Markwon/app/src/main/java/ru/noties/markwon/MainActivity.java

package ru.noties.markwon;

import android.app.Activity;
import android.content.Intent;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.net.Uri;
import android.os.Bundle;
import android.text.Layout;
import android.text.style.LeadingMarginSpan;
import android.view.View;
import android.widget.TextView;

import javax.inject.Inject;

import ru.noties.debug.Debug;

public class MainActivity extends Activity {

    @Inject
    MarkdownLoader markdownLoader;

    @Inject
    MarkdownRenderer markdownRenderer;

    @Inject
    Themes themes;

    @Inject
    UriProcessor uriProcessor;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        App.component(this)
                .mainActivitySubcomponent()
                .inject(this);

        themes.apply(this);

        // how can we obtain SpannableConfiguration after theme was applied?
        // as we inject `themes` we won't be able to inject configuration, as it requires theme set

        setContentView(R.layout.activity_main);

        // we process additionally github urls, as if url has in path `blob`, we won't receive
        // desired file, but instead rendered html
        checkUri();

        final AppBarItem.Renderer appBarRenderer
                = new AppBarItem.Renderer(findViewById(R.id.app_bar), new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                themes.toggle();
                recreate();
            }
        });

        final TextView textView = Views.findView(this, R.id.text);
        final View progress = findViewById(R.id.progress);

        appBarRenderer.render(appBarState());

        if (false) {

            final class Whatever {
                CharSequence text() {

                    final SpannableBuilder builder = new SpannableBuilder();

                    builder.append("First line\n\n");
                    builder.append(Markwon.markdown(MainActivity.this, "* first\n* second\n* * third\n* * * forth\n\n"));
                    builder.setSpan(new LeadingMarginSpan() {
                        @Override
                        public int getLeadingMargin(boolean first) {
                            return 100;
                        }

                        @Override
                        public void drawLeadingMargin(Canvas c, Paint p, int x, int dir, int top, int baseline, int bottom, CharSequence text, int start, int end, boolean first, Layout layout) {

                        }
                    }, 0);

                    builder.append("Last line\n\n");
                    return builder.text();
                }
            }
            final Whatever whatever = new Whatever();

            final SpannableBuilder builder = new SpannableBuilder();
            builder.append(whatever.text());
            builder.append(whatever.text());

            builder.setSpan(new LeadingMarginSpan() {
                @Override
                public int getLeadingMargin(boolean first) {
                    return 50;
                }

                @Override
                public void drawLeadingMargin(Canvas c, Paint p, int x, int dir, int top, int baseline, int bottom, CharSequence text, int start, int end, boolean first, Layout layout) {

                }
            }, 0);

            builder.append(whatever.text());

            textView.setText(builder.text());

            return;
        }

        markdownLoader.load(uri(), new MarkdownLoader.OnMarkdownTextLoaded() {
            @Override
            public void apply(final String text) {
                markdownRenderer.render(MainActivity.this, uri(), text, new MarkdownRenderer.MarkdownReadyListener() {
                    @Override
                    public void onMarkdownReady(CharSequence markdown) {
                        Markwon.setText(textView, markdown);
                        Views.setVisible(progress, false);
                    }
                });
            }
        });
    }

    private AppBarItem.State appBarState() {

        final String title;
        final String subtitle;

        // two possible states: just opened from launcher (no subtitle)
        // opened to display external resource (subtitle as a path/url/whatever)

        final Uri uri = uri();

        if (uri != null) {
            title = uri.getLastPathSegment();
            subtitle = uri.toString();
        } else {
            title = getString(R.string.app_name);
            subtitle = null;
        }

        return new AppBarItem.State(title, subtitle);
    }

    private void checkUri() {
        final Uri uri = uri();
        if (uri != null) {
            getIntent().setData(uriProcessor.process(uri));
        }
    }

    private Uri uri() {
        final Intent intent = getIntent();
        return intent != null
                ? intent.getData()
                : null;
    }

    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        try {
            super.onRestoreInstanceState(savedInstanceState);
        } catch (Throwable t) {
            // amazing stuff, we need this because on JB it will crash otherwise with NPE
            Debug.e(t);
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();

        markdownLoader.cancel();
        markdownRenderer.cancel();
    }
}