#include "solvespace.h"
#include <png.h>

void SolveSpace::ExportDxfTo(char *filename) {
    SPolygon *sp;
    SPolygon spa;
    ZERO(&spa);

    Vector gn = (SS.GW.projRight).Cross(SS.GW.projUp);
    gn = gn.WithMagnitude(1);

    SS.GW.GroupSelection();
#define gs (SS.GW.gs)

    Group *g = SS.GetGroup(SS.GW.activeGroup);

    // The plane in which the exported section lies; need this because we'll
    // reorient from that plane into the xy plane before exporting.
    Vector p, u, v, n;
    double d;

    if(gs.n == 0 && !(g->poly.IsEmpty())) {
        // Easiest case--export the polygon drawn in this group
        sp = &(g->poly);
        p = sp->AnyPoint();
        n = (sp->ComputeNormal()).WithMagnitude(1);
        if(n.Dot(gn) < 0) n = n.ScaledBy(-1);
        u = n.Normal(0);
        v = n.Normal(1);
        d = p.Dot(n);
        goto havepoly;
    }

    if(g->runningMesh.l.n > 0 &&
       ((gs.n == 0 && g->activeWorkplane.v != Entity::FREE_IN_3D.v) ||
        (gs.n == 1 && gs.faces == 1) ||
        (gs.n == 3 && gs.vectors == 2 && gs.points == 1)))
    {
        if(gs.n == 0) {
            Entity *wrkpl = SS.GetEntity(g->activeWorkplane);
            p = wrkpl->WorkplaneGetOffset();
            n = wrkpl->Normal()->NormalN();
            u = wrkpl->Normal()->NormalU();
            v = wrkpl->Normal()->NormalV();
        } else if(gs.n == 1) {
            Entity *face = SS.GetEntity(gs.entity[0]);
            p = face->FaceGetPointNum();
            n = face->FaceGetNormalNum();
            if(n.Dot(gn) < 0) n = n.ScaledBy(-1);
            u = n.Normal(0);
            v = n.Normal(1);
        } else if(gs.n == 3) {
            Vector ut = SS.GetEntity(gs.entity[0])->VectorGetNum(),
                   vt = SS.GetEntity(gs.entity[1])->VectorGetNum();
            ut = ut.WithMagnitude(1);
            vt = vt.WithMagnitude(1);

            if(fabs(SS.GW.projUp.Dot(vt)) < fabs(SS.GW.projUp.Dot(ut))) {
                SWAP(Vector, ut, vt);
            }
            if(SS.GW.projRight.Dot(ut) < 0) ut = ut.ScaledBy(-1);
            if(SS.GW.projUp.   Dot(vt) < 0) vt = vt.ScaledBy(-1);

            p = SS.GetEntity(gs.point[0])->PointGetNum();
            n = ut.Cross(vt);
            u = ut.WithMagnitude(1);
            v = (n.Cross(u)).WithMagnitude(1);
        } else oops();
        n = n.WithMagnitude(1);
        d = p.Dot(n);

        SMesh m;
        ZERO(&m);
        m.MakeFromCopy(&(g->runningMesh));

        m.l.ClearTags();
        int i;
        for(i = 0; i < m.l.n; i++) {
            STriangle *tr = &(m.l.elem[i]);

            if((fabs(n.Dot(tr->a) - d) >= LENGTH_EPS) ||
               (fabs(n.Dot(tr->b) - d) >= LENGTH_EPS) ||
               (fabs(n.Dot(tr->c) - d) >= LENGTH_EPS))
            {
                tr->tag  = 1;
            }
        }
        m.l.RemoveTagged();

        SKdNode *root = SKdNode::From(&m);
        root->SnapToMesh(&m);

        SEdgeList el;
        ZERO(&el);
        root->MakeCertainEdgesInto(&el, false);
        el.AssemblePolygon(&spa, NULL);
        sp = &spa;

        el.Clear();
        m.Clear();

        SS.GW.ClearSelection();
        goto havepoly;
    }

    Error("Geometry to export not specified.");
    return;

havepoly:

    FILE *f = fopen(filename, "wb");
    if(!f) {
        Error("Couldn't write to '%s'", filename);
        spa.Clear();
        return;
    }

    // Some software, like Adobe Illustrator, insists on a header.
    fprintf(f,
"  999\n"
"file created by SolveSpace\n"
"  0\n"
"SECTION\n"
"  2\n"
"HEADER\n"
"  9\n"
"$ACADVER\n"
"  1\n"
"AC1006\n"
"  9\n"
"$INSBASE\n"
"  10\n"
"0.0\n"
"  20\n"
"0.0\n"
"  30\n"
"0.0\n"
"  9\n"
"$EXTMIN\n"
"  10\n"
"0.0\n"
"  20\n"
"0.0\n"
"  9\n"
"$EXTMAX\n"
"  10\n"
"10000.0\n"
"  20\n"
"10000.0\n"
"  0\n"
"ENDSEC\n");

    // Now begin the entities, which are just line segments reproduced from
    // our piecewise linear curves.
    fprintf(f,
"  0\n"
"SECTION\n"
"  2\n"
"ENTITIES\n");

    int i, j;
    for(i = 0; i < sp->l.n; i++) {
        SContour *sc = &(sp->l.elem[i]);

        for(j = 1; j < sc->l.n; j++) {
            Vector p0 = sc->l.elem[j-1].p,
                   p1 = sc->l.elem[j].p;

            Point2d e0 = p0.Project2d(u, v),
                    e1 = p1.Project2d(u, v);

            double s = SS.exportScale;

            fprintf(f,
"  0\n"
"LINE\n"
"  8\n"     // Layer code
"%d\n"
"  10\n"    // xA
"%.6f\n"
"  20\n"    // yA
"%.6f\n"
"  30\n"    // zA
"%.6f\n"
"  11\n"    // xB
"%.6f\n"
"  21\n"    // yB
"%.6f\n"
"  31\n"    // zB
"%.6f\n",
                    0,
                    e0.x/s, e0.y/s, 0.0,
                    e1.x/s, e1.y/s, 0.0);
        }
    }

    fprintf(f,
"  0\n"
"ENDSEC\n"
"  0\n"
"EOF\n" );

    spa.Clear();
    fclose(f);
}

void SolveSpace::ExportMeshTo(char *filename) {
    SMesh *m = &(SS.GetGroup(SS.GW.activeGroup)->runningMesh);
    if(m->l.n == 0) {
        Error("Active group mesh is empty; nothing to export.");
        return;
    }
    SKdNode *root = SKdNode::From(m);
    root->SnapToMesh(m);
    SMesh vvm;
    ZERO(&vvm);
    root->MakeMeshInto(&vvm);

    FILE *f = fopen(filename, "wb");
    if(!f) {
        Error("Couldn't write to '%s'", filename);
        vvm.Clear();
        return;
    }
    char str[80];
    memset(str, 0, sizeof(str));
    strcpy(str, "STL exported mesh");
    fwrite(str, 1, 80, f);

    DWORD n = vvm.l.n;
    fwrite(&n, 4, 1, f);

    double s = SS.exportScale;
    int i;
    for(i = 0; i < vvm.l.n; i++) {
        STriangle *tr = &(vvm.l.elem[i]);
        Vector n = tr->Normal().WithMagnitude(1);
        float w;
        w = (float)n.x;           fwrite(&w, 4, 1, f);
        w = (float)n.y;           fwrite(&w, 4, 1, f);
        w = (float)n.z;           fwrite(&w, 4, 1, f);
        w = (float)((tr->a.x)/s); fwrite(&w, 4, 1, f);
        w = (float)((tr->a.y)/s); fwrite(&w, 4, 1, f);
        w = (float)((tr->a.z)/s); fwrite(&w, 4, 1, f);
        w = (float)((tr->b.x)/s); fwrite(&w, 4, 1, f);
        w = (float)((tr->b.y)/s); fwrite(&w, 4, 1, f);
        w = (float)((tr->b.z)/s); fwrite(&w, 4, 1, f);
        w = (float)((tr->c.x)/s); fwrite(&w, 4, 1, f);
        w = (float)((tr->c.y)/s); fwrite(&w, 4, 1, f);
        w = (float)((tr->c.z)/s); fwrite(&w, 4, 1, f);
        fputc(0, f);
        fputc(0, f);
    }

    vvm.Clear();
    fclose(f);
}

void SolveSpace::ExportAsPngTo(char *filename) {
    int w = (int)SS.GW.width, h = (int)SS.GW.height;
    // No guarantee that the back buffer contains anything valid right now,
    // so repaint the scene.
    SS.GW.Paint(w, h);
    
    FILE *f = fopen(filename, "wb");
    if(!f) goto err;

    png_struct *png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
        NULL, NULL, NULL);
    if(!png_ptr) goto err;

    png_info *info_ptr = png_create_info_struct(png_ptr);
    if(!png_ptr) goto err;

    if(setjmp(png_jmpbuf(png_ptr))) goto err;

    png_init_io(png_ptr, f);

    // glReadPixels wants to align things on 4-boundaries, and there's 3
    // bytes per pixel. As long as the row width is divisible by 4, all
    // works out.
    w &= ~3; h &= ~3;

    png_set_IHDR(png_ptr, info_ptr, w, h,
        8, PNG_COLOR_TYPE_RGB, PNG_INTERLACE_NONE,
        PNG_COMPRESSION_TYPE_DEFAULT,PNG_FILTER_TYPE_DEFAULT);
    
    png_write_info(png_ptr, info_ptr);

    // Get the pixel data from the framebuffer
    BYTE *pixels = (BYTE *)AllocTemporary(3*w*h);
    BYTE **rowptrs = (BYTE **)AllocTemporary(h*sizeof(BYTE *));
    glReadPixels(0, 0, w, h, GL_RGB, GL_UNSIGNED_BYTE, pixels);

    int y;
    for(y = 0; y < h; y++) {
        // gl puts the origin at lower left, but png puts it top left
        rowptrs[y] = pixels + ((h - 1) - y)*(3*w);
    }
    png_write_image(png_ptr, rowptrs);

    png_write_end(png_ptr, info_ptr);
    png_destroy_write_struct(&png_ptr, &info_ptr);
    fclose(f);
    return;

err:    
    Error("Error writing PNG file '%s'", filename);
    if(f) fclose(f);
    return;
}