clyde/src/output.rs

use crate::{error::Error, log::*};
use anyhow::{Context, Result};
use std::io::{self, Write};
use windows::Win32::{
    Foundation::{CloseHandle, HANDLE},
    System::Console,
};

#[allow(dead_code)]
fn log_output_mode(mode: Console::CONSOLE_MODE) {
    // Characters written by the WriteFile or WriteConsole function or echoed by the ReadFile or
    // ReadConsole function are parsed for ASCII control sequences, and the correct action is
    // performed. Backspace, tab, bell, carriage return, and line feed characters are processed. It
    // should be enabled when using control sequences or when ENABLE_VIRTUAL_TERMINAL_PROCESSING is
    // set.
    if (mode & Console::ENABLE_PROCESSED_OUTPUT).0 > 0 {
        debug!("Processed Output:    Enabled");
    } else {
        debug!("Processed Output:    Disabled");
    }

    // When writing with WriteFile or WriteConsole or echoing with ReadFile or ReadConsole, the
    // cursor moves to the beginning of the next row when it reaches the end of the current row.
    // This causes the rows displayed in the console window to scroll up automatically when the
    // cursor advances beyond the last row in the window. It also causes the contents of the
    // console screen buffer to scroll up (../discarding the top row of the console screen buffer)
    // when the cursor advances beyond the last row in the console screen buffer. If this mode is
    // disabled, the last character in the row is overwritten with any subsequent characters.
    if (mode & Console::ENABLE_WRAP_AT_EOL_OUTPUT).0 > 0 {
        debug!("Wrap at EOL:         Enabled");
    } else {
        debug!("Wrap at EOL:         Disabled");
    }

    // When writing with WriteFile or WriteConsole, characters are parsed for VT100 and similar
    // control character sequences that control cursor movement, color/font mode, and other
    // operations that can also be performed via the existing Console APIs. For more information,
    // see Console Virtual Terminal Sequences.
    //
    // Ensure ENABLE_PROCESSED_OUTPUT is set when using this flag.
    if (mode & Console::ENABLE_VIRTUAL_TERMINAL_PROCESSING).0 > 0 {
        debug!("Terminal Processing: Enabled");
    } else {
        debug!("Terminal Processing: Disabled");
    }

    // When writing with WriteFile or WriteConsole, this adds an additional state to end-of-line
    // wrapping that can delay the cursor move and buffer scroll operations.
    //
    // Normally when ENABLE_WRAP_AT_EOL_OUTPUT is set and text reaches the end of the line, the
    // cursor will immediately move to the next line and the contents of the buffer will scroll up
    // by one line. In contrast with this flag set, the cursor does not move to the next line, and
    // the scroll operation is not performed. The written character will be printed in the final
    // position on the line and the cursor will remain above this character as if
    // ENABLE_WRAP_AT_EOL_OUTPUT was off, but the next printable character will be printed as if
    // ENABLE_WRAP_AT_EOL_OUTPUT is on. No overwrite will occur. Specifically, the cursor quickly
    // advances down to the following line, a scroll is performed if necessary, the character is
    // printed, and the cursor advances one more position.
    //
    // The typical usage of this flag is intended in conjunction with setting
    // ENABLE_VIRTUAL_TERMINAL_PROCESSING to better emulate a terminal emulator where writing the
    // final character on the screen (../in the bottom right corner) without triggering an
    // immediate scroll is the desired behavior.
    if (mode & Console::DISABLE_NEWLINE_AUTO_RETURN).0 > 0 {
        debug!("Newline Auto Return: Enabled");
    } else {
        debug!("Newline Auto Return: Disabled");
    }

    // The APIs for writing character attributes including WriteConsoleOutput and
    // WriteConsoleOutputAttribute allow the usage of flags from character attributes to adjust the
    // color of the foreground and background of text. Additionally, a range of DBCS flags was
    // specified with the COMMON_LVB prefix. Historically, these flags only functioned in DBCS code
    // pages for Chinese, Japanese, and Korean languages.
    //
    // With exception of the leading byte and trailing byte flags, the remaining flags describing
    // line drawing and reverse video (../swap foreground and background colors) can be useful for
    // other languages to emphasize portions of output.
    //
    // Setting this console mode flag will allow these attributes to be used in every code page on
    // every language.
    //
    // It is off by default to maintain compatibility with known applications that have
    // historically taken advantage of the console ignoring these flags on non-CJK machines to
    // store bits in these fields for their own purposes or by accident.
    //
    // Note that using the ENABLE_VIRTUAL_TERMINAL_PROCESSING mode can result in LVB grid and
    // reverse video flags being set while this flag is still off if the attached application
    // requests underlining or inverse video via Console Virtual Terminal Sequences.
    if (mode & Console::ENABLE_LVB_GRID_WORLDWIDE).0 > 0 {
        debug!("LVB Grid:            Enabled");
    } else {
        debug!("LVB Grid:            Disabled");
    }
}

pub struct Writer {
    output: HANDLE,
}

impl Writer {
    pub fn stdout() -> Result<Self> {
        unsafe {
            let handle = Console::GetStdHandle(Console::STD_OUTPUT_HANDLE)
                .context("unable to get stdout handle")?;
            let mut stdout = Self{output: handle};
            stdout.reset()?;
            Ok(stdout)
        }
    }

    pub fn close(&mut self) -> Result<()> {
        unsafe {
            CloseHandle(self.output);
        }
        Ok(())
    }

    pub fn reset(&mut self) -> Result<()> {
        unsafe {
            Console::SetConsoleOutputCP(65001);
        }
        Ok(())
    }

    pub fn newline(&mut self) -> Result<()> {
        self.write(b"\r\n")?;
        Ok(())
    }

    pub fn back(&mut self, n: usize) -> Result<()> {
        if n > 0 {
            let text = format!("\x1b[{}D", n);
            self.write(text.as_bytes())?;
        }
        Ok(())
    }

    pub fn forward(&mut self, n: usize) -> Result<()> {
        let text = format!("\x1b[{}C", n);
        self.write(text.as_bytes())?;
        Ok(())
    }

    pub fn clear(&mut self) -> Result<()> {
        self.write(b"\x1b[2J\x1b[0;0H")?;
        Ok(())
    }

    // pub fn hide_cursor(&mut self) -> Result<()> {
    //     self.write(b"\x1b[?25l")?;
    //     Ok(())
    // }
}

impl Write for Writer {
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        unsafe {
            Error::check(Console::WriteConsoleA(self.output, buf, None, None))?;
        }
        Ok(0)
    }

    fn flush(&mut self) -> io::Result<()> {
        Ok(())
    }
}