#include <Arduino.h>
#include <ESP8266HTTPClient.h>
#include <ESP8266WiFi.h>
#include <U8g2lib.h>

#include "PulseTimer.h"
#include "config.h"

namespace {

constexpr uint8_t kOledAddress = 0x3C;
constexpr uint8_t kPinEncoderA = 14;
constexpr uint8_t kPinEncoderB = 13;
constexpr uint8_t kPinButton = 12;
constexpr uint8_t kPinSda = 4;
constexpr uint8_t kPinScl = 5;

constexpr unsigned long kDisplayRefreshMs = 150;
constexpr unsigned long kWifiRetryMs = 10000;
constexpr unsigned long kButtonDebounceMs = 35;
constexpr unsigned long kStatusHoldMs = 2500;

uint16_t timerMs = trbc::clampTimerMs(INITIAL_TIMER_MS);
bool needsDisplayUpdate = true;
unsigned long lastDisplayRefresh = 0;
unsigned long lastWifiAttempt = 0;
unsigned long statusUntil = 0;
String statusLine = "Bereit";

uint8_t lastEncoderState = 0;
int8_t encoderAccumulator = 0;
bool lastButtonReading = HIGH;
bool stableButtonState = HIGH;
unsigned long lastButtonChange = 0;

U8G2_SSD1309_128X64_NONAME0_F_HW_I2C display(U8G2_R0, U8X8_PIN_NONE, kPinScl, kPinSda);

void setStatus(const String &text) {
  statusLine = text;
  statusUntil = millis() + kStatusHoldMs;
  needsDisplayUpdate = true;
}

String formatTimer() {
  const uint16_t seconds = timerMs / 1000;
  const uint16_t tenths = (timerMs % 1000) / 100;
  return String(seconds) + "." + String(tenths) + " S";
}

String wifiStatus() {
  if (WiFi.status() == WL_CONNECTED) {
    return String("IP ") + WiFi.localIP().toString();
  }
  return "WLAN verbindet";
}

void refreshDisplay() {
  display.clearBuffer();
  display.setFont(u8g2_font_6x10_tf);
  display.drawStr(0, 10, "TASMOTA PULSE");
  display.drawStr(0, 26, ("ZEIT " + formatTimer()).c_str());
  display.drawStr(0, 42, wifiStatus().c_str());
  display.drawStr(0, 58, (millis() < statusUntil ? statusLine : "DRUECKEN START").c_str());
  display.sendBuffer();
}

void connectWifi() {
  if (WiFi.status() == WL_CONNECTED) {
    return;
  }
  if (millis() - lastWifiAttempt < kWifiRetryMs && lastWifiAttempt != 0) {
    return;
  }
  lastWifiAttempt = millis();
  WiFi.mode(WIFI_STA);
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  needsDisplayUpdate = true;
}

bool sendTasmotaCommand(const String &command) {
  if (WiFi.status() != WL_CONNECTED) {
    return false;
  }

  WiFiClient client;
  HTTPClient http;
  const String url = String("http://") + TASMOTA_HOST + "/cm?cmnd=" + command;
  if (!http.begin(client, url)) {
    return false;
  }
  const int code = http.GET();
  http.end();
  return code >= 200 && code < 300;
}

void triggerPulse() {
  setStatus("SENDE...");
  const uint16_t pulseValue = trbc::tasmotaPulseTimeValue(timerMs);
  const bool pulseOk = sendTasmotaCommand("PulseTime1%20" + String(pulseValue));
  const bool powerOk = pulseOk && sendTasmotaCommand("Power1%20ON");
  setStatus(powerOk ? "GETRIGGERT" : "FEHLER");
}

void readEncoder() {
  const uint8_t state = (digitalRead(kPinEncoderA) << 1) | digitalRead(kPinEncoderB);
  if (state == lastEncoderState) {
    return;
  }

  const uint8_t transition = (lastEncoderState << 2) | state;
  if (transition == 0b0001 || transition == 0b0111 || transition == 0b1110 || transition == 0b1000) {
    encoderAccumulator++;
  } else if (transition == 0b0010 || transition == 0b1011 || transition == 0b1101 || transition == 0b0100) {
    encoderAccumulator--;
  }
  lastEncoderState = state;

  if (encoderAccumulator >= 4 || encoderAccumulator <= -4) {
    const int ticks = encoderAccumulator / 4;
    encoderAccumulator = 0;
    timerMs = trbc::adjustTimerMs(timerMs, ticks);
    needsDisplayUpdate = true;
  }
}

void readButton() {
  const bool reading = digitalRead(kPinButton);
  if (reading != lastButtonReading) {
    lastButtonChange = millis();
    lastButtonReading = reading;
  }
  if (millis() - lastButtonChange <= kButtonDebounceMs || reading == stableButtonState) {
    return;
  }

  stableButtonState = reading;
  if (stableButtonState == LOW) {
    triggerPulse();
  }
}

} // namespace

void setup() {
  Serial.begin(115200);
  pinMode(kPinEncoderA, INPUT_PULLUP);
  pinMode(kPinEncoderB, INPUT_PULLUP);
  pinMode(kPinButton, INPUT_PULLUP);

  lastEncoderState = (digitalRead(kPinEncoderA) << 1) | digitalRead(kPinEncoderB);

  display.setI2CAddress(kOledAddress << 1);
  display.begin();
  connectWifi();
  refreshDisplay();
}

void loop() {
  connectWifi();
  readEncoder();
  readButton();

  if (needsDisplayUpdate || millis() - lastDisplayRefresh >= kDisplayRefreshMs) {
    refreshDisplay();
    lastDisplayRefresh = millis();
    needsDisplayUpdate = false;
  }
  delay(2);
}