pyxis/lib/tdeck_ui/Hardware/TDeck/Trackball.cpp

// Copyright (c) 2024 microReticulum contributors
// SPDX-License-Identifier: MIT

#include "Trackball.h"

#ifdef ARDUINO

#include "Log.h"
#include <driver/gpio.h>

using namespace RNS;

namespace Hardware {
namespace TDeck {

// Static member initialization
lv_indev_t* Trackball::_indev = nullptr;
volatile int16_t Trackball::_pulse_up = 0;
volatile int16_t Trackball::_pulse_down = 0;
volatile int16_t Trackball::_pulse_left = 0;
volatile int16_t Trackball::_pulse_right = 0;
volatile uint32_t Trackball::_last_pulse_time = 0;

bool Trackball::_button_pressed = false;
uint32_t Trackball::_last_button_time = 0;
Trackball::State Trackball::_state;
bool Trackball::_initialized = false;

bool Trackball::init() {
    if (_initialized) {
        return true;
    }

    INFO("Initializing T-Deck trackball");

    // Initialize hardware first
    if (!init_hardware_only()) {
        return false;
    }

    // Register LVGL input device as KEYPAD for focus navigation
    static lv_indev_drv_t indev_drv;
    lv_indev_drv_init(&indev_drv);
    indev_drv.type = LV_INDEV_TYPE_KEYPAD;  // KEYPAD for 2D focus navigation
    indev_drv.read_cb = lvgl_read_cb;

    _indev = lv_indev_drv_register(&indev_drv);
    if (!_indev) {
        ERROR("Failed to register trackball with LVGL");
        return false;
    }

    INFO("Trackball initialized successfully");
    return true;
}

bool Trackball::init_hardware_only() {
    if (_initialized) {
        return true;
    }

    INFO("Initializing trackball hardware");

    // Use ESP-IDF gpio driver for reliable interrupt handling on strapping pins
    gpio_config_t io_conf = {};
    io_conf.intr_type = GPIO_INTR_NEGEDGE;  // Falling edge trigger
    io_conf.mode = GPIO_MODE_INPUT;
    io_conf.pull_up_en = GPIO_PULLUP_ENABLE;
    io_conf.pull_down_en = GPIO_PULLDOWN_DISABLE;

    // Configure all trackball directional pins
    io_conf.pin_bit_mask = (1ULL << Pin::TRACKBALL_UP) |
                           (1ULL << Pin::TRACKBALL_DOWN) |
                           (1ULL << Pin::TRACKBALL_LEFT) |
                           (1ULL << Pin::TRACKBALL_RIGHT);
    gpio_config(&io_conf);

    // Configure button separately (just input with pullup, no interrupt)
    gpio_config_t btn_conf = {};
    btn_conf.intr_type = GPIO_INTR_DISABLE;
    btn_conf.mode = GPIO_MODE_INPUT;
    btn_conf.pull_up_en = GPIO_PULLUP_ENABLE;
    btn_conf.pull_down_en = GPIO_PULLDOWN_DISABLE;
    btn_conf.pin_bit_mask = (1ULL << Pin::TRACKBALL_BUTTON);
    gpio_config(&btn_conf);

    // Install GPIO ISR service
    gpio_install_isr_service(0);

    // Attach ISR handlers
    gpio_isr_handler_add((gpio_num_t)Pin::TRACKBALL_UP, isr_up, nullptr);
    gpio_isr_handler_add((gpio_num_t)Pin::TRACKBALL_DOWN, isr_down, nullptr);
    gpio_isr_handler_add((gpio_num_t)Pin::TRACKBALL_LEFT, isr_left, nullptr);
    gpio_isr_handler_add((gpio_num_t)Pin::TRACKBALL_RIGHT, isr_right, nullptr);

    // Initialize state
    _state.delta_x = 0;
    _state.delta_y = 0;
    _state.button_pressed = false;
    _state.timestamp = millis();

    _initialized = true;
    INFO("  Trackball hardware ready");
    return true;
}

bool Trackball::poll() {
    if (!_initialized) {
        return false;
    }

    bool state_changed = false;
    uint32_t now = millis();

    // Read pulse counters (critical section to avoid race with ISRs)
    noInterrupts();
    int16_t up = _pulse_up;
    int16_t down = _pulse_down;
    int16_t left = _pulse_left;
    int16_t right = _pulse_right;
    uint32_t last_pulse = _last_pulse_time;
    interrupts();


    // Calculate net movement
    int16_t delta_y = down - up;  // Positive = down, negative = up
    int16_t delta_x = right - left;  // Positive = right, negative = left

    // Apply sensitivity multiplier
    delta_x *= Trk::PIXELS_PER_PULSE;
    delta_y *= Trk::PIXELS_PER_PULSE;

    // Update state if movement detected
    if (delta_x != 0 || delta_y != 0) {
        _state.delta_x = delta_x;
        _state.delta_y = delta_y;
        _state.timestamp = now;
        state_changed = true;

        // Reset pulse counters after reading
        noInterrupts();
        _pulse_up = 0;
        _pulse_down = 0;
        _pulse_left = 0;
        _pulse_right = 0;
        interrupts();
    } else {
        // Reset deltas if no recent pulses (timeout)
        if (now - last_pulse > Trk::PULSE_RESET_MS) {
            if (_state.delta_x != 0 || _state.delta_y != 0) {
                _state.delta_x = 0;
                _state.delta_y = 0;
                state_changed = true;
            }
        }
    }

    // Read button state with debouncing
    bool button = read_button_debounced();
    if (button != _state.button_pressed) {
        _state.button_pressed = button;
        state_changed = true;
    }

    return state_changed;
}

void Trackball::get_state(State& state) {
    state = _state;
}

void Trackball::reset_deltas() {
    _state.delta_x = 0;
    _state.delta_y = 0;
}

bool Trackball::is_button_pressed() {
    return _state.button_pressed;
}

lv_indev_t* Trackball::get_indev() {
    return _indev;
}

void Trackball::lvgl_read_cb(lv_indev_drv_t* drv, lv_indev_data_t* data) {
    // Static accumulators for threshold-based navigation
    static int16_t accum_x = 0;
    static int16_t accum_y = 0;
    static uint32_t last_key_time = 0;
    // Key press/release state machine
    static uint32_t pending_key = 0;      // Key waiting to be pressed
    static uint32_t pressed_key = 0;      // Key currently pressed (needs release)
    static bool button_was_pressed = false;  // Track physical button state for release
    // Poll for new trackball data
    poll();

    // Get current state
    State state;
    get_state(state);

    // Accumulate movement (convert back from pixels to pulses)
    accum_x += state.delta_x / Trk::PIXELS_PER_PULSE;
    accum_y += state.delta_y / Trk::PIXELS_PER_PULSE;

    // Button handling - trigger on release only to avoid double-activation
    // When screen changes on press, release would hit new screen's focused element
    if (state.button_pressed) {
        button_was_pressed = true;
        // Don't send anything yet, wait for release
    } else if (button_was_pressed) {
        // Button just released - queue ENTER key for press/release cycle
        button_was_pressed = false;
        pending_key = LV_KEY_ENTER;
        // Fall through to let pending_key logic handle it
    }

    // Check if we need to release a previously pressed navigation key
    if (pressed_key != 0) {
        data->key = pressed_key;
        data->state = LV_INDEV_STATE_RELEASED;
        pressed_key = 0;
        reset_deltas();
        return;
    }

    // Check if we have a pending key to press
    if (pending_key != 0) {
        data->key = pending_key;
        data->state = LV_INDEV_STATE_PRESSED;
        pressed_key = pending_key;  // Mark for release on next callback
        pending_key = 0;
        reset_deltas();
        return;
    }

    uint32_t now = millis();

    // Check thresholds - use NEXT/PREV for group focus navigation
    // LVGL groups only support linear navigation with NEXT/PREV
    if (abs(accum_y) >= Trk::NAV_THRESHOLD && abs(accum_y) >= abs(accum_x)) {
        if (now - last_key_time >= Trk::KEY_REPEAT_MS) {
            pending_key = (accum_y > 0) ? LV_KEY_NEXT : LV_KEY_PREV;
            last_key_time = now;
        }
        accum_y = 0;
    } else if (abs(accum_x) >= Trk::NAV_THRESHOLD) {
        if (now - last_key_time >= Trk::KEY_REPEAT_MS) {
            pending_key = (accum_x > 0) ? LV_KEY_NEXT : LV_KEY_PREV;
            last_key_time = now;
        }
        accum_x = 0;
    }

    // If we have a pending key, check if anything visible is focused
    // If nothing is focused or focused object is hidden, find a visible object
    if (pending_key != 0) {
        lv_group_t* group = lv_group_get_default();
        if (group) {
            lv_obj_t* focused = lv_group_get_focused(group);
            bool need_refocus = !focused;

            // Check if focused object or any parent is hidden
            if (focused && !need_refocus) {
                lv_obj_t* obj = focused;
                while (obj) {
                    if (lv_obj_has_flag(obj, LV_OBJ_FLAG_HIDDEN)) {
                        need_refocus = true;
                        break;
                    }
                    obj = lv_obj_get_parent(obj);
                }
            }

            if (need_refocus) {
                // Find first visible object in group
                uint32_t obj_cnt = lv_group_get_obj_count(group);
                for (uint32_t i = 0; i < obj_cnt; i++) {
                    lv_group_focus_next(group);
                    lv_obj_t* candidate = lv_group_get_focused(group);
                    if (candidate) {
                        bool visible = true;
                        lv_obj_t* obj = candidate;
                        while (obj) {
                            if (lv_obj_has_flag(obj, LV_OBJ_FLAG_HIDDEN)) {
                                visible = false;
                                break;
                            }
                            obj = lv_obj_get_parent(obj);
                        }
                        if (visible) break;  // Found a visible object
                    }
                }
                pending_key = 0;  // Don't send the key, just focus
                accum_x = 0;
                accum_y = 0;
            }
        }
    }

    // Default: no key activity
    data->key = 0;
    data->state = LV_INDEV_STATE_RELEASED;
    reset_deltas();
}

bool Trackball::read_button_debounced() {
    bool current = (digitalRead(Pin::TRACKBALL_BUTTON) == LOW);  // Active low
    uint32_t now = millis();

    // Debounce: only accept change if stable for debounce period
    if (current != _button_pressed) {
        if (now - _last_button_time > Trk::DEBOUNCE_MS) {
            _last_button_time = now;
            return current;
        }
    } else {
        _last_button_time = now;
    }

    return _button_pressed;
}

// ISR handlers - MUST be in IRAM for ESP32
// ESP-IDF gpio_isr_handler signature requires void* arg
void IRAM_ATTR Trackball::isr_up(void* arg) {
    _pulse_up++;
    _last_pulse_time = millis();
}

void IRAM_ATTR Trackball::isr_down(void* arg) {
    _pulse_down++;
    _last_pulse_time = millis();
}

void IRAM_ATTR Trackball::isr_left(void* arg) {
    _pulse_left++;
    _last_pulse_time = millis();
}

void IRAM_ATTR Trackball::isr_right(void* arg) {
    _pulse_right++;
    _last_pulse_time = millis();
}

} // namespace TDeck
} // namespace Hardware

#endif // ARDUINO