import org.apache.commons.io.IOUtils;
import org.lwjgl.BufferUtils;
import org.lwjgl.opengl.GL11;
import org.lwjgl.stb.STBImage;
import org.lwjgl.stb.STBImageWrite;
import org.lwjgl.stb.STBTTFontinfo;
import org.lwjgl.stb.STBTruetype;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.FloatBuffer;
import java.nio.IntBuffer;
import java.nio.ShortBuffer;
import java.nio.channels.FileChannel;

public class FontTest {
    public static ByteBuffer fileToByteBuffer(String filename, boolean isResource) {
        ByteBuffer fileBuffer;
        if (isResource) {
            InputStream is = FontTest.class.getResourceAsStream(filename);
            try {
                byte array[] = IOUtils.toByteArray(is);
                fileBuffer = FontTest.buildBuffer(array);
                is.close();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        } else {
            assert filename != null;
            try {
                FileChannel fc = new FileInputStream(filename).getChannel();
                fileBuffer = BufferUtils.createByteBuffer((int) fc.size() + 1);
                //noinspection StatementWithEmptyBody
                while (fc.read(fileBuffer) != -1);
                fc.close();
                fileBuffer.flip();
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        }
        return fileBuffer;
    }

    public static FloatBuffer buildBuffer(float[] array) {
        FloatBuffer buffer = BufferUtils.createFloatBuffer(array.length);
        buffer.put(array);
        buffer.flip();
        return buffer;
    }

    public static ShortBuffer buildBuffer(short[] array) {
        ShortBuffer buffer = BufferUtils.createShortBuffer(array.length);
        buffer.put(array);
        buffer.flip();
        return buffer;
    }

    public static ByteBuffer buildBuffer(byte[] array) {
        ByteBuffer buffer = BufferUtils.createByteBuffer(array.length);
        buffer.put(array);
        buffer.flip();
        return buffer;
    }

    public static void main(String[] args) {
        String path = new File("natives").getAbsolutePath();
        System.setProperty("org.lwjgl.librarypath", path);
        ByteBuffer fontBuffer = fileToByteBuffer("/NotoSans-Regular.ttf", true);
        //ByteBuffer fontInfo = STBTTFontinfo.malloc();
        ByteBuffer fontInfo = BufferUtils.createByteBuffer(56);
        if (STBTruetype.stbtt_InitFont(fontInfo, fontBuffer) == GL11.GL_FALSE) {
            System.err.println("ERROR INIT");
        }

        int b_w = 512;
        int b_h = 512;
        int l_h = 64;
        ByteBuffer bitmap = BufferUtils.createByteBuffer(b_w * b_h);

        float scale = STBTruetype.stbtt_ScaleForPixelHeight(fontInfo, l_h);

        String word = "How are you?";

        int x = 0;

        IntBuffer ascentB = BufferUtils.createIntBuffer(1), descentB = BufferUtils.createIntBuffer(1), linegapB = BufferUtils.createIntBuffer(1);

        STBTruetype.stbtt_GetFontVMetrics(fontInfo, ascentB, descentB, linegapB);

        int ascent = ascentB.get(0);
        int descent = descentB.get(0);
        int linegap = descentB.get(0);

        ascent *= scale;
        descent *= scale;

        for (int i = 0; i < word.length(); ++i) {
            IntBuffer c_x1B = BufferUtils.createIntBuffer(1);
            IntBuffer c_y1B = BufferUtils.createIntBuffer(1);
            IntBuffer c_x2B = BufferUtils.createIntBuffer(1);
            IntBuffer c_y2B = BufferUtils.createIntBuffer(1);

            STBTruetype.stbtt_GetCodepointBitmapBox(fontInfo, (int) (word.charAt(i)), scale, scale, c_x1B, c_y1B, c_x2B, c_y2B);

            int c_x1 = c_x1B.get(0);
            int c_y1 = c_y1B.get(0);
            int c_x2 = c_x2B.get(0);
            int c_y2 = c_y2B.get(0);

            int y = ascent + c_y1;

            int byteOffset = x + (y * b_w);
            bitmap.position(byteOffset);
            STBTruetype.stbtt_MakeCodepointBitmap(fontInfo, bitmap, c_x2 - c_x1, c_y2 - c_y1, b_w, scale, scale, (int) word.charAt(i));

            IntBuffer axB = BufferUtils.createIntBuffer(1);
            IntBuffer zero = BufferUtils.createIntBuffer(1);
            zero.put(0);
            zero.flip();
            STBTruetype.stbtt_GetCodepointHMetrics(fontInfo, (int)word.charAt(i), axB, zero);
            x += axB.get(0) * scale;

            if (i != word.length() - 1) {
                int kern = STBTruetype.stbtt_GetCodepointKernAdvance(fontInfo, (int)word.charAt(i), (int)word.charAt(i + 1));
                x += kern * scale;
            }
        }

        bitmap.rewind();

        STBImageWrite.stbi_write_png("out.png", b_w, b_h, 1, bitmap, b_w);
    }
}