/*
 * Copyright (C) 2011 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 android.support.v4.util;

import android.support.annotation.RestrictTo;

import java.io.PrintWriter;

import static android.support.annotation.RestrictTo.Scope.GROUP_ID;

/**
 * Helper for accessing features in {@link android.util.TimeUtils}
 * introduced after API level 4 in a backwards compatible fashion.
 *
 * @hide
 */
@RestrictTo(GROUP_ID)
public final class TimeUtils {
    /** @hide Field length that can hold 999 days of time */
    public static final int HUNDRED_DAY_FIELD_LEN = 19;
    
    private static final int SECONDS_PER_MINUTE = 60;
    private static final int SECONDS_PER_HOUR = 60 * 60;
    private static final int SECONDS_PER_DAY = 24 * 60 * 60;

    private static final Object sFormatSync = new Object();
    private static char[] sFormatStr = new char[HUNDRED_DAY_FIELD_LEN+5];
    
    static private int accumField(int amt, int suffix, boolean always, int zeropad) {
        if (amt > 99 || (always && zeropad >= 3)) {
            return 3+suffix;
        }
        if (amt > 9 || (always && zeropad >= 2)) {
            return 2+suffix;
        }
        if (always || amt > 0) {
            return 1+suffix;
        }
        return 0;
    }
    
    static private int printField(char[] formatStr, int amt, char suffix, int pos,
            boolean always, int zeropad) {
        if (always || amt > 0) {
            final int startPos = pos;
            if ((always && zeropad >= 3) || amt > 99) {
                int dig = amt/100;
                formatStr[pos] = (char)(dig + '0');
                pos++;
                amt -= (dig*100);
            }
            if ((always && zeropad >= 2) || amt > 9 || startPos != pos) {
                int dig = amt/10;
                formatStr[pos] = (char)(dig + '0');
                pos++;
                amt -= (dig*10);
            }
            formatStr[pos] = (char)(amt + '0');
            pos++;
            formatStr[pos] = suffix;
            pos++;
        }
        return pos;
    }
    
    private static int formatDurationLocked(long duration, int fieldLen) {
        if (sFormatStr.length < fieldLen) {
            sFormatStr = new char[fieldLen];
        }
        
        char[] formatStr = sFormatStr;
        
        if (duration == 0) {
            int pos = 0;
            fieldLen -= 1;
            while (pos < fieldLen) {
                formatStr[pos] = ' ';
            }
            formatStr[pos] = '0';
            return pos+1;
        }
        
        char prefix;
        if (duration > 0) {
            prefix = '+';
        } else {
            prefix = '-';
            duration = -duration;
        }

        int millis = (int)(duration%1000);
        int seconds = (int) Math.floor(duration / 1000);
        int days = 0, hours = 0, minutes = 0;

        if (seconds > SECONDS_PER_DAY) {
            days = seconds / SECONDS_PER_DAY;
            seconds -= days * SECONDS_PER_DAY;
        }
        if (seconds > SECONDS_PER_HOUR) {
            hours = seconds / SECONDS_PER_HOUR;
            seconds -= hours * SECONDS_PER_HOUR;
        }
        if (seconds > SECONDS_PER_MINUTE) {
            minutes = seconds / SECONDS_PER_MINUTE;
            seconds -= minutes * SECONDS_PER_MINUTE;
        }

        int pos = 0;
        
        if (fieldLen != 0) {
            int myLen = accumField(days, 1, false, 0);
            myLen += accumField(hours, 1, myLen > 0, 2);
            myLen += accumField(minutes, 1, myLen > 0, 2);
            myLen += accumField(seconds, 1, myLen > 0, 2);
            myLen += accumField(millis, 2, true, myLen > 0 ? 3 : 0) + 1;
            while (myLen < fieldLen) {
                formatStr[pos] = ' ';
                pos++;
                myLen++;
            }
        }
        
        formatStr[pos] = prefix;
        pos++;
        
        int start = pos;
        boolean zeropad = fieldLen != 0;
        pos = printField(formatStr, days, 'd', pos, false, 0);
        pos = printField(formatStr, hours, 'h', pos, pos != start, zeropad ? 2 : 0);
        pos = printField(formatStr, minutes, 'm', pos, pos != start, zeropad ? 2 : 0);
        pos = printField(formatStr, seconds, 's', pos, pos != start, zeropad ? 2 : 0);
        pos = printField(formatStr, millis, 'm', pos, true, (zeropad && pos != start) ? 3 : 0);
        formatStr[pos] = 's';
        return pos + 1;
    }
    
    /** @hide Just for debugging; not internationalized. */
    public static void formatDuration(long duration, StringBuilder builder) {
        synchronized (sFormatSync) {
            int len = formatDurationLocked(duration, 0);
            builder.append(sFormatStr, 0, len);
        }
    }

    /** @hide Just for debugging; not internationalized. */
    public static void formatDuration(long duration, PrintWriter pw, int fieldLen) {
        synchronized (sFormatSync) {
            int len = formatDurationLocked(duration, fieldLen);
            pw.print(new String(sFormatStr, 0, len));
        }
    }

    /** @hide Just for debugging; not internationalized. */
    public static void formatDuration(long duration, PrintWriter pw) {
        formatDuration(duration, pw, 0);
    }
    
    /** @hide Just for debugging; not internationalized. */
    public static void formatDuration(long time, long now, PrintWriter pw) {
        if (time == 0) {
            pw.print("--");
            return;
        }
        formatDuration(time-now, pw, 0);
    }

    private TimeUtils() {}
}