simplicitty/project.md

Module Breakdown and Responsibilities

1. src/pty.rs (The Shell Interface)

Responsibilities:

• Use portable-pty to create a new PTY.
• Spawn a default shell process (e.g., bash) connected to the PTY.
• Provide a way to write user input (from winit) to the PTY.
• Provide a way to read shell output from the PTY.

Key Implementation Detail: Reading from the PTY is a blocking operation. You should do this on a separate thread. This thread will read data and send it back to the main UI thread using a channel (like crossbeam-channel). This prevents the UI from freezing while waiting for the shell to output something.

2. src/terminal.rs (The Brains / State Model)

Responsibilities:

• Hold the state of the terminal grid: a 2D array of cells, where each cell contains a character, foreground color, background color, and style flags (bold, italic, etc.).

• Contain a vte::Parser.

• Implement the vte::Perform trait. This is the core of this module. The vte parser will call methods on your implementation as it processes the byte stream from the PTY. For example:

  • print(char): You update the character at the current cursor position in your grid and advance the cursor.
  • execute(byte): You handle control characters like newline (\n) or backspace (\b).
  • csi_dispatch(...): You handle complex ANSI escape sequences for changing colors, moving the cursor, clearing the screen, etc.

• Keep track of the cursor's position and the current color/style settings.

3. src/renderer.rs (The Painter)

Responsibilities:

• Initialize wgpu: get an adapter and device, configure a surface on the winit window.
• Initialize glyphon: create a FontSystem, Cache, Atlas, and TextRenderer.
• Contain the main render() function. This function will be called on every frame.
• Inside render():
  • Get the current terminal state.
  • Iterate through the terminal grid.
  • For each line of text, create a glyphon::Buffer. Set its text content, colors, and styles based on the data in your grid.
  • Use the glyphon::TextRenderer to prepare and draw all the buffers to the wgpu surface.
  • Draw the cursor as a solid block or underline.

4. src/main.rs (The Conductor)

Responsibilities:

• The main function.
• Initialize logging (env_logger).
• Create the winit event loop and window.
• Initialize your Pty, Terminal, and Renderer modules.
• Start the PTY reader thread.
• Run the main event loop.

The Main Event Loop (winit::event_loop::run)

This is where everything comes together. You'll have a match statement to handle different events:

• Event::WindowEvent::Resized: Tell the renderer about the new size. You'll also need to inform the PTY of the new dimensions so that applications running in the shell (like vim) can reflow correctly.
• Event::WindowEvent::KeyboardInput: Translate the keyboard event into characters or escape sequences and write them to the pty module.
• Event::UserEvent: This is how your PTY thread will communicate with the main thread. When the PTY thread reads new data, it sends it through the channel, and you receive it here. You then feed this data into the terminal.vte_parser.
• Event::WindowEvent::RedrawRequested: This is the signal to render a new frame. You call your renderer.render() function here. After processing PTY data, you should always request a redraw.
• Event::WindowEvent::CloseRequested: Terminate the application.