/*
 * Copyright (C) 2004-2007 Andrew Mihal
 *
 * This file is part of Enblend.
 *
 * Enblend is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * Enblend 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with Enblend; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
#ifndef __BOUNDS_H__
#define __BOUNDS_H__

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "common.h"
#include "pyramid.h"

using std::cerr;
using std::cout;
using std::endl;
using std::min;

using vigra::Point2D;

namespace enblend {

/** Characterize the overlap between src1 and src2.
 *  The images may overlap completely (CompleteOverlap),
 *  partially (PartialOverlap),
 *  or not at all (NoOverlap).
 */
template <typename SrcImageIterator, typename SrcAccessor>
Overlap inspectOverlap(
        SrcImageIterator src1_upperleft,
        SrcImageIterator src1_lowerright,
        SrcAccessor s1a,
        SrcImageIterator src2_upperleft,
        SrcAccessor s2a) {

    SrcImageIterator s1y = src1_upperleft;
    SrcImageIterator s2y = src2_upperleft;
    SrcImageIterator send = src1_lowerright;

    bool foundOverlap = false;
    bool foundDistinctS2 = false;

    for (; s1y.y < send.y; ++s1y.y, ++s2y.y) {

        SrcImageIterator s1x = s1y;
        SrcImageIterator s2x = s2y;

        for (; s1x.x < send.x; ++s1x.x, ++s2x.x) {
            if (s1a(s1x) && s2a(s2x)) {
                foundOverlap = true;
            } else if (s2a(s2x)) {
                foundDistinctS2 = true;
            }
            if (foundOverlap && foundDistinctS2) {
                // If we have found a pixel where there is overlap,
                // and also a pixel where src2 alone contributes,
                // then we know it's PartialOverlap and we can quit.
                return PartialOverlap;
            }
        }
    }

    if (foundOverlap) {
        return CompleteOverlap;
    } else {
        return NoOverlap;
    }

};

// Argument object factory version.
template <typename SrcImageIterator, typename SrcAccessor>
Overlap inspectOverlap(
        triple<SrcImageIterator, SrcImageIterator, SrcAccessor> src1,
        pair<SrcImageIterator, SrcAccessor> src2) {
    return inspectOverlap(src1.first, src1.second, src1.third,
                          src2.first, src2.second);
};

/** Determine the region-of-interest and number of blending levels to use,
 *  given the current mask-bounding-box and intersection-bounding-box.
 *  We also need to know if the image is a 360-degree pano so we can check
 *  for the case that the ROI wraps around the left and right edges.
 */
template <typename ImagePixelComponentType>
unsigned int roiBounds(const Rect2D &inputUnion,
        const Rect2D &iBB,
        const Rect2D &mBB,
        const Rect2D &uBB,
        Rect2D &roiBB,
        bool wraparoundForMask) {

    unsigned int levels = 1;

    if (ExactLevels == 0) {
        // Estimate the number of blending levels to use based on the size of the iBB.
        // Assume the transition line runs approximately down the center of the iBB.
        // Choose a number of levels that makes the mask spread out to the edges
        // of the iBB.
        // Calculate short dimension of iBB.
        unsigned int shortDimension = min(iBB.width(), iBB.height());
        while (levels < 30) {
            unsigned int extent = filterHalfWidth<ImagePixelComponentType>(levels + 1);
            if ((2 * extent) > shortDimension) {
                // levels + 1 is too many levels.
                break;
            }
            levels++;
        }

        if (levels == 1) {
            cerr << "enblend: overlap region is too small to make "
                 << "more than one pyramid level."
                 << endl;
        }

    } else {
        levels = ExactLevels;
    }

    unsigned int extent = filterHalfWidth<ImagePixelComponentType>(levels);
    roiBB = mBB;
    roiBB.addBorder(extent);

    if (wraparoundForMask &&
            (roiBB.left() < 0 || roiBB.right() > uBB.right())) {
        // If the ROI goes off either edge of the uBB,
        // and the uBB is the full size of the output image,
        // and the wraparound flag is specified,
        // then make roiBB the full width of uBB.
        roiBB.setUpperLeft(Point2D(0, roiBB.top()));
        roiBB.setLowerRight(Point2D(uBB.right(), roiBB.bottom()));
    }

    // ROI must not be bigger than uBB.
    roiBB &= uBB;

    // Verify the number of levels based on the size of the ROI.
    unsigned int roiShortDimension = min(roiBB.width(), roiBB.height());
    unsigned int allowableLevels;
    for (allowableLevels = 1; allowableLevels < levels; allowableLevels++) {
        if (roiShortDimension <= 8) {
            // ROI dimensions preclude using more levels than allowableLevels.
            break;
        }
        roiShortDimension = (roiShortDimension + 1) >> 1;
    }

    if (allowableLevels < ExactLevels) {
        cerr << "enblend: image geometry precludes using more than "
             << allowableLevels
             << " levels." << endl;
    }

    if (Verbose > VERBOSE_NUMLEVELS_MESSAGES) {
        cout << "Using " << allowableLevels << " blending levels" << endl;
    }
    if (Verbose > VERBOSE_ROIBB_SIZE_MESSAGES) {
        cout << "Region of Interest bounding box: " << roiBB << endl;
    }

    return allowableLevels;
}

} // namespace enblend

#endif /* __BOUNDS_H__ */