Magisk/stub/src/main/java/com/topjohnwu/magisk/MainActivity.java

package com.topjohnwu.magisk;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.content.Context;
import android.os.Bundle;
import android.util.Log;
import android.view.ContextThemeWrapper;

import com.topjohnwu.magisk.net.Networking;
import com.topjohnwu.magisk.net.Request;
import com.topjohnwu.magisk.utils.APKInstall;

import org.json.JSONException;
import org.json.JSONObject;

import java.io.File;

import static android.R.string.no;
import static android.R.string.ok;
import static android.R.string.yes;
import static com.topjohnwu.magisk.R.string.dling;
import static com.topjohnwu.magisk.R.string.no_internet_msg;
import static com.topjohnwu.magisk.R.string.upgrade_msg;

public class MainActivity extends Activity {

    private static final String APP_NAME = "Magisk Manager";
    private static final String CDN_URL = "https://cdn.jsdelivr.net/gh/topjohnwu/magisk_files@%s/%s";

    private String apkLink;
    private String sha;
    private Context themed;
    private ProgressDialog dialog;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Networking.init(this);
        themed = new ContextThemeWrapper(this, android.R.style.Theme_DeviceDefault);

        if (Networking.checkNetworkStatus(this)) {
            fetchAPKURL();
        } else {
            new AlertDialog.Builder(themed)
                    .setCancelable(false)
                    .setTitle(APP_NAME)
                    .setMessage(getString(no_internet_msg))
                    .setNegativeButton(ok, (d, w) -> finish())
                    .show();
        }
    }

    private void fetchAPKURL() {
        dialog = ProgressDialog.show(themed, "", "", true);
        String url;
        if (BuildConfig.DEV_CHANNEL != null) {
            url = BuildConfig.DEV_CHANNEL;
        } else if (!BuildConfig.CANARY) {
            url = "https://topjohnwu.github.io/magisk_files/stable.json";
        } else {
            url = "https://api.github.com/repos/topjohnwu/magisk_files/branches/canary";
            request(url).getAsJSONObject(this::handleCanary);
            return;
        }
        request(url).getAsJSONObject(this::handleJSON);
    }

    private void error(Throwable e) {
        Log.e(getClass().getSimpleName(), "", e);
        finish();
    }

    private Request request(String url) {
        return Networking.get(url).setErrorHandler((conn, e) -> error(e));
    }

    private void handleCanary(JSONObject json) {
        try {
            sha = json.getJSONObject("commit").getString("sha");
            String url = String.format(CDN_URL, sha, "canary.json");
            request(url).getAsJSONObject(this::handleJSON);
        } catch (JSONException e) {
            error(e);
        }
    }

    private void handleJSON(JSONObject json) {
        dialog.dismiss();
        try {
            apkLink = json.getJSONObject("app").getString("link");
            if (!apkLink.startsWith("http"))
                apkLink = String.format(CDN_URL, sha, apkLink);
            new AlertDialog.Builder(themed)
                    .setCancelable(false)
                    .setTitle(APP_NAME)
                    .setMessage(getString(upgrade_msg))
                    .setPositiveButton(yes, (d, w) -> dlAPK())
                    .setNegativeButton(no, (d, w) -> finish())
                    .show();
        } catch (JSONException e) {
            error(e);
        }
    }

    private void dlAPK() {
        dialog = ProgressDialog.show(themed, getString(dling), getString(dling) + " " + APP_NAME, true);
        // Download and upgrade the app
        File apk = new File(getCacheDir(), "manager.apk");
        request(apkLink).getAsFile(apk, file -> {
            dialog.dismiss();
            APKInstall.install(this, file);
            finish();
        });
    }
}