/*
 * Copyright (C) 2006 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.text.format;

import android.annotation.NonNull;
import android.annotation.Nullable;
import android.content.Context;
import android.content.res.Resources;
import android.icu.text.DecimalFormat;
import android.icu.text.MeasureFormat;
import android.icu.text.NumberFormat;
import android.icu.text.UnicodeSet;
import android.icu.text.UnicodeSetSpanner;
import android.icu.util.Measure;
import android.icu.util.MeasureUnit;
import android.net.NetworkUtils;
import android.text.BidiFormatter;
import android.text.TextUtils;
import android.view.View;

import java.lang.reflect.Constructor;
import java.math.BigDecimal;
import java.util.Locale;

/**
 * Utility class to aid in formatting common values that are not covered
 * by the {@link java.util.Formatter} class in {@link java.util}
 */
public final class Formatter {

    /** {@hide} */
    public static final int FLAG_DEFAULT = 0;
    /** {@hide} */
    public static final int FLAG_SHORTER = 1 << 0;
    /** {@hide} */
    public static final int FLAG_CALCULATE_ROUNDED = 1 << 1;

    /** {@hide} */
    public static class BytesResult {
        public final String value;
        public final String units;
        public final long roundedBytes;

        public BytesResult(String value, String units, long roundedBytes) {
            this.value = value;
            this.units = units;
            this.roundedBytes = roundedBytes;
        }
    }

    private static Locale localeFromContext(@NonNull Context context) {
        return context.getResources().getConfiguration().getLocales().get(0);
    }

    /**
     * Wraps the source string in bidi formatting characters in RTL locales.
     */
    private static String bidiWrap(@NonNull Context context, String source) {
        final Locale locale = localeFromContext(context);
        if (TextUtils.getLayoutDirectionFromLocale(locale) == View.LAYOUT_DIRECTION_RTL) {
            return BidiFormatter.getInstance(true /* RTL*/).unicodeWrap(source);
        } else {
            return source;
        }
    }

    /**
     * Formats a content size to be in the form of bytes, kilobytes, megabytes, etc.
     *
     * <p>As of O, the prefixes are used in their standard meanings in the SI system, so kB = 1000
     * bytes, MB = 1,000,000 bytes, etc.</p>
     *
     * <p class="note">In {@link android.os.Build.VERSION_CODES#N} and earlier, powers of 1024 are
     * used instead, with KB = 1024 bytes, MB = 1,048,576 bytes, etc.</p>
     *
     * <p>If the context has a right-to-left locale, the returned string is wrapped in bidi
     * formatting characters to make sure it's displayed correctly if inserted inside a
     * right-to-left string. (This is useful in cases where the unit strings, like "MB", are
     * left-to-right, but the locale is right-to-left.)</p>
     *
     * @param context Context to use to load the localized units
     * @param sizeBytes size value to be formatted, in bytes
     * @return formatted string with the number
     */
    public static String formatFileSize(@Nullable Context context, long sizeBytes) {
        return formatFileSize(context, sizeBytes, FLAG_DEFAULT);
    }

    /**
     * Like {@link #formatFileSize}, but trying to generate shorter numbers
     * (showing fewer digits of precision).
     */
    public static String formatShortFileSize(@Nullable Context context, long sizeBytes) {
        return formatFileSize(context, sizeBytes, FLAG_SHORTER);
    }

    private static String formatFileSize(@Nullable Context context, long sizeBytes, int flags) {
        if (context == null) {
            return "";
        }
        final RoundedBytesResult res = RoundedBytesResult.roundBytes(sizeBytes, flags);
        return bidiWrap(context, formatRoundedBytesResult(context, res));
    }

    private static String getSuffixOverride(@NonNull Resources res, MeasureUnit unit) {
        if (unit == MeasureUnit.BYTE) {
            return res.getString(com.android.internal.R.string.byteShort);
        } else { // unit == PETABYTE
            return res.getString(com.android.internal.R.string.petabyteShort);
        }
    }

    private static NumberFormat getNumberFormatter(Locale locale, int fractionDigits) {
        final NumberFormat numberFormatter = NumberFormat.getInstance(locale);
        numberFormatter.setMinimumFractionDigits(fractionDigits);
        numberFormatter.setMaximumFractionDigits(fractionDigits);
        numberFormatter.setGroupingUsed(false);
        if (numberFormatter instanceof DecimalFormat) {
            // We do this only for DecimalFormat, since in the general NumberFormat case, calling
            // setRoundingMode may throw an exception.
            numberFormatter.setRoundingMode(BigDecimal.ROUND_HALF_UP);
        }
        return numberFormatter;
    }

    private static String deleteFirstFromString(String source, String toDelete) {
        final int location = source.indexOf(toDelete);
        if (location == -1) {
            return source;
        } else {
            return source.substring(0, location)
                    + source.substring(location + toDelete.length(), source.length());
        }
    }

    private static String formatMeasureShort(Locale locale, NumberFormat numberFormatter,
            float value, MeasureUnit units) {
        final MeasureFormat measureFormatter = MeasureFormat.getInstance(
                locale, MeasureFormat.FormatWidth.SHORT, numberFormatter);
        return measureFormatter.format(new Measure(value, units));
    }

    private static final UnicodeSetSpanner SPACES_AND_CONTROLS =
            new UnicodeSetSpanner(new UnicodeSet("[[:Zs:][:Cf:]]").freeze());

    private static String formatRoundedBytesResult(
            @NonNull Context context, @NonNull RoundedBytesResult input) {
        final Locale locale = localeFromContext(context);
        final NumberFormat numberFormatter = getNumberFormatter(locale, input.fractionDigits);
        if (input.units == MeasureUnit.BYTE || input.units == PETABYTE) {
            // ICU spells out "byte" instead of "B", and can't format petabytes yet.
            final String formattedNumber = numberFormatter.format(input.value);
            return context.getString(com.android.internal.R.string.fileSizeSuffix,
                    formattedNumber, getSuffixOverride(context.getResources(), input.units));
        } else {
            return formatMeasureShort(locale, numberFormatter, input.value, input.units);
        }
    }

    /** {@hide} */
    public static BytesResult formatBytes(Resources res, long sizeBytes, int flags) {
        final RoundedBytesResult rounded = RoundedBytesResult.roundBytes(sizeBytes, flags);
        final Locale locale = res.getConfiguration().getLocales().get(0);
        final NumberFormat numberFormatter = getNumberFormatter(locale, rounded.fractionDigits);
        final String formattedNumber = numberFormatter.format(rounded.value);
        final String units;
        if (rounded.units == MeasureUnit.BYTE || rounded.units == PETABYTE) {
            // ICU spells out "byte" instead of "B", and can't format petabytes yet.
            units = getSuffixOverride(res, rounded.units);
        } else {
            // Since ICU does not give us access to the pattern, we need to extract the unit string
            // from ICU, which we do by taking out the formatted number out of the formatted string
            // and trimming the result of spaces and controls.
            final String formattedMeasure = formatMeasureShort(
                    locale, numberFormatter, rounded.value, rounded.units);
            final String numberRemoved = deleteFirstFromString(formattedMeasure, formattedNumber);
            units = SPACES_AND_CONTROLS.trim(numberRemoved).toString();
        }
        return new BytesResult(formattedNumber, units, rounded.roundedBytes);
    }

    /**
     * ICU doesn't support PETABYTE yet. Fake it so that we can treat all units the same way.
     */
    private static final MeasureUnit PETABYTE = createPetaByte();

    /**
     * Create a petabyte MeasureUnit without registering it with ICU.
     * ICU doesn't support user-create MeasureUnit and the only public (but hidden) method to do so
     * is {@link MeasureUnit#internalGetInstance(String, String)} which also registers the unit as
     * an available type and thus leaks it to code that doesn't expect or support it.
     * <p>This method uses reflection to create an instance of MeasureUnit to avoid leaking it. This
     * instance is <b>only</b> to be used in this class.
     */
    private static MeasureUnit createPetaByte() {
        try {
            Constructor<MeasureUnit> constructor = MeasureUnit.class
                    .getDeclaredConstructor(String.class, String.class);
            constructor.setAccessible(true);
            return constructor.newInstance("digital", "petabyte");
        } catch (ReflectiveOperationException e) {
            throw new RuntimeException("Failed to create petabyte MeasureUnit", e);
        }
    }

    private static class RoundedBytesResult {
        public final float value;
        public final MeasureUnit units;
        public final int fractionDigits;
        public final long roundedBytes;

        private RoundedBytesResult(
                float value, MeasureUnit units, int fractionDigits, long roundedBytes) {
            this.value = value;
            this.units = units;
            this.fractionDigits = fractionDigits;
            this.roundedBytes = roundedBytes;
        }

        /**
         * Returns a RoundedBytesResult object based on the input size in bytes and the rounding
         * flags. The result can be used for formatting.
         */
        static RoundedBytesResult roundBytes(long sizeBytes, int flags) {
            final boolean isNegative = (sizeBytes < 0);
            float result = isNegative ? -sizeBytes : sizeBytes;
            MeasureUnit units = MeasureUnit.BYTE;
            long mult = 1;
            if (result > 900) {
                units = MeasureUnit.KILOBYTE;
                mult = 1000;
                result = result / 1000;
            }
            if (result > 900) {
                units = MeasureUnit.MEGABYTE;
                mult *= 1000;
                result = result / 1000;
            }
            if (result > 900) {
                units = MeasureUnit.GIGABYTE;
                mult *= 1000;
                result = result / 1000;
            }
            if (result > 900) {
                units = MeasureUnit.TERABYTE;
                mult *= 1000;
                result = result / 1000;
            }
            if (result > 900) {
                units = PETABYTE;
                mult *= 1000;
                result = result / 1000;
            }
            // Note we calculate the rounded long by ourselves, but still let NumberFormat compute
            // the rounded value. NumberFormat.format(0.1) might not return "0.1" due to floating
            // point errors.
            final int roundFactor;
            final int roundDigits;
            if (mult == 1 || result >= 100) {
                roundFactor = 1;
                roundDigits = 0;
            } else if (result < 1) {
                roundFactor = 100;
                roundDigits = 2;
            } else if (result < 10) {
                if ((flags & FLAG_SHORTER) != 0) {
                    roundFactor = 10;
                    roundDigits = 1;
                } else {
                    roundFactor = 100;
                    roundDigits = 2;
                }
            } else { // 10 <= result < 100
                if ((flags & FLAG_SHORTER) != 0) {
                    roundFactor = 1;
                    roundDigits = 0;
                } else {
                    roundFactor = 100;
                    roundDigits = 2;
                }
            }

            if (isNegative) {
                result = -result;
            }

            // Note this might overflow if abs(result) >= Long.MAX_VALUE / 100, but that's like
            // 80PB so it's okay (for now)...
            final long roundedBytes =
                    (flags & FLAG_CALCULATE_ROUNDED) == 0 ? 0
                    : (((long) Math.round(result * roundFactor)) * mult / roundFactor);

            return new RoundedBytesResult(result, units, roundDigits, roundedBytes);
        }
    }

    /**
     * Returns a string in the canonical IPv4 format ###.###.###.### from a packed integer
     * containing the IP address. The IPv4 address is expected to be in little-endian
     * format (LSB first). That is, 0x01020304 will return "4.3.2.1".
     *
     * @deprecated Use {@link java.net.InetAddress#getHostAddress()}, which supports both IPv4 and
     *     IPv6 addresses. This method does not support IPv6 addresses.
     */
    @Deprecated
    public static String formatIpAddress(int ipv4Address) {
        return NetworkUtils.intToInetAddress(ipv4Address).getHostAddress();
    }

    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 int MILLIS_PER_MINUTE = 1000 * 60;

    /**
     * Returns elapsed time for the given millis, in the following format:
     * 1 day, 5 hr; will include at most two units, can go down to seconds precision.
     * @param context the application context
     * @param millis the elapsed time in milli seconds
     * @return the formatted elapsed time
     * @hide
     */
    public static String formatShortElapsedTime(Context context, long millis) {
        long secondsLong = millis / 1000;

        int days = 0, hours = 0, minutes = 0;
        if (secondsLong >= SECONDS_PER_DAY) {
            days = (int)(secondsLong / SECONDS_PER_DAY);
            secondsLong -= days * SECONDS_PER_DAY;
        }
        if (secondsLong >= SECONDS_PER_HOUR) {
            hours = (int)(secondsLong / SECONDS_PER_HOUR);
            secondsLong -= hours * SECONDS_PER_HOUR;
        }
        if (secondsLong >= SECONDS_PER_MINUTE) {
            minutes = (int)(secondsLong / SECONDS_PER_MINUTE);
            secondsLong -= minutes * SECONDS_PER_MINUTE;
        }
        int seconds = (int)secondsLong;

        final Locale locale = localeFromContext(context);
        final MeasureFormat measureFormat = MeasureFormat.getInstance(
                locale, MeasureFormat.FormatWidth.SHORT);
        if (days >= 2) {
            days += (hours+12)/24;
            return measureFormat.format(new Measure(days, MeasureUnit.DAY));
        } else if (days > 0) {
            return measureFormat.formatMeasures(
                    new Measure(days, MeasureUnit.DAY),
                    new Measure(hours, MeasureUnit.HOUR));
        } else if (hours >= 2) {
            hours += (minutes+30)/60;
            return measureFormat.format(new Measure(hours, MeasureUnit.HOUR));
        } else if (hours > 0) {
            return measureFormat.formatMeasures(
                    new Measure(hours, MeasureUnit.HOUR),
                    new Measure(minutes, MeasureUnit.MINUTE));
        } else if (minutes >= 2) {
            minutes += (seconds+30)/60;
            return measureFormat.format(new Measure(minutes, MeasureUnit.MINUTE));
        } else if (minutes > 0) {
            return measureFormat.formatMeasures(
                    new Measure(minutes, MeasureUnit.MINUTE),
                    new Measure(seconds, MeasureUnit.SECOND));
        } else {
            return measureFormat.format(new Measure(seconds, MeasureUnit.SECOND));
        }
    }

    /**
     * Returns elapsed time for the given millis, in the following format:
     * 1 day, 5 hr; will include at most two units, can go down to minutes precision.
     * @param context the application context
     * @param millis the elapsed time in milli seconds
     * @return the formatted elapsed time
     * @hide
     */
    public static String formatShortElapsedTimeRoundingUpToMinutes(Context context, long millis) {
        long minutesRoundedUp = (millis + MILLIS_PER_MINUTE - 1) / MILLIS_PER_MINUTE;

        if (minutesRoundedUp == 0 || minutesRoundedUp == 1) {
            final Locale locale = localeFromContext(context);
            final MeasureFormat measureFormat = MeasureFormat.getInstance(
                    locale, MeasureFormat.FormatWidth.SHORT);
            return measureFormat.format(new Measure(minutesRoundedUp, MeasureUnit.MINUTE));
        }

        return formatShortElapsedTime(context, minutesRoundedUp * MILLIS_PER_MINUTE);
    }
}