package geniusweb.progress;

import java.util.Date;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonTypeName;

import geniusweb.deadline.DeadlineTime;

/**
 * keeps track of progress towards the Deadline and the time/rounds left.
 * immutable. However, the time progresses nevertheless since this refers to the
 * system clocks.
 *
 */
@JsonTypeName("time")
public class ProgressTime implements Progress {

	/**
	 * time in millis as returned from {@link System#currentTimeMillis()}. Note,
	 * we do not use RFC 3339 because we need millisecond accuracy.
	 */
	private final Date start;

	/**
	 * duration in millis. we do not use ISO 8601 because we need millisecond
	 * accuracy.
	 */
	private final Long duration;

	/**
	 * 
	 * @param d     the duration, eg {@link DeadlineTime#getDuration()}. Must be
	 *              > 0.
	 * @param start the start Date (unix time in millisecs since 1970). See
	 *              {@link System#currentTimeMillis()}.
	 */
	@JsonCreator
	public ProgressTime(@JsonProperty("duration") Long d,
			@JsonProperty("start") Date start) {
		this.start = start;
		duration = (d == null || d <= 0) ? 1 : d;
	}

	@Override
	public Double get(Long currentTimeMs) {
		long delta = currentTimeMs - start.getTime();
		// double should have ~53 digits of precision, and we're computing
		// deltas here.
		// 2^53 millis seems plenty for our purposes so no need to use
		// BigDecimal here.
		Double ratio = delta / (double) duration;
		if (ratio > 1d)
			ratio = 1d;
		else if (ratio < 0d)
			ratio = 0d;
		return ratio;
	}

	@Override
	public boolean isPastDeadline(Long currentTimeMs) {
		return currentTimeMs > start.getTime() + duration;
	}

	/**
	 * 
	 * @return time measured in milliseconds, between the start time and
	 *         midnight, January 1, 1970 UTCas returned from
	 *         {@link System#currentTimeMillis()}
	 * 
	 */
	public Date getStart() {
		return start;
	}

	/**
	 * 
	 * @return duration in milliseconds.
	 */
	public Long getDuration() {
		return duration;
	}

	@Override
	public Date getTerminationTime() {
		return new Date(start.getTime() + duration);
	}

	@Override
	public String toString() {
		return "ProgressTime[" + start.getTime() + " , " + duration + "ms]";
	}

	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result
				+ ((duration == null) ? 0 : duration.hashCode());
		result = prime * result + ((start == null) ? 0 : start.hashCode());
		return result;
	}

	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		ProgressTime other = (ProgressTime) obj;
		if (duration == null) {
			if (other.duration != null)
				return false;
		} else if (!duration.equals(other.duration))
			return false;
		if (start == null) {
			if (other.start != null)
				return false;
		} else if (!start.equals(other.start))
			return false;
		return true;
	}

}