DisplayableUtil.java

package net.morimekta.strings;

import java.time.Duration;
import java.time.Instant;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.OffsetDateTime;
import java.time.ZoneOffset;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.function.Function;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import static java.lang.Integer.parseInt;
import static java.lang.Long.parseLong;
import static java.time.Duration.ofDays;
import static java.time.Duration.ofHours;
import static java.time.Duration.ofMillis;
import static java.time.Duration.ofMinutes;
import static java.time.Duration.ofNanos;
import static java.time.Duration.ofSeconds;
import static java.util.concurrent.TimeUnit.DAYS;
import static java.util.concurrent.TimeUnit.HOURS;
import static java.util.concurrent.TimeUnit.MICROSECONDS;
import static java.util.concurrent.TimeUnit.MILLISECONDS;
import static java.util.concurrent.TimeUnit.MINUTES;
import static java.util.concurrent.TimeUnit.NANOSECONDS;
import static java.util.concurrent.TimeUnit.SECONDS;
import static net.morimekta.strings.EscapeUtil.javaEscape;

public class DisplayableUtil {
    /**
     * Make a displayable string out of a duration. This string is meant to be
     * easy readable. Examples:
     * <ul>
     *   <li><code>null</code>
     *   <li><code>immediately</code>
     *   <li><code>123456 nano</code>
     *   <li><code>0.123 sec</code>
     *   <li><code>0.123456789 sec</code>
     *   <li><code>2 min 3.456 sec</code>
     *   <li><code>2 min 3.456789000 sec</code>
     *   <li><code>1 day 10 hr 17 min 36 sec</code>
     *   <li><code>-1 day 10 hr 17 min 36 sec</code>
     *   <li><code>142 days 21 hr 20 min</code>
     * </ul>
     *
     * @param duration The duration to make displayable string from.
     * @return A displayable duration string. E.g. "1 day 2 hr 3 min 4.567 sec"
     * or "null".
     */
    static String displayableDuration(Duration duration) {
        if (duration == null) {
            return Stringable.NULL;
        }
        if (duration.isZero()) {
            return "none";
        }
        if (duration.isNegative()) {
            return "-" + displayableDuration(duration.abs());
        }

        StringBuilder builder = new StringBuilder();
        var           days    = DAYS.convert(duration);
        if (days > 0) {
            builder.append(days).append(days > 1 ? " days " : " day ");
            duration = duration.minusDays(days);
        }
        var hours = HOURS.convert(duration);
        if (hours > 0) {
            builder.append(hours).append(" hr ");
            duration = duration.minusHours(hours);
        }
        var minutes = MINUTES.convert(duration);
        if (minutes > 0) {
            builder.append(minutes).append(" min ");
            duration = duration.minusMinutes(minutes);
        }
        var seconds = SECONDS.convert(duration);
        if (seconds > 0) {
            builder.append(seconds);
            duration = duration.minusSeconds(seconds);
        }
        var millis = MILLISECONDS.convert(duration);
        duration = duration.minusMillis(millis);
        var micros = MICROSECONDS.convert(duration);
        duration = duration.minusNanos(micros * 1000);
        var nanos = NANOSECONDS.convert(duration);
        if (nanos > 0) {
            if (seconds == 0 && millis == 0) {
                if (micros > 0) {
                    nanos += micros * 1000;
                }
                builder.append(nanos).append(" nanos");
            } else {
                if (seconds > 0) {
                    builder.append(".");
                } else {
                    builder.append("0.");
                }
                builder.append(String.format("%03d%03d%03d sec", millis, micros, nanos));
            }
        } else if (micros > 0) {
            if (seconds == 0 && millis == 0) {
                builder.append(micros).append(" micros");
            } else {
                if (seconds > 0) {
                    builder.append(".");
                } else {
                    builder.append("0.");
                }
                builder.append(String.format("%03d%03d sec", millis, micros));
            }
        } else if (millis > 0) {
            if (seconds > 0) {
                builder.append(".");
            } else {
                builder.append("0.");
            }
            builder.append(String.format("%03d sec", millis));
        } else if (seconds > 0) {
            builder.append(" sec");
        }
        return builder.toString().trim();
    }

    /**
     * Make a simple duration string from a proto duration instance.
     *
     * @param duration The duration instance.
     * @return The simple duration string.
     */
    public static String simpleDurationString(Duration duration) {
        if (duration == null) {
            return Stringable.NULL;
        }
        if (duration.isNegative()) {
            return "-" + simpleDurationString(duration.abs());
        } else {
            if (duration.getNano() != 0) {
                var nanos = String.format("%09d", duration.getNano());
                var i     = nanos.length();
                while (nanos.charAt(i - 1) == '0') {
                    --i;
                }
                return duration.getSeconds() + "." + nanos.substring(0, i) + "s";
            }
            return duration.getSeconds() + "s";
        }
    }

    /**
     * @param value A simple duration string.
     * @return Parsed java duration from the string value.
     */
    public static Duration parseDisplayableDuration(String value) {
        if (value == null || value.isEmpty() || "null".equals(value)) {
            return null;
        } else if ("none".equals(value)) {
            return Duration.ZERO;
        }
        Matcher duration = DURATION_COMPLEX.matcher(value);
        if (duration.matches()) {
            var out = Duration.ZERO;
            out = updatedDuration(out, duration.group("weeks"), s -> ofDays(7L * parseInt(s)));
            out = updatedDuration(out, duration.group("days"), s -> ofDays(parseInt(s)));
            out = updatedDuration(out, duration.group("hours"), s -> ofHours(parseInt(s)));
            out = updatedDuration(out, duration.group("minutes"), s -> ofMinutes(parseInt(s)));
            out = updatedDuration(out, duration.group("seconds"), s -> {
                var parts = s.split("\\.");
                if (parts.length == 2) {
                    var nanos = parts[1] + "0".repeat(9 - parts[1].length());
                    return ofSeconds(parseLong(parts[0]), parseInt(nanos));
                }
                return ofSeconds(parseLong(s));
            });
            out = updatedDuration(out, duration.group("millis"), s -> ofMillis(parseInt(s)));
            out = updatedDuration(out, duration.group("micros"), s -> ofNanos(parseInt(s) * 1000L));
            out = updatedDuration(out, duration.group("nanos"), s -> ofNanos(parseInt(s)));
            if (duration.group("minus") != null) {
                return out.negated();
            }
            return out;
        }
        throw new IllegalArgumentException(
                "Expected duration string, but found: \"" +
                javaEscape(value) +
                "\"");
    }


    /**
     * Get displayable string for local date time.
     *
     * @param localDateTime Date-Time object to make display string of.
     * @return The formatted local date string.
     */
    static String displayableDateTime(LocalDateTime localDateTime) {
        if (localDateTime == null) return Stringable.NULL;
        return DateTimeFormatter.ISO_LOCAL_DATE_TIME
                .format(localDateTime)
                // replace T with space.
                .replace('T', ' ');
    }

    /**
     * Get displayable string for offset date time.
     *
     * @param offsetDateTime Date-Time object to make display string of.
     * @return The formatted local date string.
     */
    static String displayableDateTime(OffsetDateTime offsetDateTime) {
        if (offsetDateTime == null) return Stringable.NULL;
        return DateTimeFormatter.ISO_OFFSET_DATE_TIME
                .format(offsetDateTime)
                // replace T with space.
                .replace('T', ' ')
                // Remove offset if none.
                .replaceAll("\\+00:00$", "")
                // Add space before offset.
                .replaceAll("([+-]\\d\\d):(\\d\\d)$", " $1:$2");
    }

    /**
     * Get displayable string for zoned date time.
     *
     * @param zonedDateTime Date-Time object to make display string of.
     * @return The formatted local date string.
     */
    static String displayableDateTime(ZonedDateTime zonedDateTime) {
        if (zonedDateTime == null) return Stringable.NULL;
        // Just use the (current) zone offset + zone name.
        return displayableDateTime(zonedDateTime.toOffsetDateTime()) + " " + zonedDateTime.getZone().toString();
    }

    /**
     * Get displayable string for instant date time.
     *
     * @param instant Instant to make display string of.
     * @return The formatted instant string.
     */
    public static String displayableInstant(Instant instant) {
        if (instant == null) return Stringable.NULL;
        return DateTimeFormatter.ISO_INSTANT
                .format(instant)
                // replace T with space.
                .replace('T', ' ')
                // Add space before Z (and use UTC).
                .replaceAll("(\\d)Z$", "$1 UTC");
    }

    /**
     * @param value ISO formatted timestamp string.
     * @return Parsed timestamp as java instant.
     */
    public static Instant parseTimestamp(String value) {
        if (value == null || value.isEmpty() || "null".equals(value)) {
            return null;
        }
        Matcher isoDateTime = ISO_DATE_TIME.matcher(value);
        if (!isoDateTime.matches()) {
            throw new IllegalArgumentException(
                    "Expected ISO date format, but found: \"" + javaEscape(value) + "\"");
        }
        var year  = parseInt(isoDateTime.group("year"));
        var month = parseInt(isoDateTime.group("month"));
        var day   = parseInt(isoDateTime.group("day"));
        if (isoDateTime.group("hour") == null) {
            return LocalDate.of(year, month, day).atStartOfDay().toInstant(ZoneOffset.UTC);
        }
        var hour         = parseInt(isoDateTime.group("hour"));
        var minute       = parseInt(isoDateTime.group("minute"));
        var second       = parseInt(isoDateTime.group("second"));
        var dateTime     = LocalDateTime.of(year, month, day, hour, minute, second);
        var fractionsStr = isoDateTime.group("fractionSeconds");
        if (fractionsStr != null) {
            var fractionsInt = parseInt(fractionsStr);
            if (fractionsInt > 0) {
                for (int i = fractionsStr.length(); i < 9; ++i) {
                    fractionsInt *= 10;
                }
                dateTime = dateTime.plusNanos(fractionsInt);
            }
        }
        return dateTime.toInstant(ZoneOffset.UTC);
    }

    // ----------------------------------------------------------------
    // --------                    PRIVATE                     --------
    // ----------------------------------------------------------------

    private static Duration updatedDuration(Duration orig, String amount, Function<String, Duration> parser) {
        if (amount == null) {
            return orig;
        } else {
            return orig.plus(parser.apply(amount));
        }
    }

    private static final Pattern DURATION_COMPLEX = Pattern.compile(
            "(?<minus>-)?" +
            "(?:(?<weeks>\\d+) ?(?:w|weeks?) ?)?" +
            "(?:(?<days>\\d+) ?(?:d|days?) ?)?" +
            "(?:(?<hours>\\d+) ?(?:h|hr|hours?) ?)?" +
            "(?:(?<minutes>\\d+) ?(?:m|min|minutes?) ?)?" +
            "(?:(?<seconds>\\d+(?:\\.\\d{1,9})?) ?(?:s|sec|seconds?) ?)?" +
            "(?:(?<millis>\\d+) ?(?:ms|millis?) ?)?" +
            "(?:(?<micros>\\d+) ?(?:µs?|micros?) ?)?" +
            "(?:(?<nanos>\\d+) ?(?:ns|nanos?))?");
    private static final Pattern ISO_DATE_TIME    = Pattern.compile(
            "^(?<year>\\d{4})-(?<month>\\d{2})-(?<day>\\d{2})" +
            "(?:[ tT](?<hour>\\d{2}):(?<minute>\\d{2}):(?<second>\\d{2})" +
            "(?:\\.(?<fractionSeconds>\\d{1,9}))?" +
            "(?: ?(Z|UTC|[-+]00:?00))?)?$");

    private DisplayableUtil() {
    }
}