local ffi = require 'ffi'

-- from
local VK_SERVER_EXECUTABLE                  = "/usr/bin/texture-share-vk-server"
local VK_SERVER_DEFAULT_LOCKFILE_PATH       = "/tmp/vk_server/vk_server.lock"
local VK_SERVER_DEFAULT_SOCKET_PATH         = "/tmp/vk_server/vk_server.sock"
local VK_SERVER_DEFAULT_SHMEM_PREFIX        = "shmem_img_"

-- from gl.h
local GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME = 0x8CD1
local GL_COLOR_ATTACHMENT0                  = 0x8CE0
local GL_FRAMEBUFFER                        = 0x8D40
local GL_TEXTURE_2D                         = 0x0DE1

ffi.cdef [[
// gl.h
typedef int GLint;
typedef unsigned int GLuint;
typedef unsigned int GLenum;

void glGetFramebufferAttachmentParameteriv(GLenum target, GLenum attachment,
                                           GLenum pname, GLint *params);

// texture_share_ipc.h
typedef enum ImgFormat {
    R8G8B8A8,
    R8G8B8,
    B8G8R8A8,
    B8G8R8,
    Undefined,
} ImgFormat;

// texture_share_gl_client.h
typedef enum ImageLookupResult {
    Error = -1,
    NotFound = 0,
    Found = 1,
    RequiresUpdate = 2,
} ImageLookupResult;

typedef struct ClientImageDataGuard ClientImageDataGuard;

typedef struct GlClient GlClient;

typedef struct GlImageExtent {
    GLint top_left[2];
    GLint bottom_right[2];
} GlImageExtent;

bool gl_client_initialize_external_gl(void);

struct GlClient *gl_client_new(const char *socket_path, uint64_t timeout_in_millis);
struct GlClient *gl_client_new_with_server_launch(const char *socket_path,
                                                  uint64_t client_timeout_in_millis,
                                                  const char *server_program,
                                                  const char *server_lock_path,
                                                  const char *server_socket_path,
                                                  const char *shmem_prefix,
                                                  uint64_t server_socket_timeout_in_millis,
                                                  uint64_t server_connection_wait_timeout_in_millis,
                                                  uint64_t server_ipc_timeout_in_millis,
                                                  uint64_t server_lockfile_timeout_in_millis,
                                                  uint64_t server_spawn_timeout_in_millis);

void gl_client_destroy(struct GlClient *gl_client);

enum ImageLookupResult gl_client_init_image(struct GlClient *gl_client,
                                            const char *image_name,
                                            uint32_t width,
                                            uint32_t height,
                                            ImgFormat format,
                                            bool overwrite_existing);

int gl_client_send_image(struct GlClient *gl_client,
                         const char *image_name,
                         GLuint src_texture_id,
                         GLenum src_texture_target,
                         bool invert,
                         GLuint prev_fbo,
                         const struct GlImageExtent *extents);
]]
local tvs = ffi.load("texture_share_gl_client")
local gl = ffi.load("GL")

local width, height
local canvas
local client, image

function love.load()
  width, height = love.graphics.getDimensions()
  canvas = love.graphics.newCanvas(width, height)

  assert(tvs.gl_client_initialize_external_gl(), "no init")
  client = assert(tvs.gl_client_new_with_server_launch(
    VK_SERVER_DEFAULT_SOCKET_PATH,
    1000,
    VK_SERVER_EXECUTABLE,
    VK_SERVER_DEFAULT_LOCKFILE_PATH,
    VK_SERVER_DEFAULT_SOCKET_PATH,
    VK_SERVER_DEFAULT_SHMEM_PREFIX,
    2000,
    2000,
    2000,
    2000,
    2000
  ), "failed to connect or launch tsv server")
  image = assert(tvs.gl_client_init_image(client, "love2d", width, height, ffi.C.R8G8B8A8, true) > 0)
end

local angle = 0

function love.update(dt)
  angle = angle + 5 * dt
end

function love.draw()
  love.graphics.setCanvas(canvas)
    love.graphics.clear(0, 0, 0, 0)
    love.graphics.translate(width/2, height/2)
    love.graphics.rotate(angle)

    love.graphics.setColor(1, 0, 0, 1)
    love.graphics.rectangle("fill", -150,-150, 300,300)

    local name_ptr = ffi.typeof('GLint[1]')()
    gl.glGetFramebufferAttachmentParameteriv(
      GL_FRAMEBUFFER,
      GL_COLOR_ATTACHMENT0,
      GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME,
      name_ptr
    )
  love.graphics.setCanvas()

  tvs.gl_client_send_image(
    client, "love2d",
    name_ptr[0],
    GL_TEXTURE_2D,
    false, 0, nil
  )

  love.graphics.reset()
  love.graphics.setBlendMode("alpha", "premultiplied")
  love.graphics.draw(canvas)
end