// src/render/loop.cpp
#include "loop.h"
#include "../background_dark_inverted.h"
#include "player_positioning.h"
#include "background.h"
#include "mbed.h"
#include "player.h"
#include "player_mask.h"
#include <cstring>

extern BufferedSerial serial_port;
extern DigitalOut led;

// Constants
constexpr size_t BUFFER_SIZE = 64;
constexpr auto CRAWL_DURATION = 300ms;
constexpr auto ANIMATION_TICK = 170ms;
constexpr auto MESSAGE_DISPLAY_DURATION = 1s;
constexpr int PLAYER_X = 9;
constexpr int PLAYER_Y = 6;

// PlayerState is what user pressed. We are mapping CharacterState to it
enum class PlayerState { Walk1, Walk2, Crawl1 };

struct WalkingState {
  PlayerState current_state = PlayerState::Walk1;
  Timer state_timer;
};

static char rx_buffer[BUFFER_SIZE];
static char message[BUFFER_SIZE];
static bool message_active = false;

void draw_mask(const char *unused_filename, int shift, const char *text);

// Returns:
// 0 = no change - walk1
// 1 = normal redraw - walk2
// 2 = button triggered - crawl1
static int read_uart() {
  bool changed = false;
  bool triggered = false;

  // cita spravu z uartu
  if (serial_port.readable()) {
    memset(rx_buffer, 0, sizeof(rx_buffer));
    ssize_t num = serial_port.read(rx_buffer, sizeof(rx_buffer) - 1);
    if (num > 0) {
      led = !led; // toogle ledky
      strncpy(message, rx_buffer, sizeof(message) - 1);
      message_active = true;
      changed = true;
      triggered = true;
    }
  }

  // casovac na 1s zobrazenia spravy
  static Timer msg_timer;
  static bool timer_started = false;
  if (!timer_started) {
    msg_timer.start();
    timer_started = true;
  }

  // po jednu sekundu sa sprava zobrazi
  if (message_active && msg_timer.elapsed_time() > MESSAGE_DISPLAY_DURATION) {
    message_active = false;
    memset(message, 0, sizeof(message));
    msg_timer.reset();
    changed = true;
  }

  if (triggered)
    return 2; // LED toggled press
  if (changed)
    return 1;
  return 0;
}

static bool update_animation(Timer &anim_timer, int &shift, int speed) {
  if (anim_timer.elapsed_time() >= ANIMATION_TICK) {
    // speed determines scroll steps per tick
    shift += speed;
    anim_timer.reset();
    return true;
  }
  return false;
}

static CharacterFrame get_character_frame(PlayerState state) {
  switch (state) {
  case PlayerState::Walk1:
    return CharacterFrame::Walk1;
  case PlayerState::Walk2:
    return CharacterFrame::Walk2;
  case PlayerState::Crawl1:
    return CharacterFrame::Crawl1;
  default:
    return CharacterFrame::Walk1;
  }
}

static void update_player_state(WalkingState &state) {
  // stop crawling
  if (state.current_state == PlayerState::Crawl1 &&
      state.state_timer.elapsed_time() >= CRAWL_DURATION) {
    state.current_state = PlayerState::Walk1;
    state.state_timer.stop();
  }
}

static void toggle_walk_frame(WalkingState &state) {
  if (state.current_state == PlayerState::Walk1) {
    state.current_state = PlayerState::Walk2;
  } else if (state.current_state == PlayerState::Walk2) {
    state.current_state = PlayerState::Walk1;
  }
}

static void start_crawl(WalkingState &state) {
  state.current_state = PlayerState::Crawl1;
  state.state_timer.reset();
  state.state_timer.start();
}

void render_loop(int speed) {
  WalkingState player_state;

  Timer anim_timer;
  anim_timer.start();
  int shift = 0;

  CharacterPosition pos = {PLAYER_X, PLAYER_Y};

  const char *bg_file = "background_dark_inverted.txt";
  bool need_redraw = false;

  while (true) {
    need_redraw = false;
    int uart_state = read_uart(); // returns 0/1/2

    if (uart_state == 1) {
      need_redraw = true;
    }

    if (uart_state == 2) {
      // start crawl frame for x time
      start_crawl(player_state);
      need_redraw = true;
    }

    // Check if crawl duration expired
    update_player_state(player_state);

    if (update_animation(anim_timer, shift, speed)) {
      need_redraw = true;
    }

    if (need_redraw) {
      draw_mask(bg_file, shift, message_active ? message : nullptr);
      CharacterFrame player_frame = get_character_frame(player_state.current_state);
      CharacterPosition draw_pos = get_aligned_frame_position(pos, player_frame);
      draw_character(draw_pos.x, draw_pos.y, player_frame);

      // alternate between frame 0 and 1 when not crawling
      if (player_state.current_state != PlayerState::Crawl1) {
        toggle_walk_frame(player_state);
      }

      ThisThread::sleep_for(50ms);
    }

    ThisThread::sleep_for(25ms);
  }
}