From 9b67c18b5f3b9502f39546b87fecce04937d7760 Mon Sep 17 00:00:00 2001
From: Peter Johanson <peter@peterjohanson.com>
Date: Tue, 17 Dec 2024 18:24:28 -0700
Subject: [PATCH] feat(pointing): Release pressed keys on disconnect

Match the behavior for key press release on split peripheral disconnect,
and track pressed input keys to release them as needed on disconnect.
---
 app/include/zmk/pointing/input_split.h |  3 +-
 app/src/pointing/Kconfig               |  5 +++
 app/src/pointing/input_split.c         | 60 ++++++++++++++++++++++++++
 app/src/split/bluetooth/central.c      |  2 +-
 4 files changed, 68 insertions(+), 2 deletions(-)

diff --git a/app/include/zmk/pointing/input_split.h b/app/include/zmk/pointing/input_split.h
index 812035477e2..235ea4954b1 100644
--- a/app/include/zmk/pointing/input_split.h
+++ b/app/include/zmk/pointing/input_split.h
@@ -7,4 +7,5 @@
 #pragma once
 
 int zmk_input_split_report_peripheral_event(uint8_t reg, uint8_t type, uint16_t code, int32_t value,
-                                            bool sync);
\ No newline at end of file
+                                            bool sync);
+int zmk_input_split_peripheral_disconnected(uint8_t reg);
\ No newline at end of file
diff --git a/app/src/pointing/Kconfig b/app/src/pointing/Kconfig
index b4051e1fcef..9331fd5e7bb 100644
--- a/app/src/pointing/Kconfig
+++ b/app/src/pointing/Kconfig
@@ -73,6 +73,11 @@ config ZMK_INPUT_SPLIT_INIT_PRIORITY
     int "Input Split initialization priority"
     default INPUT_INIT_PRIORITY
 
+
+config ZMK_INPUT_SPLIT_MAX_TRACKED_KEYS
+    int "Input Split max tracked keys to release on peripheral disconnect"
+    default 5
+
 endif # ZMK_INPUT_SPLIT
 
 endif # ZMK_POINTING
diff --git a/app/src/pointing/input_split.c b/app/src/pointing/input_split.c
index 55a84ea4624..f4106c8f5d0 100644
--- a/app/src/pointing/input_split.c
+++ b/app/src/pointing/input_split.c
@@ -26,11 +26,40 @@ struct zis_entry {
 
 static const struct zis_entry proxy_inputs[] = {DT_INST_FOREACH_STATUS_OKAY(ZIS_ENTRY)};
 
+#define PLUS_ONE(n) +1
+
+static uint16_t proxy_active_keys[(0 DT_INST_FOREACH_STATUS_OKAY(PLUS_ONE))]
+                                 [CONFIG_ZMK_INPUT_SPLIT_MAX_TRACKED_KEYS];
+
+static int replace_active_key(size_t input, uint16_t find, uint16_t replace) {
+    for (size_t k = 0; k < CONFIG_ZMK_INPUT_SPLIT_MAX_TRACKED_KEYS; k++) {
+        if (proxy_active_keys[input][k] == find) {
+            proxy_active_keys[input][k] = replace;
+            return 0;
+        }
+    }
+
+    return -ENODEV;
+}
+
 int zmk_input_split_report_peripheral_event(uint8_t reg, uint8_t type, uint16_t code, int32_t value,
                                             bool sync) {
     LOG_DBG("Got peripheral event for %d!", reg);
     for (size_t i = 0; i < ARRAY_SIZE(proxy_inputs); i++) {
         if (reg == proxy_inputs[i].reg) {
+            if (type == INPUT_EV_KEY) {
+                if (value) {
+                    int ret = replace_active_key(i, 0, code);
+                    if (ret < 0) {
+                        LOG_WRN("Failed to track pressed key %d", ret);
+                    }
+                } else {
+                    int ret = replace_active_key(i, code, 0);
+                    if (ret < 0) {
+                        LOG_WRN("Failed to untrack released key %d", ret);
+                    }
+                }
+            }
             return input_report(proxy_inputs[i].dev, type, code, value, sync, K_NO_WAIT);
         }
     }
@@ -38,6 +67,37 @@ int zmk_input_split_report_peripheral_event(uint8_t reg, uint8_t type, uint16_t
     return -ENODEV;
 }
 
+int zmk_input_split_peripheral_disconnected(uint8_t reg) {
+    for (size_t i = 0; i < ARRAY_SIZE(proxy_inputs); i++) {
+        if (reg == proxy_inputs[i].reg) {
+            uint16_t prev = 0;
+            for (size_t k = 0; k < CONFIG_ZMK_INPUT_SPLIT_MAX_TRACKED_KEYS; k++) {
+                if (proxy_active_keys[i][k] != 0) {
+                    if (prev != 0) {
+                        int ret = input_report(proxy_inputs[i].dev, INPUT_EV_KEY, prev, 0, false,
+                                               K_NO_WAIT);
+                        if (ret < 0) {
+                            LOG_WRN("Failed to report release event on disconnect (%d)", ret);
+                        }
+                    }
+
+                    prev = proxy_active_keys[i][k];
+                    proxy_active_keys[i][k] = 0;
+                }
+            }
+
+            if (prev != 0) {
+                int ret = input_report(proxy_inputs[i].dev, INPUT_EV_KEY, prev, 0, true, K_NO_WAIT);
+                if (ret < 0) {
+                    LOG_WRN("Failed to report release event on disconnect (%d)", ret);
+                }
+            }
+        }
+    }
+
+    return -ENODEV;
+}
+
 #define ZIS_INST(n)                                                                                \
     DEVICE_DT_INST_DEFINE(n, NULL, NULL, NULL, NULL, POST_KERNEL,                                  \
                           CONFIG_ZMK_INPUT_SPLIT_INIT_PRIORITY, NULL);
diff --git a/app/src/split/bluetooth/central.c b/app/src/split/bluetooth/central.c
index 4c354b36b16..f16884bbe0e 100644
--- a/app/src/split/bluetooth/central.c
+++ b/app/src/split/bluetooth/central.c
@@ -121,7 +121,7 @@ void release_peripheral_input_subs(struct bt_conn *conn) {
     for (size_t i = 0; i < ARRAY_SIZE(peripheral_input_slots); i++) {
         if (peripheral_input_slots[i].conn == conn) {
             peripheral_input_slots[i].conn = NULL;
-            // memset(&peripheral_input_slots[i], 0, sizeof(struct peripheral_input_slot));
+            zmk_input_split_peripheral_disconnected(peripheral_input_slots[i].reg);
         }
     }
 }