/*
 * Copyright (C) 2019 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.server.protolog;

import static com.android.server.protolog.ProtoLogImpl.logAndPrintln;

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

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.Map;
import java.util.TreeMap;
import java.util.zip.GZIPInputStream;

/**
 * Handles loading and parsing of ProtoLog viewer configuration.
 */
public class ProtoLogViewerConfigReader {
    private Map<Integer, String> mLogMessageMap = null;

    /** Returns message format string for its hash or null if unavailable. */
    public synchronized String getViewerString(int messageHash) {
        if (mLogMessageMap != null) {
            return mLogMessageMap.get(messageHash);
        } else {
            return null;
        }
    }

    /**
     * Reads the specified viewer configuration file. Does nothing if the config is already loaded.
     */
    public synchronized void loadViewerConfig(PrintWriter pw, String viewerConfigFilename) {
        if (mLogMessageMap != null) {
            return;
        }
        try {
            InputStreamReader config = new InputStreamReader(
                    new GZIPInputStream(new FileInputStream(viewerConfigFilename)));
            BufferedReader reader = new BufferedReader(config);
            StringBuilder builder = new StringBuilder();
            String line;
            while ((line = reader.readLine()) != null) {
                builder.append(line).append('\n');
            }
            reader.close();
            JSONObject json = new JSONObject(builder.toString());
            JSONObject messages = json.getJSONObject("messages");

            mLogMessageMap = new TreeMap<>();
            Iterator it = messages.keys();
            while (it.hasNext()) {
                String key = (String) it.next();
                try {
                    int hash = Integer.parseInt(key);
                    JSONObject val = messages.getJSONObject(key);
                    String msg = val.getString("message");
                    mLogMessageMap.put(hash, msg);
                } catch (NumberFormatException expected) {
                    // Not a messageHash - skip it
                }
            }
            logAndPrintln(pw, "Loaded " + mLogMessageMap.size() + " log definitions from "
                    + viewerConfigFilename);
        } catch (FileNotFoundException e) {
            logAndPrintln(pw, "Unable to load log definitions: File "
                    + viewerConfigFilename + " not found." + e);
        } catch (IOException e) {
            logAndPrintln(pw, "Unable to load log definitions: IOException while reading "
                    + viewerConfigFilename + ". " + e);
        } catch (JSONException e) {
            logAndPrintln(pw,
                    "Unable to load log definitions: JSON parsing exception while reading "
                            + viewerConfigFilename + ". " + e);
        }
    }

    /**
     * Returns the number of loaded log definitions kept in memory.
     */
    public synchronized int knownViewerStringsNumber() {
        if (mLogMessageMap != null) {
            return mLogMessageMap.size();
        }
        return 0;
    }
}