/*
 * RiskScape™ Copyright New Zealand Institute for Earth Science Limited
 * (Earth Sciences New Zealand) is distributed for research purposes only
 * under the terms of AGPLv3.
 *
 * RiskScape™ Copyright 2026 New Zealand Institute for Earth Science
 * Limited (Earth Sciences New Zealand). All rights reserved. Source code
 * available under the AGPLv3.
 * 
 * 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 for RESEARCH PURPOSES ONLY, in the hope that it will
 * be useful for research and education initiatives.
 * 
 * If you are not a researcher, or you are a researcher who wishes to use this
 * program on terms other than AGPLv3 (including those who wish to restrict the
 * distribution of any source code created using this program), please contact:
 * https://riskscape.org.nz
 * 
 * This program is distributed 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/>.
 * 
 * By way of summary only, under the AGPLv3:
 *     • Permissions of this strongest copyleft license are conditioned
 *       on making available complete source code of licensed works and
 *       modifications, which include larger works using a licensed work,
 *       under the same license.
 *     • Copyright and license notices must be preserved.
 *     • Contributors provide an express grant of patent rights.
 *     • When a modified version is used to provide a service over a
 *       network, the complete source code of the modified version must be made
 *       available.
 */
package nz.org.riskscape.defaults.interp;

import lombok.Getter;
import lombok.RequiredArgsConstructor;
import nz.org.riskscape.engine.Tuple;
import nz.org.riskscape.engine.rl.RealizedExpression;
import nz.org.riskscape.engine.types.Struct;
import nz.org.riskscape.engine.types.Type;

/**
 * Expressions and types needed for doing a linear interpolation between two known points.
 */
@RequiredArgsConstructor
class LinearContinuousExpressions {

  @Getter
  private final RealizedExpression yExpression;

  // expression for computing the slope of a line formed between two points, computed from a pair of
  // neighbouring x-y coordinates
  private final Struct slopeInputType;
  private final RealizedExpression slopeExpression;

  // expression for computing y-intercepts from the slope (m) and a known x and y
  private final Struct yInterceptInputType;
  private final RealizedExpression yInterceptExpression;

  // expression for computing an interpolated y value from a slope and a y intercept
  private final Struct solveForYExpressionInputType;
  private final RealizedExpression solveForYExpression;

  Type getYInterceptType() {
    return yInterceptExpression.getResultType();
  }

  Type getSlopeType() {
    return slopeExpression.getResultType();
  }

  // TODO renameto get ResultType?
  Type getSolveForYType() {
    return solveForYExpression.getResultType();
  }

  Object solveForY(Object slope, double xValue, Object yIntercept) {
    Tuple inputType = Tuple.ofValues(solveForYExpressionInputType, slope, xValue, yIntercept);
    return solveForYExpression.evaluate(inputType);
  }

  Object computeYIntercept(Object slope, double x1, Object y1) {
    Tuple tuple = Tuple.ofValues(yInterceptInputType, y1, slope, x1);
    return yInterceptExpression.evaluate(tuple);
  }

  Object computeSlope(double x0, double x1, Object y0, Object y1) {
    Tuple tuple = Tuple.ofValues(slopeInputType, x0, x1, y0, y1);
    return slopeExpression.evaluate(tuple);
  }
}
