package android.util;

import java.io.PrintWriter;
import java.io.StringWriter;

/**
 * A stub for {@link android.util.Log} to be used in unit tests.
 *
 * It outputs the log statements to standard error.
 */
public final class Log {

    /**
     * Priority constant for the println method; use Log.v.
     */
    public static final int VERBOSE = 2;

    /**
     * Priority constant for the println method; use Log.d.
     */
    public static final int DEBUG = 3;

    /**
     * Priority constant for the println method; use Log.i.
     */
    public static final int INFO = 4;

    /**
     * Priority constant for the println method; use Log.w.
     */
    public static final int WARN = 5;

    /**
     * Priority constant for the println method; use Log.e.
     */
    public static final int ERROR = 6;

    /**
     * Priority constant for the println method.
     */
    public static final int ASSERT = 7;

    private Log() {
    }

    /**
     * Send a {@link #VERBOSE} log message.
     * @param tag Used to identify the source of a log message.  It usually identifies
     *        the class or activity where the log call occurs.
     * @param msg The message you would like logged.
     */
    public static int v(String tag, String msg) {
        return println_native(LOG_ID_MAIN, VERBOSE, tag, msg);
    }

    /**
     * Send a {@link #VERBOSE} log message and log the exception.
     * @param tag Used to identify the source of a log message.  It usually identifies
     *        the class or activity where the log call occurs.
     * @param msg The message you would like logged.
     * @param tr An exception to log
     */
    public static int v(String tag, String msg, Throwable tr) {
        return printlns(LOG_ID_MAIN, VERBOSE, tag, msg, tr);
    }

    /**
     * Send a {@link #DEBUG} log message.
     * @param tag Used to identify the source of a log message.  It usually identifies
     *        the class or activity where the log call occurs.
     * @param msg The message you would like logged.
     */
    public static int d(String tag, String msg) {
        return println_native(LOG_ID_MAIN, DEBUG, tag, msg);
    }

    /**
     * Send a {@link #DEBUG} log message and log the exception.
     * @param tag Used to identify the source of a log message.  It usually identifies
     *        the class or activity where the log call occurs.
     * @param msg The message you would like logged.
     * @param tr An exception to log
     */
    public static int d(String tag, String msg, Throwable tr) {
        return printlns(LOG_ID_MAIN, DEBUG, tag, msg, tr);
    }

    /**
     * Send an {@link #INFO} log message.
     * @param tag Used to identify the source of a log message.  It usually identifies
     *        the class or activity where the log call occurs.
     * @param msg The message you would like logged.
     */
    public static int i(String tag, String msg) {
        return println_native(LOG_ID_MAIN, INFO, tag, msg);
    }

    /**
     * Send a {@link #INFO} log message and log the exception.
     * @param tag Used to identify the source of a log message.  It usually identifies
     *        the class or activity where the log call occurs.
     * @param msg The message you would like logged.
     * @param tr An exception to log
     */
    public static int i(String tag, String msg, Throwable tr) {
        return printlns(LOG_ID_MAIN, INFO, tag, msg, tr);
    }

    /**
     * Send a {@link #WARN} log message.
     * @param tag Used to identify the source of a log message.  It usually identifies
     *        the class or activity where the log call occurs.
     * @param msg The message you would like logged.
     */
    public static int w(String tag, String msg) {
        return println_native(LOG_ID_MAIN, WARN, tag, msg);
    }

    /**
     * Send a {@link #WARN} log message and log the exception.
     * @param tag Used to identify the source of a log message.  It usually identifies
     *        the class or activity where the log call occurs.
     * @param msg The message you would like logged.
     * @param tr An exception to log
     */
    public static int w(String tag, String msg, Throwable tr) {
        return printlns(LOG_ID_MAIN, WARN, tag, msg, tr);
    }

    /**
     * Checks to see whether or not a log for the specified tag is loggable at the specified level.
     *
     * @return true in all cases (for unit test environment)
     */
    public static boolean isLoggable(String tag, int level) {
        return true;
    }

    /*
     * Send a {@link #WARN} log message and log the exception.
     * @param tag Used to identify the source of a log message.  It usually identifies
     *        the class or activity where the log call occurs.
     * @param tr An exception to log
     */
    public static int w(String tag, Throwable tr) {
        return printlns(LOG_ID_MAIN, WARN, tag, "", tr);
    }

    /**
     * Send an {@link #ERROR} log message.
     * @param tag Used to identify the source of a log message.  It usually identifies
     *        the class or activity where the log call occurs.
     * @param msg The message you would like logged.
     */
    public static int e(String tag, String msg) {
        return println_native(LOG_ID_MAIN, ERROR, tag, msg);
    }

    /**
     * Send a {@link #ERROR} log message and log the exception.
     * @param tag Used to identify the source of a log message.  It usually identifies
     *        the class or activity where the log call occurs.
     * @param msg The message you would like logged.
     * @param tr An exception to log
     */
    public static int e(String tag, String msg, Throwable tr) {
        return printlns(LOG_ID_MAIN, ERROR, tag, msg, tr);
    }

    /**
     * What a Terrible Failure: Report a condition that should never happen.
     * The error will always be logged at level ASSERT with the call stack.
     * Depending on system configuration, a report may be added to the
     * {@link android.os.DropBoxManager} and/or the process may be terminated
     * immediately with an error dialog.
     * @param tag Used to identify the source of a log message.
     * @param msg The message you would like logged.
     */
    public static int wtf(String tag, String msg) {
        return wtf(LOG_ID_MAIN, tag, msg, null, false, false);
    }

    /**
     * Like {@link #wtf(String, String)}, but also writes to the log the full
     * call stack.
     * @hide
     */
    public static int wtfStack(String tag, String msg) {
        return wtf(LOG_ID_MAIN, tag, msg, null, true, false);
    }

    /**
     * What a Terrible Failure: Report an exception that should never happen.
     * Similar to {@link #wtf(String, String)}, with an exception to log.
     * @param tag Used to identify the source of a log message.
     * @param tr An exception to log.
     */
    public static int wtf(String tag, Throwable tr) {
        return wtf(LOG_ID_MAIN, tag, tr.getMessage(), tr, false, false);
    }

    /**
     * What a Terrible Failure: Report an exception that should never happen.
     * Similar to {@link #wtf(String, Throwable)}, with a message as well.
     * @param tag Used to identify the source of a log message.
     * @param msg The message you would like logged.
     * @param tr An exception to log.  May be null.
     */
    public static int wtf(String tag, String msg, Throwable tr) {
        return wtf(LOG_ID_MAIN, tag, msg, tr, false, false);
    }

    /**
     * Priority Constant for wtf.
     * Added for this custom Log implementation, not in android sources.
     */
    private static final int WTF = 8;
    static int wtf(int logId, String tag, String msg, Throwable tr, boolean localStack,
                   boolean system) {
        return printlns(LOG_ID_MAIN, WTF, tag, msg, tr);
    }

    private static final int LOG_ID_MAIN = 0;

    private static final String[] PRIORITY_ABBREV = { "0", "1", "V", "D", "I", "W", "E", "A", "WTF" };

    private static int println_native(int bufID, int priority, String tag, String msg) {
        String res = PRIORITY_ABBREV[priority] + "/" + tag + " " + msg + System.lineSeparator();
        System.err.print(res);
        return res.length();
    }

    private static int printlns(int bufID, int priority, String tag, String msg,
                               Throwable tr) {
        StringWriter trSW = new StringWriter();
        if (tr != null) {
            trSW.append(" , Exception: ");
            PrintWriter trPW = new PrintWriter(trSW);
            tr.printStackTrace(trPW);
            trPW.flush();
        }
        return println_native(bufID, priority, tag, msg + trSW.toString());
    }

}