#include <u.h>
#include <libn.h>
#include <libfont.h>

#include <fontconfig/fontconfig.h>
#include <freetype2/ft2build.h>
#include FT_FREETYPE_H /* ugh */

#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb_image_write.h"

#define DIV 2
#define W 1920/DIV
#define H 1080/2
#define L H/35

static char *phrase   = "abcdefghijklmnopqrstuvwxyx";
static byte *fontpath = "/home/nolln/root/data/Inconsolata-Regular.ttf";

static FT_Library   lib;
static FT_Face      face;

static
void
loadfonts(int size)
{
    FT_New_Face(lib, (const byte*)fontpath, 0, &face);
    FT_Set_Char_Size(face, 0, size << 6, 72, 72);
}

int
main()
{
    int i, x, y, x0, y0, c, r, err;
    FT_GlyphSlot slot;
    FT_Bitmap    bitmap;
    FT_UInt      index;
    uchar       *pixel;
    font·Info   *info;

    pixel = calloc(H,W);
    mmap·Reader fontfile;

    err = 0;
    fontfile = mmap·open(fontpath);
    if (!fontfile.len) {
        panicf("fail");
    }

    // info   = font·make(fontfile.ubuf, 0, mem·sys, nil);
    if (!info) 
        panicf("failed to load info");

    if (!FcInit())
        panicf("could not initialize fontconfig");
    if (FT_Init_FreeType(&lib))
        panicf("could not initialize freetype");

    loadfonts(14);

    x0 = 10, y0 = 100;
    slot = face->glyph;
    for (i = 0; i < strlen(phrase); i++) {
        printf("phrase[i]='%c'\n", phrase[i]);
        err = FT_Load_Char(face, (rune)phrase[i], FT_LOAD_RENDER);
        if (err)
            panicf("failed to load font face");

        x = x0 + slot->bitmap_left;
        y = y0 - slot->bitmap_top;
        printf("buffer size: [%d, %d]\n", slot->bitmap.rows, slot->bitmap.width);
        for (c = 0; c < slot->bitmap.width; c++) {
            for (r = 0; r < slot->bitmap.rows; r++) {
                if (x+c < 0 || x+c > W || y+r < 0 || y+r > H)
                    continue;
                pixel[(x+c)+W*(y+r)] += slot->bitmap.buffer[c + slot->bitmap.width*r];
            }
        }
        x0 += slot->advance.x >> 6;
        y0 += slot->advance.y >> 6;
    }

    // {
    //     float x  = 0.;
    //     float dy = 0., dx;
    //     float scale;
    //     int ascent, descent, baseln;
    //     int adv, lsb, off, r0[2] = {0}, r1[2] = {0}, w, h, i, j, k ;

    //     uchar *work;

    //     font·vmetrics(info, &ascent, &descent, &baseln);
    //     scale = font·scaleheightto(info, L);
    //     for (i = 0; i < strlen(phrase); i++) {
    //         dx = x - (float)floor(x);
    //         font·code_hmetrics(info, phrase[i], &adv, &lsb);
    //         font·code_bbox_subpixel(info, phrase[i], scale, scale, dx, 0, r0, r0+1, r1, r1+1);

    //         y   = ascent + r0[1];
    //         dy  = y - (float)floor(y);

    //         w = r1[0]-r0[0];
    //         h = r1[1]-r0[1];

    //         work = calloc(w, h); 
    //         font·code_fillbitmap_subpixel(info, work, w, h, w, scale, scale, dx, 0, phrase[i]);

    //         off = (int)floor(x+10) + r0[0] + ((int)y-100) * W; 
    //         for (j = 0; j < h; j++) {
    //             for (k = 0; k < w; k++) {
    //                 pixel[off + k + W*j] += work[k + w*j];
    //             }
    //         }
    //         free(work);

    //         x += scale * adv;
    //         if (phrase[i+1])
    //             x += scale * font·code_kernadvance(info, phrase[i], phrase[i+1]);
    //     }
    // }
    stbi_write_png("out.png", W, H, 1, pixel, W);
    
    exit(0);
}

#if 0
int
main()
{
    int i, j, k, err;
    float x, dx, dy, scale, sx, sy;
    uchar *bitmap, *work;
    font·Info *info;
    mmap·Reader fontfile;
    int w, h, off, y, ascent, descent, baseln;
    int adv, lsb, r0[2], r1[2];

    err = 0;
    fontfile = mmap·open("/home/nolln/root/data/Inconsolata-Regular.ttf");
    if (!fontfile.len) {
        err = 1;
        goto end;
    }

    info   = font·make(fontfile.ubuf, 0, mem·sys, nil);
    if (!info) 
        panicf("failed to load info");

    bitmap = calloc(W*H, sizeof(*bitmap)); 
    scale  = font·scaleheightto(info, L);

    font·vmetrics(info, &ascent, &descent, &baseln);
    ascent *= scale;

    x  = 0.;
    dy = 0.;
    for (i = 0; i < strlen(phrase); i++) {
        dx = x - (float)floor(x);
        font·code_hmetrics(info, phrase[i], &adv, &lsb);
        font·code_bbox_subpixel(info, phrase[i], scale, scale, dx, 0, r0, r0+1, r1, r1+1);

        y   = ascent + r0[1];
        dy  = y - (float)floor(y);

        w = r1[0]-r0[0];
        h = r1[1]-r0[1];

        work = calloc(w*h, sizeof(*bitmap)); 
        font·code_fillbitmap_subpixel_prefilter(info, work, w, h, w, scale, scale, dx, 0, 1, 1, &sx, &sy, phrase[i]);

        off = (int)floor(x+sx) + r0[0] + ((int)floor(sy)+y) * W; 
        for (j = 0; j < h; j++) {
            for (k = 0; k < w; k++) {
                bitmap[off + W*j + k] += work[k + w*j];
            }
        }
        free(work);

        x += scale * adv;
        if (phrase[i+1])
            x += scale * font·code_kernadvance(info, phrase[i], phrase[i+1]);
    }

    stbi_write_png("out.png", W, H, 1, bitmap, W);

    font·free(info);
    free(bitmap);
end:
    mmap·close(fontfile);
    return err;
}
#endif