#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)

#define BORDER_LIGHT 0x1c
#define BORDER_DARK  0x08

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;

#define SCREEN_HEIGHT 200
#define SCREEN_WIDTH  320
#define VGA_MEMORY    ((uint8_t *)0xa0000)

static inline void draw_hz_line(uint16_t y, uint16_t xs, uint16_t xm, uint8_t color) {
  if (y >= SCREEN_HEIGHT)
    return;
  if (xs >= SCREEN_WIDTH)
    xs = 0;
  if (xm > SCREEN_WIDTH)
    xm = SCREEN_WIDTH;
  uint8_t *const line_start = VGA_MEMORY + y * SCREEN_WIDTH;
  for (uint8_t *p = line_start + xs; p < line_start + xm; ++p)
    *p = color;
}

static inline void draw_vt_line(uint16_t x, uint16_t ys, uint16_t ym, uint8_t color) {
  if (x >= SCREEN_WIDTH)
    return;
  if (ys >= SCREEN_HEIGHT)
    ys = 0;
  if (ym > SCREEN_HEIGHT)
    ym = SCREEN_HEIGHT;
  uint8_t *const line_start = VGA_MEMORY + x;
  for (uint8_t *p = line_start + ys * SCREEN_WIDTH; p < line_start + ym * SCREEN_WIDTH; p += SCREEN_WIDTH)
    *p = color;
}

static void paint_and_above(const struct window *w) {
  switch_to_kernel_cr3();
  for (const struct window *i = w; i; i = i->above) {
    const uint16_t ys = i->ypos < SCREEN_HEIGHT ? 0 : -i->ypos;
    const uint16_t xs = i->xpos < SCREEN_WIDTH  ? 0 : -i->xpos;
    const uint16_t ym = i->ypos + i->height <= SCREEN_HEIGHT ? i->height : SCREEN_HEIGHT - i->ypos;
    const uint16_t xm = i->xpos + i->width  <= SCREEN_WIDTH  ? i->width  : SCREEN_WIDTH  - i->xpos;

    for (uint16_t y = ys; y < ym; ++y)
      for (uint16_t x = xs; x < xm; ++x) {
        const uint8_t pixel = ((uint8_t *)i->pixel_buffer_pma)[y * i->width + x];
        if (pixel)
          VGA_MEMORY[(y + i->ypos) * SCREEN_WIDTH + x + i->xpos] = pixel;
      }

    draw_hz_line(i->ypos - 2, i->xpos - 2, i->xpos + i->width  + 2, BORDER_LIGHT);
    draw_vt_line(i->xpos - 2, i->ypos - 1, i->ypos + i->height + 2, BORDER_LIGHT);
    draw_hz_line(i->ypos - 1, i->xpos - 1, i->xpos + i->width  + 2, BORDER_DARK);
    draw_vt_line(i->xpos - 1, i->ypos,     i->ypos + i->height + 2, BORDER_DARK);
    draw_hz_line(i->ypos + i->height, i->xpos, i->xpos + i->width + 1, BORDER_LIGHT);
    draw_vt_line(i->xpos + i->width,  i->ypos, i->ypos + i->height,    BORDER_LIGHT);
    draw_hz_line(i->ypos + i->height + 1, i->xpos, i->xpos + i->width  + 2, BORDER_DARK);
    draw_vt_line(i->xpos + i->width  + 1, i->ypos, i->ypos + i->height + 1, BORDER_DARK);
  }
  switch_to_task_cr3();
}

void paint_bg() {
  for (uint16_t y = 0; y < SCREEN_HEIGHT; ++y)
    for (uint16_t x = 0; x < SCREEN_WIDTH; ++x)
      VGA_MEMORY[y * SCREEN_WIDTH + x] = 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;
  w->xpos = 10;
  w->ypos = 10;

  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;
}

static void del_no_paint(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;
}

void del_window(struct window *w) {
  del_no_paint(w);
  paint_all();
}

void delete_any_windows_from(struct task_state *tstate) {
  bool need_to_paint = false;
  for (struct window *w = windows; w < windows + MAX_WINDOWS; ++w)
    if (w->pixel_buffer_pma && (w->from_task == tstate)) {
      del_no_paint(w);
      need_to_paint = true;
    }
  if (need_to_paint)
    paint_all();
}

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

  w->width = width;
  w->height = height;
  reassign_pixel_buffer(w, pixel_buffer);

  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);
  }
}