#include "display.h"
#include "config.h"
#include "game_logic.h"
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

static Adafruit_SSD1306 oled(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);
static unsigned long lastUpdateMs = 0;

// ── Screens ─────────────────────────────────────────────────────────

static void screenSplash() {
  oled.clearDisplay();
  oled.setTextColor(SSD1306_WHITE);

  oled.setTextSize(2);
  oled.setCursor(8, 10);
  oled.print("HEISSER");
  oled.setCursor(20, 30);
  oled.print("DRAHT");

  oled.setTextSize(1);
  oled.setCursor(48, 52);
  oled.print(VERSION_STR);

  oled.display();
}

static void screenIdle() {
  oled.clearDisplay();
  oled.setTextColor(SSD1306_WHITE);

  oled.setTextSize(2);
  oled.setCursor(8, 5);
  oled.print("HEISSER");
  oled.setCursor(20, 23);
  oled.print("DRAHT");

  // Blinking "Druecke START"
  if ((millis() / 500) % 2 == 0) {
    oled.setTextSize(1);
    oled.setCursor(12, 50);
    oled.print("Druecke START");
  }

  oled.display();
}

static void screenCountdown() {
  GameData& gd = gameGetData();
  oled.clearDisplay();
  oled.setTextColor(SSD1306_WHITE);

  if (gd.countdownValue > 0) {
    oled.setTextSize(4);
    oled.setCursor(52, 16);
    oled.print(gd.countdownValue);
  } else {
    oled.setTextSize(3);
    oled.setCursor(36, 20);
    oled.print("GO!");
  }

  oled.display();
}

static void screenPlaying() {
  GameData& gd = gameGetData();
  oled.clearDisplay();
  oled.setTextColor(SSD1306_WHITE);

  // Timer MM:SS
  unsigned long remainMs = 0;
  unsigned long totalMs = (unsigned long)GAME_DURATION_S * 1000UL;
  if (gd.elapsedMs < totalMs) remainMs = totalMs - gd.elapsedMs;
  uint8_t mins = (remainMs / 1000) / 60;
  uint8_t secs = (remainMs / 1000) % 60;

  oled.setTextSize(1);
  oled.setCursor(0, 0);
  oled.print("Zeit: ");
  if (mins < 10) oled.print('0');
  oled.print(mins);
  oled.print(':');
  if (secs < 10) oled.print('0');
  oled.print(secs);

  // Strikes
  oled.setCursor(0, 14);
  oled.print("Fehler: ");
  oled.print(gd.strikes);
  oled.print('/');
  oled.print(MAX_STRIKES);

  // Score (large)
  oled.setTextSize(3);
  oled.setCursor(10, 34);
  oled.print(gd.score);

  oled.display();
}

static void screenGameOver() {
  GameData& gd = gameGetData();
  oled.clearDisplay();
  oled.setTextColor(SSD1306_WHITE);

  oled.setTextSize(1);
  oled.setCursor(20, 0);
  oled.print(gd.won ? "GESCHAFFT!" : "GAME OVER!");

  // Final score
  oled.setTextSize(2);
  oled.setCursor(10, 14);
  oled.print("Score:");
  oled.print(gd.score);

  // Stats
  oled.setTextSize(1);
  unsigned long totalSec = gd.elapsedMs / 1000;
  oled.setCursor(0, 36);
  oled.print("Zeit: ");
  oled.print(totalSec);
  oled.print("s  Fehler: ");
  oled.print(gd.strikes);

  // Restart hint (blinking)
  if ((millis() / 600) % 2 == 0) {
    oled.setCursor(8, 54);
    oled.print("START = Nochmal");
  }

  oled.display();
}

// ── Public API ──────────────────────────────────────────────────────

void displayInit() {
  Wire.begin(PIN_SDA, PIN_SCL);

  if (!oled.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR)) {
    Serial.println("[OLED] Init FAILED");
    return;
  }

  Serial.println("[OLED] Init OK");
  screenSplash();
  delay(1500);
}

void displayUpdate() {
  unsigned long now = millis();
  if (now - lastUpdateMs < DISPLAY_UPDATE_MS) return;
  lastUpdateMs = now;

  GameData& gd = gameGetData();
  switch (gd.state) {
    case STATE_IDLE:      screenIdle(); break;
    case STATE_COUNTDOWN: screenCountdown(); break;
    case STATE_PLAYING:   screenPlaying(); break;
    case STATE_GAME_OVER: screenGameOver(); break;
  }
}