GameConsole/app/src/main/java/com/xugame/gameconsole/preferences/UserPreferences.java

package com.xugame.gameconsole.preferences;

import android.annotation.TargetApi;
import android.content.Context;
import android.content.SharedPreferences;
import android.content.pm.PackageManager;
import android.media.AudioManager;
import android.media.AudioTrack;
import android.os.Build;
import android.preference.PreferenceManager;
import android.util.Log;

import com.xugame.gameconsole.util.DebugUtil;

import java.io.File;
import java.io.IOException;

public class UserPreferences {

    // Logging tag.
    private static final String TAG = "UserPreferences";

    // Disallow explicit instantiation.
    private UserPreferences()
    {
    }

    /**
     * Retrieves the path to the default location of the libretro config.
     *
     * @param ctx the current {@link Context}
     *
     * @return the path to the default location of the libretro config.
     */
    public static String getDefaultConfigPath(Context ctx)
    {
        // Internal/External storage dirs.
        final String internal = ctx.getFilesDir().getAbsolutePath();
        String external = null;

        // Get the App's external storage folder
        final String state = android.os.Environment.getExternalStorageState();
        if (android.os.Environment.MEDIA_MOUNTED.equals(state)) {
            File extsd = ctx.getExternalFilesDir(null);
            external = extsd.getAbsolutePath();
        }

        // Native library directory and data directory for this front-end.
        final String dataDir = ctx.getApplicationInfo().dataDir;
        final String coreDir = dataDir + "/cores/";

        // Get libretro name and path
        final SharedPreferences prefs = getPreferences(ctx);
        final String libretro_path = prefs.getString("libretro_path", coreDir);

        // Check if global config is being used. Return true upon failure.
        final boolean globalConfigEnabled = prefs.getBoolean("global_config_enable", true);

        String append_path;
        // If we aren't using the global config.
        if (!globalConfigEnabled && !libretro_path.equals(coreDir))
        {
            String sanitized_name = sanitizeLibretroPath(libretro_path);
            append_path = File.separator + sanitized_name + ".cfg";
        }
        else // Using global config.
        {
            append_path = File.separator + "retroarch.cfg";
        }

        if (external != null)
        {
            String confPath = external + append_path;
            if (new File(confPath).exists())
                return confPath;
        }
        else if (internal != null)
        {
            String confPath = internal + append_path;
            if (new File(confPath).exists())
                return confPath;
        }
        else
        {
            String confPath = "/mnt/extsd" + append_path;
            if (new File(confPath).exists())
                return confPath;
        }

        // Config file does not exist. Create empty one.

        // emergency fallback
        String new_path = "/mnt/sd" + append_path;

        if (external != null)
            new_path = external + append_path;
        else if (internal != null)
            new_path = internal + append_path;
        else if (dataDir != null)
            new_path = dataDir + append_path;

        try {
            new File(new_path).createNewFile();
        }
        catch (IOException e)
        {
            Log.e(TAG, "Failed to create config file to: " + new_path);
        }
        return new_path;
    }

    /**
     * Updates the libretro configuration file
     * with new values if settings have changed.
     *
     * @param ctx the current {@link Context}.
     */
    public static void updateConfigFile(Context ctx)
    {
        String path = getDefaultConfigPath(ctx);
        ConfigFile config = new ConfigFile(path);

        Log.i(TAG, "Writing config to: " + path);

        final String dataDir = ctx.getApplicationInfo().dataDir;
        final String coreDir = dataDir + "/cores/";

        final SharedPreferences prefs = getPreferences(ctx);

        config.setString("libretro_directory", coreDir);

        int samplingRate = getOptimalSamplingRate(ctx);
        if (samplingRate != -1) {
            config.setInt("audio_out_rate", samplingRate);
        }

        try
        {
            int version							= ctx.getPackageManager().
                    getPackageInfo(ctx.getPackageName(), 0).versionCode;
            final String dst_path			= dataDir;
            final String dst_path_subdir	= "assets";

            Log.i(TAG, "dst dir is: " + dst_path);
            Log.i(TAG, "dst subdir is: " + dst_path_subdir);

            config.setString("bundle_assets_src_path", ctx.getApplicationInfo().sourceDir);
            DebugUtil.i(TAG,"source="+ctx.getApplicationInfo().sourceDir);
            DebugUtil.i(TAG,"versionCode="+version);
            config.setString("bundle_assets_dst_path", dst_path);
            config.setString("bundle_assets_dst_path_subdir", dst_path_subdir);
            config.setInt("bundle_assets_extract_version_current", version);
        }
        catch (PackageManager.NameNotFoundException ignored)
        {
        }

        // Refactor this entire mess and make this usable for per-core config
        if (Build.VERSION.SDK_INT >= 17 && prefs.getBoolean("audio_latency_auto", true))
        {
            int bufferSize = getLowLatencyBufferSize(ctx);
            if (bufferSize != -1) {
                config.setInt("audio_block_frames", bufferSize);
            }
        }

        try
        {
            config.write(path);
        }
        catch (IOException e)
        {
            Log.e(TAG, "Failed to save config file to: " + path);
        }
    }

    private static void readbackString(ConfigFile cfg, SharedPreferences.Editor edit, String key)
    {
        if (cfg.keyExists(key))
            edit.putString(key, cfg.getString(key));
        else
            edit.remove(key);
    }

    private static void readbackBool(ConfigFile cfg, SharedPreferences.Editor edit, String key)
    {
        if (cfg.keyExists(key))
            edit.putBoolean(key, cfg.getBoolean(key));
        else
            edit.remove(key);
    }

    private static void readbackDouble(ConfigFile cfg, SharedPreferences.Editor edit, String key)
    {
        if (cfg.keyExists(key))
            edit.putFloat(key, (float)cfg.getDouble(key));
        else
            edit.remove(key);
    }

	/*
	private static void readbackFloat(ConfigFile cfg, SharedPreferences.Editor edit, String key)
	{
		if (cfg.keyExists(key))
			edit.putFloat(key, cfg.getFloat(key));
		else
			edit.remove(key);
	}
	*/

    /**
     private static void readbackInt(ConfigFile cfg, SharedPreferences.Editor edit, String key)
     {
     if (cfg.keyExists(key))
     edit.putInt(key, cfg.getInt(key));
     else
     edit.remove(key);
     }
     */

    /**
     * Sanitizes a libretro core path.
     *
     * @param path The path to the libretro core.
     *
     * @return the sanitized libretro path.
     */
    private static String sanitizeLibretroPath(String path)
    {
        String sanitized_name = path.substring(
                path.lastIndexOf('/') + 1,
                path.lastIndexOf('.'));
        sanitized_name = sanitized_name.replace("neon", "");
        sanitized_name = sanitized_name.replace("libretro_", "");

        return sanitized_name;
    }

    /**
     * Gets a {@link SharedPreferences} instance containing current settings.
     *
     * @param ctx the current {@link Context}.
     *
     * @return A SharedPreference instance containing current settings.
     */
    public static SharedPreferences getPreferences(Context ctx)
    {
        return PreferenceManager.getDefaultSharedPreferences(ctx);
    }

    /**
     * Gets the optimal sampling rate for low-latency audio playback.
     *
     * @param ctx the current {@link Context}.
     *
     * @return the optimal sampling rate for low-latency audio playback in Hz.
     */
    @TargetApi(17)
    private static int getLowLatencyOptimalSamplingRate(Context ctx)
    {
        AudioManager manager = (AudioManager) ctx.getSystemService(Context.AUDIO_SERVICE);
        String value = manager.getProperty(AudioManager.PROPERTY_OUTPUT_SAMPLE_RATE);

        if(value == null || value.isEmpty()) {
            return -1;
        }

        return Integer.parseInt(value);
    }

    /**
     * Gets the optimal buffer size for low-latency audio playback.
     *
     * @param ctx the current {@link Context}.
     *
     * @return the optimal output buffer size in decimal PCM frames.
     */
    @TargetApi(17)
    private static int getLowLatencyBufferSize(Context ctx)
    {
        AudioManager manager = (AudioManager) ctx.getSystemService(Context.AUDIO_SERVICE);
        String value = manager.getProperty(AudioManager.PROPERTY_OUTPUT_FRAMES_PER_BUFFER);

        if(value == null || value.isEmpty()) {
            return -1;
        }

        int buffersize = Integer.parseInt(value);
        Log.i(TAG, "Queried ideal buffer size (frames): " + buffersize);
        return buffersize;
    }

    /**
     * Gets the optimal audio sampling rate.
     * <p>
     * On Android 4.2+ devices this will retrieve the optimal low-latency sampling rate,
     * since Android 4.2 adds support for low latency audio in general.
     * <p>
     * On other devices, it simply returns the regular optimal sampling rate
     * as returned by the hardware.
     *
     * @param ctx The current {@link Context}.
     *
     * @return the optimal audio sampling rate in Hz.
     */
    private static int getOptimalSamplingRate(Context ctx)
    {
        int ret;
        if (Build.VERSION.SDK_INT >= 17)
            ret = getLowLatencyOptimalSamplingRate(ctx);
        else
            ret = AudioTrack.getNativeOutputSampleRate(AudioManager.STREAM_MUSIC);

        Log.i(TAG, "Using sampling rate: " + ret + " Hz");
        return ret;
    }

}