/*  Copyright (C) 1996-1997  Id Software, Inc.
Copyright (C) 2018 MaxED

This program 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.

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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

See file, 'COPYING', for details.
*/

#include <cassert>
//#include <cstdio>
#include <iostream>

#include <light/light.hh>
#include <light/bounce.hh>
#include <light/surflight.hh>
#include <light/ltface.hh>

#include <common/polylib.hh>
#include <common/bsputils.hh>
#include <common/parallel.hh>

#include <vector>
#include <map>
#include <mutex>
#include <string>

#include <common/qvec.hh>

using namespace std;
using namespace polylib;

mutex surfacelights_lock;
std::vector<surfacelight_t> surfacelights;
std::map<int, std::vector<int>> surfacelightsByFacenum;
int total_surflight_points = 0;

static void MakeSurfaceLightsThread(const mbsp_t *bsp, const settings::worldspawn_keys &cfg, size_t i)
{
    const mface_t *face = BSP_GetFace(bsp, i);

    // Face casts light?
    const gtexinfo_t *info = Face_Texinfo(bsp, face);
    if (info == nullptr)
        return;
    if (!(info->flags.native & Q2_SURF_LIGHT) || info->value == 0) {
        if (info->flags.native & Q2_SURF_LIGHT) {
            qvec3d wc = winding_t::from_face(bsp, face).center();
            logging::print("WARNING: surface light '{}' at [{}] has 0 intensity.\n", Face_TextureName(bsp, face), wc);
        }
        return;
    }

    // Create face points...
    auto poly = GLM_FacePoints(bsp, face);
    const float facearea = qv::PolyArea(poly.begin(), poly.end());

    // Avoid small, or zero-area faces
    if (facearea < 1)
        return;

    // Create winding...
    winding_t winding = winding_t::from_winding_points(poly);
    winding.remove_colinear();

    // Get face normal and midpoint...
    qvec3d facenormal = Face_Normal(bsp, face);
    qvec3d facemidpoint = winding.center() + facenormal; // Lift 1 unit

    // Dice winding...
    vector<qvec3f> points;
    winding.dice(cfg.surflightsubdivision.value(), [&points](winding_t &w) { points.push_back(w.center()); });
    total_surflight_points += points.size();

    // Get texture color
    qvec3f texturecolor = qvec3f(Face_LookupTextureColor(bsp, face)) / 255.f;

    // Calculate emit color and intensity...

    // Handle arghrad sky light settings http://www.bspquakeeditor.com/arghrad/sunlight.html#sky
    if (info->flags.native & Q2_SURF_SKY) {
        // FIXME: this only handles the "_sky_surface"  "red green blue" format.
        //        There are other more complex variants we could handle documented in the link above.
        // FIXME: we require value to be nonzero, see the check above - not sure if this matches arghrad
        if (cfg.sky_surface.isChanged()) {
            texturecolor = cfg.sky_surface.value();
        }
    }

    texturecolor *= info->value; // Scale by light value

    // Calculate intensity...
    float intensity = qv::max(texturecolor);

    if (intensity == 0.0f)
        return;

    // Normalize color...
    if (intensity > 1.0f)
        texturecolor *= 1.0f / intensity;

    // Sanity checks...
    Q_assert(!points.empty());

    // Add surfacelight...
    surfacelight_t l;
    l.surfnormal = facenormal;
    l.omnidirectional = true;//(info->flags.native & Q2_SURF_SKY) ? true : false;
    l.points = points;
    l.pos = facemidpoint;

    // Store surfacelight settings...
    l.totalintensity = intensity * facearea;
    l.intensity = l.totalintensity / points.size();
    l.color = texturecolor;

    // Init bbox...
    l.bounds = qvec3d(0);

    if (!options.novisapprox.value())
        l.bounds = EstimateVisibleBoundsAtPoint(facemidpoint);

    // Store light...
    unique_lock<mutex> lck{surfacelights_lock};
    surfacelights.push_back(l);

    const int index = static_cast<int>(surfacelights.size()) - 1;
    surfacelightsByFacenum[Face_GetNum(bsp, face)].push_back(index);
}

const std::vector<surfacelight_t> &SurfaceLights()
{
    return surfacelights;
}

int TotalSurfacelightPoints()
{
    return total_surflight_points;
}

// No surflight_debug (yet?), so unused...
const std::vector<int> &SurfaceLightsForFaceNum(int facenum)
{
    const auto &vec = surfacelightsByFacenum.find(facenum);
    if (vec != surfacelightsByFacenum.end())
        return vec->second;

    static std::vector<int> empty;
    return empty;
}

void // Quake 2 surface lights
MakeSurfaceLights(const settings::worldspawn_keys &cfg, const mbsp_t *bsp)
{
    logging::print("--- MakeSurfaceLights ---\n");

    logging::parallel_for(static_cast<size_t>(0), bsp->dfaces.size(), [&](size_t i) { MakeSurfaceLightsThread(bsp, cfg, i); });
}