#include "SignalProbe.h"
#include "Config.h"
#include <esp32-hal-cpu.h>

namespace {
constexpr uint32_t DISPLAY_INTERVAL_MS = 250;
constexpr uint8_t PERIOD_TOLERANCE_PCT = 10;

bool pwmPointAvailable(uint32_t frequencyHz, uint32_t pulseNs) {
  return static_cast<uint64_t>(frequencyHz) * pulseNs < 1000000000ULL;
}

void formatWidth(uint64_t nanoseconds, char *out, size_t size) {
  if (nanoseconds < 1000ULL)
    snprintf(out, size, "%lluns", nanoseconds);
  else if (nanoseconds < 1000000ULL)
    snprintf(out, size, "%.2fus", nanoseconds / 1000.0);
  else
    snprintf(out, size, "%.2fms", nanoseconds / 1000000.0);
}

void formatPulseCount(uint64_t count, char *out, size_t size) {
  if (count < 1000000ULL) snprintf(out, size, "%llu", count);
  else if (count < 1000000000ULL) snprintf(out, size, "%lluM", count / 1000000ULL);
  else snprintf(out, size, "%lluG", count / 1000000000ULL);
}
}

SignalProbe::SignalProbe() : startButton_(GPIO_BUTTON_START),
  modeButton_(GPIO_BUTTON_MODE) {}

void SignalProbe::begin() {
  Serial.begin(SERIAL_BAUD);
#if ARDUINO_USB_CDC_ON_BOOT
  Serial.setTxTimeoutMs(SERIAL_TX_TIMEOUT_MS);
#endif
  setCpuFrequencyMhz(160);
  startButton_.begin();
  modeButton_.begin();
  pwm_.begin();
  pwm_.configureActiveLight(true);
  display_.begin();
  receiverInitialized_ = receiver_.begin();
  rxReady_ = receiverInitialized_ && captureStart();
  applyPwm();
  Serial.printf("Signal probe: MODE short=frequency, MODE long=pulse, START short=reset RX minimum, START long=PWM on/off, hold both=RX active level; RX=%s\n",
    rxActiveHigh_ ? "HIGH" : "LOW");
  show();
}

bool SignalProbe::captureStart() {
  if (!receiver_.startRaw()) {
    Serial.println("RX capture start failed");
    return false;
  }
  havePulseStart_ = false;
  havePulseEnd_ = false;
  extraEdgeInPeriod_ = false;
  return true;
}

void SignalProbe::resetMinimum() {
  if (rxReady_) receiver_.stop();
  rxReady_ = receiverInitialized_ && captureStart();
  minTicks_ = UINT64_MAX;
  pulseCount_ = 0;
  edgeCount_ = 0;
  rejectedPeriods_ = 0;
  displayDirty_ = true;
  Serial.println("RX minimum reset");
}

void SignalProbe::updateCapture() {
  if (!rxReady_) return;
  CaptureEvent edges[64];
  for (uint8_t batch = 0; batch < 8; ++batch) {
    const size_t count = receiver_.readRawEdges(edges, countOf(edges));
    if (!count) break;
    uint64_t batchMinimum = minTicks_;
    uint64_t batchPulses = 0;
    uint64_t batchRejected = 0;
    const bool activeRising = rxActiveHigh_;
    const uint32_t expectedHz = PWM_FREQUENCY_OPTIONS_HZ[frequencyIndex_];
    const uint64_t expectedPeriod = receiver_.tickHz() / expectedHz;
    for (size_t i = 0; i < count; ++i) {
      if (edges[i].rising == activeRising) {
        if (havePulseStart_) {
          const uint64_t period = edges[i].tick - pulseStartTick_;
          const uint64_t width = havePulseEnd_
            ? pulseEndTick_ - pulseStartTick_ : 0;
          const uint64_t error = period > expectedPeriod
            ? period - expectedPeriod : expectedPeriod - period;
          if (havePulseEnd_ && !extraEdgeInPeriod_ && period && width && width < period &&
              error * 100U <= expectedPeriod * PERIOD_TOLERANCE_PCT) {
            if (width < batchMinimum) batchMinimum = width;
            ++batchPulses;
          } else {
            ++batchRejected;
          }
        }
        pulseStartTick_ = edges[i].tick;
        havePulseStart_ = true;
        havePulseEnd_ = false;
        extraEdgeInPeriod_ = false;
      } else if (havePulseStart_ && !havePulseEnd_ &&
                 edges[i].tick > pulseStartTick_) {
        pulseEndTick_ = edges[i].tick;
        havePulseEnd_ = true;
      } else if (havePulseStart_) {
        extraEdgeInPeriod_ = true;
      }
    }
    const uint32_t dropped = receiver_.takeDroppedItems();
    if (dropped) {
      Serial.printf("RX capture overflow: %lu edges lost; restarting capture\n", dropped);
      receiver_.stop();
      rxReady_ = captureStart();
      displayDirty_ = true;
      return;
    }
    edgeCount_ += count;
    pulseCount_ += batchPulses;
    rejectedPeriods_ += batchRejected;
    displayDirty_ = true;
    if (batchMinimum < minTicks_) {
      minTicks_ = batchMinimum;
      displayDirty_ = true;
    }
  }
}

void SignalProbe::applyPwm() {
  pwm_.stop();
  if (!pwmEnabled_) {
    Serial.println("PWM off");
    displayDirty_ = true;
    return;
  }
  const uint32_t frequency = PWM_FREQUENCY_OPTIONS_HZ[frequencyIndex_];
  const uint32_t pulse = MAX_PULSE_OPTIONS_NS[pulseIndex_];
  if (!pwm_.start(frequency, pulse, actual_)) {
    Serial.printf("PWM start failed: %lu Hz, %lu ns\n", frequency, pulse);
    pwmEnabled_ = false;
  } else {
    Serial.printf("PWM GPIO=%u requested=%luHz/%luns actual=%luHz/%luns\n",
      GPIO_PWM, frequency, pulse, actual_.actualHz, actual_.actualPulseNs);
  }
  displayDirty_ = true;
}

void SignalProbe::advanceFrequency() {
  const uint8_t count = static_cast<uint8_t>(countOf(PWM_FREQUENCY_OPTIONS_HZ));
  for (uint8_t step = 0; step < count; ++step) {
    frequencyIndex_ = static_cast<uint8_t>((frequencyIndex_ + 1U) % count);
    if (pwmPointAvailable(PWM_FREQUENCY_OPTIONS_HZ[frequencyIndex_],
                          MAX_PULSE_OPTIONS_NS[pulseIndex_])) break;
  }
  applyPwm();
  resetMinimum();
}

void SignalProbe::advancePulse() {
  const uint8_t count = static_cast<uint8_t>(countOf(MAX_PULSE_OPTIONS_NS));
  for (uint8_t step = 0; step < count; ++step) {
    pulseIndex_ = static_cast<uint8_t>((pulseIndex_ + 1U) % count);
    if (pwmPointAvailable(PWM_FREQUENCY_OPTIONS_HZ[frequencyIndex_],
                          MAX_PULSE_OPTIONS_NS[pulseIndex_])) break;
  }
  applyPwm();
  resetMinimum();
}

void SignalProbe::show() {
  char frequency[16], pulse[16], first[64], second[64];
  const uint32_t shownFrequency = pwm_.running() ? actual_.actualHz
    : PWM_FREQUENCY_OPTIONS_HZ[frequencyIndex_];
  const uint32_t shownPulse = pwm_.running() ? actual_.actualPulseNs
    : MAX_PULSE_OPTIONS_NS[pulseIndex_];
  Display::formatPwmFrequency(shownFrequency,
    frequency, sizeof(frequency));
  Display::formatPulse(shownPulse, pulse, sizeof(pulse));
  snprintf(first, sizeof(first), "PWM%s %s %s", pwmEnabled_ ? "" : " OFF",
    frequency, pulse);
  if (!rxReady_) {
    snprintf(second, sizeof(second), "RX: ERROR");
  } else if (minTicks_ == UINT64_MAX) {
    snprintf(second, sizeof(second), "RX E:%llu BAD:%llu", edgeCount_, rejectedPeriods_);
  } else {
    char width[24], count[12];
    const uint64_t nanoseconds =
      (minTicks_ * 1000000000ULL + receiver_.tickHz() / 2U) / receiver_.tickHz();
    formatWidth(nanoseconds, width, sizeof(width));
    formatPulseCount(pulseCount_, count, sizeof(count));
    snprintf(second, sizeof(second), "MIN:%s N:%s", width, count);
    Serial.printf("RX minimum=%lluns, periods=%llu, rejected=%llu, edges=%llu\n",
      nanoseconds, pulseCount_, rejectedPeriods_, edgeCount_);
  }
  display_.show(first, second, 0, 0, rxActiveHigh_ ? "H" : "L");
  lastDisplayMs_ = millis();
  displayDirty_ = false;
}

void SignalProbe::update() {
  const uint32_t now = millis();
  const ButtonEvent start = startButton_.update(now);
  const ButtonEvent mode = modeButton_.update(now);
  if (startButton_.pressed() && modeButton_.pressed()) {
    if (!bothHeld_) {
      bothHeld_ = true;
      bothHeldSinceMs_ = now;
      startButton_.suppressUntilRelease();
      modeButton_.suppressUntilRelease();
    }
    if (!bothHeldHandled_ && now - bothHeldSinceMs_ >= BUTTON_LONG_PRESS_MS) {
      rxActiveHigh_ = !rxActiveHigh_;
      bothHeldHandled_ = true;
      resetMinimum();
      Serial.printf("RX active level=%s\n", rxActiveHigh_ ? "HIGH" : "LOW");
    }
  } else if (bothHeld_) {
    if (!startButton_.pressed() && !modeButton_.pressed()) {
      bothHeld_ = false;
      bothHeldHandled_ = false;
    }
  } else {
    if (mode == ButtonEvent::SHORT) advanceFrequency();
    else if (mode == ButtonEvent::LONG) advancePulse();
    if (start == ButtonEvent::SHORT) resetMinimum();
    else if (start == ButtonEvent::LONG) {
      pwmEnabled_ = !pwmEnabled_;
      applyPwm();
    }
  }
  updateCapture();
  if (displayDirty_ && now - lastDisplayMs_ >= DISPLAY_INTERVAL_MS) show();
}