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    use std::fmt;
    use std::io::prelude::*;

    use is_terminal::IsTerminal;
    use termcolor::Color::{Cyan, Green, Red, Yellow};
    use termcolor::{self, Color, ColorSpec, StandardStream, WriteColor};

    use crate::util::errors::CargoResult;

    pub enum TtyWidth {
        NoTty,
        Known(usize),
        Guess(usize),
    }

    impl TtyWidth {
        /// Returns the width of the terminal to use for diagnostics (which is
        /// relayed to rustc via `--diagnostic-width`).
        pub fn diagnostic_terminal_width(&self) -> Option<usize> {
            // ALLOWED: For testing cargo itself only.
            #[allow(clippy::disallowed_methods)]
            if let Ok(width) = std::env::var("__CARGO_TEST_TTY_WIDTH_DO_NOT_USE_THIS") {
                return Some(width.parse().unwrap());
            }
            match *self {
                TtyWidth::NoTty | TtyWidth::Guess(_) => None,
                TtyWidth::Known(width) => Some(width),
            }
        }

        /// Returns the width used by progress bars for the tty.
        pub fn progress_max_width(&self) -> Option<usize> {
            match *self {
                TtyWidth::NoTty => None,
                TtyWidth::Known(width) | TtyWidth::Guess(width) => Some(width),
            }
        }
    }

    /// The requested verbosity of output.
    #[derive(Debug, Clone, Copy, PartialEq)]
    pub enum Verbosity {
        Verbose,
        Normal,
        Quiet,
    }

    /// An abstraction around console output that remembers preferences for output
    /// verbosity and color.
    pub struct Shell {
        /// Wrapper around stdout/stderr. This helps with supporting sending
        /// output to a memory buffer which is useful for tests.
        output: ShellOut,
        /// How verbose messages should be.
        verbosity: Verbosity,
        /// Flag that indicates the current line needs to be cleared before
        /// printing. Used when a progress bar is currently displayed.
        needs_clear: bool,
    }

    impl fmt::Debug for Shell {
        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
            match self.output {
                ShellOut::Write(_) => f
                    .debug_struct("Shell")
                    .field("verbosity", &self.verbosity)
                    .finish(),
                ShellOut::Stream { color_choice, .. } => f
                    .debug_struct("Shell")
                    .field("verbosity", &self.verbosity)
                    .field("color_choice", &color_choice)
                    .finish(),
            }
        }
    }

    /// A `Write`able object, either with or without color support
    enum ShellOut {
        /// A plain write object without color support
        Write(Box<dyn Write>),
        /// Color-enabled stdio, with information on whether color should be used
        Stream {
            stdout: StandardStream,
            stderr: StandardStream,
            stderr_tty: bool,
            color_choice: ColorChoice,
        },
    }

    /// Whether messages should use color output
    #[derive(Debug, PartialEq, Clone, Copy)]
    pub enum ColorChoice {
        /// Force color output
        Always,
        /// Force disable color output
        Never,
        /// Intelligently guess whether to use color output
        CargoAuto,
    }

    impl Shell {
        /// Creates a new shell (color choice and verbosity), defaulting to 'auto' color and verbose
        /// output.
        pub fn new() -> Shell {
            let auto_clr = ColorChoice::CargoAuto;
            Shell {
                output: ShellOut::Stream {
                    stdout: StandardStream::stdout(auto_clr.to_termcolor_color_choice(Stream::Stdout)),
                    stderr: StandardStream::stderr(auto_clr.to_termcolor_color_choice(Stream::Stderr)),
                    color_choice: ColorChoice::CargoAuto,
                    stderr_tty: std::io::stderr().is_terminal(),
                },
                verbosity: Verbosity::Verbose,
                needs_clear: false,
            }
        }

        /// Creates a shell from a plain writable object, with no color, and max verbosity.
        pub fn from_write(out: Box<dyn Write>) -> Shell {
            Shell {
                output: ShellOut::Write(out),
                verbosity: Verbosity::Verbose,
                needs_clear: false,
            }
        }

        /// Prints a message, where the status will have `color` color, and can be justified. The
        /// messages follows without color.
        fn print(
            &mut self,
            status: &dyn fmt::Display,
            message: Option<&dyn fmt::Display>,
            color: Color,
            justified: bool,
        ) -> CargoResult<()> {
            match self.verbosity {
                Verbosity::Quiet => Ok(()),
                _ => {
                    if self.needs_clear {
                        self.err_erase_line();
                    }
                    self.output
                        .message_stderr(status, message, color, justified)
                }
            }
        }

        /// Sets whether the next print should clear the current line.
        pub fn set_needs_clear(&mut self, needs_clear: bool) {
            self.needs_clear = needs_clear;
        }

        /// Returns `true` if the `needs_clear` flag is unset.
        pub fn is_cleared(&self) -> bool {
            !self.needs_clear
        }

        /// Returns the width of the terminal in spaces, if any.
        pub fn err_width(&self) -> TtyWidth {
            match self.output {
                ShellOut::Stream {
                    stderr_tty: true, ..
                } => imp::stderr_width(),
                _ => TtyWidth::NoTty,
            }
        }

        /// Returns `true` if stderr is a tty.
        pub fn is_err_tty(&self) -> bool {
            match self.output {
                ShellOut::Stream { stderr_tty, .. } => stderr_tty,
                _ => false,
            }
        }

        /// Gets a reference to the underlying stdout writer.
        pub fn out(&mut self) -> &mut dyn Write {
            if self.needs_clear {
                self.err_erase_line();
            }
            self.output.stdout()
        }

        /// Gets a reference to the underlying stderr writer.
        pub fn err(&mut self) -> &mut dyn Write {
            if self.needs_clear {
                self.err_erase_line();
            }
            self.output.stderr()
        }

        /// Erase from cursor to end of line.
        pub fn err_erase_line(&mut self) {
            if self.err_supports_color() {
                imp::err_erase_line(self);
                self.needs_clear = false;
            }
        }

        /// Shortcut to right-align and color green a status message.
        pub fn status<T, U>(&mut self, status: T, message: U) -> CargoResult<()>
        where
            T: fmt::Display,
            U: fmt::Display,
        {
            self.print(&status, Some(&message), Green, true)
        }

        pub fn status_header<T>(&mut self, status: T) -> CargoResult<()>
        where
            T: fmt::Display,
        {
            self.print(&status, None, Cyan, true)
        }

        /// Shortcut to right-align a status message.
        pub fn status_with_color<T, U>(
            &mut self,
            status: T,
            message: U,
            color: Color,
        ) -> CargoResult<()>
        where
            T: fmt::Display,
            U: fmt::Display,
        {
            self.print(&status, Some(&message), color, true)
        }

        /// Runs the callback only if we are in verbose mode.
        pub fn verbose<F>(&mut self, mut callback: F) -> CargoResult<()>
        where
            F: FnMut(&mut Shell) -> CargoResult<()>,
        {
            match self.verbosity {
                Verbosity::Verbose => callback(self),
                _ => Ok(()),
            }
        }

        /// Runs the callback if we are not in verbose mode.
        pub fn concise<F>(&mut self, mut callback: F) -> CargoResult<()>
        where
            F: FnMut(&mut Shell) -> CargoResult<()>,
        {
            match self.verbosity {
                Verbosity::Verbose => Ok(()),
                _ => callback(self),
            }
        }

        /// Prints a red 'error' message.
        pub fn error<T: fmt::Display>(&mut self, message: T) -> CargoResult<()> {
            if self.needs_clear {
                self.err_erase_line();
            }
            self.output
                .message_stderr(&"error", Some(&message), Red, false)
        }

        /// Prints an amber 'warning' message.
        pub fn warn<T: fmt::Display>(&mut self, message: T) -> CargoResult<()> {
            match self.verbosity {
                Verbosity::Quiet => Ok(()),
                _ => self.print(&"warning", Some(&message), Yellow, false),
            }
        }

        /// Prints a cyan 'note' message.
        pub fn note<T: fmt::Display>(&mut self, message: T) -> CargoResult<()> {
            self.print(&"note", Some(&message), Cyan, false)
        }

        /// Updates the verbosity of the shell.
        pub fn set_verbosity(&mut self, verbosity: Verbosity) {
            self.verbosity = verbosity;
        }

        /// Gets the verbosity of the shell.
        pub fn verbosity(&self) -> Verbosity {
            self.verbosity
        }

        /// Updates the color choice (always, never, or auto) from a string..
        pub fn set_color_choice(&mut self, color: Option<&str>) -> CargoResult<()> {
            if let ShellOut::Stream {
                ref mut stdout,
                ref mut stderr,
                ref mut color_choice,
                ..
            } = self.output
            {
                let cfg = match color {
                    Some("always") => ColorChoice::Always,
                    Some("never") => ColorChoice::Never,

                    Some("auto") | None => ColorChoice::CargoAuto,

                    Some(arg) => anyhow::bail!(
                        "argument for --color must be auto, always, or \
                         never, but found `{}`",
                        arg
                    ),
                };
                *color_choice = cfg;
                *stdout = StandardStream::stdout(cfg.to_termcolor_color_choice(Stream::Stdout));
                *stderr = StandardStream::stderr(cfg.to_termcolor_color_choice(Stream::Stderr));
            }
            Ok(())
        }

        /// Gets the current color choice.
        ///
        /// If we are not using a color stream, this will always return `Never`, even if the color
        /// choice has been set to something else.
        pub fn color_choice(&self) -> ColorChoice {
            match self.output {
                ShellOut::Stream { color_choice, .. } => color_choice,
                ShellOut::Write(_) => ColorChoice::Never,
            }
        }

        /// Whether the shell supports color.
        pub fn err_supports_color(&self) -> bool {
            match &self.output {
                ShellOut::Write(_) => false,
                ShellOut::Stream { stderr, .. } => stderr.supports_color(),
            }
        }

        pub fn out_supports_color(&self) -> bool {
            match &self.output {
                ShellOut::Write(_) => false,
                ShellOut::Stream { stdout, .. } => stdout.supports_color(),
            }
        }

        /// Write a styled fragment
        ///
        /// Caller is responsible for deciding whether [`Shell::verbosity`] is affects output.
        pub fn write_stdout(
            &mut self,
            fragment: impl fmt::Display,
            color: &ColorSpec,
        ) -> CargoResult<()> {
            self.output.write_stdout(fragment, color)
        }

        /// Write a styled fragment
        ///
        /// Caller is responsible for deciding whether [`Shell::verbosity`] is affects output.
        pub fn write_stderr(
            &mut self,
            fragment: impl fmt::Display,
            color: &ColorSpec,
        ) -> CargoResult<()> {
            self.output.write_stderr(fragment, color)
        }

        /// Prints a message to stderr and translates ANSI escape code into console colors.
        pub fn print_ansi_stderr(&mut self, message: &[u8]) -> CargoResult<()> {
            if self.needs_clear {
                self.err_erase_line();
            }
            #[cfg(windows)]
            {
                if let ShellOut::Stream { stderr, .. } = &mut self.output {
                    ::fwdansi::write_ansi(stderr, message)?;
                    return Ok(());
                }
            }
            self.err().write_all(message)?;
            Ok(())
        }

        /// Prints a message to stdout and translates ANSI escape code into console colors.
        pub fn print_ansi_stdout(&mut self, message: &[u8]) -> CargoResult<()> {
            if self.needs_clear {
                self.err_erase_line();
            }
            #[cfg(windows)]
            {
                if let ShellOut::Stream { stdout, .. } = &mut self.output {
                    ::fwdansi::write_ansi(stdout, message)?;
                    return Ok(());
                }
            }
            self.out().write_all(message)?;
            Ok(())
        }

        pub fn print_json<T: serde::ser::Serialize>(&mut self, obj: &T) -> CargoResult<()> {
            // Path may fail to serialize to JSON ...
            let encoded = serde_json::to_string(&obj)?;
            // ... but don't fail due to a closed pipe.
            drop(writeln!(self.out(), "{}", encoded));
            Ok(())
        }
    }

    impl Default for Shell {
        fn default() -> Self {
            Self::new()
        }
    }

    impl ShellOut {
        /// Prints out a message with a status. The status comes first, and is bold plus the given
        /// color. The status can be justified, in which case the max width that will right align is
        /// 12 chars.
        fn message_stderr(
            &mut self,
            status: &dyn fmt::Display,
            message: Option<&dyn fmt::Display>,
            color: Color,
            justified: bool,
        ) -> CargoResult<()> {
            match *self {
                ShellOut::Stream { ref mut stderr, .. } => {
                    stderr.reset()?;
                    stderr.set_color(ColorSpec::new().set_bold(true).set_fg(Some(color)))?;
                    if justified {
                        write!(stderr, "{:>12}", status)?;
                    } else {
                        write!(stderr, "{}", status)?;
                        stderr.set_color(ColorSpec::new().set_bold(true))?;
                        write!(stderr, ":")?;
                    }
                    stderr.reset()?;
                    match message {
                        Some(message) => writeln!(stderr, " {}", message)?,
                        None => write!(stderr, " ")?,
                    }
                }
                ShellOut::Write(ref mut w) => {
                    if justified {
                        write!(w, "{:>12}", status)?;
                    } else {
                        write!(w, "{}:", status)?;
                    }
                    match message {
                        Some(message) => writeln!(w, " {}", message)?,
                        None => write!(w, " ")?,
                    }
                }
            }
            Ok(())
        }

        /// Write a styled fragment
        fn write_stdout(&mut self, fragment: impl fmt::Display, color: &ColorSpec) -> CargoResult<()> {
            match *self {
                ShellOut::Stream { ref mut stdout, .. } => {
                    stdout.reset()?;
                    stdout.set_color(&color)?;
                    write!(stdout, "{}", fragment)?;
                    stdout.reset()?;
                }
                ShellOut::Write(ref mut w) => {
                    write!(w, "{}", fragment)?;
                }
            }
            Ok(())
        }

        /// Write a styled fragment
        fn write_stderr(&mut self, fragment: impl fmt::Display, color: &ColorSpec) -> CargoResult<()> {
            match *self {
                ShellOut::Stream { ref mut stderr, .. } => {
                    stderr.reset()?;
                    stderr.set_color(&color)?;
                    write!(stderr, "{}", fragment)?;
                    stderr.reset()?;
                }
                ShellOut::Write(ref mut w) => {
                    write!(w, "{}", fragment)?;
                }
            }
            Ok(())
        }

        /// Gets stdout as a `io::Write`.
        fn stdout(&mut self) -> &mut dyn Write {
            match *self {
                ShellOut::Stream { ref mut stdout, .. } => stdout,
                ShellOut::Write(ref mut w) => w,
            }
        }

        /// Gets stderr as a `io::Write`.
        fn stderr(&mut self) -> &mut dyn Write {
            match *self {
                ShellOut::Stream { ref mut stderr, .. } => stderr,
                ShellOut::Write(ref mut w) => w,
            }
        }
    }

    impl ColorChoice {
        /// Converts our color choice to termcolor's version.
        fn to_termcolor_color_choice(self, stream: Stream) -> termcolor::ColorChoice {
            match self {
                ColorChoice::Always => termcolor::ColorChoice::Always,
                ColorChoice::Never => termcolor::ColorChoice::Never,
                ColorChoice::CargoAuto => {
                    if stream.is_terminal() {
                        termcolor::ColorChoice::Auto
                    } else {
                        termcolor::ColorChoice::Never
                    }
                }
            }
        }
    }

    enum Stream {
        Stdout,
        Stderr,
    }

    impl Stream {
        fn is_terminal(self) -> bool {
            match self {
                Self::Stdout => std::io::stdout().is_terminal(),
                Self::Stderr => std::io::stderr().is_terminal(),
            }
        }
    }

    #[cfg(unix)]
    mod imp {
        use super::{Shell, TtyWidth};
        use std::mem;

        pub fn stderr_width() -> TtyWidth {
            unsafe {
                let mut winsize: libc::winsize = mem::zeroed();
                // The .into() here is needed for FreeBSD which defines TIOCGWINSZ
                // as c_uint but ioctl wants c_ulong.
                if libc::ioctl(libc::STDERR_FILENO, libc::TIOCGWINSZ.into(), &mut winsize) < 0 {
                    return TtyWidth::NoTty;
                }
                if winsize.ws_col > 0 {
                    TtyWidth::Known(winsize.ws_col as usize)
                } else {
                    TtyWidth::NoTty
                }
            }
        }

        pub fn err_erase_line(shell: &mut Shell) {
            // This is the "EL - Erase in Line" sequence. It clears from the cursor
            // to the end of line.
            // https://en.wikipedia.org/wiki/ANSI_escape_code#CSI_sequences
            let _ = shell.output.stderr().write_all(b"\x1B[K");
        }
    }

    #[cfg(windows)]
    mod imp {
        use std::{cmp, mem, ptr};

        use windows_sys::core::PCSTR;
        use windows_sys::Win32::Foundation::CloseHandle;
        use windows_sys::Win32::Foundation::INVALID_HANDLE_VALUE;
        use windows_sys::Win32::Foundation::{GENERIC_READ, GENERIC_WRITE};
        use windows_sys::Win32::Storage::FileSystem::{
            CreateFileA, FILE_SHARE_READ, FILE_SHARE_WRITE, OPEN_EXISTING,
        };
        use windows_sys::Win32::System::Console::{
            GetConsoleScreenBufferInfo, GetStdHandle, CONSOLE_SCREEN_BUFFER_INFO, STD_ERROR_HANDLE,
        };

        pub(super) use super::{default_err_erase_line as err_erase_line, TtyWidth};

        pub fn stderr_width() -> TtyWidth {
            unsafe {
                let stdout = GetStdHandle(STD_ERROR_HANDLE);
                let mut csbi: CONSOLE_SCREEN_BUFFER_INFO = mem::zeroed();
                if GetConsoleScreenBufferInfo(stdout, &mut csbi) != 0 {
                    return TtyWidth::Known((csbi.srWindow.Right - csbi.srWindow.Left) as usize);
                }

                // On mintty/msys/cygwin based terminals, the above fails with
                // INVALID_HANDLE_VALUE. Use an alternate method which works
                // in that case as well.
                let h = CreateFileA(
                    "CONOUT$\0".as_ptr() as PCSTR,
                    GENERIC_READ | GENERIC_WRITE,
                    FILE_SHARE_READ | FILE_SHARE_WRITE,
                    ptr::null_mut(),
                    OPEN_EXISTING,
                    0,
                    0,
                );
                if h == INVALID_HANDLE_VALUE {
                    return TtyWidth::NoTty;
                }

                let mut csbi: CONSOLE_SCREEN_BUFFER_INFO = mem::zeroed();
                let rc = GetConsoleScreenBufferInfo(h, &mut csbi);
                CloseHandle(h);
                if rc != 0 {
                    let width = (csbi.srWindow.Right - csbi.srWindow.Left) as usize;
                    // Unfortunately cygwin/mintty does not set the size of the
                    // backing console to match the actual window size. This
                    // always reports a size of 80 or 120 (not sure what
                    // determines that). Use a conservative max of 60 which should
                    // work in most circumstances. ConEmu does some magic to
                    // resize the console correctly, but there's no reasonable way
                    // to detect which kind of terminal we are running in, or if
                    // GetConsoleScreenBufferInfo returns accurate information.
                    return TtyWidth::Guess(cmp::min(60, width));
                }

                TtyWidth::NoTty
            }
        }
    }

    #[cfg(windows)]
    fn default_err_erase_line(shell: &mut Shell) {
        match imp::stderr_width() {
            TtyWidth::Known(max_width) | TtyWidth::Guess(max_width) => {
                let blank = " ".repeat(max_width);
                drop(write!(shell.output.stderr(), "{}\r", blank));
            }
            _ => (),
        }
    }