/**
 * Looking Glass
 * Copyright © 2017-2023 The Looking Glass Authors
 * https://looking-glass.io
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program 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 General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc., 59
 * Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include "core.h"
#include "main.h"
#include "app.h"
#include "util.h"

#include "common/time.h"
#include "common/debug.h"
#include "common/array.h"

#include <math.h>

#define RESIZE_TIMEOUT (10 * 1000) // 10ms

static bool isInView(void)
{
  return
    g_cursor.pos.x >= g_state.dstRect.x                     &&
    g_cursor.pos.x <  g_state.dstRect.x + g_state.dstRect.w &&
    g_cursor.pos.y >= g_state.dstRect.y                     &&
    g_cursor.pos.y <  g_state.dstRect.y + g_state.dstRect.h;
}

bool core_inputEnabled(void)
{
  return g_params.useSpiceInput && !g_state.ignoreInput &&
    ((g_cursor.grab && g_params.captureInputOnly) || !g_params.captureInputOnly);
}

void core_invalidatePointer(bool detectInView)
{
  /* if the display server does not support warp, then we can not operate in
   * always relative mode and we should not grab the pointer */
  enum LG_DSWarpSupport warpSupport = LG_DS_WARP_NONE;
  app_getProp(LG_DS_WARP_SUPPORT, &warpSupport);

  if (detectInView)
  {
    bool inView = isInView();
    // do not allow the view to become active if any mouse buttons are being held,
    // this fixes issues with meta window resizing.
    if (inView && g_cursor.buttons)
      return;

    g_cursor.inView = inView;
  }

  g_cursor.draw = (g_params.alwaysShowCursor || g_params.captureInputOnly)
    ? true : g_cursor.inView;
  g_cursor.redraw = true;

  g_cursor.warpState = g_cursor.inView ? WARP_STATE_ON : WARP_STATE_OFF;
  if (g_cursor.inView)
  {
    if (g_params.hideMouse)
      g_state.ds->setPointer(LG_POINTER_NONE);

    if (warpSupport != LG_DS_WARP_NONE && !g_params.captureInputOnly)
      g_state.ds->grabPointer();

    if (g_params.grabKeyboardOnFocus)
      g_state.ds->grabKeyboard();
  }
  else
  {
    if (g_params.hideMouse)
      g_state.ds->setPointer(LG_POINTER_SQUARE);

    if (warpSupport != LG_DS_WARP_NONE)
      g_state.ds->ungrabPointer();

    g_state.ds->ungrabKeyboard();
  }

  g_cursor.warpState = WARP_STATE_ON;
}

void core_setCursorInView(bool enable)
{
  // if the state has not changed, don't do anything else
  if (g_cursor.inView == enable)
    return;

  if (enable && !g_state.focused)
    return;

  g_cursor.inView = enable;
  core_invalidatePointer(false);
}

void core_setGrab(bool enable)
{
  core_setGrabQuiet(enable);

  app_alert(
    g_cursor.grab ? LG_ALERT_SUCCESS  : LG_ALERT_WARNING,
    g_cursor.grab ? "Capture Enabled" : "Capture Disabled"
  );
}

void core_setGrabQuiet(bool enable)
{
  /* we always do this so that at init the cursor is in the right state */
  if (g_params.captureInputOnly && g_params.hideMouse)
    g_state.ds->setPointer(enable ? LG_POINTER_NONE : LG_POINTER_SQUARE);

  if (g_cursor.grab == enable)
    return;

  g_cursor.grab = enable;
  g_cursor.acc.x = 0.0;
  g_cursor.acc.y = 0.0;

  /* if the display server does not support warp we need to ungrab the pointer
   * here instead of in the move handler */
  enum LG_DSWarpSupport warpSupport = LG_DS_WARP_NONE;
  app_getProp(LG_DS_WARP_SUPPORT, &warpSupport);

  if (enable)
  {
    core_setCursorInView(true);
    g_state.ignoreInput = false;

    if (g_params.grabKeyboard)
      g_state.ds->grabKeyboard();

    g_state.ds->capturePointer();
  }
  else
  {
    if (g_params.grabKeyboard)
    {
      if (!g_params.grabKeyboardOnFocus ||
          !g_state.focused || g_params.captureInputOnly)
        g_state.ds->ungrabKeyboard();
    }

    g_state.ds->uncapturePointer();

    /* if exiting capture when input on capture only we need to align the local
     * cursor to the guest's location before it is shown. */
    if (g_params.captureInputOnly || !g_params.hideMouse)
      core_alignToGuest();
  }
}

bool core_warpPointer(int x, int y, bool exiting)
{
  if ((!g_cursor.inWindow && !exiting) ||
      app_isOverlayMode() ||
      g_cursor.warpState == WARP_STATE_OFF)
    return false;

  if (exiting)
    g_cursor.warpState = WARP_STATE_OFF;

  if (g_cursor.pos.x == x && g_cursor.pos.y == y)
    return true;

  g_state.ds->warpPointer(x, y, exiting);
  return true;
}

void core_updatePositionInfo(void)
{
  if (!g_state.haveSrcSize)
    goto done;

  float srcW;
  float srcH;

  switch(g_params.winRotate)
  {
    case LG_ROTATE_0:
    case LG_ROTATE_180:
      srcW = g_state.srcSize.x;
      srcH = g_state.srcSize.y;
      break;

    case LG_ROTATE_90:
    case LG_ROTATE_270:
      srcW = g_state.srcSize.y;
      srcH = g_state.srcSize.x;
      break;

    default:
      DEBUG_UNREACHABLE();
  }

  if (g_params.keepAspect)
  {
    const float srcAspect = srcH / srcW;
    const float wndAspect = (float)g_state.windowH / (float)g_state.windowW;
    bool force = true;

    if (g_params.dontUpscale &&
        srcW <= g_state.windowW &&
        srcH <= g_state.windowH)
    {
      force = false;
      g_state.dstRect.w = srcW;
      g_state.dstRect.h = srcH;
      g_state.dstRect.x = g_state.windowCX - srcW / 2;
      g_state.dstRect.y = g_state.windowCY - srcH / 2;
    }
    else
    if (g_params.intUpscale &&
        srcW <= g_state.windowW &&
        srcH <= g_state.windowH)
    {
      force = false;
      const int scale = min(
          floor(g_state.windowW / srcW),
          floor(g_state.windowH / srcH));
      g_state.dstRect.w = srcW * scale;
      g_state.dstRect.h = srcH * scale;
      g_state.dstRect.x = g_state.windowCX - g_state.dstRect.w / 2;
      g_state.dstRect.y = g_state.windowCY - g_state.dstRect.h / 2;
    }
    else
    if ((int)(wndAspect * 1000) == (int)(srcAspect * 1000))
    {
      force           = false;
      g_state.dstRect.w = g_state.windowW;
      g_state.dstRect.h = g_state.windowH;
      g_state.dstRect.x = 0;
      g_state.dstRect.y = 0;
    }
    else
    if (wndAspect < srcAspect)
    {
      g_state.dstRect.w = (float)g_state.windowH / srcAspect;
      g_state.dstRect.h = g_state.windowH;
      g_state.dstRect.x = (g_state.windowW >> 1) - (g_state.dstRect.w >> 1);
      g_state.dstRect.y = 0;
    }
    else
    {
      g_state.dstRect.w = g_state.windowW;
      g_state.dstRect.h = (float)g_state.windowW * srcAspect;
      g_state.dstRect.x = 0;
      g_state.dstRect.y = (g_state.windowH >> 1) - (g_state.dstRect.h >> 1);
    }

    if (g_params.dontUpscale && g_params.shrinkOnUpscale)
    {
      if (g_state.windowW > srcW)
      {
        force = true;
        g_state.dstRect.w = (int) (srcW + 0.5);
      }
      if (g_state.windowH > srcH)
      {
        force = true;
        g_state.dstRect.h = (int) (srcH + 0.5);
      }
    }

    if (force && g_params.forceAspect)
    {
      g_state.resizeTimeout = microtime() + RESIZE_TIMEOUT;
      g_state.resizeDone    = false;
    }
  }
  else
  {
    g_state.dstRect.x = 0;
    g_state.dstRect.y = 0;
    g_state.dstRect.w = g_state.windowW;
    g_state.dstRect.h = g_state.windowH;
  }
  g_state.dstRect.valid = true;

  g_cursor.useScale = (
      srcH       != g_state.dstRect.h ||
      srcW       != g_state.dstRect.w);

  g_cursor.scale.x  = (float)srcW / (float)g_state.dstRect.w;
  g_cursor.scale.y  = (float)srcH / (float)g_state.dstRect.h;

  if (!g_state.posInfoValid)
  {
    g_state.posInfoValid = true;
    g_state.ds->realignPointer();

    // g_cursor.guest.valid could have become true in the meantime.
    if (g_cursor.guest.valid)
    {
      // Since posInfoValid was false, core_handleGuestMouseUpdate becomes a
      // noop when called on the cursor thread, which means we need to call it
      // again in order for the cursor to show up.
      core_handleGuestMouseUpdate();

      // Similarly, the position needs to be valid before the initial mouse
      // move, otherwise we wouldn't know if the cursor is in the viewport.
      app_handleMouseRelative(0.0, 0.0, 0.0, 0.0);
    }
  }

done:
  atomic_fetch_add(&g_state.lgrResize, 1);
}

void core_alignToGuest(void)
{
  if (!g_cursor.guest.valid || !g_state.focused)
    return;

  struct DoublePoint local;
  if (util_guestCurToLocal(&local))
    if (core_warpPointer(round(local.x), round(local.y), false))
      core_setCursorInView(true);
}

bool core_isValidPointerPos(int x, int y)
{
  return g_state.ds->isValidPointerPos(x, y);
}

bool core_startCursorThread(void)
{
  if (g_state.cursorThread)
    return true;

  g_state.stopVideo = false;
  if (!lgCreateThread("cursorThread", main_cursorThread, NULL,
        &g_state.cursorThread))
  {
    DEBUG_ERROR("cursor create thread failed");
    return false;
  }
  return true;
}

void core_stopCursorThread(void)
{
  g_state.stopVideo = true;
  if (g_state.cursorThread)
    lgJoinThread(g_state.cursorThread, NULL);

  g_state.cursorThread = NULL;
}

bool core_startFrameThread(void)
{
  if (g_state.frameThread)
    return true;

  g_state.stopVideo = false;
  if (!lgCreateThread("frameThread", main_frameThread, NULL,
        &g_state.frameThread))
  {
    DEBUG_ERROR("frame create thread failed");
    return false;
  }
  return true;
}

void core_stopFrameThread(void)
{
  g_state.stopVideo = true;
  if (g_state.frameThread)
    lgJoinThread(g_state.frameThread, NULL);

  g_state.frameThread = NULL;
}

void core_handleGuestMouseUpdate(void)
{
  struct DoublePoint localPos;
  if (!util_guestCurToLocal(&localPos))
    return;

  if (app_isOverlayMode() || !g_cursor.inView)
    return;

  g_state.ds->guestPointerUpdated(
    g_cursor.guest.x, g_cursor.guest.y,
    util_clamp(localPos.x, g_state.dstRect.x,
      g_state.dstRect.x + g_state.dstRect.w),
    util_clamp(localPos.y, g_state.dstRect.y,
      g_state.dstRect.y + g_state.dstRect.h)
  );
}

void core_handleMouseGrabbed(double ex, double ey)
{
  if (!core_inputEnabled())
    return;

  int x, y;
  if (g_params.rawMouse && !g_cursor.sens)
  {
    /* raw unscaled input are always round numbers */
    x = floor(ex);
    y = floor(ey);
  }
  else
  {
    /* apply sensitivity */
    ex = (ex / 10.0) * (g_cursor.sens + 10);
    ey = (ey / 10.0) * (g_cursor.sens + 10);
    util_cursorToInt(ex, ey, &x, &y);
  }

  if (x == 0 && y == 0)
    return;

  if (!purespice_mouseMotion(x, y))
    DEBUG_ERROR("failed to send mouse motion message");
}

void core_handleMouseNormal(double ex, double ey)
{
  // prevent cursor handling outside of capture if the position is not known
  if (!g_cursor.guest.valid)
    return;

  if (g_cursor.realigning)
    return;

  if (!core_inputEnabled())
    return;

  /* scale the movement to the guest */
  if (g_cursor.useScale && g_params.scaleMouseInput)
  {
    ex *= g_cursor.scale.x;
    ey *= g_cursor.scale.y;
  }

  bool testExit = true;
  const bool inView = isInView();
  if (!g_cursor.inView)
  {
    if (inView)
      g_cursor.realign = true;
    else /* nothing to do if we are outside the viewport */
      return;
  }

  /*
   * do not pass mouse events to the guest if we do not have focus, this must be
   * done after the inView test has been performed so that when focus is gained
   * we know if we should be drawing the cursor.
   */
  if (!g_state.focused)
  {
    core_setCursorInView(inView);
    return;
  }

  /* if we have been instructed to realign */
  if (g_cursor.realign)
  {
    struct DoublePoint guest;
    util_localCurToGuest(&guest);

    if (!g_state.stopVideo &&
      g_state.kvmfrFeatures & KVMFR_FEATURE_SETCURSORPOS)
    {
      const KVMFRSetCursorPos msg = {
        .msg.type = KVMFR_MESSAGE_SETCURSORPOS,
        .x        = round(guest.x),
        .y        = round(guest.y)
      };

      uint32_t setPosSerial;
      LGMP_STATUS status;
      if ((status = lgmpClientSendData(g_state.pointerQueue,
            &msg, sizeof(msg), &setPosSerial)) != LGMP_OK)
      {
        DEBUG_WARN("Message send failed: %s", lgmpStatusString(status));
        goto fallback;
      }
      else
      {
        /* wait for the move request to be processed */
        g_cursor.realigning = true;
        do
        {
          LG_LOCK(g_state.pointerQueueLock);
          if (!g_state.pointerQueue)
          {
            /* the queue is nolonger valid, assume complete */
            g_cursor.realigning = false;
            LG_UNLOCK(g_state.pointerQueueLock);
            break;
          }

          uint32_t hostSerial;
          if (lgmpClientGetSerial(g_state.pointerQueue, &hostSerial) != LGMP_OK)
          {
            g_cursor.realigning = false;
            LG_UNLOCK(g_state.pointerQueueLock);
            return;
          }
          LG_UNLOCK(g_state.pointerQueueLock);

          if (hostSerial >= setPosSerial)
            break;

          g_state.ds->wait(1);
        }
        while(app_isRunning());

        g_cursor.guest.x    = msg.x;
        g_cursor.guest.y    = msg.y;
        g_cursor.realign    = false;
        g_cursor.realigning = false;
        g_cursor.redraw     = true;

        if (!g_cursor.inWindow)
          return;

        core_setCursorInView(true);
        return;
      }
    }
    else
    {
fallback:
      /* add the difference to the offset */
      ex += guest.x - (g_cursor.guest.x + g_cursor.guest.hx);
      ey += guest.y - (g_cursor.guest.y + g_cursor.guest.hy);
      core_setCursorInView(true);
    }

    g_cursor.realign = false;

    /* don't test for an exit as we just entered, we can get into a enter/exit
     * loop otherwise */
    testExit = false;
  }

  /* if we are in "autoCapture" and the delta was large don't test for exit */
  if (g_params.autoCapture &&
      (fabs(ex) > 20.0 / g_cursor.scale.x || fabs(ey) > 20.0 / g_cursor.scale.y))
    testExit = false;

  /* if any buttons are held we should not allow exit to happen */
  if (g_cursor.buttons)
    testExit = false;

  if (testExit)
  {
    enum LG_DSWarpSupport warpSupport = LG_DS_WARP_NONE;
    app_getProp(LG_DS_WARP_SUPPORT, &warpSupport);

    /* translate the move to the guests orientation */
    struct DoublePoint move = {.x = ex, .y = ey};
    util_rotatePoint(&move);

    /* translate the guests position to our coordinate space */
    struct DoublePoint local;
    util_guestCurToLocal(&local);

    /* check if the move would push the cursor outside the guest's viewport */
    if (
        local.x + move.x <  g_state.dstRect.x ||
        local.y + move.y <  g_state.dstRect.y ||
        local.x + move.x >= g_state.dstRect.x + g_state.dstRect.w ||
        local.y + move.y >= g_state.dstRect.y + g_state.dstRect.h)
    {
      local.x += move.x;
      local.y += move.y;
      const int tx = (local.x <= 0.0) ? floor(local.x) : ceil(local.x);
      const int ty = (local.y <= 0.0) ? floor(local.y) : ceil(local.y);

      switch (warpSupport)
      {
        case LG_DS_WARP_NONE:
          break;

        case LG_DS_WARP_SURFACE:
          g_state.ds->ungrabPointer();
          core_warpPointer(tx, ty, true);

          if (!isInView() &&
              tx >= 0 && tx < g_state.windowW &&
              ty >= 0 && ty < g_state.windowH)
            core_setCursorInView(false);
          break;

        case LG_DS_WARP_SCREEN:
          if (core_isValidPointerPos(
                g_state.windowPos.x + g_state.border.left + tx,
                g_state.windowPos.y + g_state.border.top  + ty))
          {
            core_setCursorInView(false);

            /* preempt the window leave flag if the warp will leave our window */
            if (tx < 0 || ty < 0 || tx > g_state.windowW || ty > g_state.windowH)
              g_cursor.inWindow = false;

            /* ungrab the pointer and move the local cursor to the exit point */
            g_state.ds->ungrabPointer();
            core_warpPointer(tx, ty, true);
            return;
          }
      }
    }
    else if (warpSupport == LG_DS_WARP_SURFACE && isInView())
    {
      /* regrab the pointer in case the user did not move off the surface */
      g_state.ds->grabPointer();
      g_cursor.warpState = WARP_STATE_ON;
    }
  }

  int x, y;
  util_cursorToInt(ex, ey, &x, &y);

  if (x == 0 && y == 0)
    return;

  if (g_params.autoCapture)
  {
    g_cursor.delta.x += x;
    g_cursor.delta.y += y;

    if (fabs(g_cursor.delta.x) > 50.0 || fabs(g_cursor.delta.y) > 50.0)
    {
      g_cursor.delta.x = 0;
      g_cursor.delta.y = 0;
    }
  }
  else
  {
    /* assume the mouse will move to the location we attempt to move it to so we
     * avoid warp out of window issues. The cursorThread will correct this if
     * wrong after the movement has ocurred on the guest */
    g_cursor.guest.x += x;
    g_cursor.guest.y += y;
  }

  if (!purespice_mouseMotion(x, y))
    DEBUG_ERROR("failed to send mouse motion message");
}

void core_resetOverlayInputState(void)
{
  g_state.io->MouseDown[ImGuiMouseButton_Left  ] = false;
  g_state.io->MouseDown[ImGuiMouseButton_Right ] = false;
  g_state.io->MouseDown[ImGuiMouseButton_Middle] = false;
  for(int key = 0; key < ARRAY_LENGTH(g_state.io->KeysDown); key++)
    g_state.io->KeysDown[key] = false;
}

void core_updateOverlayState(void)
{
  g_state.cursorLast = -2;

  static bool wasGrabbed = false;
  if (app_isOverlayMode())
  {
    wasGrabbed = g_cursor.grab;

    g_state.io->ConfigFlags &= ~ImGuiConfigFlags_NoMouse;
    g_state.io->MousePos = (ImVec2) { g_cursor.pos.x, g_cursor.pos.y };

    core_setGrabQuiet(false);
    core_setCursorInView(false);
  }
  else
  {
    g_state.io->ConfigFlags |= ImGuiConfigFlags_NoMouse;
    core_resetOverlayInputState();
    core_setGrabQuiet(wasGrabbed);
    core_invalidatePointer(true);
    app_invalidateWindow(false);

    if (!g_cursor.grab)
    {
      g_cursor.realign = true;
      core_handleMouseNormal(0, 0);
    }
  }
}