package com.avaje.ebeaninternal.server.autofetch;

import java.io.Serializable;

import com.avaje.ebean.bean.ObjectGraphOrigin;
import com.avaje.ebeaninternal.api.SpiQuery;
import com.avaje.ebeaninternal.server.querydefn.OrmQueryDetail;

/**
 * Holds tuned query information. Is immutable so this represents the tuning at
 * a given point in time.
 */
public class TunedQueryInfo implements Serializable {

	private static final long serialVersionUID = 7381493228797997282L;

	private final ObjectGraphOrigin origin;

	/**
	 * The tuned query details with joins and properties.
	 */
	private OrmQueryDetail tunedDetail;

	/**
	 * The number of times profiling has been collected for this query point.
	 */
	private int profileCount;
	
	private Long lastTuneTime = Long.valueOf(0);

	private final String rateMonitor = new String();

	/**
	 * The number of queries tuned by this object.
	 * Could use AtomicInteger perhaps.
	 */
	private transient int tunedCount;

	private transient int rateTotal;

	private transient int rateHits;

	private transient double lastRate;

	public TunedQueryInfo(ObjectGraphOrigin queryPoint, OrmQueryDetail tunedDetail, int profileCount) {
		this.origin = queryPoint;
		this.tunedDetail = tunedDetail;
		this.profileCount = profileCount;
	}

	/**
	 * Return true if this query should be profiled based on a percentage rate.
	 */
	public boolean isPercentageProfile(double rate) {
		
		synchronized (rateMonitor) {

			if (lastRate != rate) {
				// the rate has changed so resetting
				lastRate = rate;
				rateTotal = 0;
				rateHits = 0;
			}

			rateTotal++;
			if (rate > (double) rateHits / rateTotal) {
				rateHits++;
				return true;
			} else {
				return false;
			}
		}
	}

	/**
	 * Set the number of times profiling has been collected for this query
	 * point.
	 */
	public void setProfileCount(int profileCount) {
		// int assignment is atomic
		this.profileCount = profileCount;
	}

	/**
	 * Set the tuned query detail.
	 */
	public void setTunedDetail(OrmQueryDetail tunedDetail) {
		// assignment is atomic
		this.tunedDetail = tunedDetail;
		this.lastTuneTime = Long.valueOf(System.currentTimeMillis());
	}

	/**
	 * Return true if the fetches are essentially the same.
	 */
	public boolean isSame(OrmQueryDetail newQueryDetail) {
		if (tunedDetail == null) {
			return false;
		}
		return tunedDetail.isAutoFetchEqual(newQueryDetail);
	}

	/**
	 * Tune the query by replacing its OrmQueryDetail with a tuned one.
	 * 
	 * @return true if the query was tuned, otherwise false.
	 */
	public boolean autoFetchTune(SpiQuery<?> query) {
		if (tunedDetail == null) {
		    return false;
		}
		
		boolean tuned = false;
		//Note: tunedDetail is immutable by convention
	    if (query.isDetailEmpty()) {
            tuned = true;
            // tune by 'replacement'
            query.setDetail(tunedDetail.copy());  
	    } else {
	        // tune by 'addition'
	        tuned = query.tuneFetchProperties(tunedDetail);
	    }
	    if (tuned){
            query.setAutoFetchTuned(true);
    		// a case for AtomicInteger but good enough for statistics
    		tunedCount++;	
	    }
		return tuned;
	}
	
	/**
	 * Return the time of the last tune.
	 */
	public Long getLastTuneTime() {
		return lastTuneTime;
	}

	/**
	 * Return the number of queries tuned by this object.
	 */
	public int getTunedCount() {
		return tunedCount;
	}

	/**
	 * Return the number of times profiling has been collected for this query
	 * point.
	 */
	public int getProfileCount() {
		return profileCount;
	}

	public OrmQueryDetail getTunedDetail() {
		return tunedDetail;
	}

	public ObjectGraphOrigin getOrigin() {
		return origin;
	}

	public String getLogOutput(OrmQueryDetail newQueryDetail) {
		
		boolean changed = newQueryDetail != null;
		
		StringBuilder sb = new StringBuilder(150);
		sb.append( changed ? "\"Changed\",":"\"New\",");
		sb.append("\"").append(origin.getBeanType()).append("\",");
		sb.append("\"").append(origin.getKey()).append("\",");
		if (changed){
			sb.append("\"to: ").append(newQueryDetail.toString()).append("\",");
			sb.append("\"from: ").append(tunedDetail.toString()).append("\",");
		} else {
			sb.append("\"to: ").append(tunedDetail.toString()).append("\",");			
			sb.append("\"\",");
		}
		sb.append("\"").append(origin.getFirstStackElement()).append("\"");
		
		return sb.toString();
	}
	
	public String toString() {
		return origin.getBeanType()+" "+origin.getKey()+" " + tunedDetail;
	}

}