/*
 * Copyright 2007 ZXing authors
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.jwetherell.quick_response_code.qrcode.detector;

import com.google.zxing.ResultPoint;

/**
 * <p>
 * Encapsulates a finder pattern, which are the three square patterns found in
 * the corners of QR Codes. It also encapsulates a count of similar finder
 * patterns, as a convenience to the finder's bookkeeping.
 * </p>
 * 
 * @author Sean Owen
 */
public final class FinderPattern extends ResultPoint {

    private final float estimatedModuleSize;
    private int count;

    FinderPattern(float posX, float posY, float estimatedModuleSize) {
        this(posX, posY, estimatedModuleSize, 1);
    }

    FinderPattern(float posX, float posY, float estimatedModuleSize, int count) {
        super(posX, posY);
        this.estimatedModuleSize = estimatedModuleSize;
        this.count = count;
    }

    public float getEstimatedModuleSize() {
        return estimatedModuleSize;
    }

    int getCount() {
        return count;
    }

    void incrementCount() {
        this.count++;
    }

    /**
     * <p>
     * Determines if this finder pattern "about equals" a finder pattern at the
     * stated position and size -- meaning, it is at nearly the same center with
     * nearly the same size.
     * </p>
     */
    boolean aboutEquals(float moduleSize, float i, float j) {
        if (Math.abs(i - getY()) <= moduleSize && Math.abs(j - getX()) <= moduleSize) {
            float moduleSizeDiff = Math.abs(moduleSize - estimatedModuleSize);
            return moduleSizeDiff <= 1.0f || moduleSizeDiff <= estimatedModuleSize;
        }
        return false;
    }

    /**
     * Combines this object's current estimate of a finder pattern position and
     * module size with a new estimate. It returns a new {@code FinderPattern}
     * containing a weighted average based on count.
     */
    FinderPattern combineEstimate(float i, float j, float newModuleSize) {
        int combinedCount = count + 1;
        float combinedX = (count * getX() + j) / combinedCount;
        float combinedY = (count * getY() + i) / combinedCount;
        float combinedModuleSize = (count * estimatedModuleSize + newModuleSize) / combinedCount;
        return new FinderPattern(combinedX, combinedY, combinedModuleSize, combinedCount);
    }

}
