bracket-terminal 0.8.7

use crate::hal::scaler::FontScaler;
use crate::hal::{Font, Shader, VertexArray, VertexArrayEntry, BACKEND};
use crate::prelude::SparseTile;
use crate::BResult;
use bracket_color::prelude::RGBA;

pub struct SparseConsoleBackend {
    vao: VertexArray,
    previous_console: Option<Vec<SparseTile>>,
}

impl SparseConsoleBackend {
    pub fn new(_width: usize, _height: usize, gl: &glow::Context) -> SparseConsoleBackend {
        let vao = SparseConsoleBackend::init_gl_for_console(gl, 1000, 1000);
        SparseConsoleBackend {
            vao,
            previous_console: None,
        }
    }

    fn init_gl_for_console(
        gl: &glow::Context,
        vertex_capacity: usize,
        index_capacity: usize,
    ) -> VertexArray {
        VertexArray::float_builder(
            gl,
            &[
                VertexArrayEntry { index: 0, size: 3 }, // Position
                VertexArrayEntry { index: 1, size: 4 }, // Color
                VertexArrayEntry { index: 2, size: 4 }, // Background
                VertexArrayEntry { index: 3, size: 2 }, // Texture Coordinates
            ],
            vertex_capacity,
            index_capacity,
        )
    }

    /// Helper to push a point to the shader.
    fn push_point(
        vertex_buffer: &mut Vec<f32>,
        x: f32,
        y: f32,
        fg: RGBA,
        bg: RGBA,
        ux: f32,
        uy: f32,
    ) {
        vertex_buffer.extend_from_slice(&[
            x, y, 0.0, fg.r, fg.g, fg.b, fg.a, bg.r, bg.g, bg.b, bg.a, ux, uy,
        ]);
    }

    /// Helper to build vertices for the sparse grid.
    #[allow(clippy::too_many_arguments)]
    pub fn rebuild_vertices(
        &mut self,
        height: u32,
        width: u32,
        offset_x: f32,
        offset_y: f32,
        scale: f32,
        scale_center: (i32, i32),
        tiles: &Vec<SparseTile>,
        font_scaler: FontScaler,
        needs_resize: bool,
    ) {
        if !needs_resize {
            if let Some(old) = &self.previous_console {
                if old.len() == tiles.len() {
                    let no_change = tiles.iter().zip(old.iter()).all(|(a, b)| *a == *b);
                    if no_change {
                        return;
                    }
                }
            }
        }

        self.vao.vertex_buffer.clear();
        self.vao.index_buffer.clear();

        let (step_x, step_y) = {
            let be = BACKEND.lock();
            let (step_x, step_y) = be.screen_scaler.calc_step(width, height, scale);

            (step_x, step_y)
        };

        //let step_x: f32 = scale * 2.0 / width as f32;
        //let step_y: f32 = scale * 2.0 / height as f32;

        let mut index_count: i32 = 0;
        let screen_x_start: f32 = -1.0 * scale
            - 2.0 * (scale_center.0 - width as i32 / 2) as f32 * (scale - 1.0) / width as f32;
        let screen_y_start: f32 = -1.0 * scale
            + 2.0 * (scale_center.1 - height as i32 / 2) as f32 * (scale - 1.0) / height as f32;
        for t in tiles.iter() {
            let x = t.idx % width as usize;
            let y = t.idx / width as usize;

            let screen_x = ((step_x * x as f32) + screen_x_start) + offset_x;
            let screen_y = ((step_y * y as f32) + screen_y_start) + offset_y;
            let fg = t.fg;
            let bg = t.bg;
            let glyph = t.glyph;
            let gp = font_scaler.glyph_position(glyph);

            SparseConsoleBackend::push_point(
                &mut self.vao.vertex_buffer,
                screen_x + step_x,
                screen_y + step_y,
                fg,
                bg,
                gp.glyph_right,
                gp.glyph_top,
            );
            SparseConsoleBackend::push_point(
                &mut self.vao.vertex_buffer,
                screen_x + step_x,
                screen_y,
                fg,
                bg,
                gp.glyph_right,
                gp.glyph_bottom,
            );
            SparseConsoleBackend::push_point(
                &mut self.vao.vertex_buffer,
                screen_x,
                screen_y,
                fg,
                bg,
                gp.glyph_left,
                gp.glyph_bottom,
            );
            SparseConsoleBackend::push_point(
                &mut self.vao.vertex_buffer,
                screen_x,
                screen_y + step_y,
                fg,
                bg,
                gp.glyph_left,
                gp.glyph_top,
            );

            self.vao.index_buffer.push(index_count);
            self.vao.index_buffer.push(1 + index_count);
            self.vao.index_buffer.push(3 + index_count);
            self.vao.index_buffer.push(1 + index_count);
            self.vao.index_buffer.push(2 + index_count);
            self.vao.index_buffer.push(3 + index_count);

            index_count += 4;
        }

        self.vao.upload_buffers();
        self.previous_console = Some(tiles.clone());
    }

    pub fn gl_draw(&mut self, font: &Font, shader: &Shader) -> BResult<()> {
        self.vao.draw_elements(shader, font);
        Ok(())
    }
}