Move list auto continuation to own class

Signed-off-by: Stefan Niedermann <info@niedermann.it>

2 files changed, 120 insertions, 76 deletions

diff --git a/markdown/src/main/java/it/niedermann/android/markdown/markwon/MarkwonMarkdownEditor.java b/markdown/src/main/java/it/niedermann/android/markdown/markwon/MarkwonMarkdownEditor.java
index 887b35620..1e4a1fba7 100644
--- a/markdown/src/main/java/it/niedermann/android/markdown/markwon/MarkwonMarkdownEditor.java
+++ b/markdown/src/main/java/it/niedermann/android/markdown/markwon/MarkwonMarkdownEditor.java
@@ -1,8 +1,6 @@
 package it.niedermann.android.markdown.markwon;
 
 import android.content.Context;
-import android.text.Editable;
-import android.text.TextWatcher;
 import android.util.AttributeSet;
 
 import androidx.annotation.NonNull;
@@ -11,11 +9,8 @@ import androidx.appcompat.widget.AppCompatEditText;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
-import java.util.concurrent.Executors;
-
 import io.noties.markwon.Markwon;
 import io.noties.markwon.editor.MarkwonEditor;
-import io.noties.markwon.editor.MarkwonEditorTextWatcher;
 import io.noties.markwon.editor.handler.EmphasisEditHandler;
 import io.noties.markwon.editor.handler.StrongEmphasisEditHandler;
 import it.niedermann.android.markdown.MarkdownEditor;
@@ -24,18 +19,10 @@ import it.niedermann.android.markdown.markwon.handler.CodeBlockEditHandler;
 import it.niedermann.android.markdown.markwon.handler.CodeEditHandler;
 import it.niedermann.android.markdown.markwon.handler.HeadingEditHandler;
 import it.niedermann.android.markdown.markwon.handler.StrikethroughEditHandler;
+import it.niedermann.android.markdown.markwon.textwatcher.AutoContinuationTextWatcher;
 
 public class MarkwonMarkdownEditor extends AppCompatEditText implements MarkdownEditor {
 
-    private static final String CHECKBOX_UNCHECKED_MINUS = "- [ ]";
-    private static final String CHECKBOX_UNCHECKED_MINUS_TRAILING_SPACE = CHECKBOX_UNCHECKED_MINUS + " ";
-    private static final String CHECKBOX_UNCHECKED_STAR = "* [ ]";
-    private static final String CHECKBOX_UNCHECKED_STAR_TRAILING_SPACE = CHECKBOX_UNCHECKED_STAR + " ";
-    private static final String CHECKBOX_CHECKED_MINUS = "- [x]";
-    private static final String CHECKBOX_CHECKED_STAR = "* [x]";
-
-    private static final int lengthCheckbox = 6;
-
     private final MutableLiveData<CharSequence> unrenderedText$ = new MutableLiveData<>();
 
     public MarkwonMarkdownEditor(@NonNull Context context) {
@@ -59,29 +46,8 @@ public class MarkwonMarkdownEditor extends AppCompatEditText implements Markdown
                 .useEditHandler(new HeadingEditHandler())
                 .build();
 
-        MarkwonEditorTextWatcher originalWatcher = MarkwonEditorTextWatcher.withPreRender(editor, Executors.newSingleThreadExecutor(), this);
-
-        // intercept behavior of the original MarkwonEditorTextWatcher.
-        addTextChangedListener(new TextWatcher() {
-            @Override
-            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
-                originalWatcher.beforeTextChanged(s, start, count, after);
-            }
-
-            @Override
-            public void onTextChanged(CharSequence s, int start, int before, int count) {
-                if (count == 1 && s.charAt(start) == '\n') {
-                    autoContinueCheckboxListsOnEnter(s, start, count);
-                }
-                originalWatcher.onTextChanged(s, start, before, count);
-//                unrenderedText$.setValue(s.toString());
-            }
-
-            @Override
-            public void afterTextChanged(Editable s) {
-                originalWatcher.afterTextChanged(s);
-            }
-        });
+        // addTextChangedListener(MarkwonEditorTextWatcher.withPreRender(editor, Executors.newSingleThreadExecutor(), this));
+        addTextChangedListener(new AutoContinuationTextWatcher(editor, this));
     }
 
     @Override
@@ -94,43 +60,4 @@ public class MarkwonMarkdownEditor extends AppCompatEditText implements Markdown
     public LiveData<CharSequence> getMarkdownString() {
         return unrenderedText$;
     }
-
-    private boolean autoContinueCheckboxListsOnEnter(@NonNull CharSequence originalSequence, int start, int count) {
-        final CharSequence s = originalSequence.subSequence(0, originalSequence.length());
-        final int startOfLine = getStartOfLine(s, start);
-        final String line = s.subSequence(startOfLine, start).toString();
-
-        if (line.equals(CHECKBOX_UNCHECKED_MINUS_TRAILING_SPACE) || line.equals(CHECKBOX_UNCHECKED_STAR_TRAILING_SPACE)) {
-            setSelection(startOfLine + 1);
-            setNewText(new StringBuilder(s).replace(startOfLine, startOfLine + lengthCheckbox + 1, "\n"), startOfLine + 1);
-            return true;
-        } else if (lineStartsWithCheckbox(line, false)) {
-            setNewText(new StringBuilder(s).insert(start + count, CHECKBOX_UNCHECKED_MINUS_TRAILING_SPACE), start + lengthCheckbox + 1);
-            return true;
-        } else if (lineStartsWithCheckbox(line, true)) {
-            setNewText(new StringBuilder(s).insert(start + count, CHECKBOX_UNCHECKED_STAR_TRAILING_SPACE), start + lengthCheckbox + 1);
-            return true;
-        }
-        return false;
-    }
-
-    private void setNewText(@NonNull StringBuilder newText, int selection) {
-        setMarkdownString(newText.toString());
-        unrenderedText$.setValue(newText.toString());
-        setSelection(selection);
-    }
-
-    private static int getStartOfLine(@NonNull CharSequence s, int cursorPosition) {
-        int startOfLine = cursorPosition;
-        while (startOfLine > 0 && s.charAt(startOfLine - 1) != '\n') {
-            startOfLine--;
-        }
-        return startOfLine;
-    }
-
-    private static boolean lineStartsWithCheckbox(@NonNull String line, boolean starAsLeadingCharacter) {
-        return starAsLeadingCharacter
-                ? line.startsWith(CHECKBOX_UNCHECKED_STAR) || line.startsWith(CHECKBOX_CHECKED_STAR)
-                : line.startsWith(CHECKBOX_UNCHECKED_MINUS) || line.startsWith(CHECKBOX_CHECKED_MINUS);
-    }
 }
diff --git a/markdown/src/main/java/it/niedermann/android/markdown/markwon/textwatcher/AutoContinuationTextWatcher.java b/markdown/src/main/java/it/niedermann/android/markdown/markwon/textwatcher/AutoContinuationTextWatcher.java
new file mode 100644
index 000000000..55a446f3f
--- /dev/null
+++ b/markdown/src/main/java/it/niedermann/android/markdown/markwon/textwatcher/AutoContinuationTextWatcher.java
@@ -0,0 +1,117 @@
+package it.niedermann.android.markdown.markwon.textwatcher;
+
+import android.text.Editable;
+import android.text.TextWatcher;
+import android.util.Log;
+
+import androidx.annotation.NonNull;
+
+import java.util.concurrent.Executors;
+
+import io.noties.markwon.editor.MarkwonEditor;
+import io.noties.markwon.editor.MarkwonEditorTextWatcher;
+import it.niedermann.android.markdown.markwon.MarkwonMarkdownEditor;
+
+/**
+ * Automatically continues lists and checkbox lists when pressing enter
+ */
+public class AutoContinuationTextWatcher implements TextWatcher {
+
+    private static final String TAG = AutoContinuationTextWatcher.class.getSimpleName();
+
+    private static final String CHECKBOX_CHECKED_DASH = "- [x]";
+    private static final String CHECKBOX_CHECKED_STAR = "* [x]";
+    private static final String CHECKBOX_CHECKED_PLUS = "+ [x]";
+    private static final String CHECKBOX_UNCHECKED_DASH = "- [ ]";
+    private static final String CHECKBOX_UNCHECKED_STAR = "* [ ]";
+    private static final String CHECKBOX_UNCHECKED_PLUS = "+ [ ]";
+    private static final String CHECKBOX_UNCHECKED_DASH_TRAILING_SPACE = CHECKBOX_UNCHECKED_DASH + " ";
+    private static final String CHECKBOX_UNCHECKED_STAR_TRAILING_SPACE = CHECKBOX_UNCHECKED_STAR + " ";
+    private static final String CHECKBOX_UNCHECKED_PLUS_TRAILING_SPACE = CHECKBOX_UNCHECKED_PLUS + " ";
+
+    private static final int CHECKBOX_TRAILING_SPACE_LENGTH = 6;
+
+    private final MarkwonEditorTextWatcher originalWatcher;
+    private final MarkwonMarkdownEditor editText;
+
+    public AutoContinuationTextWatcher(@NonNull MarkwonEditor editor, @NonNull MarkwonMarkdownEditor editText) {
+        this.editText = editText;
+        originalWatcher = MarkwonEditorTextWatcher.withPreRender(editor, Executors.newSingleThreadExecutor(), editText);
+    }
+
+    @Override
+    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
+        originalWatcher.beforeTextChanged(s, start, count, after);
+    }
+
+    @Override
+    public void onTextChanged(CharSequence s, int start, int before, int count) {
+        if (count == 1 && s.charAt(start) == '\n') {
+            autoContinueCheckboxListsOnEnter(s, start, count);
+        }
+        originalWatcher.onTextChanged(s, start, before, count);
+    }
+
+    @Override
+    public void afterTextChanged(Editable s) {
+        originalWatcher.afterTextChanged(s);
+    }
+
+    /**
+     * @return added characters in front of the current line (can be negative)
+     */
+    private int autoContinueCheckboxListsOnEnter(@NonNull CharSequence originalSequence, int start, int count) {
+        final CharSequence s = originalSequence.subSequence(0, originalSequence.length());
+        final int startOfLine = getStartOfLine(s, start);
+        final String line = s.subSequence(startOfLine, start).toString();
+
+        if (line.equals(CHECKBOX_UNCHECKED_DASH_TRAILING_SPACE) || line.equals(CHECKBOX_UNCHECKED_STAR_TRAILING_SPACE)) {
+            editText.setSelection(startOfLine + 1);
+            setNewText(new StringBuilder(s).replace(startOfLine, startOfLine + CHECKBOX_TRAILING_SPACE_LENGTH + 1, "\n"), startOfLine + 1);
+            return CHECKBOX_TRAILING_SPACE_LENGTH * -1;
+        } else if (lineStartsWithCheckbox(line, EListType.DASH)) {
+            setNewText(new StringBuilder(s).insert(start + count, CHECKBOX_UNCHECKED_DASH_TRAILING_SPACE), start + CHECKBOX_TRAILING_SPACE_LENGTH + 1);
+            return CHECKBOX_TRAILING_SPACE_LENGTH;
+        } else if (lineStartsWithCheckbox(line, EListType.STAR)) {
+            setNewText(new StringBuilder(s).insert(start + count, CHECKBOX_UNCHECKED_STAR_TRAILING_SPACE), start + CHECKBOX_TRAILING_SPACE_LENGTH + 1);
+            return CHECKBOX_TRAILING_SPACE_LENGTH;
+        } else if (lineStartsWithCheckbox(line, EListType.PLUS)) {
+            setNewText(new StringBuilder(s).insert(start + count, CHECKBOX_UNCHECKED_PLUS_TRAILING_SPACE), start + CHECKBOX_TRAILING_SPACE_LENGTH + 1);
+            return CHECKBOX_TRAILING_SPACE_LENGTH;
+        }
+        return 0;
+    }
+
+    private void setNewText(@NonNull StringBuilder newText, int selection) {
+        editText.setMarkdownString(newText.toString());
+        editText.setSelection(selection);
+    }
+
+    private static int getStartOfLine(@NonNull CharSequence s, int cursorPosition) {
+        int startOfLine = cursorPosition;
+        while (startOfLine > 0 && s.charAt(startOfLine - 1) != '\n') {
+            startOfLine--;
+        }
+        return startOfLine;
+    }
+
+    private static boolean lineStartsWithCheckbox(@NonNull String line, @NonNull EListType listType) {
+        switch (listType) {
+            case STAR:
+                return line.startsWith(CHECKBOX_UNCHECKED_STAR) || line.startsWith(CHECKBOX_CHECKED_STAR);
+            case DASH:
+                return line.startsWith(CHECKBOX_UNCHECKED_DASH) || line.startsWith(CHECKBOX_CHECKED_DASH);
+            case PLUS:
+                return line.startsWith(CHECKBOX_UNCHECKED_PLUS) || line.startsWith(CHECKBOX_CHECKED_PLUS);
+            default:
+                Log.w(TAG, "List type " + listType + " is not supported.");
+                return false;
+        }
+    }
+
+    private enum EListType {
+        STAR,
+        DASH,
+        PLUS
+    }
+}