cat_engine 1.0.0-alpha5

use crate::{
    Colour,
    text::Scale,
};

use super::{
    TextVertex2D,
    DrawParameters,
    GlyphImageBuilder,
};

use cat_engine_basement::graphics::{
    GCore,
    core::UNPACK_ALIGNMENT,
    core::buffer::BufferUsage,
    core::drawing::PrimitiveType,
    core::texture::{
        Texture2DInternalFormat,
        TextureMagFilter,
        TextureMinFilter,
        ImageDataFormat,
    },
    level0::{
        VertexArray,
    },
    level1::{
        VertexBuffer,
        VertexShader,
        FragmentShader,
        Texture2D,
    },
    level2::Program,
};


use ttf_parser::{
    GlyphId,
    Face,
};

use std::cell::UnsafeCell;

pub struct TextGraphics{
    vertex_buffer:VertexBuffer<TextVertex2D>,

    vertex_array:VertexArray<TextVertex2D>,

    /// For dynamic building glyphs
    glyph_image_builder:UnsafeCell<GlyphImageBuilder>,
    texture:Texture2D,
    texture_size:[f32;2],

    draw:Program,
}

impl TextGraphics{
    pub fn new(glyph_texture_size:[u32;2])->TextGraphics{
        let vertex_shader=VertexShader::new(&include_str!("shaders/text/vertex_shader.glsl")).unwrap();
        let fragment_shader=FragmentShader::new(&include_str!("shaders/text/fragment_shader.glsl")).unwrap();

        let program=Program::new(&vertex_shader,&fragment_shader).unwrap();

        let vertex_buffer=VertexBuffer::<TextVertex2D>::empty(4,BufferUsage::DynamicDraw).unwrap();
        let vertex_array=VertexArray::<TextVertex2D>::new(vertex_buffer.as_raw());

        let texture=Texture2D::empty(
            Texture2DInternalFormat::R8,
            TextureMagFilter::Linear,
            TextureMinFilter::Linear,
            glyph_texture_size
        ).unwrap();

        Self{
            vertex_buffer,
            vertex_array,

            glyph_image_builder:UnsafeCell::new(
                GlyphImageBuilder::new([
                    glyph_texture_size[0] as usize,
                    glyph_texture_size[1] as usize
                ])
            ),
            texture,
            texture_size:[
                glyph_texture_size[0] as f32,
                glyph_texture_size[1] as f32,
            ],

            draw:program,
        }
    }
}


impl TextGraphics{
    fn load_vertices(&self,vertices:&[TextVertex2D;4]){
        self.vertex_buffer.write(0,vertices);
    }

    pub fn load_glyph_image(&self,size:[u32;2],image:&[u8]){
        unsafe{GCore.set_pixel_storage_modei(UNPACK_ALIGNMENT,1)}
        self.texture.write_image([0,0,size[0],size[1]],ImageDataFormat::R_U8,image);
        unsafe{GCore.set_pixel_storage_modei(UNPACK_ALIGNMENT,4)}
    }

    /// [offset_x,offset_y,width,height]
    pub fn build_glyph_image(&self,glyph_id:GlyphId,scale:Scale,font:&Face)->Option<([f32;4],&[u8])>{
        let glyph_image_builder=unsafe{&mut *self.glyph_image_builder.get()};

        // Setting parameters
        glyph_image_builder.set_scale(scale);

        // Building
        if let Some(bounding_box)=glyph_image_builder.build_image(glyph_id,font){
            Some((bounding_box,glyph_image_builder.image()))
        }
        else{
            None
        }
    }

    /// [offset_x,offset_y,width,height]
    pub fn load_glyph(&self,glyph_id:GlyphId,scale:Scale,font:&Face)->Option<[f32;4]>{
        if let Some((bounding_box,image))=self.build_glyph_image(glyph_id,scale,font){
            let width=bounding_box[2];
            let height=bounding_box[3];

            if width>self.texture_size[0] || height>self.texture_size[1]{
                panic!("Invalid glyph size")
            }

            self.load_glyph_image([width as u32,height as u32],image);

            Some(bounding_box)
        }
        else{
            None
        }
    }
}

impl TextGraphics{
    pub fn draw_loaded_glyph(
        &self,
        colour:Colour,
        position:[f32;2],
        draw_parameters:&DrawParameters
    ){
        // The size of the loaded glyph image
        let [width,height]=unsafe{(&mut *self.glyph_image_builder.get()).dimensions()};

        let [x1,y1,x2,y2]=[
            position[0],
            position[1],
            position[0]+width as f32,
            position[1]+height as f32,
        ];

        // The normalized size of the loaded glyph image
        let uwidth=width as f32/self.texture_size[0];
        let vheight=height as f32/self.texture_size[1];

        let vertices=&[
            TextVertex2D::new([x1,y1],[0f32,vheight]),
            TextVertex2D::new([x2,y1],[uwidth,vheight]),
            TextVertex2D::new([x1,y2],[0f32,0f32]),
            TextVertex2D::new([x2,y2],[uwidth,0f32]),
        ];

        self.load_vertices(vertices);
        self.draw.bind();
        self.vertex_array.bind();
        self.vertex_buffer.bind();
        self.texture.bind();

        let _=self.draw.set_uniform_value("viewport",draw_parameters.viewport());

        let _=self.draw.set_uniform_value("draw_mode",draw_parameters.flag());

        if let Some(shift)=draw_parameters.shift(){
            let _=self.draw.set_uniform_value("vertex_shift",shift);
        }

        if let Some(rotation)=draw_parameters.rotation(){
            let _=self.draw.set_uniform_value("vertex_rotation",rotation);
        }

        let _=self.draw.set_uniform_value("glyph_colour",colour);

        unsafe{
            GCore.drawing.draw_arrays(0,4,PrimitiveType::TriangleStrip)
        }
        self.vertex_array.unbind();
    }

    pub fn draw_glyph(
        &self,
        glyph_texture:&Texture2D,
        colour:Colour,
        [x,y]:[f32;2],
        [width,height]:[f32;2],
        draw_parameters:&DrawParameters
    ){
        let [x1,y1,x2,y2]=[
            x,
            y,
            x+width,
            y+height,
        ];

        let vertices=&[
            TextVertex2D::new([x1,y1],[0f32,1f32]),
            TextVertex2D::new([x2,y1],[1f32,1f32]),
            TextVertex2D::new([x1,y2],[0f32,0f32]),
            TextVertex2D::new([x2,y2],[1f32,0f32]),
        ];

        self.load_vertices(vertices);
        self.draw.bind();
        self.vertex_array.bind();
        self.vertex_buffer.bind();
        glyph_texture.bind();

        let _=self.draw.set_uniform_value("viewport",draw_parameters.viewport());

        let _=self.draw.set_uniform_value("draw_mode",draw_parameters.flag());

        if let Some(shift)=draw_parameters.shift(){
            let _=self.draw.set_uniform_value("vertex_shift",shift);
        }

        if let Some(rotation)=draw_parameters.rotation(){
            let _=self.draw.set_uniform_value("vertex_rotation",rotation);
        }

        let _=self.draw.set_uniform_value("glyph_colour",colour);

        unsafe{
            GCore.drawing.draw_arrays(0,4,PrimitiveType::TriangleStrip)
        }
        self.vertex_array.unbind();
    }
}