1 files changed, 95 insertions, 0 deletions
diff --git a/src/tangara/input/input_trigger.cpp b/src/tangara/input/input_trigger.cpp
new file mode 100644
index 00000000..eb67bcca
--- /dev/null
+++ b/src/tangara/input/input_trigger.cpp
@@ -0,0 +1,95 @@
+/*
+ * Copyright 2024 jacqueline <me@jacqueline.id.au>
+ *
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+#include "input/input_trigger.hpp"
+
+#include <cstdint>
+
+#include "esp_timer.h"
+
+namespace input {
+
+Trigger::Trigger()
+    : touch_time_ms_(),
+      was_pressed_(false),
+      was_double_click_(false),
+      times_long_pressed_(0) {}
+
+auto Trigger::update(bool is_pressed) -> State {
+  // Bail out early if we're in a steady-state of not pressed.
+  if (!is_pressed && !was_pressed_) {
+    was_double_click_ = false;
+    times_long_pressed_ = 0;
+    return State::kNone;
+  }
+
+  uint64_t now_ms = esp_timer_get_time() / 1000;
+
+  // This key wasn't being pressed, but now it is.
+  if (is_pressed && !was_pressed_) {
+    // Is this a double click?
+    if (now_ms - *touch_time_ms_ < kDoubleClickDelayMs) {
+      // Don't update touch_time_ms_, since we don't want triple clicks to
+      // register as double clicks.
+      was_double_click_ = true;
+      was_pressed_ = true;
+      return State::kDoubleClick;
+    }
+    // Not a double click; update our accounting info and wait for the next
+    // call.
+    touch_time_ms_ = now_ms;
+    was_double_click_ = false;
+    times_long_pressed_ = 0;
+    was_pressed_ = true;
+    return State::kNone;
+  }
+
+  // The key was released. If there were no long-press events fired during the
+  // press, then this was a standard click.
+  if (!is_pressed && was_pressed_) {
+    was_pressed_ = false;
+    if (!was_double_click_ && times_long_pressed_ == 0) {
+      return State::kClick;
+    } else {
+      return State::kNone;
+    }
+  }
+
+  // Now the more complicated case: the user is continuing to press the button.
+  if (times_long_pressed_ == 0) {
+    // We haven't fired yet, so we wait for the long-press event.
+    if (now_ms - *touch_time_ms_ >= kLongPressDelayMs) {
+      times_long_pressed_++;
+      return State::kLongPress;
+    }
+  } else {
+    // We've already fired at least once. How long has the user been holding
+    // the key for?
+    uint64_t time_since_long_press =
+        now_ms - (*touch_time_ms_ + kLongPressDelayMs);
+
+    // How many times should we have fired?
+    // 1 initial fire (for the long-press), plus one additional fire every
+    // kRepeatDelayMs since the long-press event.
+    uint16_t expected_times_fired =
+        1 + (time_since_long_press / kRepeatDelayMs);
+    if (times_long_pressed_ < expected_times_fired) {
+      times_long_pressed_++;
+      return State::kRepeatPress;
+    }
+  }
+
+  return State::kNone;
+}
+
+auto Trigger::cancel() -> void {
+  touch_time_ms_.reset();
+  was_pressed_ = false;
+  was_double_click_ = false;
+  times_long_pressed_ = 0;
+}
+
+}  // namespace input