#include "backend/x11/tray.h"

#include <assert.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <xcb/xcb.h>
#include <xcb/xcb_aux.h>
#include <xcb/xproto.h>
#include <zdwm/types.h>

#include "backend/x11/window.h"
#include "base/array.h"
#include "base/log.h"
#include "base/macros.h"
#include "base/memory.h"
#include "interface/tray.h"
#include "interface/types.h"
#include "internal.h"

typedef enum tray_opcode_t {
  SYSTEM_TRAY_REQUEST_DOCK = 0,
  SYSTEM_TRAY_BEGIN_MESSAGE = 1,
  SYSTEM_TRAY_CANCEL_MESSAGE = 2,
} tray_opcode_t;

typedef enum xembed_message_t {
  XEMBED_EMBEDDED_NOTIFY = 0,
} xembed_message_t;

static constexpr auto XEMBED_VERSION = 0;

typedef struct tray_icon_t {
  xcb_window_t window;
  int32_t natural_width;
  int32_t natural_height;
} tray_icon_t;

typedef struct tray_host_t {
  bool enabled;
  bool initialized;
  xcb_atom_t selection_atom;
  xcb_window_t host_window;
  xcb_window_t container;
  int32_t icon_size;

  tray_icon_t *icons;
  size_t icon_count;
  size_t icon_capacity;

  tray_icons_change_cb_t icon_change_cb;
  void *cb_user_data;
} tray_host_t;

static tray_host_t *get_tray_host(void *handle) {
  backend_t *backend = handle;
  if (!backend) return nullptr;

  auto tray = backend->tray;
  if (!tray || !tray->enabled) return nullptr;

  return tray;
}

static size_t tray_find_icon(tray_host_t *tray, xcb_window_t window) {
  for (size_t i = 0; i < tray->icon_count; ++i) {
    if (tray->icons[i].window == window) return i;
  }

  return SIZE_MAX;
}

static tray_icon_t *tray_get_icon(tray_host_t *tray, xcb_window_t window) {
  for (size_t i = 0; i < tray->icon_count; ++i) {
    auto icon = &tray->icons[i];
    if (icon->window == window) return icon;
  }

  return nullptr;
}

static inline void tray_dispatch_callback(tray_host_t *tray) {
  assert(tray);
  if (tray->icon_change_cb) tray->icon_change_cb(tray->cb_user_data);
}

static void tray_release_icon_window(backend_t *backend, tray_icon_t *icon) {
  if (!icon || icon->window == XCB_WINDOW_NONE) return;

  auto tray = get_tray_host(backend);
  if (!tray || !tray->initialized) return;

  auto conn = backend->conn;
  auto root = backend->screen->root;
  auto window = icon->window;
  auto mask = XCB_CW_EVENT_MASK;
  xcb_params_cw_t params = {.event_mask = XCB_EVENT_MASK_NO_EVENT};
  xcb_change_save_set(conn, XCB_SET_MODE_DELETE, window);
  xcb_aux_change_window_attributes(conn, window, mask, &params);
  xcb_reparent_window(conn, window, root, 0, 0);
}

static void tray_remove_icon_by_index(
  backend_t *backend,
  size_t index,
  bool release_window
) {
  auto tray = backend->tray;
  if (index >= tray->icon_count) return;

  auto icon = &tray->icons[index];
  if (release_window) tray_release_icon_window(backend, icon);

  array_erase(tray->icons, tray->icon_count, index);
  tray_dispatch_callback(tray);
}

static zdwm_size_t tray_get_icon_size(tray_host_t *tray, size_t index) {
  auto target_size = MAX(tray->icon_size, (int32_t)1);
  auto natural_width = tray->icons[index].natural_width;
  auto natural_height = tray->icons[index].natural_height;

  if (natural_width == 0) natural_width = target_size;
  if (natural_height == 0) natural_height = target_size;

  double width_scale = (double)target_size / (double)natural_width;
  double height_scale = (double)target_size / (double)natural_height;
  auto scale = MIN(width_scale, height_scale);
  zdwm_size_t size = {
    .width = (int32_t)(natural_width * scale),
    .height = (int32_t)(natural_height * scale),
  };
  return size;
}

static void tray_layout_icons(backend_t *backend, int32_t start_x) {
  auto tray = get_tray_host(backend);
  if (!tray || !tray->initialized) return;
  if (tray->container == XCB_WINDOW_NONE) return;

  auto conn = backend->conn;
  if (tray->icon_count == 0) {
    xcb_unmap_window(conn, tray->container);
    return;
  }

  auto height = tray->icon_size;
  auto width = height * (int32_t)tray->icon_count;
  xcb_configure_window_value_list_t value_list = {
    .x = start_x,
    .y = 0,
    .width = (uint32_t)width,
    .height = (uint32_t)height,
  };
  uint16_t value_mask = XCB_CONFIG_WINDOW_X | XCB_CONFIG_WINDOW_Y |
                        XCB_CONFIG_WINDOW_WIDTH | XCB_CONFIG_WINDOW_HEIGHT;
  xcb_configure_window_aux(conn, tray->container, value_mask, &value_list);
  xcb_map_window(conn, tray->container);

  for (size_t i = 0; i < tray->icon_count; ++i) {
    auto window = tray->icons[i].window;
    auto icon_size = tray_get_icon_size(tray, i);
    value_mask |= XCB_CONFIG_WINDOW_BORDER_WIDTH;
    auto offset_x = height * (int32_t)i;
    value_list = (xcb_configure_window_value_list_t){
      .x = offset_x + (icon_size.width - height) / 2,
      .y = (icon_size.height - height) / 2,
      .width = icon_size.width,
      .height = icon_size.height,
      .border_width = 0,
    };
    xcb_configure_window_aux(conn, window, value_mask, &value_list);
    xcb_map_window(conn, window);
  }
}

static window_id_t tray_host_window(void *handle) {
  auto tray = get_tray_host(handle);
  if (!tray) return ZDWM_WINDOW_ID_INVALID;

  return tray->host_window;
}

static size_t tray_icon_count(void *handle) {
  auto tray = get_tray_host(handle);

  return tray ? tray->icon_count : 0;
}

static int32_t tray_icon_size(void *handle) {
  auto tray = get_tray_host(handle);

  return tray ? tray->icon_size : 0;
}

static void tray_place(void *handle, int32_t x) {
  auto tray = get_tray_host(handle);
  if (!tray) return;

  tray_layout_icons((backend_t *)handle, x);
}

static void
tray_set_listeners(void *handle, tray_icons_change_cb_t cb, void *user_data) {
  auto tray = get_tray_host(handle);
  if (!tray) return;

  tray->icon_change_cb = cb;
  tray->cb_user_data = user_data;
}

const tray_api_t tray_api = {
  .host_window = tray_host_window,
  .icon_count = tray_icon_count,
  .icon_size = tray_icon_size,
  .place = tray_place,
  .set_listener = tray_set_listeners,
};

static bool tray_intern_selection_atom(tray_host_t *tray, backend_t *backend) {
  auto conn = backend->conn;
  auto screenp = backend->screenp;

  char selection_name[64] = {0};
  auto atom_name_format = "_NET_SYSTEM_TRAY_S%d";
  snprintf(selection_name, sizeof(selection_name), atom_name_format, screenp);

  uint16_t name_length = strlen(selection_name);
  auto cookie = xcb_intern_atom(conn, false, name_length, selection_name);
  auto reply = xcb_intern_atom_reply(conn, cookie, nullptr);
  if (!reply) {
    warn("cannot intern tray selection atom: %s", selection_name);
    return false;
  }

  tray->selection_atom = reply->atom;
  p_delete(&reply);
  return true;
}

static bool tray_create_container_window(
  tray_host_t *tray,
  backend_t *backend,
  tray_host_window_t host_window
) {
  auto conn = backend->conn;
  auto window_id = xcb_generate_id(conn);
  auto depth = backend->screen->root_depth;
  auto visual_id = backend->screen->root_visual;

  static xcb_colormap_t colormap = XCB_NONE;
  if (colormap == XCB_NONE) {
    colormap = xcb_generate_id(conn);
    auto root = backend->screen->root;
    uint8_t alloc = XCB_COLORMAP_ALLOC_NONE;
    xcb_create_colormap(conn, alloc, colormap, root, visual_id);
  }

  uint32_t value_mask = XCB_CW_BACK_PIXEL | XCB_CW_BORDER_PIXEL |
                        XCB_CW_OVERRIDE_REDIRECT | XCB_CW_EVENT_MASK |
                        XCB_CW_COLORMAP;
  xcb_create_window_value_list_t value_list = {
    .background_pixel = host_window.bg_pixel,
    .border_pixel = 0,
    .override_redirect = true,
    .event_mask =
      XCB_EVENT_MASK_SUBSTRUCTURE_NOTIFY | XCB_EVENT_MASK_STRUCTURE_NOTIFY,
    .colormap = colormap,
  };
  auto cookie = xcb_create_window_aux_checked(
    conn,
    depth,
    window_id,
    host_window.window,
    (int16_t)host_window.width,
    0,
    1,
    (uint16_t)MAX(1, host_window.height),
    0,
    XCB_WINDOW_CLASS_INPUT_OUTPUT,
    visual_id,
    value_mask,
    &value_list
  );

  if (xcb_request_check(conn, cookie)) {
    warn("cannot create system tray container window: 0x%x", window_id);
    return false;
  }

  tray->container = window_id;

  window_set_class_instance(conn, window_id);

#define TRAY_CONTAINER_WINDOW_NAME APP_NAME "_tray"
  window_set_name_static(conn, window_id, TRAY_CONTAINER_WINDOW_NAME);
  auto name = TRAY_CONTAINER_WINDOW_NAME;
  auto name_len = sizeof(TRAY_CONTAINER_WINDOW_NAME) - 1;
#undef TRAY_CONTAINER_WINDOW_NAME

  uint8_t mode = XCB_PROP_MODE_REPLACE;
  auto atoms = &backend->atoms;
  auto prop = atoms->_NET_WM_NAME;
  auto type = atoms->UTF8_STRING;
  xcb_change_property(conn, mode, window_id, prop, type, 8, name_len, name);

  return true;
}

static bool tray_take_selection_owner(tray_host_t *tray, backend_t *backend) {
  auto conn = backend->conn;
  auto atom = tray->selection_atom;
  auto cookie = xcb_get_selection_owner(conn, atom);
  auto reply = xcb_get_selection_owner_reply(conn, cookie, nullptr);
  if (reply && reply->owner != XCB_WINDOW_NONE) {
    warn(
      "system tray selection is already owned by window: 0x%x",
      reply->owner
    );
    p_delete(&reply);
    return false;
  }

  p_delete(&reply);

  auto owner = tray->container;
  xcb_set_selection_owner(conn, owner, atom, XCB_CURRENT_TIME);

  cookie = xcb_get_selection_owner(conn, atom);
  reply = xcb_get_selection_owner_reply(conn, cookie, nullptr);
  bool success = reply && reply->owner == owner;
  p_delete(&reply);

  if (!success) warn("cannot acquire system tray selection");
  return success;
}

static void tray_broadcast_manager(tray_host_t *tray, backend_t *backend) {
  auto conn = backend->conn;
  auto root = backend->screen->root;

  xcb_client_message_event_t event = {
    .response_type = XCB_CLIENT_MESSAGE,
    .window = root,
    .format = 32,
    .type = backend->atoms.MANAGER,
    .data.data32 = {
      [0] = XCB_CURRENT_TIME,
      [1] = tray->selection_atom,
      [2] = tray->container,
    },
  };
  uint32_t event_mask = XCB_EVENT_MASK_STRUCTURE_NOTIFY;
  xcb_send_event(conn, false, root, event_mask, (char *)&event);
}

void tray_init(backend_t *backend, tray_host_window_t host_window) {
  auto tray = get_tray_host(backend);
  if (!tray) {
    tray = p_new(tray_host_t, 1);
    backend->tray = tray;
  }

  if (tray->initialized) return;

  if (!tray_intern_selection_atom(tray, backend)) return;

  if (!tray_create_container_window(tray, backend, host_window)) return;
  if (!tray_take_selection_owner(tray, backend)) {
    tray_cleanup(backend);
    return;
  }

  tray->enabled = true;
  tray->initialized = true;
  tray->host_window = host_window.window;
  tray->icon_size = host_window.height;

  tray_broadcast_manager(tray, backend);
  tray_layout_icons(backend, host_window.width);
  xcb_flush(backend->conn);
}

void tray_cleanup(backend_t *backend) {
  auto tray = backend->tray;
  if (!tray) return;

  for (size_t i = 0; i < tray->icon_count; ++i) {
    tray_release_icon_window(backend, &tray->icons[i]);
  }
  p_delete(&tray->icons);
  tray->icon_count = 0;
  tray->icon_capacity = 0;

  auto conn = backend->conn;

  auto atom = tray->selection_atom;
  if (atom != XCB_ATOM_NONE) {
    xcb_set_selection_owner(conn, XCB_WINDOW_NONE, atom, XCB_CURRENT_TIME);
  }

  if (tray->container != XCB_WINDOW_NONE) {
    xcb_destroy_window(conn, tray->container);
  }

  p_clear(backend->tray, 1);
  p_delete(&backend->tray);
}

static void
tray_select_icon_events(xcb_connection_t *conn, xcb_window_t window) {
  xcb_params_cw_t params = {
    .event_mask =
      XCB_EVENT_MASK_STRUCTURE_NOTIFY | XCB_EVENT_MASK_PROPERTY_CHANGE,
  };
  uint32_t mask = XCB_CW_EVENT_MASK;
  xcb_aux_change_window_attributes(conn, window, mask, &params);
  xcb_clear_area(conn, false, window, 0, 0, 0, 0);
}

/* reference:
 * https://specifications.freedesktop.org/xembed/latest-single/#id-1.7.4 */
typedef struct xembed_message_data_t {
  uint32_t message; /* message opcode */
  uint32_t detail;  /* message detail */
  uint32_t data1;   /* message data 1 */
  uint32_t data2;   /* message data 2 */
} xembed_message_data_t;

static void tray_send_xembed_message(
  backend_t *backend,
  xcb_window_t window,
  xembed_message_data_t message
) {
  auto conn = backend->conn;
  auto message_type = backend->atoms._XEMBED;

  xcb_client_message_event_t event = {
    .response_type = XCB_CLIENT_MESSAGE,
    .format = 32,
    .window = window,
    .type = message_type,
    .data.data32 = {
      [0] = XCB_CURRENT_TIME,
      [1] = message.message,
      [2] = message.detail,
      [3] = message.data1,
      [4] = message.data2,
    },
  };
  uint32_t event_mask = XCB_EVENT_MASK_NO_EVENT;
  xcb_send_event(conn, false, window, event_mask, (char *)&event);
}

static void tray_add_icon(backend_t *backend, xcb_window_t window) {
  if (window == XCB_WINDOW_NONE) return;

  auto tray = get_tray_host(backend);
  if (!tray || !tray->initialized || tray_get_icon(tray, window)) return;

  rect_t geometry = {0};
  if (!window_get_geometry(backend, window, &geometry)) return;

  auto icon = array_push(tray->icons, tray->icon_count, tray->icon_capacity);
  *icon = (tray_icon_t){
    .window = window,
    .natural_width = geometry.width,
    .natural_height = geometry.height,
  };

  auto conn = backend->conn;
  auto container = tray->container;
  xembed_message_data_t message = {
    .message = XEMBED_EMBEDDED_NOTIFY,
    .detail = 0,
    .data1 = container,
    .data2 = XEMBED_VERSION,
  };
  xcb_change_save_set(conn, XCB_SET_MODE_INSERT, window);
  xcb_reparent_window(conn, window, tray->container, 0, 0);
  tray_select_icon_events(conn, window);
  tray_send_xembed_message(backend, window, message);
  xcb_map_window(conn, window);
  tray_dispatch_callback(tray);
}

bool tray_handle_client_message(
  backend_t *backend,
  const xcb_client_message_event_t *ev
) {
  auto tray = get_tray_host(backend);
  if (!tray || !tray->enabled || !tray->initialized) return false;
  if (ev->window != tray->container && ev->window != backend->screen->root) {
    return false;
  }

  auto opcode = ev->data.data32[1];
  switch (opcode) {
  case SYSTEM_TRAY_REQUEST_DOCK:
    auto window = ev->data.data32[2];
    tray_add_icon(backend, window);
    break;
  case SYSTEM_TRAY_BEGIN_MESSAGE:
  case SYSTEM_TRAY_CANCEL_MESSAGE:
  default:
    break;
  }

  xcb_flush(backend->conn);

  return true;
}

bool tray_handle_configure_request(
  backend_t *backend,
  const xcb_configure_request_event_t *ev
) {
  auto tray = get_tray_host(backend);
  if (!tray || !tray->initialized) return false;

  if (ev->window == tray->container) {
    tray_dispatch_callback(tray);
    return true;
  }

  auto icon = tray_get_icon(tray, ev->window);
  if (!icon) return false;

  if ((ev->value_mask & XCB_CONFIG_WINDOW_WIDTH) && ev->width > 0) {
    icon->natural_width = (int32_t)ev->width;
  }
  if ((ev->value_mask & XCB_CONFIG_WINDOW_HEIGHT) && ev->height > 0) {
    icon->natural_height = (int32_t)ev->height;
  }

  tray_dispatch_callback(tray);
  return true;
}

bool tray_handle_map_request(
  backend_t *backend,
  const xcb_map_request_event_t *ev
) {
  auto tray = get_tray_host(backend);
  if (!tray || !tray->initialized) return false;

  auto conn = backend->conn;
  if (ev->window == tray->container) {
    tray_dispatch_callback(tray);
    return true;
  }

  auto icon = tray_get_icon(tray, ev->window);
  if (!icon && ev->parent != tray->container) return false;

  xcb_map_window(conn, ev->window);
  xcb_flush(conn);

  tray_dispatch_callback(tray);
  return true;
}

bool tray_handle_property_notify(
  backend_t *backend,
  const xcb_property_notify_event_t *ev
) {
  auto tray = get_tray_host(backend);
  if (!tray || !tray->initialized) return false;

  if (ev->window == XCB_WINDOW_NONE) return false;
  if (ev->window == tray->container) return true;
  return tray_get_icon(tray, ev->window) != nullptr;
}

bool tray_handle_unmap_notify(
  backend_t *backend,
  const xcb_unmap_notify_event_t *ev
) {
  auto tray = get_tray_host(backend);
  if (!tray || !tray->initialized) return false;

  auto index = tray_find_icon(tray, ev->window);
  if (index == SIZE_MAX) return ev->window == tray->container;

  tray_remove_icon_by_index(backend, index, true);
  return true;
}

bool tray_handle_destroy_notify(
  backend_t *backend,
  const xcb_destroy_notify_event_t *ev
) {
  auto tray = get_tray_host(backend);
  if (!tray || !tray->initialized) return false;

  if (ev->window == tray->container) {
    tray_cleanup(backend);
    return true;
  }

  auto index = tray_find_icon(tray, ev->window);
  if (index == SIZE_MAX) return false;

  tray_remove_icon_by_index(backend, index, false);
  return true;
}