylandWayland_impl;
import :WindowWaylandWayland;
import std;
import Crafter.Event;
using namespace Crafter;


static void randname(char *buf) {
	struct timespec ts;
	clock_gettime(CLOCK_REALTIME, &ts);
	long r = ts.tv_nsec;
	for (int i = 0; i < 6; ++i) {
		buf[i] = 'A'+(r&15)+(r&16)*2;
		r >>= 5;
	}
}

static int anonymous_shm_open(void) {
	char name[] = "/hello-wayland-XXXXXX";
	int retries = 100;

	do {
		randname(name + strlen(name) - 6);

		--retries;
		// shm_open guarantees that O_CLOEXEC is set
		int fd = shm_open(name, O_RDWR | O_CREAT | O_EXCL, 0600);
		if (fd >= 0) {
			shm_unlink(name);
			return fd;
		}
	} while (retries > 0 && errno == EEXIST);

	return -1;
}

int create_shm_file(off_t size) {
	int fd = anonymous_shm_open();
	if (fd < 0) {
		return fd;
	}

	if (ftruncate(fd, size) < 0) {
		close(fd);
		return -1;
	}

	return fd;
}


void ScaleBitmapR8G8B8(Pixel_BU8_GU8_RU8_AU8* dst, const Pixel_BU8_GU8_RU8_AU8* src, std::uint32_t srcWidth, std::uint32_t srcHeight, std::uint32_t dstWidth, std::uint32_t dstHeight) {
    for (std::uint32_t y = 0; y < dstHeight; y++) {
		std::uint32_t srcY = y * srcHeight / dstHeight;
        for (std::uint32_t x = 0; x < dstWidth; x++) {
            std::uint32_t srcX = x * srcWidth / dstWidth;
            const Pixel_BU8_GU8_RU8_AU8* srcPixel = src + (srcY * srcWidth + srcX);
			Pixel_BU8_GU8_RU8_AU8* dstPixel = dst + (y * dstWidth + x);
            dstPixel[0] = srcPixel[0];
        }
    }
}

WindowWaylandWayland::WindowWaylandWayland(std::string name, std::uint32_t width, std::uint32_t height) : WindowWayland(name, width, height) {
	// Create a wl_buffer, attach it to the surface and commit the surface
	int stride = width * 4;
	int size = stride * height;

	// Allocate a shared memory file with the right size
	int fd = create_shm_file(size);
	if (fd < 0) {
		fprintf(stderr, "creating a buffer file for %d B failed: %m\n", size);
	}

	// Map the shared memory file
	frontFramebuffer = reinterpret_cast<Pixel_BU8_GU8_RU8_AU8*>(mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0));
	if (frontFramebuffer == MAP_FAILED) {
		fprintf(stderr, "mmap failed: %m\n");
		close(fd);
	}
	backFramebuffer = reinterpret_cast<Pixel_BU8_GU8_RU8_AU8*>(mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0));
	if (backFramebuffer == MAP_FAILED) {
		fprintf(stderr, "mmap failed: %m\n");
		close(fd);
	}

	// Create a wl_buffer from our shared memory file descriptor
	wl_shm_pool *pool = wl_shm_create_pool(shm, fd, size);
	frontBuffer = wl_shm_pool_create_buffer(pool, 0, width, height, stride, WL_SHM_FORMAT_ARGB8888);
	backBuffer = wl_shm_pool_create_buffer(pool, 0, width, height, stride, WL_SHM_FORMAT_ARGB8888);
	wl_shm_pool_destroy(pool);

	// Now that we've mapped the file and created the wl_buffer, we no longer
	// need to keep file descriptor opened
	close(fd);

	if (frontBuffer == NULL || backBuffer == NULL) {
		exit(EXIT_FAILURE);
	}

	wl_surface_attach(surface, frontBuffer, 0, 0);
	wl_surface_commit(surface);
}

WindowWaylandWayland::~WindowWaylandWayland() {
	open = false;
	thread.join();
}

void WindowWaylandWayland::StartAsync() {
	thread = std::thread(&WindowWaylandWayland::StartSync, this);
}

void WindowWaylandWayland::StartSync() {
	while (open && wl_display_dispatch(display) != -1) {
		std::vector<UiElement*> drawOrder;
		drawOrder.reserve(elements.size());
		for (UiElement& e : elements) drawOrder.push_back(&e);
		std::sort(drawOrder.begin(), drawOrder.end(), [](UiElement* a, UiElement* b){ return a->z < b->z; });

		for(const UiElement* element : drawOrder) {
			std::cout << element->bufferWidth << std::endl;
			ScaleData data = ScaleElement(*element);
			std::vector<Pixel_BU8_GU8_RU8_AU8> scaled(data.width*data.height);
			ScaleBitmapR8G8B8(scaled.data(), element->buffer.data(), element->bufferWidth, element->bufferHeight, data.width, data.height);
			for (std::int32_t x = data.x; x - data.x < data.width; x++) {
				for (std::int32_t y = data.y; y - data.y < data.height; y++) {
					if (x >= 0 && x < width && y >= 0 && y < height) {
						Pixel_BU8_GU8_RU8_AU8& dst = backFramebuffer[y * width + x];
						const Pixel_BU8_GU8_RU8_AU8& src = scaled[(y - data.y) * data.width + (x - data.x)];

						float srcA = src.a / 255.0f;
						float dstA = dst.a / 255.0f;

						float outA = srcA + dstA * (1.0f - srcA);
						if (outA > 0.0f) {
							dst.r = static_cast<uint8_t>((src.r * srcA + dst.r * dstA * (1.0f - srcA)) / outA);
							dst.g = static_cast<uint8_t>((src.g * srcA + dst.g * dstA * (1.0f - srcA)) / outA);
							dst.b = static_cast<uint8_t>((src.b * srcA + dst.b * dstA * (1.0f - srcA)) / outA);
							dst.a = static_cast<uint8_t>(outA * 255);
						}
					}
				}
			}
		}

		wl_surface_attach(surface, backBuffer, 0, 0);
		wl_surface_damage(surface, 0, 0, width, height);
		wl_surface_commit(surface);

		std::swap(frontFramebuffer, backFramebuffer);
		std::swap(frontBuffer, backBuffer);
	}
}