JsonSearchFieldDataSource.java

package de.geeksfactory.opacclient.storage;

import android.content.Context;
import android.content.pm.PackageManager.NameNotFoundException;

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

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.List;

import de.geeksfactory.opacclient.searchfields.SearchField;

public class JsonSearchFieldDataSource implements SearchFieldDataSource {

    private static final String KEY_FIELDS = "fields";
    private static final String KEY_TIME = "time";
    private static final String KEY_VERSION = "version";
    private static final String KEY_LANGUAGE = "lang";
    private File dir;
    private Context context;

    public JsonSearchFieldDataSource(Context context) {
        this.dir = new File(context.getFilesDir(), "fields");
        dir.mkdirs();
        this.context = context;
    }

    @Override
    public void saveSearchFields(String libraryId, List<SearchField> fields) {
        JSONObject object = new JSONObject();
        JSONArray array = new JSONArray();
        try {
            for (SearchField field : fields) {
                if (field.getId().length() > 0)
                    array.put(field.toJSON());
            }
            object.put(KEY_FIELDS, array);
            object.put(KEY_TIME, System.currentTimeMillis());
            object.put(KEY_LANGUAGE, context.getResources().getConfiguration().locale
                    .getLanguage());
            try {
                object.put(
                        KEY_VERSION,
                        context.getPackageManager().getPackageInfo(
                                context.getPackageName(), 0).versionCode);
            } catch (NameNotFoundException e) {
                // should never happen
                e.printStackTrace();
            }
            writeToJsonFile(libraryId, object);
        } catch (JSONException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public List<SearchField> getSearchFields(String libraryId) {
        try {
            JSONObject json = readJsonFile(libraryId);
            List<SearchField> list = new ArrayList<>();
            JSONArray fields = json.getJSONArray(KEY_FIELDS);
            for (int i = 0; i < fields.length(); i++) {
                list.add(SearchField.fromJSON(fields.getJSONObject(i)));
            }
            return list;
        } catch (IOException | JSONException e) {
            e.printStackTrace();
        }
        return null;
    }

    @Override
    public boolean hasSearchFields(String libraryId) {
        return jsonFileExists(libraryId);
    }

    @Override
    public void clearSearchFields(String libraryId) {
        removeJsonFile(libraryId);
    }

    @Override
    public void clearAll() {
        File[] files = dir.listFiles();
        for (File file : files) {
            file.delete();
        }
    }

    @Override
    public long getLastSearchFieldUpdateTime(String libraryId) {
        try {
            JSONObject json = readJsonFile(libraryId);
            return json.getLong(KEY_TIME);
        } catch (IOException | JSONException e) {
            e.printStackTrace();
        }
        return 0;
    }

    @Override
    public int getLastSearchFieldUpdateVersion(String libraryId) {
        try {
            JSONObject json = readJsonFile(libraryId);
            return json.getInt(KEY_VERSION);
        } catch (IOException | JSONException e) {
            e.printStackTrace();
        }
        return 0;
    }


    @Override
    public String getSearchFieldLanguage(String libraryId) {
        try {
            JSONObject json = readJsonFile(libraryId);
            return json.getString(KEY_LANGUAGE);
        } catch (IOException | JSONException e) {
            e.printStackTrace();
        }
        return null;
    }

    private void writeToJsonFile(String filename, JSONObject data) {
        File file = new File(dir, filename + ".json");
        try {
            PrintWriter writer = new PrintWriter(file, "UTF-8");
            writer.print(data.toString());
            writer.close();
        } catch (FileNotFoundException | UnsupportedEncodingException e) {
            e.printStackTrace();
        }
    }

    private JSONObject readJsonFile(String filename) throws IOException,
            JSONException {
        File file = new File(dir, filename + ".json");
        BufferedReader br = new BufferedReader(new FileReader(file));
        try {
            StringBuilder sb = new StringBuilder();
            String line = br.readLine();

            while (line != null) {
                sb.append(line);
                sb.append("\n");
                line = br.readLine();
            }
            String data = sb.toString();
            return new JSONObject(data);
        } finally {
            br.close();
        }
    }

    private boolean jsonFileExists(String filename) {
        File file = new File(dir, filename + ".json");
        return file.exists();
    }

    private void removeJsonFile(String filename) {
        File file = new File(dir, filename + ".json");
        file.delete();
    }
}