/*****************************************************************************************
 *                                                                                       *
 * OpenSpace                                                                             *
 *                                                                                       *
 * Copyright (c) 2014-2020                                                               *
 *                                                                                       *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this  *
 * software and associated documentation files (the "Software"), to deal in the Software *
 * without restriction, including without limitation the rights to use, copy, modify,    *
 * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to    *
 * permit persons to whom the Software is furnished to do so, subject to the following   *
 * conditions:                                                                           *
 *                                                                                       *
 * The above copyright notice and this permission notice shall be included in all copies *
 * or substantial portions of the Software.                                              *
 *                                                                                       *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,   *
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A         *
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT    *
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF  *
 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE  *
 * OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                                         *
 ****************************************************************************************/

#ifndef _RESOLVEHELPERS_GLSL_
#define _RESOLVEHELPERS_GLSL_

float acc = 0;

#if RAYCASTING_ENABLED
#include "raycasterdata.glsl"




// Include all ray caster helpers
#for id, helperPath in resolveData.helperPaths
#include <#{helperPath}>
#endfor


// Include all ray casters
#for id, raycaster in resolveData.raycasters
#include <#{raycaster.raycastPath}>
#endfor

#for index in 1..#{resolveData.nRaycasters}
uniform bool insideRaycaster#{index};
uniform vec3 cameraPosInRaycaster#{index}
#endfor


#endif




uniform int nAaSamples;

void sortFragments(uint nFrags) {
    ABufferFragment tmp;
    uint i, j;

    // Insertion sort
    for(i = 1; i < nFrags; ++i) {
        tmp = fragments[i];
        for(j = i; j > 0 && _depth_(tmp) < _depth_(fragments[j-1]); --j) {
            fragments[j] = fragments[j-1];
        }
        fragments[j] = tmp;
    }
}

uint countSamples(uint mask) {
    return ((mask >> 0) & 1)
        + ((mask >> 1) & 1)
        + ((mask >> 2) & 1)
        + ((mask >> 3) & 1)
        + ((mask >> 4) & 1)
        + ((mask >> 5) & 1)
        + ((mask >> 6) & 1)
        + ((mask >> 7) & 1);
}

uint depthFilterFragments(uint nFrags, float depthThreshold) {
    uint j = 0;
    for (uint i = 0; i < nFrags; i++) {
        if (_type_(fragments[i]) != 0 || _depth_(fragments[i]) < depthThreshold) {
            fragments[j] = fragments[i];
            j++;
        }
    }
    return j;
}


uint mergeFragments(uint nFrags) {
    uint outputIndex = 0;
    for (uint inputIndex = 0; inputIndex < nFrags; inputIndex++, outputIndex++) {

        ABufferFragment frag = fragments[inputIndex];
        uint accumulatedMask = _msaa_(fragments[inputIndex]);
        uint newMask = _msaa_(fragments[inputIndex]);
        int type = _type_(fragments[inputIndex]);

        // Accumulate sample mask
        for (uint j = inputIndex + 1;
//abs(_depth_(fragments[j]) - _depth_(fragments[inputIndex])) < 0.000000001; //&&
j < nFrags && ((newMask = _msaa_(fragments[j])) & accumulatedMask) == 0 && _type_(fragments[j]) == type;
             j++) {
            accumulatedMask |= newMask;
            inputIndex = j;
        }
        uint nSamples = countSamples(accumulatedMask);
        ABufferFragment outputFragment = fragments[inputIndex];
        if (type == 0) {
            vec4 color = _color_(fragments[inputIndex]); // TODO: Possibly weigh all samples together?
            // Adjust the alpha by the ratio of accumulated samples
            float alpha = float(nSamples) / float(nAaSamples);
            color.a *= alpha;
            _color_(outputFragment, color);
        }
        fragments[outputIndex] = outputFragment;
    }

    // return number of outputted fragments
    return outputIndex;
}

#if RAYCASTING_ENABLED

/**
 * Iterate through list of sorted fragments,
 * and retrieve raycasting position, direction, scale
 */
void retrieveRaycasterData(uint nFrags) {
    float entryDepths[N_RAYCASTERS];
#for i in 1..#{resolveData.nRaycasters}
    {
    int j = #{i} - 1;
    entryDepths[j] = -1;
    raycasterData[j].scale = -1;    
    bool inside = insideRaycaster#{i};
    if (inside) {
        entryDepths[j] = 0;
        raycasterData[j].position = cameraPosInRaycaster#{i};
        raycasterData[j].previousJitterDistance = 0;
    }
    }
#endfor
    
    for (int i = 0; i < nFrags; i++) {
        int type = _type_(fragments[i]); // - 1;
        vec3 position = _position_(fragments[i]);
        float depth = _depth_(fragments[i]);
        uint blend = _blend_(fragments[i]);
        if (type > 0) { // enter raycaster
            int raycasterId = type - 1;
            if (entryDepths[raycasterId] < 0) { // first entry
                raycasterData[raycasterId].position = position;
                raycasterData[raycasterId].previousJitterDistance = 0;
                entryDepths[raycasterId] = depth;
                raycasterData[raycasterId].scale = -1;
            }
        } else if (type < 0) { // exit raycaster
            int raycasterId = -type - 1;
            vec3 localDirection = position - raycasterData[raycasterId].position;
            
            raycasterData[raycasterId].direction = safeNormalize(localDirection);
            raycasterData[raycasterId].scale = safeLength(localDirection) / (depth - entryDepths[raycasterId]);
            raycasterData[raycasterId].blend = blend;
        }
    }
}


/**
 * Perform raycasting
 */
void raycast(float raycastDepth, uint raycasterMask, inout vec3 accumulatedColor, inout vec3 accumulatedAlpha) {
    float nextStepSize = raycastDepth;
    float currentStepSize = 0.0;
    float jitterFactor = 0.5 + 0.5 * rand(gl_FragCoord.xy); // should be between 0.5 and 1.0

#for index, raycaster in resolveData.raycasters
    if ((raycasterMask & #{raycaster.bitmask}) != 0) {
        RaycasterData data = raycasterData[#{index}];
        float maxStepSizeLocal = stepSize#{raycaster.id}(data.position, data.direction);
        float maxStepSize = maxStepSizeLocal / data.scale;
        nextStepSize = min(nextStepSize, maxStepSize);
    }
#endfor

    float currentDepth = 0.0;
    for (int steps = 0;
         (accumulatedAlpha.x < ALPHA_LIMIT ||
          accumulatedAlpha.y < ALPHA_LIMIT ||
          accumulatedAlpha.z < ALPHA_LIMIT) &&
         steps < RAYCAST_MAX_STEPS;
         ++steps) {
        bool exceededDepth = currentDepth + nextStepSize * jitterFactor > raycastDepth;
        bool shortStepSize = nextStepSize < raycastDepth / 10000000000.0;

        if (exceededDepth || shortStepSize) {
            break;
        }

        currentStepSize = nextStepSize;
        currentDepth += currentStepSize;
        nextStepSize = raycastDepth - currentDepth;

#for index, raycaster in resolveData.raycasters
        if ((raycasterMask & #{raycaster.bitmask}) != 0) {
            RaycasterData data = raycasterData[#{raycaster.id}];
            float stepSizeLocal = currentStepSize * data.scale;
            float jitteredStepSizeLocal = stepSizeLocal * jitterFactor;

            vec3 jitteredPosition = data.position + data.direction*jitteredStepSizeLocal;
            raycasterData[#{raycaster.id}].position += data.direction * stepSizeLocal;

            float maxStepSizeLocal;

            acc += 1.0;
            sample#{raycaster.id}(jitteredPosition,
                                  data.direction,
                                  accumulatedColor,
                                  accumulatedAlpha,
                                  maxStepSizeLocal);

            
            float sampleDistance = jitteredStepSizeLocal + data.previousJitterDistance;
            uint blend = raycasterData[#{raycaster.id}].blend;

            /*
            if (blend == BLEND_MODE_NORMAL) {
                normalBlendStep(finalColor, raycasterContribution, sampleDistance);
            } else if (blend == BLEND_MODE_ADDITIVE) {
                additiveBlendStep(finalColor, raycasterContribution, sampleDistance);
                }*/
            //finalColor = raycasterContribution;

            raycasterData[#{raycaster.id}].previousJitterDistance = stepSizeLocal - jitteredStepSizeLocal;
            float maxStepSize = maxStepSizeLocal/data.scale;
            nextStepSize = min(nextStepSize, maxStepSize);
        }
#endfor
    }
}

bool initRaycasterMask(inout uint raycasterMask) {
    bool insideAnyRaycaster = false;
    raycasterMask = 0;
#for i in 1..#{resolveData.nRaycasters}
    {
    int j = #{i} - 1;
    if (insideRaycaster#{i} && raycasterData[j].scale > 0) {
        raycasterMask |= (1 << j);
        insideAnyRaycaster = true;
    }
    }
#endfor
    return insideAnyRaycaster;
}



#endif // RAYCASTING_ENABLED

#endif // _RESOLVEHELPERS_GLSL_
