FairEmail/app/src/main/java/eu/faircode/email/StyleHelper.java

package eu.faircode.email;

import android.graphics.Typeface;
import android.text.SpannableString;
import android.text.Spanned;
import android.text.style.ForegroundColorSpan;
import android.text.style.RelativeSizeSpan;
import android.text.style.StyleSpan;
import android.text.style.URLSpan;
import android.text.style.UnderlineSpan;
import android.widget.EditText;

import java.util.ArrayList;
import java.util.List;

public class StyleHelper {
    static boolean apply(int action, EditText etBody, Object... args) {
        Log.i("Style action=" + action);

        try {
            int start = etBody.getSelectionStart();
            int end = etBody.getSelectionEnd();

            if (start < 0)
                start = 0;
            if (end < 0)
                end = 0;

            if (start > end) {
                int tmp = start;
                start = end;
                end = tmp;
            }

            SpannableString ss = new SpannableString(etBody.getText());

            switch (action) {
                case R.id.menu_bold:
                case R.id.menu_italic: {
                    int style = (action == R.id.menu_bold ? Typeface.BOLD : Typeface.ITALIC);
                    boolean has = false;
                    for (StyleSpan span : ss.getSpans(start, end, StyleSpan.class))
                        if (span.getStyle() == style) {
                            has = true;
                            ss.removeSpan(span);
                        }

                    if (!has)
                        ss.setSpan(new StyleSpan(style), start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);

                    etBody.setText(ss);
                    etBody.setSelection(start, end);

                    return true;
                }

                case R.id.menu_underline: {
                    boolean has = false;
                    for (UnderlineSpan span : ss.getSpans(start, end, UnderlineSpan.class)) {
                        has = true;
                        ss.removeSpan(span);
                    }

                    if (!has)
                        ss.setSpan(new UnderlineSpan(), start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);

                    etBody.setText(ss);
                    etBody.setSelection(start, end);

                    return true;
                }

                case R.id.menu_size: {
                    RelativeSizeSpan[] spans = ss.getSpans(start, end, RelativeSizeSpan.class);
                    float size = (spans.length > 0 ? spans[0].getSizeChange() : 1.0f);

                    // Match small/big
                    if (size == 0.8f)
                        size = 1.0f;
                    else if (size == 1.0)
                        size = 1.25f;
                    else
                        size = 0.8f;

                    for (RelativeSizeSpan span : spans)
                        ss.removeSpan(span);

                    if (size != 1.0f)
                        ss.setSpan(new RelativeSizeSpan(size), start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);

                    etBody.setText(ss);
                    etBody.setSelection(start, end);

                    return true;
                }

                case R.id.menu_color: {
                    for (ForegroundColorSpan span : ss.getSpans(start, end, ForegroundColorSpan.class))
                        ss.removeSpan(span);

                    ss.setSpan(new ForegroundColorSpan((int) args[0]), start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);

                    etBody.setText(ss);
                    etBody.setSelection(start, end);

                    return true;
                }

                case R.id.menu_link: {
                    List<Object> spans = new ArrayList<>();
                    for (Object span : ss.getSpans(start, end, Object.class)) {
                        if (!(span instanceof URLSpan))
                            spans.add(span);
                        ss.removeSpan(span);
                    }

                    ss.setSpan(new URLSpan((String) args[0]), start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);

                    for (Object span : spans)
                        ss.setSpan(span, start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);

                    etBody.setText(ss);
                    etBody.setSelection(end, end);

                    return true;
                }

                default:
                    return false;
            }
        } catch (Throwable ex) {
            Log.e(ex);
            return false;
        }
    }
}