/*
XOWA: the XOWA Offline Wiki Application
Copyright (C) 2012 gnosygnu@gmail.com

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as
published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
package gplx.dbs.percentiles; import gplx.*; import gplx.dbs.*;
public class Percentile_rng {
	private long total_max; private int total_needed;
	private int score_max, score_len_max;
	private long prv_time;
	public int Score_bgn()		{return score_bgn;} private int score_bgn;
	public int Score_end()		{return score_end;} private int score_end;
	public int Score_len()		{return score_len;} private int score_len;
	public int Found_rdr()		{return found_rdr;} private int found_rdr;
	public int Found_all()		{return found_all;} private int found_all;
	public int Elapsed()		{return elapsed;}	private int elapsed;
	public Percentile_rng Init(long total_max, int score_max) {
		this.total_max = total_max;
		this.score_max = score_max;
		this.score_len_max = score_max / 20;	// limit to 5%
		return this;
	}
	public void Select_init(int total_needed, int prv_score_bgn, int prv_score_len, int score_len_adj) {
		this.total_needed = total_needed;
		this.found_all = 0;
		this.prv_time = gplx.core.envs.Env_.TickCount();
		int score_unit = Calc_score_unit(total_needed, total_max, score_max);
		if (prv_score_bgn == Score_null) {
			score_len = score_unit + (score_unit * score_len_adj);
			score_bgn = score_max;
			Rng_len_(Bool_.Y);
		}
		else {
			score_len = prv_score_len;
			score_bgn = prv_score_bgn;
			score_end = score_bgn + score_len;
		}
	}
	public void Update(int found_rdr) {
		this.found_rdr    = found_rdr;
		this.found_all += found_rdr;

		// calc rng_multiplier based on found_rdr and total_needed; EX: 100=total_needed; 10=found_rdr; 40=found_all -> 6=rng_multiplier; (100 - 40 / 10)
		int rng_multiplier = 1;
		if (found_rdr == 0) {
			rng_multiplier = 4;
		} else {
			int total_remaining = total_needed - found_all;
			rng_multiplier = total_remaining == 0 ? 1 : Math_.Ceil_as_int(total_remaining / found_rdr);
		}

		// calc new score_len
		int new_score_len = score_len * rng_multiplier;
		if		(new_score_len < 1)				new_score_len = score_len;
		else if (new_score_len > score_len_max) new_score_len = score_len_max;
		score_len = new_score_len;
		Rng_len_(Bool_.N);

		// update times
		long new_time = gplx.core.envs.Env_.TickCount();
		this.elapsed = Int_.Subtract_long(new_time, prv_time);
		prv_time = new_time;
	}
	private void Rng_len_(boolean first) {
		score_end = score_bgn + (first ? 1 : 0);	// + 1 to include rows with scores at max; EX: > 999,998 AND < 1,000,001
		score_bgn = score_end - score_len;
		if (score_bgn < 0) score_bgn = 0;			// make sure score is not negative
	}
	@gplx.Internal protected static int Calc_score_unit(int total_needed, long total_max, int score_max) {// TEST:
		int rv = (int)Math_.Ceil(Math_.Div_safe_as_double(total_needed, Math_.Div_safe_as_double(total_max, score_max)));	// EX: 100 needed / (16 M / 1 M) -> 7 units to fill 100
		if (rv > score_max) rv = score_max;			// never allow score_unit to be > score_max; occurs when total_needed > total_max; EX: 50 needed; 10 available
		return rv;
	}
	public static final int Score_null = -1;
}