#include "lua_host.h"

#include <algorithm>

#include "../settings.h"

extern "C" {
#include <lauxlib.h>
#include <lua.h>
}

namespace {

esp32lua::Paths slatePaths() {
  esp32lua::Paths paths;
  paths.apps = "/.lua/apps";
  paths.data = "/.lua/data";
  paths.lib = "/.lua/lib";
  paths.home = "Home";
  return paths;
}

// Reads an optional positive integer field off the bar module on the stack top.
lua_Integer barField(lua_State *state, const char *key, lua_Integer fallback) {
  lua_getfield(state, -1, key);
  const lua_Integer value =
      lua_isinteger(state, -1) ? lua_tointeger(state, -1) : fallback;
  lua_pop(state, 1);
  return value > 0 ? value : fallback;
}

} // namespace

// Called from the initializer list once every provider member exists, which
// declaration order guarantees: the runtime holds pointers to them for its
// whole life.
esp32lua::Providers LuaHost::wire() {
  esp32lua::Providers providers;
  providers.log = &logProvider;
  providers.settings = &settingsProvider;
  providers.sys = &sysProvider;
  providers.fs = &fsProvider;
  providers.gui = &guiProvider;
  providers.http = &httpProvider;
  providers.timer = &timerProvider;
  providers.wifi = &wifiProvider;
  providers.ble = &bleProvider;
  providers.touch = &touchProvider;
  // No buttons on this board, so sys.hasFeature("buttons") is false and input
  // gains nothing.
  return providers;
}

LuaHost::LuaHost(TFT_eSPI &tft, XPT2046_Touchscreen &touch)
    : tft(tft), touchPanel(touch), settingsProvider(*this),
      guiProvider(tft, *this), touchProvider(touch, *this),
      runtime(wire(), slatePaths()) {}

void LuaHost::mapTouch(const TS_Point &point, int16_t &x, int16_t &y) const {
  const int16_t nx =
      constrain(map(point.y, settings.touchX0, settings.touchX1, 0, PANEL_W), 0,
                PANEL_W - 1);
  const int16_t ny =
      constrain(map(point.x, settings.touchY0, settings.touchY1, 0, PANEL_H), 0,
                PANEL_H - 1);
  switch (tft.getRotation() & 3) {
  case 1:
    x = ny;
    y = PANEL_W - 1 - nx;
    break;
  case 2:
    x = PANEL_W - 1 - nx;
    y = PANEL_H - 1 - ny;
    break;
  case 3:
    x = PANEL_H - 1 - ny;
    y = nx;
    break;
  default:
    x = nx;
    y = ny;
    break;
  }
  // App space starts below the bar, matching the viewport apps draw into. A tap
  // on the bar itself lands at a negative y, which pollTouch() drops.
  y -= barInset();
}

// resetViewport() first: width()/height() report the viewport once one is set,
// so re-applying over an existing one would shrink the app area again every
// time. setRotation() leaves the old viewport metrics behind, so every rotation
// needs this too.
void LuaHost::applyViewport() {
  const int16_t inset = barInset();
  tft.resetViewport();
  if (inset > 0)
    tft.setViewport(0, inset, tft.width(), tft.height() - inset, true);
}

void LuaHost::applyRotation() {
  tft.setRotation(settings.rotationIndex());
  applyViewport();
  refreshStatusBar(); // every slot in the bar just moved
}

void LuaHost::setFullscreen(bool on) {
  fullscreen = on;
  applyViewport();
  nextBarMs = 0; // leaving fullscreen left the bar's rows painted by the app
}

bool LuaHost::begin() {
  prepareForApp();
  if (!runtime.startApp("Home"))
    return false;
  settleNewApp();
  return true;
}

void LuaHost::prepareForApp() {
  tft.setRotation(
      settings.rotationIndex()); // the previous app may have rotated the frame
  fullscreen = false;
  // Applied before the app loads, because init() measures the panel it was
  // given. The height is the last app's, which is the same module, and
  // settleNewApp() corrects it if that changes.
  applyViewport();
  lastTouched = true;   // the tap that launched this app may still be down
  ignoreRelease = true; // and its release is not this app's gesture
  backArmed = false;
  Serial.printf("[lua] launching free=%u largest=%u\n", ESP.getFreeHeap(),
                ESP.getMaxAllocHeap());
}

void LuaHost::settleNewApp() {
  hasBack = runtime.canGoBack(); // the runtime keeps the history; the bar only
                                 // offers the control
  loadStatusBar();
  applyViewport();
  if (barInset() > 0 && !barBroken)
    drawStatusBar();
  const uint32_t now = millis();
  nextDrawMs = now;
  lastDrawMs = now;
  Serial.printf("[lua] running %s\n", runtime.appPath().c_str());
}

// The bar is a Lua module like any other, loaded per app because the state is
// too.
void LuaHost::loadStatusBar() {
  lua_State *state = runtime.state();
  barBroken = false;
  barIntervalMs = BAR_INTERVAL_MS;

  lua_getglobal(state, "require");
  lua_pushstring(state, "statusbar");
  if (lua_pcall(state, 1, 1, 0) != LUA_OK || !lua_istable(state, -1)) {
    Serial.printf("[statusbar] unavailable: %s\n",
                  luaL_tolstring(state, -1, nullptr));
    // Nothing has measured the panel yet, so surrendering the strip here is
    // free.
    barBroken = true;
    barHeight = 0;
    lua_pop(state, 2);
    return;
  }
  barHeight = barField(state, "height", DEFAULT_BAR_H);
  barIntervalMs = std::max<lua_Integer>(
      DRAW_INTERVAL_MS, barField(state, "interval", BAR_INTERVAL_MS));
  lua_setglobal(state, "__statusbar");
  nextBarMs = 0;
}

// Errors here disable the bar rather than killing the app: chrome that fails
// should not take the running program with it.
void LuaHost::drawStatusBar() {
  lua_State *state = runtime.state();
  lua_getglobal(state, "__statusbar");
  lua_getfield(state, -1, "draw");
  lua_remove(state, -2);
  lua_pushboolean(state, hasBack);
  tft.resetViewport(); // the bar paints in panel coordinates, the app does not
  if (lua_pcall(state, 1, 0, 0) != LUA_OK) {
    Serial.printf("[statusbar] %s\n", luaL_tolstring(state, -1, nullptr));
    lua_pop(state, 2);
    barBroken = true;
  }
  applyViewport();
}

// Deliberately not themed: this can fire when the settings naming the theme are
// themselves unreadable, so it stays high contrast.
void LuaHost::fail(const char *message) {
  Serial.printf("[lua] %s\n", message ? message : "(unknown)");
  tft.resetViewport();
  tft.fillScreen(TFT_WHITE);
  tft.setTextSize(2);
  tft.setTextColor(TFT_RED, TFT_WHITE);
  tft.drawString("Lua error:", 8, 8);
  tft.setTextColor(TFT_BLACK, TFT_WHITE);
  tft.drawString(message ? message : "(unknown)", 8, 28);
}

void LuaHost::pollTouch() {
  bool touched = touchPanel.touched();
  if (touched)
    mapTouch(touchPanel.getPoint(), lastX, lastY);

  // The bar is the host's: apps never see a touch in it, and its one control
  // acts on release, so a press that slides off into the app cancels like any
  // other button.
  if (touched && lastY < 0) {
    backArmed = backArmed || inBackButton();
    touched = false;
  } else if (backArmed) {
    backArmed = false;
    if (inBackButton()) {
      runtime.requestBack();
      return;
    }
  }

  if (touched && !lastTouched) {
    movedX = lastX;
    movedY = lastY;
    runtime.callTouch(esp32lua::TouchPhase::Down, lastX, lastY);
  } else if (touched && lastTouched) {
    // The XPT2046 jitters a pixel or two under a still finger. Below this every
    // poll would fire a move, and a painting app would draw a blur where
    // nothing moved.
    if (abs(lastX - movedX) + abs(lastY - movedY) >= MOVE_EPSILON_PX) {
      movedX = lastX;
      movedY = lastY;
      runtime.callTouch(esp32lua::TouchPhase::Move, lastX, lastY);
    }
  } else if (!touched && lastTouched && ignoreRelease) {
    ignoreRelease = false;
  } else if (!touched && lastTouched) {
    // The runtime fires the on_touch tap alias after the release.
    runtime.callTouch(esp32lua::TouchPhase::Up, lastX, lastY);
  }
  lastTouched = touched;
}

void LuaHost::pollTimers() {
  std::vector<esp32lua::TimerId> due;
  timerProvider.collectDue(millis(), due);
  for (size_t at = 0; at < due.size(); at++) {
    runtime.callTimer(due[at]);
    if (runtime.hasPendingNavigation())
      return; // the app is leaving; its other timers can wait
  }
}

void LuaHost::navigate() {
  prepareForApp();
  if (!runtime.applyPendingNavigation()) {
    fail("app failed to start");
    return;
  }
  settleNewApp();
}

void LuaHost::loop() {
  if (!runtime.hasApp())
    return;

  pollTouch();
  if (!runtime.hasPendingNavigation())
    pollTimers();

  const uint32_t now = millis();
  if (!runtime.hasPendingNavigation() && now >= nextDrawMs) {
    nextDrawMs = now + DRAW_INTERVAL_MS;
    runtime.callDraw(static_cast<int32_t>(now - lastDrawMs));
    lastDrawMs = now;
  }

  if (!runtime.hasPendingNavigation() && barInset() > 0 && !barBroken &&
      now >= nextBarMs) {
    nextBarMs = now + barIntervalMs;
    drawStatusBar();
  }

  // Between batches, never inside one: swapping the lua_State mid-callback
  // would free the VM that is still executing.
  if (runtime.hasPendingNavigation())
    navigate();
}