pulse-trader/pulse-ui/src/render.rs

use std::{fmt::Display, io::stdout};

use crate::{
    layout::Allocation,
    unit::{Point, Rect},
    widget::Widget,
};

pub enum Instr {
    DrawText(Point, String),
}

pub struct RenderScope {
    pub rect: Rect,
    draw_instructions: Vec<Instr>,
}

struct RenderTextResult {
    text: String,
    line_len: u16,
    lines_len: u16,
}

impl RenderTextResult {
    fn insert_newline(&mut self, height: u16) -> bool {
        if self.lines_len >= height {
            return true;
        }

        self.text.push('\n');
        self.line_len = 0;
        self.lines_len += 1;

        false
    }

    fn insert(&mut self, c: char) {
        self.text.push(c);
        self.line_len += 1;
    }
}

impl RenderScope {
    pub fn draw_text<P: Into<Point>, T: Display>(&mut self, at: P, text: T) -> u16 {
        if self.rect.width == 0 || self.rect.height == 0 {
            return 0;
        }

        let point: Point = at.into();

        let text = text.to_string();

        let mut chars = text.chars().peekable();

        let mut result = RenderTextResult {
            text: String::new(),
            line_len: 0,
            lines_len: 1,
        };

        while let Some(c) = chars.next() {
            if c == '\x1b' && chars.peek() == Some(&'[') {
                result.text.push(c);

                while let Some(c) = chars.next() {
                    result.text.push(c);

                    if c.is_ascii_alphabetic() {
                        break;
                    }
                }
            } else if c == '\n' {
                if result.insert_newline(self.rect.height) {
                    break;
                }
            } else {
                result.insert(c);

                if result.line_len >= self.rect.width {
                    if result.insert_newline(self.rect.height) {
                        break;
                    }
                }
            }
        }

        self.draw_instructions
            .push(Instr::DrawText(point, result.text));

        result.lines_len
    }
}

impl RenderScope {
    pub fn new(rect: Rect) -> Self {
        Self {
            rect,
            draw_instructions: Vec::new(),
        }
    }
}

impl From<(u16, u16)> for Point {
    fn from(value: (u16, u16)) -> Self {
        Self {
            x: value.0,
            y: value.1,
        }
    }
}

impl From<u16> for Point {
    fn from(value: u16) -> Self {
        Self { x: value, y: value }
    }
}

impl From<Rect> for Point {
    fn from(value: Rect) -> Self {
        Self {
            x: value.x,
            y: value.y,
        }
    }
}

impl Allocation {
    pub fn draw<W: Widget>(&self, index: usize, widget: W) {
        let mut scope = RenderScope::new(self.widgets[index]);
        widget.render(&mut scope);
        scope.draw();
    }

    pub fn draw_frame<W: Widget>(&self, index: usize, widget: W) {
        let mut scope = RenderScope::new(self.frame[index]);
        widget.render(&mut scope);
        scope.draw();
    }
}

impl RenderScope {
    pub fn draw(self) {
        for inst in self.draw_instructions {
            match inst {
                Instr::DrawText(point, text) => {
                    for (i, line) in text.lines().enumerate() {
                        if i as u16 + point.y >= self.rect.height {
                            continue;
                        }

                        print_at(
                            self.rect.x + point.x,
                            self.rect.y + point.y + i as u16,
                            line,
                        );
                    }
                }
            }
        }
    }
}

pub fn print_at(x: u16, y: u16, text: &str) {
    crossterm::execute!(stdout(), crossterm::cursor::MoveTo(x, y)).unwrap();
    print!("{text}");
}