feat: only send HID reports to one endpoint

Added some utility functions and an event for tracking the state of the
USB connection.

Updated endpoints.c to select a single endpoint to send HID reports to
based on the status of the USB and BLE connections. Partially fixes #206.

Future commits will add a user setting to control which endpoint is used if
both USB and BLE are ready.

1 files changed, 112 insertions, 28 deletions

diff --git a/app/src/endpoints.c b/app/src/endpoints.c
index 79d294e..4f56aa5 100644
--- a/app/src/endpoints.c
+++ b/app/src/endpoints.c
@@ -8,54 +8,138 @@
 #include <zmk/hid.h>
 #include <zmk/usb.h>
 #include <zmk/hog.h>
+#include <zmk/event-manager.h>
+#include <zmk/events/usb-conn-state-changed.h>
 
 #include <logging/log.h>
 LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 
-int zmk_endpoints_send_report(u8_t usage_page) {
-    int err;
-    struct zmk_hid_keypad_report *keypad_report;
-    struct zmk_hid_consumer_report *consumer_report;
-    LOG_DBG("usage page 0x%02X", usage_page);
-    switch (usage_page) {
-    case USAGE_KEYPAD:
-        keypad_report = zmk_hid_get_keypad_report();
-#ifdef CONFIG_ZMK_USB
-        if (zmk_usb_hid_send_report((u8_t *)keypad_report, sizeof(struct zmk_hid_keypad_report)) !=
-            0) {
-            LOG_DBG("USB Send Failed");
+enum endpoint {
+    ENDPOINT_USB,
+    ENDPOINT_BLE,
+};
+
+static enum endpoint current_endpoint =
+    COND_CODE_1(IS_ENABLED(CONFIG_ZMK_BLE), (ENDPOINT_BLE), (ENDPOINT_USB));
+
+static int send_keypad_report() {
+    struct zmk_hid_keypad_report *keypad_report = zmk_hid_get_keypad_report();
+
+    switch (current_endpoint) {
+#if IS_ENABLED(CONFIG_ZMK_USB)
+    case ENDPOINT_USB: {
+        int err = zmk_usb_hid_send_report((u8_t *)keypad_report, sizeof(*keypad_report));
+        if (err) {
+            LOG_ERR("FAILED TO SEND OVER USB: %d", err);
         }
-#endif /* CONFIG_ZMK_USB */
+        return err;
+    }
+#endif /* IS_ENABLED(CONFIG_ZMK_USB) */
 
-#ifdef CONFIG_ZMK_BLE
-        err = zmk_hog_send_keypad_report(&keypad_report->body);
+#if IS_ENABLED(CONFIG_ZMK_BLE)
+    case ENDPOINT_BLE: {
+        int err = zmk_hog_send_keypad_report(&keypad_report->body);
         if (err) {
             LOG_ERR("FAILED TO SEND OVER HOG: %d", err);
         }
-#endif /* CONFIG_ZMK_BLE */
+        return err;
+    }
+#endif /* IS_ENABLED(CONFIG_ZMK_BLE) */
 
-        break;
-    case USAGE_CONSUMER:
-        consumer_report = zmk_hid_get_consumer_report();
-#ifdef CONFIG_ZMK_USB
-        if (zmk_usb_hid_send_report((u8_t *)consumer_report,
-                                    sizeof(struct zmk_hid_consumer_report)) != 0) {
-            LOG_DBG("USB Send Failed");
+    default:
+        LOG_ERR("Unsupported endpoint %d", current_endpoint);
+        return -ENOTSUP;
+    }
+}
+
+static int send_consumer_report() {
+    struct zmk_hid_consumer_report *consumer_report = zmk_hid_get_consumer_report();
+
+    switch (current_endpoint) {
+#if IS_ENABLED(CONFIG_ZMK_USB)
+    case ENDPOINT_USB: {
+        int err = zmk_usb_hid_send_report((u8_t *)consumer_report, sizeof(*consumer_report));
+        if (err) {
+            LOG_ERR("FAILED TO SEND OVER USB: %d", err);
         }
-#endif /* CONFIG_ZMK_USB */
+        return err;
+    }
+#endif /* IS_ENABLED(CONFIG_ZMK_USB) */
 
-#ifdef CONFIG_ZMK_BLE
-        err = zmk_hog_send_consumer_report(&consumer_report->body);
+#if IS_ENABLED(CONFIG_ZMK_BLE)
+    case ENDPOINT_BLE: {
+        int err = zmk_hog_send_consumer_report(&consumer_report->body);
         if (err) {
             LOG_ERR("FAILED TO SEND OVER HOG: %d", err);
         }
-#endif /* CONFIG_ZMK_BLE */
+        return err;
+    }
+#endif /* IS_ENABLED(CONFIG_ZMK_BLE) */
+
+    default:
+        LOG_ERR("Unsupported endpoint %d", current_endpoint);
+        return -ENOTSUP;
+    }
+}
+
+int zmk_endpoints_send_report(u8_t usage_page) {
 
-        break;
+    LOG_DBG("usage page 0x%02X", usage_page);
+    switch (usage_page) {
+    case USAGE_KEYPAD:
+        return send_keypad_report();
+    case USAGE_CONSUMER:
+        return send_consumer_report();
     default:
         LOG_ERR("Unsupported usage page %d", usage_page);
         return -ENOTSUP;
     }
+}
+
+static bool is_usb_ready() {
+#if IS_ENABLED(CONFIG_ZMK_USB)
+    return zmk_usb_is_hid_ready();
+#else
+    return false;
+#endif
+}
+
+static bool is_ble_ready() {
+#if IS_ENABLED(CONFIG_ZMK_BLE)
+    return zmk_ble_active_profile_is_connected();
+#else
+    return false;
+#endif
+}
+
+static enum endpoint get_selected_endpoint() {
+    if (is_ble_ready()) {
+        if (is_usb_ready()) {
+            LOG_DBG("Both endpoints ready. Selecting USB");
+            // TODO: add user setting to control this
+            return ENDPOINT_USB;
+        }
+
+        return ENDPOINT_BLE;
+    }
+
+    return ENDPOINT_USB;
+}
+
+static int endpoint_listener(const struct zmk_event_header *eh) {
+    enum endpoint new_endpoint = get_selected_endpoint();
+
+    if (new_endpoint != current_endpoint) {
+        // TODO: send null report on previous endpoint
+        current_endpoint = new_endpoint;
+        LOG_INF("Endpoint changed: %d", current_endpoint);
+    }
 
     return 0;
 }
+
+ZMK_LISTENER(endpoint_listener, endpoint_listener);
+#if IS_ENABLED(CONFIG_USB)
+ZMK_SUBSCRIPTION(endpoint_listener, usb_conn_state_changed);
+#endif
+// TODO: add BLE state subscription
\ No newline at end of file