#include "paging.h"
#include "window.h"
#include "drive.h"
#include "task.h"
#include "util.h"
#include "pmap.h"
#include "log.h"

#define MAX_WINDOWS 64
#define ACTION_BUFFER_PAGES 1
#define AB_END(buf) (buf + (ACTION_BUFFER_PAGES * 4096) / sizeof(struct window_action))

#define BACKGROUND(x, y) ((x / 16 + y / 16) % 2 ? 0x14 : 0x07)

static struct window {
  const volatile void *pixel_buffer_pma;
  uint16_t width;
  uint16_t height;

  uint16_t xpos;
  uint16_t ypos;

  struct window_action *action_buffer;
  struct window_action *next_action_read;
  struct window_action *next_action_write;

  struct window *above;
  struct window *below;

  struct task_state *from_task;
} windows[MAX_WINDOWS];

static struct window *bottom_window = 0;
static struct window *top_window = 0;

static inline void set_pix(uint16_t x, uint16_t y, uint8_t value) {
  if ((x < 320) && (y < 200))
    *(uint8_t *)(0xa0000 + y * 320 + x) = value;
}

static void paint_and_above(const struct window *w) {
  switch_to_kernel_cr3();
  for (const struct window *i = w; i; i = i->above)
    for (uint16_t y = 0; y < i->height; ++y)
      for (uint16_t x = 0; x < i->width; ++x) {
        const uint8_t pixel = ((uint8_t *)i->pixel_buffer_pma)[y * i->width + x];
        if (pixel)
          set_pix(x + i->xpos, y + i->ypos, pixel);
      }
  switch_to_task_cr3();
}

void paint_bg() {
  for (uint16_t y = 0; y < 200; ++y)
    for (uint16_t x = 0; x < 320; ++x)
      set_pix(x, y, BACKGROUND(x, y));
}

static void paint_all() {
  paint_bg();
  paint_and_above(bottom_window);
}

struct window *new_window(uint16_t width, uint16_t height, const void *pixel_buffer) {
  if (!pixel_buffer) {
    logf(LOG_WARN, "Refusing to create window with null pixel buffer for task %s.", active_task->name);
    return 0;
  }

  struct window *w;
  for (uint8_t i = 0; i < MAX_WINDOWS; ++i)
    if (!windows[i].pixel_buffer_pma) {
      w = &windows[i];
      goto got_window;
    }
  return 0;
got_window:

  w->pixel_buffer_pma = vma_to_pma(active_task->page_directory, pixel_buffer);
  w->width = width;
  w->height = height;

  struct window_action *const ab = allocate_kernel_pages(ACTION_BUFFER_PAGES);
  w->action_buffer = ab;
  w->next_action_read = ab;
  w->next_action_write = ab;

  if (top_window)
    top_window->above = w;
  else
    bottom_window = w;
  w->above = 0;
  w->below = top_window;
  top_window = w;

  w->from_task = active_task;

  paint_and_above(w);
  return w;
}

void del_window(struct window *w) {
  if (w == top_window)
    top_window = w->below;
  if (w == bottom_window)
    bottom_window = w->above;
  if (w->below)
    w->below->above = w->above;
  if (w->above)
    w->above->below = w->below;

  free_pages(w->action_buffer, ACTION_BUFFER_PAGES);
  w->pixel_buffer_pma = 0;

  paint_all();
}

void resize_window(struct window *w, uint16_t width, uint16_t height) {
  const bool smaller = (width < w->width) || (height < w->height);

  w->width = width;
  w->height = height;

  if (smaller)
    paint_all();
  else
    paint_and_above(w);
}

void reassign_pixel_buffer(struct window *w, const void *pixel_buffer) {
  w->pixel_buffer_pma = vma_to_pma(active_task->page_directory, pixel_buffer);
}

void push_window_paint(const struct window *w) {
  paint_and_above(w);
}

struct window_action next_window_action(struct window *w) {
  if (w->next_action_write == w->next_action_read)
    return (struct window_action){.action_type = NONE};
  const struct window_action *const action = w->next_action_read;
  if (++(w->next_action_read) >= AB_END(w->action_buffer))
    w->next_action_read = w->action_buffer;
  return *action;
}

static void send_action(struct window *w, struct window_action packet) {
  struct window_action *next_next = w->next_action_write + 1;
  if (next_next >= AB_END(w->action_buffer))
    next_next = w->action_buffer;
  if (next_next != w->next_action_read) {
    *(w->next_action_write) = packet;
    w->next_action_write = next_next;
    unwait(w->from_task, (struct wait){.mode = WINDOW_ACTION});
  }
}

enum wm_action {
  WM_SHUFFLE_UP,
  WM_SHUFFLE_DOWN,
  WM_MOVE_LEFT,
  WM_MOVE_RIGHT,
  WM_MOVE_UP,
  WM_MOVE_DOWN,

  N_WM_ACTIONS
};

static struct key_packet keybinds[] = {
  {.key_id = KEY_PAGE_DOWN,   .modifiers = WINS},
  {.key_id = KEY_PAGE_UP,     .modifiers = WINS},
  {.key_id = KEY_LEFT_ARROW,  .modifiers = WINS},
  {.key_id = KEY_RIGHT_ARROW, .modifiers = WINS},
  {.key_id = KEY_UP_ARROW,    .modifiers = WINS},
  {.key_id = KEY_DOWN_ARROW,  .modifiers = WINS}
};

static inline bool fuzzy_key_match(struct key_packet t, struct key_packet a) {
  if (t.key_id != a.key_id)
    return false;

  if (((t.modifiers & SHIFTS) == SHIFTS) && (a.modifiers & SHIFTS))
    a.modifiers |= SHIFTS;
  if (((t.modifiers & CTRLS)  == CTRLS)  && (a.modifiers & CTRLS))
    a.modifiers |= CTRLS;
  if (((t.modifiers & ALTS)   == ALTS)   && (a.modifiers & ALTS))
    a.modifiers |= ALTS;
  if (((t.modifiers & WINS)   == WINS)   && (a.modifiers & WINS))
    a.modifiers |= WINS;

  return a.modifiers == t.modifiers;
}

#include "log.h"

void on_action(struct window_action packet) {
//logf(LOG_INFO, "Window action, top window = 0x%d from %s.", top_window, top_window->from_task->name);

  if (packet.action_type == NOT_READY)
    return;

  if (top_window) {
    if (packet.action_type == KEY_DOWN)
      for (uint8_t i = 0; i < N_WM_ACTIONS; ++i)
        if (fuzzy_key_match(keybinds[i], packet.as_key)) {
          switch_to_kernel_cr3();
          struct window *old_top, *old_bottom;
          switch (i) {
          case WM_SHUFFLE_UP:
            old_top = top_window;
            old_bottom = bottom_window;
            top_window = old_top->below;
            top_window->above = 0;
            old_top->below = 0;
            old_top->above = old_bottom;
            old_bottom->below = old_top;
            bottom_window = old_top;
            paint_and_above(bottom_window->above);
            break;
          case WM_SHUFFLE_DOWN:
            old_top = top_window;
            old_bottom = bottom_window;
            bottom_window = old_bottom->above;
            bottom_window->below = 0;
            old_bottom->above = 0;
            old_bottom->below = old_top;
            old_top->above = old_bottom;
            top_window = old_bottom;
            paint_and_above(top_window);
            break;
          case WM_MOVE_LEFT:
            --top_window->xpos;
            paint_all();
            break;
          case WM_MOVE_RIGHT:
            ++top_window->xpos;
            paint_all();
            break;
          case WM_MOVE_UP:
            --top_window->ypos;
            paint_all();
            break;
          case WM_MOVE_DOWN:
            ++top_window->ypos;
            paint_all();
          }
          switch_to_task_cr3();
          return;
        }

    send_action(top_window, packet);
  }
}