Font_Handle :: #type, distinct u32;

Glyph :: struct {
    ax: float; // advance.x
    ay: float; // advance.y
    bw: float; // bitmap.width;
    bh: float; // bitmap.rows;
    bl: float; // bitmap_left;
    bt: float; // bitmap_top;
    tx: float; // x offset of glyph in texture coordinates
}

Point :: struct {
    x: float;
    y: float;
    s: float;
    t: float;

    color: Vector4;
};

Font :: struct {
    glyphs: [..] Glyph;
    face: FT_Face;
    pixel_size: u32;
    atlas_width: u32;
    atlas_height: u32;
    texture: Texture_Handle;
}

ft : FT_Library;

init_freetype :: () {
    if FT_Init_FreeType(*ft) {
        log("Couldn't init Freetype\n");
    }

}

create_font :: (renderer: *Renderer, path: string, pixel_size: u32) -> Font_Handle {
    font: Font;
    font.pixel_size = pixel_size;
    array_resize(*font.glyphs, 128);

    if FT_New_Face(ft, path.data, 0, *font.face) {
        log("Couldn't create new face\n");
        assert(false);
    } else {
        FT_Set_Pixel_Sizes(font.face, 0, pixel_size);

        g := font.face.glyph;
        w : u32 = 0;
        h : u32 = 0;

        index := 0;
        for 32..128-1 {
            if FT_Load_Char(font.face, xx it, FT_LOAD_RENDER) {
                continue;
            }

            w += g.bitmap.width + 1;
            h = max(h, g.bitmap.rows);
        }

        atlas_width := w;

        bytes : [..] u8;
        bytes.allocator = temp;
        array_resize(*bytes, w * h);

        texture := create_texture(renderer, bytes.data, w, h, 1, generate_mips=false, format=.R8_UNORM);

        font.atlas_width = w;
        font.atlas_height = h;

        font.texture = texture;

        x : u32 = 0;

        pixel_width := 1.0 / cast(float)atlas_width;

        for 32..128-1 {
            if FT_Load_Char(font.face, xx it, FT_LOAD_RENDER) continue;

            // @Speed: We should put this buffer data into an array and upload everything once after this loop
            update_texture_region(renderer, texture, x, 0, g.bitmap.width, g.bitmap.rows, 1, g.bitmap.buffer);

            font.glyphs[it].ax = cast(float)(g.advance.x >> 6);
            font.glyphs[it].ay = cast(float)(g.advance.y >> 6);
            font.glyphs[it].bw = cast(float)g.bitmap.width;
            font.glyphs[it].bh = cast(float)g.bitmap.rows;
            font.glyphs[it].bl = cast(float)g.bitmap_left;
            font.glyphs[it].bt = cast(float)g.bitmap_top;
            font.glyphs[it].tx = cast(float)x / cast(float)w;
            x += g.bitmap.width + 1;
        }

        array_add(*renderer.fonts, font);
        return xx renderer.fonts.count;
    }

    return 0;
}

#import "freetype-2.12.1";