1 files changed, 143 insertions, 0 deletions
diff --git a/users/drashna/keyrecords/autocorrection/autocorrection.c b/users/drashna/keyrecords/autocorrection/autocorrection.c
new file mode 100644
index 0000000000..7c8c28c674
--- /dev/null
+++ b/users/drashna/keyrecords/autocorrection/autocorrection.c
@@ -0,0 +1,143 @@
+// Copyright 2021 Google LLC
+// Copyright 2022 @filterpaper
+// SPDX-License-Identifier: Apache-2.0
+// Original source: https://getreuer.info/posts/keyboards/autocorrection
+
+#include "autocorrection.h"
+#include <string.h>
+
+#if __has_include("autocorrection_data.h")
+#    include "autocorrection_data.h"
+#    if AUTOCORRECTION_MIN_LENGTH < 4
+#        error Minimum Length is too short and may cause overflows
+#    endif
+
+bool process_autocorrection(uint16_t keycode, keyrecord_t* record) {
+    static uint8_t typo_buffer[AUTOCORRECTION_MAX_LENGTH] = {KC_SPC};
+    static uint8_t typo_buffer_size                       = 1;
+
+    if (keycode == AUTO_CTN) {
+        if (record->event.pressed) {
+            typo_buffer_size = 0;
+            userspace_config.autocorrection ^= 1;
+            eeconfig_update_user(userspace_config.raw);
+        }
+        return false;
+    }
+
+    if (!userspace_config.autocorrection) {
+        typo_buffer_size = 0;
+        return true;
+    }
+
+    switch (keycode) {
+        case KC_LSFT:
+        case KC_RSFT:
+            return true;
+#    ifndef NO_ACTION_TAPPING
+        case QK_MOD_TAP ... QK_MOD_TAP_MAX:
+            if (((keycode >> 8) & 0xF) == MOD_LSFT) {
+                return true;
+            }
+#        ifndef NO_ACTION_LAYER
+        case QK_LAYER_TAP ... QK_LAYER_TAP_MAX:
+#        endif
+            if (record->event.pressed || !record->tap.count) {
+                return true;
+            }
+            keycode &= 0xFF;
+            break;
+#    endif
+#    ifndef NO_ACTION_ONESHOT
+        case QK_ONE_SHOT_MOD ... QK_ONE_SHOT_MOD_MAX:
+            if ((keycode & 0xF) == MOD_LSFT) {
+                return true;
+            }
+#    endif
+        default:
+            if (!record->event.pressed) {
+                return true;
+            }
+    }
+
+    // Subtract buffer for Backspace key, reset for other non-alpha.
+    if (!(KC_A <= keycode && keycode <= KC_Z)) {
+        if (keycode == KC_BSPC) {
+            // Remove last character from the buffer.
+            if (typo_buffer_size > 0) {
+                --typo_buffer_size;
+            }
+            return true;
+        } else if (KC_1 <= keycode && keycode <= KC_SLSH && keycode != KC_ESC) {
+            // Set a word boundary if space, period, digit, etc. is pressed.
+            // Behave more conservatively for the enter key. Reset, so that enter
+            // can't be used on a word ending.
+            if (keycode == KC_ENT) {
+                typo_buffer_size = 0;
+            }
+            keycode = KC_SPC;
+        } else {
+            // Clear state if some other non-alpha key is pressed.
+            typo_buffer_size = 0;
+            return true;
+        }
+    }
+
+    // Rotate oldest character if buffer is full.
+    if (typo_buffer_size >= AUTOCORRECTION_MAX_LENGTH) {
+        memmove(typo_buffer, typo_buffer + 1, AUTOCORRECTION_MAX_LENGTH - 1);
+        typo_buffer_size = AUTOCORRECTION_MAX_LENGTH - 1;
+    }
+
+    // Append `keycode` to buffer.
+    typo_buffer[typo_buffer_size++] = keycode;
+    // Return if buffer is smaller than the shortest word.
+    if (typo_buffer_size < AUTOCORRECTION_MIN_LENGTH) {
+        return true;
+    }
+
+    // Check for typo in buffer using a trie stored in `autocorrection_data`.
+    uint16_t state = 0;
+    uint8_t  code  = pgm_read_byte(autocorrection_data + state);
+    for (uint8_t i = typo_buffer_size - 1; i >= 0; --i) {
+        uint8_t const key_i = typo_buffer[i];
+
+        if (code & 64) {  // Check for match in node with multiple children.
+            code &= 63;
+            for (; code != key_i; code = pgm_read_byte(autocorrection_data + (state += 3))) {
+                if (!code) return true;
+            }
+            // Follow link to child node.
+            state = (pgm_read_byte(autocorrection_data + state + 1) | pgm_read_byte(autocorrection_data + state + 2) << 8);
+            // Check for match in node with single child.
+        } else if (code != key_i) {
+            return true;
+        } else if (!(code = pgm_read_byte(autocorrection_data + (++state)))) {
+            ++state;
+        }
+
+        code = pgm_read_byte(autocorrection_data + state);
+
+        if (code & 128) {  // A typo was found! Apply autocorrection.
+            const uint8_t backspaces = code & 63;
+            for (uint8_t i = 0; i < backspaces; ++i) {
+                tap_code(KC_BSPC);
+            }
+            send_string_P((char const*)(autocorrection_data + state + 1));
+
+            if (keycode == KC_SPC) {
+                typo_buffer[0]   = KC_SPC;
+                typo_buffer_size = 1;
+                return true;
+            } else {
+                typo_buffer_size = 0;
+                return false;
+            }
+        }
+    }
+    return true;
+}
+#else
+#    pragma message "Warning!!! Autocorrect is not corretly setup!"
+bool process_autocorrection(uint16_t keycode, keyrecord_t* record) { return true; }
+#endif